Guideline Adherence and Subjective Effects of a Mobile Clinical Decision Support System on Physicians' Practice: A Nationwide Survey-Based Within-Subject Study

Study DesignCross-sectional, within-subject observational study using a nationwide survey of physicians. ObjectiveTo evaluate whether recent use of a mobile Clinical Decision Support System (CDSS) is associated with physicians perceived clinical update, adherence to guideline-based recommendations, and confidence in decision-making across common clinical conditions. MethodsBetween March and May 2025, 1,055 Brazilian physicians--active users of the Afya Whitebook(R) mobile CDSS--completed two standardized clinical vignettes each, randomly drawn from eight prevalent diseases covering acute and chronic conditions. Exposure was defined as self-reported consultation of the CDSS within the previous 24 hours. Primary outcomes included perceived clinical update (Likert 1-5), guideline-concordant decision (binary), and confidence in decision-making (Likert 1-5). Fixed-effects regressions with clustered standard errors at the participant level were applied, controlling for clinical case type and individual heterogeneity. ResultsA total of 4,220 responses were analyzed (1,054 CDSS; 3,166 control). Recent CDSS use was associated with higher perceived update ({beta} = 0.22; 95% CI 0.12-0.32; p < 0.001), greater likelihood of guideline-concordant answers ({beta} = 0.22; 95% CI 0.05-0.39; p = 0.013), and higher confidence ({beta} = 0.12; 95% CI 0.04-0.20; p = 0.003), with consistent effects across conditions and subgroups. ConclusionBrief, real-world exposure to a mobile CDSS yielded small but meaningful improvements in both cognitive and affective dimensions of clinical practice, extending beyond decision accuracy to perceived confidence and sense of update. These findings highlight CDSS as complementary tools that reinforce evidence-based care while fostering continuous learning and professional assurance in everyday clinical decision-making. Key messagesO_LIWhat is already known on this topic: Clinical Decision Support Systems (CDSS) improve adherence to evidence-based guidelines and reduce medical errors. However, their immediate and subjective effects--such as physicians perceived update and confidence--remain poorly understood. C_LIO_LIWhat this study adds: This nationwide within-subject study provides empirical evidence that recent use of a mobile CDSS (Afya Whitebook(R)) is associated with modest but statistically significant improvements in perceived clinical update, decision accuracy, and confidence. These findings expand understanding of the proximal cognitive and affective effects of CDSS use in everyday medical practice. C_LIO_LIHow this study might affect research, practice or policy: CDSS may contribute not only to evidence-aligned decisions but also to a more positive professional experience. These effects should inform digital health strategies aimed at improving care quality and clinician well-being. C_LI