Reference value models for predicting preoperative six-minute walk test in patients scheduled for abdominal and pelvic cancer surgery

Preoperative assessment of functional capacity with the six-minute walk test (6MWT) allows for estimation of surgical risk and targeted triage to prehabilitation services. Patient with abdominal and pelvic cancers have worse preoperative function compared with the general population. However, six-minute walk distance (6MWD) reference values from cancer patients are unknown, which limits the interpretation of 6MWT in this population. This study aimed to establish an explanatory reference value model for preoperative 6MWD in patients with abdominal or pelvic cancers undergoing elective surgery. Adult patients undergoing surgery for abdominal or pelvic cancers at major international hospitals were included. The 6MWT was assessed before surgery using a standardised protocol. Anthropometric data including age, sex, height, weight and body mass index (BMI) were collected and included in multiple linear regression analysis to model preoperative 6MWD. A total of 742 patients were included. Age, height and BMI were correlated with 6MWD. Six regression models were estimated, including two from the entire cohort, two from the subset of males and two from the subset of females. A sex-neutral model was the most representative, explaining 15% of the variance in 6MWD (6MWD = 761.00–3.00 * Age (years) –2.86 * BMI (kg/m 2 ) – 48.09 * Sex (M1, F2)). The explored regression models, using anthropometric variables, poorly explained the variance between measured and modelled 6MWD, which suggests that these models have no clinical utility in the cancer population. Consideration of additional, non-anthropometric variables may improve regression modelling of preoperative 6MWD in patients in abdominal and pelvic cancers.