Missing BMI Data

In fully adjusted regression, missing BMI was associated with increased odds of emergency presentation for colon cancer but not for rectal cancer. Patients with missing BMI were younger, less deprived, and had fewer comorbidities. Among colon cancer patients, missing BMI was associated with lower endoscopy percentage and higher emergency presentation percentage. Sensitivity analyses showed little change when individual comorbidities replaced the Charlson Comorbidity Index or when BMI was measured within three rather than six years before diagnosis. Standard multiple imputation was not considered appropriate because BMI data were likely missing not at random.