Importance: Inaccurate clinician expectations of the benefits and harms of interventions can profoundly influence decision making and may be contributing to increasing intervention overuse.
Objective: To systematically review all studies that have quantitatively assessed clinicians' expectations of the benefits and/or harms of any treatment, test, or screening test.
Evidence Review: A comprehensive search strategy of 4 databases (MEDLINE, EMBASE, Cumulative Index of Nursing and Allied Health Literature, and PsycINFO) from the start years to March 17-20, 2015, with no language or study type restriction, was performed. Searches were also conducted on cited references of the included studies, and experts and study authors were contacted. Two researchers independently evaluated methodologic quality and extracted participants' estimates of benefit and harms and authors' contemporaneous estimates.
Findings: Of the 8166 records screened, 48 articles (13 011 clinicians) were eligible. Twenty studies focused on treatment, 20 on medical imaging, and 8 on screening. Of the 48 studies, 30 (67%) assessed only harm expectations, 9 (20%) evaluated only benefit expectations, and 6 (13%) assessed both benefit and harm expectations. Among the studies comparing benefit expectations with a correct answer (total of 28 outcomes), most participants provided correct estimation for only 3 outcomes (11%). Of the studies comparing expectations of harm with a correct answer (total of 69 outcomes), a majority of participants correctly estimated harm for 9 outcomes (13%). Where overestimation or underestimation data were provided, most participants overestimated benefit for 7 (32%) and underestimated benefit for 2 (9%) of the 22 outcomes, and underestimated harm for 20 (34%) and overestimated harm for 3 (5%) of the 58 outcomes.
Conclusions and Relevance: Clinicians rarely had accurate expectations of benefits or harms, with inaccuracies in both directions. However, clinicians more often underestimated rather than overestimated harms and overestimated rather than underestimated benefits. Inaccurate perceptions about the benefits and harms of interventions are likely to result in suboptimal clinical management choices.