Functional Assessment for Surgery by a Timed Walk (FAST Walk) study: protocol for a multicentre prospective cohort study of the 6 min walk test for preoperative risk stratification in major non-cardiac surgery

INTRODUCTION: Poor cardiopulmonary fitness is an important risk factor for postoperative complications, yet a feasible, objective and prognostically accurate method to assess preoperative fitness has not been established. The 6 min walk test (6MWT) is a simple, inexpensive and widely applicable measure that shows promise for predicting postoperative risk. However, robust data are lacking on whether the 6MWT accurately predicts complications, provides incremental prognostic value beyond routinely collected clinical factors or outperforms simpler alternatives such as questionnaires, cardiac biomarkers or grip strength testing. The Functional Assessment for Surgery by a Timed Walk (FAST Walk) study is designed to address these knowledge gaps by evaluating whether the 6MWT improves prediction of key postoperative outcomes compared with clinical factors and simpler measures of fitness. METHODS AND ANALYSIS: The FAST Walk study is an international multicentre prospective cohort study of 1672 adults (≥40 years) undergoing major elective non-cardiac surgery at centres in Canada, Hong Kong, Australia, Spain and the Netherlands. Participants complete a preoperative 6MWT and baseline assessments of comorbidities, self-reported cardiopulmonary fitness (MET: Re-evaluation for Perioperative Cardiac Risk questionnaire), biomarkers (N-terminal pro-B-type natriuretic peptide) and grip strength. The primary outcome is 30-day death or major postoperative complication, defined as Clavien-Dindo grade II or higher. Secondary outcomes are (1) death or new significant disability at 90 days after surgery and (2) days alive and out of hospital at 30 days after surgery. Disability is measured using the short-form WHO Disability Assessment Schedule 2.0 instrument. Multivariable regression models and complementary metrics of prediction performance will be used to determine whether 6MWT distance adds prognostic value beyond routinely collected clinical factors and simpler measures of fitness. ETHICS AND DISSEMINATION: The FAST Walk study has received research ethics board approval at all participating sites. Recruitment commenced in June 2024, with completion of participant follow-up expected in 2026. Findings will be disseminated through peer-reviewed publications and conference presentations, with the primary results anticipated in 2027. TRIAL REGISTRATION NUMBER: NCT06412367.