Association of waist circumference with outcomes in an acute general surgical unit

Obesity prevalence is increasing in Australia, particularly in non-metropolitan areas. The effect of obesity on acute surgical outcomes is not known. We aimed to record waist circumference (WC) (surrogate for obesity) amongst acute surgical unit (ASU) patients in a New South Wales regional hospital, and compare outcome measures (length of stay (LOS), unplanned return to theatre, readmission rates, intensive care unit (ICU) admission and mortality).

Retrospective cohort study of 4 months of consecutive ASU admissions, excluding age <16, pregnancy, out-of-area transfer and incomplete data. Patients were classified according to World Health Organization WC definitions as high-risk or non-high-risk (increased-risk and no-risk).

Of 695 admissions, 512 met the inclusion criteria (47.1% female, average age 52.8 years (SD 22.3)), with 85.1% (P < 0.001) of females and 69.4% (P = 0.166) of males having an increased- or high-risk WC. This compares to rates amongst inner regional populations of 71.0% (female) and 66.4% (male). LOS was longer for high-risk patients (5.0 days versus 3.7 days, P = 0.002). However, the mean age of high-risk patients was greater (56.6 years versus 46.9 years, P = 0.001) and LOS was longer for those aged ≥60 (P < 0.001). After controlling for age, high-risk WC was not associated with any outcome measure, except amongst ICU admissions, where high-risk patients stayed longer (15.5 days versus 6.8 days, P < 0.001).

Increased- and high-risk WC was overrepresented amongst female ASU patients. High-risk WC was associated with a significantly greater LOS in patients admitted to ICU. High-risk WC was not associated with other outcomes independent of age. WC is useful for quantifying obesity in the inpatient setting.