More Details on Number Needed to Treat

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Definition

The NNT is the number of patients who need to be treated in order to prevent one additional bad outcome. It is the inverse of the Absolute Risk Reduction (ARR).

How to Calculate NNTs

NNT = 1/ARR
ARR = |CER - EER|

where

CER = control group event rate
EER = experimental group event rate

Sample Calculation

The results of the Diabetes Control and Complications Trial (Ann Intern Med 1995; 122:561-8) into the effect of intensive diabetes therapy on the development and progression of neuropathy indicated that neuropathy occurred in 9.6% of patients randomised to usual care and 2.8% of patients randomised to intensive therapy. The number of patients we need to treat with the intensive diabetes therapy to prevent one additional occurrence of neuropathy can be determined by calculating the absolute risk reduction as follows:

ARR = |CER - EER| = |9.6% - 2.8%| = 6.8%
NNT = 1/ARR = 1/6.8% = 14.7 or 15

We therefore need to treat 15 diabetic patients with intensive therapy to prevent one from developing neuropathy.

Practice Calculation

In a randomised controlled trial (Stroke 1997; 28:1861-6) looking into the long-term outcome for stroke patients treated in stroke units (SU) compared with patients treated in general wards (GW), the mortality rate 5 years after the onset of stroke was 59.1% in the patients treated in SU and 70.9% in those treated in the GW. How many patients need to be treated in stroke units to prevent one additional death?

NNT = _______

See our answer and compare

ARR = |CER - EER| = |0.709 - 0.591| = 0.118
NNT = 1/ARR = 1/0.118 = 9

Nine patients would need to be treated in stroke units to prevent one additional death.

Examples

Criteria for Inclusion of Examples

(Modified from criteria used by ACP Journal Club)
  1. Random allocation of participants to comparison groups.
  2. ≥ 80% follow-up of people enrolled.
  3. Outcome of clinical significance.

Disciplines

Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Acute myocardial infarction1 Angiotensin-converting enzyme (ACE) inhibitors vs. placebo Mortality 30 days 7.6 7.1 210 (125 to 662)
Acute myocardial infarction2 Angiotensin-converting enzyme (ACE) inhibitors vs. placebo Nonfatal heart failure 30 days 15.2 14.6 165 (111 to 488)
Cardiology Chronic heart failure (CHF)3 b-blockers vs. placebo Hospitalisation for CHF 7 months 17 13 24 (16 to 51)
Cardiology Chronic heart failure (CHF)4 b-blockers vs. placebo All-cause mortality 7 months 12 9 40 (24 to 149)
Congestive heart failure5 Spironolactone vs. placebo Mortality 24 months 46 35 9 (7 to 16)
Non-Q-wave coronary events (unstable angina or non-Q-wave MI)6 Enoxaparin vs. unfractionated heparin Composite end point of death, MI or recurrent angina 14 days 19.7 16.6 31 (17 to 191)
Coronary events in healthy persons with low HDL cholesterol levels7 Lovastatin vs. placebo First acute major coronary events and adverse events 5.2 years 6 4 50 (33 to 97)
Cardiovascular events in treated hypertension8 Aspirin vs. placebo Major cardiovascular events 3.8 years 3.9 3.4 176 (90 to 3115)
Myocardial infarction (MI) 1.4 0.9 208 (127 to 551)
Myocardial infarction and average cholesterol levels in older patients9 Pravastatin vs. placebo Major coronary events 5 years 28.1 19.7 11 (8 to 24)
Stroke 7.3 4.5 34 (22 to 333)
Death from coronary artery disease 10.3 5.8 22 (15 to 53)
Coronary artery bypass grafting 11.0 6.6 21 (15 to 56)
Chronic heart failure (CHF)10 Exercise vs. no exercise Death 3.4 years 40.8 18 5 (3 to 21)
All cardiac events 75.5 34 3 (2 to 5)
Hospitalization for CHF 28.6 10 6 (3 to 32)
Severe vasovagal syncope; patients with ≥6 syncopal episodes and a positive tilt-table test result with syncope or presyncope and relative bradycardia11 Pacemaker vs. usual care First recurrence of syncope 2 years 70.4 22.2 3 (1 to 5)
Congestive heart failure12 Home-based intervention vs. usual care Proportion of patients with the combined end point of unplanned readmission or out-of-hospital death 18 months 81.3 67.3 Not significant
Out-of-hospital death 18.8 4.1 7 (3 to 44)
Coronary Heart Disease13 Patients invited to attend nurse led secondary prevention clinics vs. Patients who received regular care Presence, frequency and course of chest pain 12 months 11 7 24 (16 to 170)
Hospital admissions 28 20 13 (9 to 35)
Adults at high risk for cardiovascular events14 Ramipril vs. placebo Myocardial Infarction, stroke and cardiovascular mortality 4 years 18 14 26 (19 to 43)
Patients surviving Myocardial Infarction who had contraindications to b-blockers15 Amiodarone vs. placebo Cardiac mortality 1 year 11 6 23 (12 to 1323)
Arrhythmias 19 8 9 (6 to 16)
Recent-onset atrial fibrillation in patients with or without heart disease16 Oral propafenone vs. placebo Rates of conversion to sinus rhythm at 3 and 8 hours 8 hours 3 hrs: 18 3 hrs: 24 3 hrs: 4 (3 to 6)
8 hrs: 37 8 hrs: 76 8 hrs: 3 (2 to 4)
Patients resuscitated from ventricular arrhythmias; use of implantable cardioverter-defibrillators (ICD) in reducing mortality17 ICD vs. antiarrhythmic drug therapy All-cause mortality 18 months 24 16 13 (8 to 30)
Myocardial infarction with cardiogenic shock18 Immediate revascularization (angioplasty or bypass surgery to be done as soon as possible and within 6 hours of randomization) vs. medical stabilization (intraaortic balloon counterpulsation and thrombolytic therapy with delayed revascularization – minimum 54 hours after randomization) All-cause mortality 6 months 63 50 8 (5 to 66)
Coronary artery disease (CAD) and low levels of high density lipoprotein cholesterol19 Gemfibrozil vs. placebo Nonfatal myocardial infarction or CAD death 5 years 21.7 17.3 23 (13 to 74)
Stroke 6.9 5.1 56 (27 to 725)
Acute myocardial infraction (MI)20 Aspirin and heparin plus angioplasty vs. aspirin and heparin plus streptokinase (control) All-cause mortality 5 years 24 13 10 (6 to 35)
Cardiac mortality 20 7 8 (5 to 15)
Death and nonfatal MI 22 6 6 (4 to 11)
Unstable coronary artery disease21 Dalteparin vs. placebo Death, MI or both at 1 month 6 months 5.8 3.1 37 (23 to 102)
Death, MI or need for revascularization at 3 months 33 29 27 (13 to 208)
Unstable coronary artery disease22 Invasive strategy vs. noninvasive strategy Death, MI or both 6 months 12 9 37 (20 to 398)
Medically refractory angina23 Transmyocardial revascularization (TMR - consisted of a limited muscle-sparingleft thoracotomy and the creation of transmyocardial laser channels) and continued medication vs. continued medication alone Reduction of ≥ 2 angina cases 12 months 11 61 2 (2 to 3)
Congestive heart failure (CHF)24 Usual CHF medicine plus low dose of lisinopril (2.5 or 5.0 mg/d-control) vs. usual CHF medicine plus high dose of lisinopril (30 mg/d) Mortality plus hospitalization 3 years 83.8 79.7 26 (16 to 82)
Mortality plus cardiovascular (CV) hospitalization 74.1 71.1 34 (17 to 264)
Mortality Plus CHF hospitalization 60.4 55.1 17 (12 to 37)
CV mortality plus CV hospitalization 72.7 69.4 30 (16 to 281)
Recent-onset atrial fibrillation25 Oral amiodarone vs. placebo Rates of conversion to sinus rhythm (verified by Holter monitoring) 24 hours 35 87 2 (1 to 4)
Chronic heart failure26 Metroprolol vs. placebo All-cause death or hospital admission 1 year 38 32 17 (12 to 32)
Hospitalization for worsening heart failure 15 10 22 (15 to 39)
Atrial fibrillation (AF)27 Amiodarone (10 mg/kg of body weight) vs. sotalol or propafenone (control) Time to first recurrence of AF confirmed on ECG 468 days 63 35 4 (3 to 6)
Balloon angioplasty28 Routine stent implantation vs. optimal balloon angioplasty with provisional stent Composite end point 6 months 14.9 6.1 11 (7 to 30)
Target vessel Revascularization or surgery 10.1 3.9 16 (9 to 62)
Revascularization or surgery 12.9 5.2 13 (8 to 309)
Unstable coronary artery disease29 Invasive strategy (immediate angioplasty and revascularization) vs. non-invasive strategy Death or myocardial infraction (MI) 1 year 14 10 27 (16 to 92)
Death 3.9 2.2 60 (32 to 306)
Readmission 57 37 5 (4 to 6)
Cardiac intervention after discharge 31 8 5 (4 to 5)
Acute myocardial infarction30 Coronary stenting plus abciximab vs. intravenous alteplase (control) Composite of death, reinfarction or stroke 6 months 23 9 7 (5 to 36)
Angina and percutaneous transluminal coronary angioplasty31 Coumarin and aspirin vs. aspirin alone Composite end point of death, myocardial infarction, target-lesion revascularization and stoke at 30 days 1 year 6.4 3.4 33 (17 to 222)
Composite at 1 year 20 14 17 (10 to 73)
Atrial fibrillation (AF)32 Amiodarone vs. placebo Rates and time to AF or intolerable adverse effects 22 months 88 48 3 (2 to 4)
Sotalol vs. placebo Rates and time to AF or intolerable adverse effects 88 77 Not significant
Patients with cardiovascular disease (CVD) receiving long-term hemodialysis33 Vitamin E vs. placebo CDV events 512 days 34 19 6 (4 to 29)
Myocardial infraction 18 8 10 (5 to 230)
CAD and hypertension34 Acarbose vs placebo Major CV events 3.3 years 4.7 2.2 44 (30 to 436)
Myocardial infaraction35 Warfarin + aspirin, warfarin vs aspirin Composite outcomes 1445 days 15% vs 20%, 17% vs 20% 20 (12 to 51), 30 (16 to 483)
Atrial fibrillation36 Anterior-posterior versus anterior-lateral electrode position Successful cardioversion 24 hours 78 96 6 (4 to 19)
chronic heart failure37 Candesartan 4 or 8 mg vs placebo All-cause mortality 37.7 months 25 23 46 (26 to 463)
acute myocardial infarction38 Coronary angioplasty vs fibrinolytic therapy Composite endpoint 30 day 13.7 8.0 18 (12 to 38)
CAD39 Perindopril vs placebo Large MI or death 4.2 years 9.9 8.0 54 (35 to 115)

References

  1. Circulation 1998; 97:2202-12 
  2. Circulation 1998; 98:1184-91 
  3. N Engl J Med 1999 Sep 2;341(10):709-17 
  4. N Engl J Med 1997 Aug 14;337(7):447-52 
  5. JAMA 1998 May 27;279(20):1615-22 
  6. Lancet 1998 Jun 13;351(9118):1755-62 
  7. Ann Intern Med 1998 Nov 1;129(9):681-9 
  8. Circulation 1999 Mar 9;99(9):1173-82 
  9. J Am Coll Cardiol 1999 Jan;33(1):16-20 
  10. Arch Intern Med 1999 Feb 8;159(3):257-61 
  11. BMJ. 9 May 1998; 316: 1434-7 
  12. N Engl J Med. 20 Jan 2000; 342: 145-53 
  13. J Am Coll Cardiol. 1 Nov 1992; 20: 1056-62 
  14. Ann Intern Med. 15 Apr 1997; 126: 621-5 
  15. N Engl J Med. 27 Nov 1997; 337: 1576-83 
  16. N Engl J Med. 27 Nov 1997; 337: 1576-83 
  17. N Engl J Med. 27 Nov 1997; 337: 1576-83 
  18. N Engl J Med. Aug 26, 1999; 341: 625-34 
  19. N Engl J Med. Aug 5, 1999; 341: 410-8 
  20. N Engl J Med. Nov 4, 1999; 341: 1413-9 
  21. Lancet. Aug 28, 1999; 354: 701-7 
  22. Lancet. Aug 28, 1999; 354: 708-15 
  23. Lancet. Sept 11, 1999; 354: 885-90 
  24. Circulation. Dec 7, 1999; 100: 2312-8 
  25. Am J Cardiol. Feb 15, 2000; 85: 462-5 
  26. JAMA. Mar 8, 2000; 283: 1295-1302 
  27. N Engl J Med. Mar 30, 2000; 342: 913-20 
  28. Lancet. Jun 24, 2000; 355:2199-203 
  29. Lancet. Jul 1, 2000; 356:9-16 
  30. N Engl J Med. Ayg 10, 2000; 343: 385-91 
  31. Circulation. Jul 25 2000; 102: 386-91 
  32. Heart. Sept 2000; 84: 251-7 
  33. Lancet. Oct 7, 2000; 356: 1213-8 
  34. JAMA 2003;5290:486-94 
  35. NEJM 2002;347:969-74.5290:486-9 
  36. Lancet 2002;360:1275-6. 
  37. Lancet 2003;362:759-66. 
  38. N Engl J Med. 2003;349:733-42. 
  39. Lancet. 2003;362:782-8. 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Intravenous skin antisepsis1 0.5% chlorohexidine gluconate (CHG) vs. 70% isopropyl alcohol swab followed by povidone-iodine swab (control) Local catheter related infection 72 hours 12.5 1.2 9 (5 to 23)
CHG vs. povidone-iodine swab followed by 70% isopropyl alcohol swab (control) 9.9 1.2 12 (6 to 48)

References

  1. Can J Infect Con. 2000; Spring: 9-14 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Graves Hyperthyroidism1 Radioiodine and prednisone vs. radioiodine therapy Development and improvement of opthalmopathy 1 year 15 0 7 (5 to 11)
Type 2 diabetes mellitus in overweight patients2 Radioiodine and prednisone vs. radioiodine therapy Diabetes related end point 10 years 39 29 10 (6 to 29)
Deaths from diabetes 13 8> 19 (10 to 138)
All cause mortality 22 15 14 (8 to 67)
MI 18 11 16 (9 to 78)
Diabetic men with erectile dysfunction3 Sildenafil vs. placebo Improved erections 12 weeks 10.2 56.5 3 (2 to 3)
"Insulin requiring" diabetes4 Regular telephone contact with a diabetes nurse educator for advice about adjustment of insulin therapy vs. regular clinic visits and usual contact with the endocrinologist for insulin adjustment Mean HbAlc level and proportion of patients who achieved a reduction in HbAlc level ≥ 10% 6 months 35 87 2 (1 to 4)

References

  1. N Engl J Med 1998 Jan 8;338(2):73-8 
  2. Lancet 1998 Sep 12;352(9131):854-65 
  3. JAMA 1999 Feb 3;281(5):421-6 
  4. CMAJ. 19 Oct 1999; 161: 959-62 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Endoscopic re-treatment of bleeding peptic ulcer1 Endoscopy vs. surgery Mortality at 30 days, duration of hospitalization after treatment, ICU stay, need for blood transfusion and treatment-related complications 6 weeks 36 15 5 (3 to 25)
Remission rates in active Crohn disease2 Budesonide vs. mesalamine Remission 16 weeks 36 62 4 (3 to 10)
Endoscopic gastroduodenal ulcers in osteoarthritis3 Rofecoxib vs. Ibuprofen Endoscopic gastroduodenal ulcers ≥ 3 mm at 12 weeks 24 weeks 7 25 5 (4 to 9)
Women with irritable bowel syndrome4 Alosetron vs. placebo Relief of abdominal symptoms 1 month 29 41 8 (5 to 22)
Constipation 3 30 4 (3 to 5)
Bleeding peptic ulcer5 Omeprazole vs. placebo Recurrent bleeding 8 weeks 22.5 6.7 6 (4 to 14)
Hospital stay < 5 days 31.7 46.7 7 (4 to 38)
H pylori infection6 Clarithromycin. Iansoprazole, metronidazole vs clarithromycin, Iasoprazole, amoxicillin Eradication of H pylori 6 weeks 84 66 6 (3 to infinity)

References

  1. Gastroenterology. Oct 1999; 117: 776-83 
  2. N Engl J Med. 6 Aug 1998; 339: 370-4 
  3. N Engl J Med. 6 Aug 1998; 339: 370-4 
  4. Lancet. Mar 25, 2000; 355:1035-40 
  5. N Engl J Med. Aug 3, 2000; 343: 310-6 
  6. JAMA. 2003;290:1593-9 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Hip and knee arthroplasty1 Patients were allocated to a clinical pathway group (received "proactive" treatment where specific daily goals were set for the patient) vs. control group (received "reactive" treatment where the healthcare team provided care in response to the patient's conditions and wants) Complications (wound infection, chest infections deep venous thrombosis, joint dislocation, decubitus pressure areas, failure to cope at home and decreased range of motion after discharge) 3 months 28.2 10.9 6 (4 to 19)
Postoperative abdominal wound infection2 Impervious wound-edge protector vs. no wound edge protector (control) All wounds 30 days 30 14 7 (4 to 13)
Clean-contaminated wounds (minor interruption in aseptic technique or minor spillage from the gastrointestina1 tract) 13 7 Not significant
Contaminated wounds (major interruption in aseptic technique or subsequent spillage 67 24 3 (2 to 6)
Dirty wounds (gross fecal spillage) 94 75 Not significant
Hip surgery3 Aspirin vs. placebo Symptomatic deep venous thrombosis 35 days 1.5 1 232 (140 to 2239)
Pulmonary embolism 1.2 0.7 195 (140 to 466)

References

  1. Med J Aust. 18 Jan 1999; 170: 59-62 
  2. Lancet. May 8, 1999; 353: 1585 
  3. Lancet. Apr 15, 2000; 355: 1295-302 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Nonvertebral fractures in community living elderly persons1 Calcium and Vitamin D Supplementation vs.placebo Nonvertebral fractures 3 years 13 6 15 (8 to 12)
Nonvertebral fractures and bone loss2 Calcium and vitamin D vs.placebo Nonvertebral fractures 3 years 13 6 15 (8 to 12)
Alzheimer disease3 Donepezil vs.placebo Nausea 12 weeks 8 22 8 (5 to 17)
Insomnia 5 18 9 (6 to 18)
Diarrhea 3 13 10 (6 to 20)
Non-vertebral fractures and bone loss in the elderly4 Elemental calcium+vitamin D vs. placebo Non-vertebral fractures verified by radiographs or hospital records 3 years 12.9 5.9 15 (8 to 12)
Hip fractures in nursing home patients55 External hip protectors vs. control(no hip protector) Hip fracture 1 month 7.4 3.2 24 (13 to 183)
New fractures in postmenopausal women who had low bone-mineral density and existing vertebral fractures6 Alendronate sodium vs. placebo New vertebral fractures confirmed by radiography 3 years < 75 years of age: 13 < 75 years of age: 6 < 75 years of age: 15 (11 to 27)
≥75 years of age: 18 ≥75 years of age: 11 ≥75 years of age: 15 (8 to 21)
Postmenopausal77 Alendronate sodium vs. placebo ≥1 day of bed rest 3 years 15 11 23 (15 to 56)
≥7 days of bed rest 9 4 21 (17 to 32)
≥7 days of limited activity 44 41 23 (12 to 308)
Postmenopausal women with osteoporosis8 Oral risedronate vs. placebo New vertebral fractures 3 years 16 11 20 (11 to 111)
Non-vertebral fractures 8 5 32 (17 to 250)
Residents in nursing homes9 Pharmacist medication review vs. no review Deaths from 5 to 8 months (intervention phase) 8 months 9 4 17 (9 to 213)
Hip fracture patients with mild to moderate dementia10 Intensive geriatric rehabilitation (advice, training, drug treatment, physiotherapy, occupational and speech therapy) vs. control group (discharge to a local hospital) Independent living at 3 months-mild dementia 1 year 67 91 5 (3 to 16)
Independent living at 3 months -moderate dementia 1 year 17 63 3 (2 to 9)
Vertebral fractures in men with osteoporosis11 Alendronate vs. placebo Incidence of vertebral fractures 2 years 7 1 16 (7 to 56)
  1. N Engl J Med 1997; 337:670-6 
  2. N Engl J Med 1997 Sep 4;337(10):670-6 
  3. Arch Intern Med 1998 May 11;158(9):1021-31 
  4. N Engl J Med. 4 Sept 1997; 337: 670-6 
  5. Lancet. 2 Jan 1993; 341: 11-3 
  6. Arch Intern Med. 8/22 Dec 1997; 157: 2617-24 
  7. Arch Intern Med. Jan 10, 2000; 160: 77-85 
  8. JAMA. Oct 13, 1999; 282: 1344-52 
  9. Br J Psychiatry. Jun 2000; 176: 563-7 
  10. BMJ. Nov 4, 2000; 321: 1107-11 
  11. N Engl J Med. Aug 31 2000: 343: 604-10 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Reducing venous thromboembolism after elective neurosurgery1 Enoxaparin vs. placebo Pulmonary embolism (PE) or deep venous Thrombosis (DVT) 8 days 33 17 7 (4 to 18)
PE or proximal DVT 14 5 12 (6 to 73)
Overall DVT 32 17 7 (4 to 20)
Proximal DVT 13 5 13 (7 to 143)
Stroke in children with sickle-cell anaemia; periodic blood transfusions2 Transfusion vs. standard care All strokes 20 months 16 2 7 (4 to 18)
Cerebral infarction 15 2 8 (5 to 22)
Idiopathic venous thromboembolism3 Warfarin vs. placebo Recurrent venous thromboembolism 3 months 20.5 1.3 6 (3 to 9)
Total bleeding 1.2 11.4 10 (5 to 30)
Pulmonary embolism and proximal deep venous thrombosis (DVT)4 Subcutaneous low-molecular-weight heparin (tinzaparin sodium) vs. unfractionated heparin (control) Recurrent venous thromboembolism 3 months 6.8 0 15 (8 to 36)
Major bleeding 1.9 1.0 Not significant
Minor bleeding 2.9 1.0 Not significant
Death 8.7 6.2 Not significant

References

  1. N Engl J Med 1998 Jul 9;339(2):80-5 
  2. N Engl J Med 1998 Jul 30;339(5):339-40 
  3. N Engl J Med 1999 Mar 25;340(12):901-7 
  4. Arch Intern Med. Jan 24, 2000; 160: 229-36 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
AIDS1 ; Patients with HIV-1 infection and CD4+ lymphocyte count ≤ 100/mL Ritonavir vs. placebo AIDS-defining illness or death Median 28.9 weeks 37.5 21.9 6 (5 to 10)
AIDS1; as above Ritonavir vs. placebo Death from any cause Median 51 weeks 23 16 14 (9 to 43)
Herpetic gingivostomatitis2 Acyclovir vs. placebo Oral lesions 8 days 70 6.5 2 (1 to 2)
Eating difficulties 47 6.5 3 (2 to 5)
Drinking difficulties 30 3.2 4 (2 to 11)
HIV infected persons with previous antiretroviral treatment3 Indinavir, zidovudine + lamivudine vs. zidovudine + lamivudine Changes in HIV RNA levels and CD4+ cell counts. 24 weeks 0 90 2
Shigellosis in Bangladeshi children4 Vitamin A vs. no vitamin A Clinical cure by day 5 5 days 20 45 4 (2 to 18)
Bacteriological cure from day 3 39 38 Not significant
HIV infection; breast-fed infants5 Zidovudine vs. placebo HIV-1 infection in the live-born children of women in the study 6 months 27.5 18 11 (6 to 100)
Sexually transmitted diseases in minority women6 Behavioral intervention (3 weekly group sessions in which recognition of risk, commitment to change and acquisition of skills were discussed) vs. control group (received 15 minutes of standard individualized counseling by nurse clinicians according to guidelines from the US Centers for Disease Control and Prevention) Subsequent infection with Chlamydia trachomatis or Neisseria gonorrhoeae, assessed by testing endocervical samples with DNA probes 6 and 12 months 26.9 16.8 10 (6 to 32)
HIV-1-infected patients with tuberculosis7 Trimethoprim-sulfamethoxazole (co-trimoxazole) vs. placebo Death 10.5 months 22.6 13.3 11 (7 to 26)
≥ hospitalization 12.4 7.6 21 (11 to 172)
HIV-1-infection8 Efavirenz plus zidovudine and lamivudine vs. indinavir plus zidovudine and lamivudine Percentage of patients with suppression of plasma HIV-1 RNA to < 400 copies/mL 48 weeks 48 70 5 (4 to 10)
meningitis9 Dexamethasone vs placebo death 8 weeks 25 15 1 (5 to 73)

References

  1. Lancet 1998; 351:543-9 
  2. BMJ 1997 Jun 21;314(7097):1800-3 
  3. N Engl J Med 1997 Sep 11;337(11):734-9 
  4. BMJ. 7 Feb 1998; 316: 422-6 
  5. Lancet 1999 Mar 6;353(9155):786-92 
  6. N Engl J Med. 14 Jan 1999; 340: 93-100 
  7. Lancet. May 1, 1999; 353: 1469-75 
  8. N Engl J Med. Dec16, 1999; 341:1865-73 
  9. NEJM. 2002;347:1549-56 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Major depression1 Repetitive transcranial magnetic stimulation (rTMS) vs. sham rTMS ≥50% reduction in scores on the Hamilton Depression Rating Scale or Montgomery-Asberg Depression Rating Scale 2 weeks 25 49 5 (3 to 466)
Children and adolescents with non-psychotic major depressive disorder2 Fluoxetine vs. placebo Improvement 8 weeks 33 56 5 (3 to 33)
Bipolar disorder; manic relapse3 Training plus routine care vs. routine care alone Manic relapse 18 months 57 27 3 (2 to 16)
Major depression4 Slow, repetitive transcranial magnetic stimulation (rTMS) vs. Sham rTMS Severity of depression 2 weeks 25 49 5 (3 to 466)
Social phobia5 Paroxetine vs. placebo Treatment response (mean change in scores on the Liebowitz Social Anxiety Scale and the proportion of responders on the Clinical Global Impression scale) 12 weeks 32 66 4 (3 to 5)
Engaging unmotivated problem drinkers into treatment6 Concerned significant others (CSO) were allocated to Community reinforcement and family training (CRAFT- teaching behavior changing skills to use at home) or Johnson Institute (JI) intervention (to prepare for confrontational family meetings) or Al-Anon (a 12 step program) Number of problem drinkers engaged in treatment at follow up, change in concerned significant other functioning and relationship quality 1 year CRAFT: 67 vs. Al-A: 20 3 (2 to 4)
CRAFT: 67 vs. JI: 35 4 (2 to 10)
Al-A: 35 vs. JI: 20 Not significant
Relapse in residual depression7 Clinical management + cognitive therapy (CT) vs. clinical management alone Relapse 1 year 47 29 6 (4 to 42)
Non-chronic treatment resistant depression8 Venlafaxine vs. paroxetine (control) Therapeutic response 4 weeks 33 52 6 (3 to 254)
Remission 20 42 5 (3 to 21)
Alcohol related illness in ongoing drinkers 9 Integrated outpatient treatment (IOT-inpatient evaluation, treatment plan, monthly primary care visits to measure biological indicators of heavy drinking and offer help and efforts to involve family members) vs. standard care Drinking in previous 30 days 2 years 70 81 4 (3 to 35)
Social Phobia10 Paroxetine vs. placebo Mean change in scores on the Liebowitz Social Anxiety Scale and the proportion of responders on the Clinical Global Impression Scale 12 weeks 32 66 4 (3 to 5)
Relapse in residual depression11 Antidepressants plus cognitive therapy vs. clinical management alone Relapse and symptom ratings 1 year 47 29 6 (4 to 42)
Depression12 Fluozetine vs. desipramine (control) Continuing initial medication 12 months 20 42 5 (4 to 10)
Fluozetine vs. imipramine (control) 27 42 7 (4 to 25)
Moderate depression13 Hypericum extract vs. placebo ≥50% improvement in the Hamilton Depression Rating Scale 8 weeks 48 67 6 (3 to 50)
Hypericum extract vs. imipramine 67 76 Not significant
Opioid dependance14 Methadone maintenance for 14 months vs. 120 days of methadone-assisted maintenance and 60 days of methadone-assited detoxification with intensivepsychosocial serivces and 8 months of aftercare (control) Treatment retention 12 months 55 74 6 (4 to 20)
Depression15 Fluoxetine plue folic acid vs. fluoxetine plus placebo Clinical response (>50% improvement on the Hamilton Depression Rating Scale) 10 weeks 62 82 5 (3 to 30)
Depression16 Nurse telehealth care (12-14 calls to each patient during treatment in which the clinic nurse answered questions, offered support and discussed the patient's mental and overall health vs. usual physician care (counselling and treatment with a selective serotonin reuptake inhibitor) ≥50% improvement on the Hamilton Depression Rating Scale 6 weeks 37 50 8 (4 to 90)
6 months 38 57 6 (4 to 18)
≥50% improvement on Beck Depression Inventory 6 weeks 33 38 Not significant
6 months 37 48 Not significant
Alzheimer's disease17 Family intervention, which comprised 3 sessions of caregiver education, 6 sessions of stress management and 5 sessions of coping skills management vs. interview control group, which comprised of a1 session cathartic interview Caregiver psychiatric morbidity and depression 3 months 85 23 2 (2 to 5)
Family intervention vs. no interview 77 23 2 (2 to 7)
Postpartum depression18 Support group (7 psychoeducation a1 visits in which partners participated in 4 out of the 7 visits) vs. control group (7 sessions without partner) Depression status established by the Mini International Neuropsychiatric Instrument 10 weeks 62 19 3 (2 to 15)
Fear of flying19 Virtual reality exposure (8 sessions, 4 of which involved information gathering, treatment planning, brief breathing training and cognitive restructuring) vs. waiting list control Proportion of patients who went on a round trip flight at 6 weeks and changes in symptoms (determined from questionnaire) 12 months 7 53 3 (2 to 7)
Standard exposure (8 sessions done at the airport with exposure to pre-flight stimuli and sitting on a stationary airplane with imaginal exposure to takeoffs, cruising and landing) vs. waiting list control 7 67 2 (2 to 4)
Aggression and conduct disorder20 Lithium vs. placebo Responders on the Global Clinical Judgments (Consensus Scale) 4 weeks 30 80 2 (2 to 6)
Responders on the Clinical Global Impressions 70 20 2 (2 to 6)
Bulimia nervosa21 Cognitive behavioural therapy vs. interpersonal therapy (control) Recovery at 20 weeks 1 year 6 29 4 (3 to 8)
Remission at 20 weeks 28 48 5 (3 to 14)
Normal eating attitudes and behaviours at 20 weeks 27 41 7 (4 to 92)
Post-traumatic stress disorder (PTSD)22 Sertraline vs. placebo Response rate (≥ 30% reduction from baseline in Clinician Administered PTSD Scale, Part 2 total severity score and Clinical Global Improvement - Improvement (CGI - I) score of 1 or 2) 12 weeks 32 53 5 (3 to 17)
Schizophrenia or schizoaffective disorder23 Programme for relapse prevention (education about relapse and how to recognise prodromal symptoms and behaviour, active monitoring, clinical intervention when prodromal episodes were detected and 90 minuets of multifamily psychoeducation groups) vs. usual care Relapse free survival 18 months 66 83 1 (1 to 5)
No hospital admission 61 78 1 (1 to 3)
Chronic depression24 Nefazodone and psychotherapy vs. nefazodone or psychotherapy (control) Remission (a score of 8 or less on the Hamilton Rating Scale for Depression) or satisfactory response (a reduction in the HRDS by at least 50% from baseline and a score of 15 or less) 12 weeks 48 73 4 (3 to 7)
Acute mania25 Valproate vs. placebo ≥ 50% improvement on the Young Mania Rating Scale 21 days 46 70 5 (3 to 15)
Moderate to marked improvement on the Clinical Global Impression Scale 50 68 6 (4 to 74)
Major depressive disorder (MDD)26 Titrated right unilateral electroconvulsive therapy (RUL ECT) vs. fixed dose RUL ECT (control) Cognitive disturbance (decreased ≥ 5 points on the Mini-Mental State Examination) 1-2 days 30 6.7 5 (3 to 22)
Secondary insomnia27 Treatment group (4 weekly 1 hour sessions with a therapist involving sleep hygiene instructions, stimulus control and relaxation) vs. control group Clinical improvement (measured by sleep efficiency percentage) 3 months 19 57 3 (2 to 12)
Secondary insomnia28 Naltrexone plus cognitive behavioural therapy (CBT) vs. placebo plus CBT Drinking relapse (≥ 5 drinks/day for men and ≥ 4 drinks/day for women) 12 weeks 60 38 5 (3 to 21)
Secondary insomnia29 Risperidone vs. haloperidol (control) Need for antiparkinsonian drugs 6 weeks 75 50 5 (3 to 10)
Moderate depression30 Hypericum extract vs. placebo ≥ 50% improvement in Hamilton Depression Rating Scale score 8 weeks 48 67 6 (3 to 50)
Hypericum extract vs. imipramine (control) 67 76 Not significant
Drug refractory schizophrenia31 Cognitive behavioural therapy (attaining a collaborative understanding of the development of symptoms and working towards reducing distress and disability) vs. befriending (control - sessions focused on neutral topics) ≥ 50% improvement in Comprehensive Psychiatric Rating Scale (CPRS) total score 9 months 39 63 5 (3 to 28)
≥ 0% improvement in CPRS schizophrenia change scores 50 70 Not significant

References

  1. Arch Gen Psychiatry 1999; 56:315-20 
  2. Arch Gen Psychiatry 1997 Nov;54(11):1031-7 
  3. BMJ 1999 Jan 16;318(7177):149-53 
  4. Arch Gen Psychiatry. Apr 1999; 56: 15-20 
  5. Br J Psychiatry. Aug 1999; 175: 120-6 
  6. J Consult Clin Psychol. Oct 1999; 67: 688-97 
  7. Arch Gen Psychiatry. Sept 1999; 56: 829-35 
  8. Br J Psychiatry. Jul 1999; 175: 12-6 
  9. Arch Intern Med. 13 Sept 1999; 159: 1946-52 
  10. Br J Psychiatry. Aug 1999; 175: 120-6 
  11. Arch Gen Psychiatry. Sept 1999; 56: 829-94 
  12. Arch Fam Med. Jul/Aug 1999; 8: 319-25 
  13. BMJ. Dec 11, 1999; 319: 1534-9 
  14. JAMA. Mar 8, 2000; 283: 1303-10 
  15. Affect Disord. Nov 2000; 60: 121-30 
  16. Arch Fam Med. Aug 2000; 9:700-8 
  17. Br J Psychiatry. Jun 2000; 176: 557-62 
  18. Can J Psychiatry. Aug 2000; 45: 554-8 
  19. J Consult Clin Psychol. Dec 2000; 68: 1020-6 
  20. Arch Gen Psychiatry. Jul 2000; 57: 649-54 
  21. Arch Gen Psychiatry. May 2000; 57: 459-66 
  22. JAMA. Apr 12, 2000; 283: 1837-44 
  23. Arch Gen Psychiatry. Mar 2000; 57:277-83 
  24. N Engl J Med. May 18, 2000. 342; 1462-70 
  25. J Clin Psychopharmacol. Apr 2000; 20: 195-203 
  26. Arch Gen Psychiatry. May 2000; 57: 438-44 
  27. Psychol Aging. Jun 2000; 15: 232-40/a> 
  28. Am J Psychiatry. Nov 1999; 156: 1758-64 
  29. Am J Psychiatry. Nov 1999; 156: 1758-64 
  30. Schizophr Bull. 1999; 25: 721-9 
  31. BMJ. Dec 1999; 319: 1534-9 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Alcohol-related seizures1 Lorazepam vs. placebo Occurrence of a second seizure 6 hours 24 3 5 (4 to 9)
Care for acute stroke victims2 Patients were allocated to a Stroke unit or to Ward care Proportion of patients living at home 5 years 18.2 34.5 6 (4 to 21)
Migraine headaches3 Riboflavin vs. placebo Frequency of headaches 3 months 19 54 3 (2 to 11)
Headache days 15 57 3 (2 to 6)
Acute stroke unit care4 Stroke unit vs. general ward care Quality of life measured by the Frenchay Activity index ≥ 30 points 5 years 40.6 5 (2 to 80)
Non-disabling stroke; carotid endarterectomy5 Carotid endarterectomy vs. medical care Ipsolateral stroke 5 years 18.7 13.1 18 (10 to 186)
Any stroke 26.4 19.8 15 (8 to 100)
Stroke or death 36.4 27.9 12 (7 to 44)
Disabling stroke or death 20.1 14.9 19 (10 to 783)
Multiple sclerosis attacks6 Methylpredni-solone vs. placebo ≥ 1 point improvement on Kurtzke Expanded Disability Status Scale 1 year 22 50 4 (2 to 105)
Secondary progressive multiple sclerosis7 Interferon-b1b vs. placebo Progression 33 months 49.7 39.1 9 (6 to 30)
Acute Stroke7 Intra-arterial recombinant prourokinase plus intravenous heparin vs. intravenous heparin alone Proportion of patients with a modified Rankin score ≤ 2 90 days 25 40 7 (3 to 268)
Episodic cluster headache8 Verapamil vs. placebo Non-response (= having ≤ 50% reduction in cluster headache attack frequency) 2 weeks 100 20 1 (1 to 2)
Multiple sclerosis (MS)9 Interferon β-1a vs. placebo Mean change in scores on the Liebowitz Social Anxiety Scale and the proportion of responders on the Clinical Global Impression Scale 12 weeks 32 66 4 (3 to 5)

References

  1. N Engl J Med 1999 Mar 25;340(12):915-9 
  2. Stroke 1997 Oct;28(10):1861-6 
  3. Neurology 1998 Feb;50(2):466-70 
  4. Stroke 1998 May;29(5):895-9 
  5. N Engl J Med 1998 Nov 12;339(20):1415-25 
  6. Neurology 1998 Aug;51(2):529-34 
  7. BMJ 1998 Jul 25;317(7153):235-40 
  8. Neurology. Mar 2000; 54: 1382-5 
  9. N Engl J Med. Sept 28, 2000; 343: 898-904 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
CAD1 Indo-Mediterranean diet vs control Prevention of CAD 2 years 15.2 7.8 14 (9 to 29)

References

  1. Lancet. 2002; 360:1455-61 ↩
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Excessive uterine bleeding1 Levonorgestrel intrauterine system vs. control group Number of women canceling their decision to have a hysterectomy 6 months 14 64 2 (1 to 4)
First-stage labor pain2 Intracutaneous injections of sterile water vs. placebo Labor pain was measured with a 10-cm visual analog scale (0 cm = no pain; 10 cm = worst conceivable pain) 90 minutes 25 59 3 (2 to 13)
Subcutaneous injections of sterile water vs. placebo 25 52 4 (3 to 82)
Breech presentation3 Planned cesarean section vs. planned vaginal birth (control) Perinatal or neonatal mortality or serious neonatal morbidity 6 weeks 5.0 1.6 30 (20 to 54)
Perinatal or neonatal mortality 1.3 0.3 104 (54 to 416)
Serious neonatal morbidity 3.8 1.4 41 (26 to 90)

References

  1. BMJ 1998 Jul 25;317(7153):235-40 ↩
  2. Br J Obstet Gynaecol. Jul 1999; 106: 633-7 ↩
  3. Lancet. Oct 21, 2000; 356: 1375-83 ↩
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Breast cancer1; Postmenopausal women with breast cancer Radiotherapy plus tamoxifen vs. tamoxifen alone Recurrence (both locoregional recurrence and distant metastasis) 10 years 60 47 8 (6 to 13)
Stages II and III breast cancer2 Adjuvant chemotherapy + radiotherapy vs. chemotherapy alone Locoregional recurrence 10 years 26 5 5 (4 to 6)
Locally advanced prostate cancer3 Radiotherapy + goserelin vs. radiotherapy alone Death 5 years 28 17 10 (5 to 34)
Acute myeloid leukemia; autologous bone-marrow transplantation after intensive chemotherapy4 Bone-marrow transplantation vs. no further treatment Relapse 7 years 53 34 5 (3 to 11)
Relapse or cancer-specific death 57 45 9 (5 to 80)
Death 49 40 Not significant
Breast cancer; preservation of the intercostobrachial nerve during axillary node clearance5 Preservation vs. sacrifice of the intecostobrachial nerve Some sensory deficit 3 months 84 63 5 (3 to 24)
Breast cancer6 Radiotherapy plus tamoxifen vs. tamoxifen alone All recurrences 10 years 60 47 8 (6 to 13)
Locoregional recurrence with or without distant metastases 35 8 4 (4 to 5)
Node-positive prostate cancer7 Antiandrogen therapy immediately after surgery vs. observation Death 7.1 years 35 15 5 (3 to 34)
Death from prostate cancer 31 6.4 4 (3 to 10)
Any recurrence 82 15 2 (2 to 2)
Prostate cancer8 Pelvic floor re-education program (included education about the anatomy and function of the bladder and pelvic floor, active pelvic-floor muscle exercises and biofeedback) vs. placebo program (information about the origin of their incontinence and placebo electrotherapy applied to the abdomen and thighs, but that could not affect pelvic floor function) Incontinence rate at 3 months (continence was defined as a loss of ≤ 2g of urine on both the 24-hour and 1-hour pad test 1 year 44 10 3 (2 to 6)
Incontinence at 1 year 17 4 8 (4 to 72)

References

  1. Lancet 1999; 353:1641-8 
  2. N Engl J Med 1997 Oct 2;337(14):949-55 
  3. N Engl J Med 1997 Jul 31;337(5):295-300 
  4. Lancet 1998 Mar 7;351(9104):700-8 
  5. Br J Surg 1998 Oct;85(10):1443-5 
  6. Lancet 1999 May 15;353(9165):1641-8 
  7. N Engl J Med. Dec 9, 1999; 341: 1781-8 
  8. Lancet. Jan 8 2000; 355: 98-102 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Second-eye cataract surgery1 Surgery vs. control Difficulty reading normal print 6 months 35 6 4 (3 to 6)
Eyesight prevented most activities 11 0 10 (6 to 23)
Below-average overall vision 18 0 6 (4 to 10)
Eyesight interfered greatly in life 26 1 5 (3 to 7)
Stereoacuity worse than 3000-sec arc 70 12 2 (2 to 3)

References

  1. Lancet 1998 Sep 19;352(9132):925-9 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Painful stiff shoulder1 Corticosteroid injections vs. physiotherapy Treatment success 1 year 46 77 3 (2 to 8)
Subacute or chronic low back pain2 Exercise program (8 one hour sessions over 4 weeks which consisted of stretching, low impact aerobics and strengthening exercises) vs. control (standard care from GPs) Functional limitation (24 point Roland back pain disability questionnaire) 1 year 35 64 4 (3 to 8)
Lateral epicondylitis (tennis elbow)3 Local corticosteroid injection of methylprednisolone and lignocaine vs. enteric-coated naproxen Complete recovery at 4 weeks 12 months 5.7 42 3 (2 to 5)
Local corticosteroid injection of methylprednisolone and lignocaine vs. placebo Pain scores ≤ 3 at 4 weeks (on 10 point Likert scale) 50 82 4 (3 to 8)
Osteoarthritis of the knee4 Manual physical therapy and exercise vs. placebo (ultrasonography at a sub-therapeutic intensity) Knee surgery 1 year 20 5 7 (4 to 134)
Acute whiplash injuries5 Active treatment (gentle, active, small-range and small-amplitude rotational movements of the neck) vs. standard treatment (leaflet providing information about injury mechanisms, advice on suitable activities and instruction on postural correction) No pain 6 months 11 30 6 (3 to 45)
No or low pain 20 44 5 (3 to 22)

References

  1. N Engl J Med. 12 Nov 1998; 339: 1415-25 
  2. BMJ. 31 Jul 1999; 319: 279-83 
  3. BMJ. Oct 9, 1999; 319: 964-8 
  4. Ann Intern Med. Feb 1 2000; 132: 173-81 
  5. Spine. Jul 15, 2000; 25: 1782-7 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Acute otitis media (AOM)1 Xylitol syrup vs. control syrup Incidence of AOM 3 months 41 29 8 (4 to 53)
Xylitol gum vs. control gum 28 16 9 (5 to 36)
Xylitol lozenges vs. control gum 28 22 Not significant
Diarrhea incidence in children treated with antibiotics2 Lctobacillus GG vs. placebo Incidence of diarrhea 10 days 26 8 6 (4 to 13)
Stool consistency < 4§ 48 17 4 (3 to 6)
Acute otitis media3 Amoxicillin suspension vs. placebo Persistent symptoms at 4 days 6 weeks 72 59 8 (4 to 72)
Clinical treatment failure at 11 days (persistent fever, earache, crying, irritability or no improvement in appearance of the tympanic membrane) 70 60 Not significant
Constipation in children4 Cisapride vs. placebo clinical response (>3 spontaneous bowel movements/week with no fecal soiling and no use of other laxtives for ≥ 2 weeks) 12 weeks 42 76 3 (2 to 60)
Routine primary immunisation5 Longer needle vs. shorter needle (control) Any local reaction up to 3 days 3 days 84 62 5 (3 to 19)
Redness at 6 hours 66 40 5 (3 to 81)
Redness at 1 day 63 28 3 (2 to 7)
Redness at 2 days 39 9 4 (3 to 8)
Redness at 3 days 28 4 5 (3 to 9)
Swelling at 6 hours 58 23 3 (3 to 6)
Swelling at 1 day 63 28 3 (2 to 7)
Swelling at 2 days 51 19 4 (3 to 7)
Swelling at 3 days 40 13 4 (3 to 10)
Children with asthma exacerbations6 Ward care based on a clinical pathway (comprised a nurse driven protocol for weaning bronchodilators, regular peak flow measurements, asthma teaching, prescriptions for home treatments and coordination of care between the attending physician and private medical doctors) vs. usual ward care Discharge within 24 hours of admission 2 weeks 38 15 5 (3 to 14)
Acute diarrhea in children7 Oral rehydration solution (ORS) vs. standard care Unscheduled follow up visit 10 days 17 11 16 (8 to 481)
ORS use 71 85 8 (5 to 17)
Head lice in children8 Malathion lotion vs. bug busting (control) Live lice at 7 days after treatment 7 days 63 23 2 (2 to 6)
Severe watery diarrhea in children9 Racecadotril vs. placebo 5 day cure rate 5 days 66 84 6 (4 to 29)

References

  1. Pediatrics 1998 Oct;102(4 Pt 1):879-84 
  2. J Pediatr. Nov 1999; 135: 564-8 
  3. BMJ. Feb 5, 2000; 320: 350-4 
  4. J Pediatr. Jan 2000;136: 35-40 
  5. BMJ. Oct 14, 2000; 321: 931-3 
  6. Pediatrics. Nov 2000; 106: 1006-12 
  7. Pediatrics. Sep 1999; 104: e29 
  8. Br J gen Pract. Oct 2000; 50: 817-20 
  9. N Engl J Med. Aug 17, 2000; 343: 463-7 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Acute arterial leg occlusion1 Thrombolysis vs. surgery Amputation- free survival at 6 and 12 months 6 and 12 months 6 months: 25.2
12 months: 30.1		 6 months: 28.2
12 months: 35		 Not significant
Hemorrhagic complications 5.5 12.5 14 (8 to 47)

References

  1. N Engl J Med 1998 Oct 15;339(16):1105-11 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Chronic fatigue syndrome1; Patients reporting fatigue (medically unexplained, lasting ≥6 months) Cognitive behaviour therapy vs. orthodox medical care Improved function 6-7 months 26.7 73.3 3 (2 to 5)
Head lice2; Patients of any infected with live lice Pediculicides (e.g., permethrin) vs. placebo Freedom from viable lice or eggs 14 days 5.9 97 2 (1 to 2)
Nosocomial pneumonia3 Semirecumbent body position (45° from the horizontal) vs. supine body position Clinically suspected nosocomial pneumonia 72 hours 34 8 4 (3 to 11)
Microbiologically confirmed nosocomial pneumonia (by bronchoalveolar lavage or protected specimen-brush cultures 23 5 6 (4 to 29)
Influenza4 Oral oseltamivir once daily vs. placebo Laboratory-confirmed influenza-like illness 6 weeks 4.8 1.2 27 (17 to 59)
Oral oseltamivir twice daily vs. placebo 4.8 1.3 29 (17 to 69)
Ventilator-associated5 Invasive management strategy (fiberoptic bronchoscopy to obtain protected specimen-brush samples or bronchoalveolar lavage samples to guide treatment vs. Clinical management strategy (control-clinical evaluation, examination of Gram-stained endotracheal aspirates and adherence to the American Thoracic Society guideline recommendations for choosing antiboitics) All-cause mortality 28 days 26 16 11 (6 to 56)
Dissolving earwax6 Docusate sodium vs. triethanolamine polypeptide (control) Complete visualisation of the tympanic membrane (with or without irrigation) 35 81 3 (2 to 6)
Sepsis7 Immune enhancing enteral feeding formula vs. control formula Mortality 32 19 8 (4 to 637)
Acquired bacteraemia 22 8 8 (4 to 28)
≥1 acquired nosocomial infection 20 6 8 (5 to 23)
Influenza8 Influenza vaccine vs. placebo Patients reports of fever plus cough or sore throat and associated physician visits and lost work days during influenza period during flu season of 1998-99 After flu season was finished 10.2 1.4 12 (7 to 27)

References

  1. Price JR, Couper J. Cognitive behaviour therapy for adults with chronic fatigue syndrome. Cochrane Review, 24 Aug 1998. In: The Cochrane Library. Oxford: Update Software. 
  2. Interventions for treating headlice. Cochrane Review, 14 Jan 1999. In: The Cochrane Library. Oxford:Update Software. 
  3. Lancet. Nov 27, 1999; 354: 1851-8 
  4. N Engl J Med. Oct 28, 1999; 341:1336-43 
  5. Ann Intern Med. Apr 18, 2000; 132: 621-30 
  6. Ann Emerg Med. Sep 2000; 36: 228-32 
  7. Crit Care Med. Mar 2000; 28: 643-8 
  8. JAMA. Oct 4, 2000; 284: 1655-63 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Acute asthma1 Budesonide vs. placebo Relapse 21 days 25 13 9 (5 to 179)
Chronic obstructive pulmonary disease (COPD)2 Glucocorticoids vs. placebo First treatment failure (death, need for intubation and mechanical ventilation, readmission for COPD, or intensification of drug therapy) 1 and 3 months 1 month: 33 1 month: 23 10 (5 to infinity)
3 months: 48 3 months: 37 9 (4 to infinity)
Children with asthma3 Structured discharge packages vs. usual discharge packages at the time of discharge Readmission to hospital 6 months 38 15 5 (3 to 12)
Smoking cessation; using a nicotine inhaler4 Nicotine inhalers vs. placebo Self reported abstinence from smoking (verified by laboratory measurements) 1 year 18 29 10 (5 to 483)
Smoking cessation rates5 Intensive intervention (which includes a 30 minute behavioral counseling session given by nurses, a videotape from the American Heart Association and an audiotape of relaxation exercises vs. usual care (which includes printed material and a list of partially subsidized outpatient cessation programs) Confirmed smoking cessation 12 months 20 27 16 (9 to 25)
asthma; effectiveness in treating inner city patients6 Educational program vs. conventional asthma care and routine follow-up Attendance at follow up appointments, subsequent ED visits and hospitalization 6 months 27 59 3 (2 to 11)
Asthma7 Asthma clinic vs. standard treatment group Owning a peak flow meter 6 months 56 73 6 (3 to 31)
Waking at night because of asthma 20 7.0 8 (4 to 29)
Acute-on-chronic obstructive pulmonary disease8 Standard treatment plus pressure supported ventilation through a face or nasal mask vs. standard treatment alone Need for intubation After discharge 27 15 9 (5 to 69)
Death 20 10 10 (6 to 98)
Acute respiratory distress syndrome9 Lower tidal volumes vs. traditional tidal volumes (control) Death 180 days 40 31 12 (7 to 41)
Pulmonary infiltrates10 Ciprofloxacin vs. control (physician-directed antibiotics) Mortality 30 days 31 13 Not significant
Resistance or superinfection 38 14 5 (3 to 22)

References

  1. JAMA. 9 Jun 1999; 281: 2119-26 
  2. N Engl J Med. 24 Jun 1999; 340:1941-7 
  3. Arch Dis Child. Feb 1999; 80: 110-4 
  4. Arch Intern Med. 11/25 Aug 1997; 157: 1721-8 
  5. Arch Intern Med. 24 Feb 1997; 157: 409-15 
  6. Arch Intern Med. 9/23 Aug 1999; 159: 1710-6 
  7. Med J Aust. Jul 19, 1999; 171: 68-71 
  8. Lancet. Jun 3, 2000; 355: 1931-5 
  9. N Engl J Med. May 4, 2000; 342: 1301-8 
  10. Am J Respir Crit Care Med. Aug 2000; 162: 505-11 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Calcific shoulder tendinitis1 Pulsed ultrasound vs. sham therapy Changes from baseline in shoulder calcium deposits on radiography, pain, active range of motion and power of shoulder and activities of daily living were assessed. 9 months 8 42 3 (2 to 9)
Carpal tunnel syndrome2 Injection of methylprednisolone and lignocaine vs. lignocaine alone (control) Symptom improvement-defined as having no symptoms or minor symptoms requiring no further treatment 1 year 7 50 3 (2 to 9)
Rheumatoid arthritis3 Intravenous infusion of infliximab, 3mg/kg of body weight every 4 weeks vs. placebo Response rate (defined as 20% improvement from baseline according to the 1987 American College of Rheumatology criteria) 30 weeks 20 53 4 (3 to 6)
Intravenous infusion of infliximab, 3mg/kg every 8 weeks vs. placebo 20 50 4 (3 to 6)
Intravenous infusion of infliximab, 10mg/kg every 4 weeks vs. placebo 20 58 3 (2 to 5)
Intravenous infusion of infliximab, 10mg/kg every 8 weeks vs. placebo 20 52 4 (3 to 6)

References

  1. N Engl J Med. 20 May 1999; 340: 1533-8 
  2. Can J Infect Con. 2000; Spring: 9-14 
  3. Lancet. Dec 4, 1999; 354: 1932-9 
Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Benign prostatic hyperplasia1 Finasteride vs. placebo Surgery for BPH 4 years 10.1 4.6 18 (13 to 27)
Acute urine retention 6.6 2.8 27 (19 to 43)
Urinary incontinence in women2 Bladder training or pelvic muscle exercises with biofeedback assisted instruction vs. combined bladder training plus pelvic muscle exercises Frequency of self reported incontinence 3 months 13 31 5 (3 to 23)
Perceived symptom improvement 30 52 4 (3 to 20)

References

  1. N Engl J Med. 26 Feb 1998; 338: 557-63 
  2. Am J Obstet Gynecol. Oct 1998; 179: 999-1007 
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