Table 4.
Comparison of number needed to screen in primary prevention of death
| Disease | Prevalence of untreated disease | Screen (treatment) | No needed to screen for 5 years (95% CI)† |
|---|---|---|---|
| Total mortality | |||
| Dyslipidaemia | 0.26 | Lipid profile (pravastatin) | 418 (235 to 79 720)* |
| Lipid profile (diet) | 590 (292 to −610) | ||
| Lipid profile (resin) | 846 (325 to −799) | ||
| Hypertension | 0.18 | Sphygmomanometer (diuretics) (diastolic blood pressure decrease 10) | 274 (165 to 1546)* |
| Sphygmomanometer (diuretics) (diastolic blood pressure decrease 6) | 1307 (834 to 3386)* | ||
| Sphygmomanometer (β blockers) | 1961 (106 to −105) | ||
| Coronary artery disease | Question (aspirin) | 354 (155 to −795) | |
| Colon cancer | Haemoccult (standard) | 3034 (157 to −145) | |
| Breast cancer | Mammography (standard) | −11 029 (1369 to −967) | |
| Cancer specific mortality | |||
| Colon cancer | Haemoccult (standard) | 1374 (955 to 2802)* | |
| Breast cancer: | |||
| Age 60-69 | Mammography (standard) | 1251 (853 to 3058)* | |
| Age 50-59 | Mammography (standard) | 2451 (1576 to 7651)* | |
| Age 40-49 | Mammography (standard) | 8054 (3522 to −11587) | |
*
Statistically significant.
†
Only mortality trial errors taken into account; errors in quit rates not included (negative number indicates screening increased mortality).