OBESITY INCREASES THE RISK OF POSTOPERATIVE COMPLICATIONS AND REVISION RATES AFTER PRIMARY TOTAL HIP ARTHROPLASTY: AN ANALYSIS OF 131 576 TOTAL HIP ARTHROPLASTY CASES

Abstract

The presence of obesity has negative influence on the progress of osteoarthritis and increases the risk of undergoing a primary THA at an earlier age. However, the correlation of BMI and the risk for postoperative complications, revision surgery and infection rate is still controversial. In the largest cohort to this date, we used the German insurance claims database to evaluate the correlation of BMI and the risk of postoperative complications, mortality and revision rates following primary THA.

Using nationwide billing data of the German health-care insurance for inpatient hospital treatment, we identified patients over the age of 20 years who had undergone either THA or short-stem THA between January 2012 and December 2014. BMI was classified into four groups (< 30 kg/m², 30 to 34.9 kg/m², 35 to 39.9 kg/m², > 40 kg/m²). In all patients, the 90-day complication, mortality and revision rates were calculated. Furthermore, all complications and revisions were determined at a latest follow-up of 1 year. We used multivariable logistic regression to model the odds of complications as a function of BMI groups. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated.

A total of 131,576 total hip arthroplasties in 124,368 patients were included for final analysis. BMI had a significant effect on risk adjusted 1-year overall complications, 1-year revision surgery and 90-day surgical complications. The adjusted odd ratios increased significantly with BMI category. Especially morbidly obese patients with a BMI >40 kg/m² had a threefold higher risk for deep infection and a two-fold higher risk for the overall complication and revision rates as compared to patients with a BMI <30 kg/m².

Obesity plays an important role in patients undergoing primary THA, especially patients with a BMI beyond 40 kg/m² have a markedly higher risk for revision surgery and overall complication rates. This study aims to increase awareness among physicians in order to improve risk stratifications and to better educate patients with regard to obesity and postoperative expectations prior to undergoing elective total hip arthroplasty.