The phenomenon of “obesity paradox” in neck of femur fractures

Abstract

Objective: To determine the association of body mass index (BMI) with 30 days and 1-year mortality outcomes of orthopedic elderly patients after hip fracture surgery. Methods: This is prospective study conducted at Department of Orthopaedics, at a tertiary care public sector hospital in Karachi between Jan-2016 to Jan-2018. In this short follow-up study, we included the data of 490 patients, who were operated for neck of femur fractures in a public sector tertiary care hospital between Jan-2016 to Jan-2018. Patients were divided into different categories on the basis of BMI; BMI <20 Kg.m-2 underweight, 20-24.99 Kg.m-2 normal weight, BMI 25-29.99 Kg.m-2 overweight, ≥30 obese. Mortality at 30 days and 1-year mortality were primary study end-points. Results: Rate of re-admission within 30 days, major adverse cardiovascular events (MACE) within 30 days and 30 days mortality was high in underweight and lowest in obese patients. Thirty-day mortality rate was 2.7% in underweight, 1.3% in normal weight, 0.64% in over-weight and 0.0% in obese patients but this was not significant statistically (p-value 0.29). One-year mortality rate was significantly high in under-weight patients, 34.2%, 25.9% in normal weight, 21.4% in overweight and only 14.5% in obese patients (p-value 0.009). Age ≥ 65 years (odds ratio 0.40 (0.26-0.63), and ASA III-IV (odds ratio; 0.27 (0.16-0.45) are also significant risk factors of 1-year mortality Conclusion: BMI classification can serve as an important indicator of adverse early outcomes after hip fracture surgery. Over-weight and obese patients have better survival outcomes and have lower 1-year mortality rate.