The psychological harms of screening: the evidence we have versus the evidence we need.

Background: Systematic reviews for the US Preventive Services Task Force have found less high-quality evidence on psychological than physical harms of screening. To understand the extent of evidence on psychological harms, we developed an evidence map that quantifies the distribution of evidence on psychological harms for five adult screening services. We also note gaps in the literature and make recommendations for future research.

Methods: We systematically searched PubMed, PsycInfo, and CINAHL from 2002 to 2012 for studies of any research design that assessed the burden or frequency of psychological harm associated with screening for: prostate and lung cancers, osteoporosis, abdominal aortic aneurysm (AAA) and carotid artery stenosis (CAS). We also searched for studies that estimated rates of overdiagnosis (a marker for unnecessary labeling). We included studies published in English and used dual independent review to determine study inclusion and to abstract information on design, types of measures, and outcomes assessed.

Results: Sixty-eight studies assessing psychological harms met our criteria; 62 % concerned prostate cancer and 16 % concerned lung cancer. Evidence was scant for the other three screening services. Overall, only about one-third of the studies used both longitudinal designs and condition-specific measures (ranging from 0 % for AAA and CAS to 78 % for lung cancer), which can provide the best evidence on harms. An additional 20 studies that met our criteria estimated rates of overdiagnosis in lung or prostate cancer. No studies estimated overdiagnosis for the non-cancer screening services.

Discussion: Evidence on psychological harms varied markedly across screening services in number and potential usefulness. We found important evidence gaps for all five screening services. The evidence that we have on psychological harms is inadequate in number of studies and in research design and measures. Future research should focus more clearly on the evidence that we need for decision making about screening.