Common conditions and preventive interventions across primary care
| ACUTE SYMPTOMS | LONG-TERM SYMPTOMATIC CONDITIONS | CVD (PRIMARY PREVENTION) | CANCER SCREENING (CANCER-SPECIFIC MORTALITY) | SOCIAL SCREENING OR HEALTH PROMOTION |
|---|---|---|---|---|
| Headache15: ASA or sumatriptan, NNT = 5 to 9 to be pain free at 2 hours | Depression16: antidepressants, NNT = 7 to 9 for response in 6 weeks | Statin17–20: NNT = 55 to 77 over 5 years (any CVD) | Mammogram21,22: NNS = 377 to 2000 over 10 years | Alcohol screening23: No evidence of benefit in heaviest drinkers |
| Knee osteoarthritis24: intra-articular steroid, NNT = 3 to 5 for global improvement over 4 weeks | Chronic neuropathic pain25,26: duloxetine or gabapentin, NNT = 6 to 8 at 3 months for reduction of ≥ 50% | Metformin in diabetes27: NNT = 29 over 5 years (myocardial infarction) | Fecal immunochemical testing28: NNS = 1200 over 10 years (assumed similar to fecal occult blood testing) | Counseling on increased physical activity (single interventions)29–31: insufficient evidence of benefit |
| Gout32: colchicine, NNT = 5 for ≥ 50% symptom free at 24 hours | Headache33,34: tricyclic antidepressant or β-blocker, NNT = 4 to 8 over 6 months for reduction of 50% | ASA35: NNT = 346 to 427 over 5 years (any CVD) | Prostate-specific antigen36–38: NNS = 441 to 1410 over 10 years | Family violence screening39: increased awareness but insufficient evidence for improved outcomes |
| Benign positional vertigo40: Epley maneuver, NNT = 3 for symptom resolution | Constipation (chronic)41: polyethylene glycol, NNT = 2 to 3 for resolution over 6 months | Hypertension (≥ 160 mm Hg)42,43: treated, NNT = about 20 over 5 years (any CVD) | Cervical cancer44,45: NNS unknown (but 1 in 500 women die of cervical cancer when screened every 3 years compared with 1 in 100*) | Screening for obesity46,47: no evidence of improved outcomes (about 3 kg of weight loss with behavioural programs at 1 y; no evidence of improved patient outcomes) |
ASA—acetylsalicylic acid, CVD—cardiovascular disease, NNS—number needed to screen, NNT—number needed to treat.
↵* Data are based largely on national cohort and case-control studies that demonstrate a strong association between the introduction of screening and reduced incidence of cervical cancer. One cluster randomized controlled trial from rural India shows a 0.35 relative reduction in mortality with a 1-time screen.