Body Surface Area and Early Surgical Outcomes Following Coronary Artery Bypass Grafting: A Retrospective Cohort Study

Ruan Vlok

Background

Body Mass Index (BMI) has been shown to be associated with an obesity paradox in cardiothoracic surgical patients mortality. This is important, as it is commonplace to recommend weight loss pre-operatively.  Body Surface Area (BSA) has been shown to be a better predictor of coronary artery calcium than BMI. This study aims to be better explain the association between BSA and early post-coronary artery bypass graft outcomes.

Methods

This was a single-center retrospective cohort study of 2259 patients who underwent isolated on-pump coronary artery bypass grafting (CABG) from June 2000 to May 2013 at an Australian Hospital. Multivariate regression analyses were used to analyse the association between both BSA and BMI and surgical outcomes. Primary outcomes included 30 day mortality and length of stay. Secondary outcomes included ICU length of stay, return to theatre, prolonged ventilation and wound infections.

Results

Multiple regression demonstrated an association between length of stay and BSA (t2094= 2.20; p = 0.028), with a one point increase in BSA associated with a 1.6 fold increase in length of stay (coefficient 1.64, SE 0.74). BSA was not significantly associated with mortality at 30 days (t2094= -0.57; p= 0.567).

Conclusions

BSA was associated with an increased length of hospital stay but not 30 day mortality. This is in keeping with the obesity paradox for mortality but suggests that complications are higher in patients with higher BSAs.