Modeling the impact of obesity on cost of hip and knee arthroplasty

PURPOSE: This study aimed to determine the proportions of total knee arthroplasty (TKA) and total hip arthroplasty (THA) attributable to obesity in Ireland and the associated hospital costs. METHODS: Sex- and age-specific numbers of primary TKA and THA procedures and length of stay were estimated using Irish population data from the Central Statistics Office (sex and age) and data from the national Hospital Inpatient Enquiry (numbers of TKA and THA procedures, length of stay, diagnostic-related group codes, sex, and age). Population attributable fractions of TKA and THA related to obesity were calculated using relative risks for different weight groups obtained from published literature. Nationally representative weight and height data were available from the 2015 Healthy Ireland Survey (n = 6142) and extrapolated to the Irish population. Diagnostic-related group tariffs from the Healthcare Pricing Office were used to estimate hospital costs of TKA and THA. RESULTS: In 2015, 2296 TKA and 3411 THA procedures were performed in public hospitals in Ireland. Of those procedures, 43% of TKA and 20% of THA were attributable to obesity. This equates to €16.0 million out of €52.1 million of TKA- and THA-related hospital costs. CONCLUSIONS: Effective obesity control has potential to decrease the demand for joint replacements and associated costs.