Body mass index and in-hospital postoperative complications following primary total hip arthroplasty

Background: The influence of obesity measured in terms of body mass index (BMI) on the complication rates following total hip arthroplasty (THA) is a matter of debate. Methods: This retrospective study conducted at a tertiary referral centre at Brisbane, Australia, examines the association between BMI and in-hospital postoperative complications, length of operating time and duration of hospital stay in 964 patients, who underwent THA from 2006 to 2010. Results: Amongst patients undergoing primary THA, when compared to the normal weight patients, those with BMI between 25 kg/m 2 and 29.9 kg/m 2 (overweight) and those with BMI between 35 kg/m 2 and 39.9 kg/m 2 (obese class II) had lower odds of perioperative complications (odds ratio [OR]: 0.62 (95% confidence intervals [CI], 0.43–0.92, p = 0.016) and OR: 0.60 (95% CI, 0.36– 0.99, p = 0.047 respectively). Patients with BMI less than or equal to 40 kg/m 2 were also associated with significantly lower odds of cardiac complications ( p = 0.02). With unadjusted regression analysis, it was noted that those with BMI ≥40 kg/m 2 had the highest odds of developing infectious complications (OR 2.68, 95% CI, 1.08–6.65, p < 0.05). As the BMI increased, there was a statistically significant increase in length of operating time ( p < 0.001). Conclusion: There is a significant impact of BMI on the occurrence of perioperative complications following THA. Compared to normal weight category, the overweight and obese class II patients had a lower likelihood of developing overall, especially cardiac complications. Length of operating time increases along with an increase in BMI.