SPIROS 2023 (Standardized Protocol Items Recommendations for Observational Studies) is a guideline for the minimum content of an observational study protocol. We have defined the scope of the recommendations to cover three main observational study designs: cohort, case-control, and cross-sectional studies.

The SPIROS 2023 checklist recommends a full description of what is planned; it does not prescribe how to design or conduct an observational study. By providing guidance for key content, the SPIROS recommendations aim to facilitate the drafting of high-quality observational study protocols. Adherence to SPIROS would enhance the transparency and completeness of observational study protocols for the benefit of researchers, study participants, patients, sponsors, funders, research ethics committees or institutional review boards, peer reviewers, journals, research registries, policymakers, regulators, students, and other key stakeholders.

The SPIROS 2023 Statement includes a 37-item checklist (Table 1) covering six main domains namely (1) general information, (2) introduction, (3) methods, (4) ethical consideration, (5) Reporting and dissemination and (6) others. An associated explanatory paper (SPIROS 2023: Explanation and Elaboration) details the rationale and supporting evidence for each checklist item, along with guidance and model examples from existing protocols. We hope that the SPIROS statement will stimulate the research community to keep writing protocols of observational studies and to improve their quality and transparency.