Impact of body mass index on total cost of trauma and elective spine surgical procedures at a quaternary spinal referral centre

Abstract

Background: Evidence surrounding obesity concludes it places a significant burden on the healthcare sector. Our objective was to quantify the financial impacts of obesity, specifically the relationship between body mass index (BMI) and total cost of spinal surgery. The links between BMI and length of stay, readmission and theatre times were explored. It was predicted that with increasing obesity, total cost would increase. Methods: Retrospective review of patients that received spinal surgery at Middlemore Hospital between 1 October 2017 and 30 November 2019. Data were collected on patient demographics, procedure details, total cost, as well as potential variables (trauma, acute/elective, surgical complexity, readmissions, comorbidities, injury severity). Data were fitted using linear and generalized linear models, with BMI fitted using natural splines. Results: Obesity prevalence in South Auckland was reflected in the study population of 533, with the average BMI being 30.16. Results for BMI less than or equal to 24, and above 48, were statistically significant (P = 0.037, 95% CI). Total cost increased on either side of BMI 33.1. BMI 18 had 60% increase in total cost (95% CI (17, 118)) and BMI 55 of 38.3% (95% CI (À8.3, 109)). Positive associations were found with increasing BMI and induction time and readmission rate respectively. The relationship between BMI and length of stay and other variables were not significant. Conclusion:The relationship between BMI and total cost is non-linear and there is an increase in induction time with higher BMI patients.