Abstract 3130: Body Mass Index and Risk of Adverse Cardiac Events in Elderly Hip Fracture Patients: A Population-Based Study
Background: Obesity is protective for the development of hip fractures yet a risk factor for cardiac disease. Whether obesity impacts cardiac complications following hip fracture repair is unknown.
Methods: We performed a population-based, historical study of patients undergoing urgent hip fracture repair in 1988–2002 in Olmsted County, Minnesota, using the Rochester Epidemiology Project. Body mass index (BMI) was categorized as underweight (<18.5kg/m2), normal (18.5–24.9kg/m2), overweight (25.0–29.9kg/m2) and obese (≥30kg/m2). Postoperative cardiac complications were defined as myocardial infarction, angina, congestive heart failure, or new-onset arrhythmias within one-year of surgery. Incidence rates were estimated for each outcome and overall cardiac complications were assessed using Cox proportional hazard models, adjusted for age, sex, year of surgery, use of beta-blockers and the Revised Cardiac Risk Index.
Results: There were 184 (15.6%) underweight, 640 (54.2%) normal, 251 (21.3%) overweight, and 105 (8.9%) obese hip fracture repairs (mean age, 84.2±7.5 years; 80% female). Baseline American Society of Anesthesia status was similar among all groups (ASA I/II vs. III–V, p=0.14). Underweight patients had a significantly higher risk of developing myocardial infarction (odds ratio [OR] 1.44; 95%CI 1.0–2.1; p=0.05) and arrhythmias (OR 1.59; 95%CI:1.0–2.4;p=0.04) than normal BMI patients. Multivariate analysis demonstrated underweight patients had a higher risk of developing an adverse cardiac event of any type (OR 1.56; 95%CI:1.22–1.98; p<0.001). Overweight and obese hip fracture patients had no excess risk of any cardiac complication.
Conclusions: Our results suggest that the obesity paradox and low functional reserve in underweight patients may influence the development of post-operative cardiac events in the frail elderly hip fracture population.
This research has received full or partial funding support from the American Heart Association, AHA Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota & Wisconsin).