Trade-off between benefit and harm is crucial in health screening recommendations. Part I: General principles

Department of Pediatrics, University of the Philippines Manila, Ermita, Manila, Philippines.
Journal of clinical epidemiology (Impact Factor: 5.48). 03/2011; 64(3):231-9. DOI: 10.1016/j.jclinepi.2010.09.009
Source: PubMed

ABSTRACT Health screening is defined as the use of a test or a series of tests to detect unrecognized health risks or preclinical disease in apparently healthy populations to permit prevention and timely intervention. A health screening strategy consists of the sequence of a screening test, confirmatory test(s), and finally, treatment(s) for the condition detected. The potential benefits of health screening are easy to understand, but the huge potential for physical and psychological harm is less well recognized. Thus, health screening should only be recommended when five criteria are satisfied: (1) the burden of illness should be high, (2) the tests for screening and confirmation should be accurate, (3) early treatment (or prevention) must be more effective than late treatment, (4) the test(s) and treatment(s) must be safe, and (5) the cost of the screening strategy must be commensurate with potential benefit. Direct evidence from screening trials is subject to less bias. In some instances, indirect evidence may be acceptable, e.g., when the condition screened for is a risk factor for a disease rather than the disease itself.

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    ABSTRACT: To assess how often harm is quantified in randomised trials of cancer screening. Two authors independently extracted data on harms from randomised cancer screening trials. Binary outcomes were described as proportions and continuous outcomes with medians and interquartile ranges. For cancer screening previously assessed in a Cochrane review, we identified trials from their reference lists and updated the search in CENTRAL. For cancer screening not assessed in a Cochrane review, we searched CENTRAL, Medline, and Embase. Randomised trials that assessed the efficacy of cancer screening for reducing incidence of cancer, cancer specific mortality, and/or all cause mortality. Two reviewers independently assessed articles for eligibility. Two reviewers, who were blinded to the identity of the study's authors, assessed whether absolute numbers or incidence rates of outcomes related to harm were provided separately for the screening and control groups. The outcomes were false positive findings, overdiagnosis, negative psychosocial consequences, somatic complications, invasive follow-up procedures, all cause mortality, and withdrawals because of adverse events. Out of 4590 articles assessed, 198 (57 trials, 10 screening technologies) matched the inclusion criteria. False positive findings were quantified in two of 57 trials (4%, 95% confidence interval 0% to 12%), overdiagnosis in four (7%, 2% to 18%), negative psychosocial consequences in five (9%, 3% to 20%), somatic complications in 11 (19%, 10% to 32%), use of invasive follow-up procedures in 27 (47%, 34% to 61%), all cause mortality in 34 (60%, 46% to 72%), and withdrawals because of adverse effects in one trial (2%, 0% to 11%). The median percentage of space in the results section that reported harms was 12% (interquartile range 2-19%). Cancer screening trials seldom quantify the harms of screening. Of the 57 cancer screening trials examined, the most important harms of screening-overdiagnosis and false positive findings-were quantified in only 7% and 4%, respectively.
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