A parallel group randomized controlled trial using a superiority framework. Clinical vignettes will be used to assess the impact of a large language model on the clinical reasoning of physicians. Quantitative analyses will be performed on graded vignette responses.

This study is a multi-country, parallel-group randomized controlled trial designed to evaluate whether access to a large language model (LLM) improves physician clinical decision-making. The trial uses a superiority framework and compares physicians randomized to either complete standardized clinical vignettes with access to GPT-4o or without any AI assistance.

Clinical vignettes simulate common primary care conditions such as cardiovascular, respiratory, musculoskeletal, fatigue-related, and infectious diseases. Each vignette includes multiple steps in the clinical reasoning process, from initial history-taking to diagnosis, treatment, and follow-up. Physician responses are graded using rubrics developed from evidence-based, context-specific best-practice guidelines.

The study is conducted across three countries-Indonesia, Kenya, and the Netherlands-representing different income levels and health system contexts. The primary outcome is performance on clinical vignettes, defined as adherence to best-practice guidelines. Secondary objectives include examining cross-country variation in physician performance, variation in performance distributions, and the role of engagement with the LLM in shaping outcomes.

Inclusion Criteria:

• Registered medical physicians
• Training in internal or family medicine

Exclusion Criteria:

• Not currently practicing clinically