Underreporting contextual factors preclude the applicability appraisal in primary care randomized controlled trials.

Objectives: To assess applicability reporting in randomized controlled trials (RCTs) conducted in primary care (PC).

Study Design And Setting: We used a random sample of PC RCTs published between 2000 and 2020 to assess applicability. We extracted data related to setting, population, intervention (including implementation), comparator, outcomes, and context. Based on data availability, we assessed whether the five predefined applicability questions were adequately addressed by each PC RCT.

Results: Adequately described elements that were reported frequently (>50%) included the responsible organization for intervention provision (97, 93.3%), study population characteristics (94, 90.4%), intervention implementation including monitoring and evaluation (92, 88.5%), intervention components (89, 85.6%), time frame (82, 78.8%), baseline prevalence (58, 55.8%), and the type of setting and location (53, 51%). Elements that were often underreported included contextual factors, that is, evidence of differential effects across sociodemographic or other groupings (2, 1.9%), intervention components tailored for specific settings (7, 6.7%), health system structure (32, 30.8%), factors affecting implementation (40, 38.5%) and organization structure (50, 48.1%). The proportion of trials that adequately addressed each applicability question ranged between 1% and 20.2%, while none RCT could address all of them.

Conclusion: Underreporting contextual factors jeopardize the appraisal of applicability in PC RCTs.