Diabesity: a superadded effect contributing to worse total primary hip replacement operative outcomes for patients with diabetes and obesity

INTRODUCTION: Although the independent effects of diabetes mellitus and obesity on total hip replacement (THR) outcomes have been widely studied, their combined effect remains uncharacterised. This study aimed to assess the influence of diabesity on primary THR operative outcomes.

MATERIALS AND METHODS: A retrospective study was performed comparing the outcomes of patients with diabesity (diabetes mellitus and obesity [BMI ≥ 30]) with a control cohort after primary THR using an established arthroplasty database. Data were collected pre-operatively and 12 months post-operatively, including Oxford Hip Score (OHS), EuroQol 5-dimensions (EQ5D), post-operative satisfaction and complication rates.

RESULTS: 2323 THRs were analysed, of which 94 (4%) had diabesity. Diabesity was independently associated with significantly worse OHS improvement post-operatively (- 1.85 points, 95% CI - 2.93 to - 0.76, p = 0.001). This reduction in addition to the independent effect of obesity (- 0.69 points, 95% CI - 1.18 to - 0.21, p = 0.005) resulted in an overall 2.54 point OHS reduction for patients with diabesity. Diabesity was not associated with EQ5D score change or post-operative satisfaction. Diabesity was independently associated with a worse pre-operative EQ5D score (-0.08 points, 95% CI -0.12 to -0.03, p = 0.002). When combining the associated risk of obesity (Odds Ratio (OR) 1.71, 95% CI 1.15-2.54, p = 0.008) with the superadded effect of diabesity (OR 2.37, 95% CI 1.19-4.71, p = 0.014) the rate of superficial wound infection post-operatively was significantly increased (OR 4.05, 95% CI 1.38-11.95). Obesity was associated with a significantly increased risk of deep infection (OR 3.67, 95% CI 1.55-8.68, p = 0.003), but no additive effect of diabetes was found.

CONCLUSIONS: Diabesity confers a superadded effect over established associations between THR outcomes and obesity and diabetes individually. Patients with diabesity experience worse improvement in hip-specific functional outcome, worse post-operative quality of life, and an increased risk of superficial and deep wound infection following THR.