To study the medical and financial outcomes associated with surgery in the elderly obese patient and ask if obesity itself influences outcomes above and beyond effects from comorbidities known to be associated with obesity.
Obesity is a surgical risk factor not present in Medicare’s risk adjustment or payment algorithms, as BMI is not collected in administrative claims.
2045 severely or morbidly obese patients (BMI ≥ 35 kg/m2, age between 65 and 80) selected from 15,914 elderly patients in 47 hospitals undergoing hip and knee surgery, colectomy, and thoracotomy were matched to two sets of 2045 non-obese patients (BMI = 20 – 30 kg/m2). A “limited match” controlled for age, sex, race, procedure and hospital. A “complete match” also controlled for 30 additional factors such as diabetes and admission clinical data from chart abstraction.
Mean BMI in the obese was 40kg/m2 versus 26kg/m2 in the non-obese. In the complete match, obese patients displayed increased odds of wound infection: OR = 1.64 (95% CI 1.21, 2.21); renal dysfunction: OR = 2.05(1.39, 3.05); urinary tract infection: OR = 1.55 (1.24, 1.94); hypotension: OR = 1.38 (1.07, 1.80); respiratory events: OR = 1.44 (1.19, 1.75); 30-day readmission: OR = 1.38 (1.08, 1.77); and a 12% longer length of stay (8%, 17%); Provider costs were 10% (7%, 12%) greater in the obese than non-obese, while Medicare payments increased only 3% (2%, 5%). Findings were similar in the limited match.
Obesity increases the risks and costs of surgery. Better approaches are needed to reduce these risks. Furthermore, to avoid incentives to under-serve this population, Medicare should consider incorporating incremental costs of caring for obese patients into payment policy and include obesity in severity adjustment models.