Does screening for disease save lives in asymptomatic adults? Systematic review of meta-analyses and randomized trials

Background: Several popular screening tests, such as mammography and prostate-specific antigen, have met with wide controversy and/or have lost their endorsement recently. We systematically evaluated evidence from randomized controlled trials (RCTs) as to whether screening decreases mortality from diseases where death is a common outcome. Methods: We searched three sources: United States Preventive Services Task Force (USPSTF), Cochrane Database of Systematic Reviews, and PubMed. We extracted recommendation status, category of evidence and RCT availability on mortality for screening tests for diseases on asymptomatic adults (excluding pregnant women and children) from USPSTF. We identified meta-analyses and individual RCTs on screening and mortality from Cochrane and PubMed. Results: We selected 19 diseases (39 tests) out of 50 diseases/disorders for which USPSTF provides screening evaluation. Screening is recommended for 6 diseases (12 tests) out of the 19. We assessed 9 non-overlapping meta-analyses and 48 individual trials for these 19 diseases. Among the results of the meta-analyses, reductions where the 95% confidence intervals (Cis) excluded the null occurred for four disease-specific mortality estimates (ultrasound for abdominal aortic aneurysm in men; mammography for breast cancer; fecal occult blood test and flexible signnoidoscopy for colorectal cancer) and for none of the all-cause mortality estimates. Among individual RCTs, reductions in disease-specific and all-cause mortality where the 95% Cls excluded the null occurred in 30% and 11% of the estimates, respectively. Conclusions: Among currently available screening tests for diseases where death is a common outcome, reductions in disease-specific mortality are uncommon and reductions in all-cause mortality are very rare or non-existent.