Regional variability in the rates of total hip replacement in Spain

The role of economic resources, distribution of providers, and demography may explain part of the variability found in hip arthroplasty in international surveys. We aimed to investigate the influence of ageing index, health budget, and density of orthopaedic surgeons in the regional variability of the primary and revision THR rate in Spain, where regions decide on the allocation of their health budget.

Inpatient database of hip procedures for years 1997 to 2011 was obtained from the Spanish Ministry of Health, segregated for each of the 17 regional health services in Spain. Crude and adjusted rates (direct method with total Spanish population per year) were calculated and used as dependent variables. Ageing index, Health Expenditure of Gross Domestic Product (GDP), and number of orthopaedic surgeons per region were used as independent variables. Negative binomial regression analysis model and Poisson regression were calculated to estimate the risk contribution of the ecological variables.

A total of 425,914 hip procedures, with 367,489 primary (mean crude rate = 124 × 10⁵ inhabitants/year) and 58,425 revision hips (21 × 10⁵ inhabitants/year) were included in the analysis. Regional variability was higher than expected in THR in Spain, despite a universal coverage health system in which equity may be challenged in the administration of hip arthroplasty. This was found particularly for primary THR. When hip replacement rates were adjusted for sex and age, the regional ageing index, the density of orthopaedic surgeons and the regional health budget could only partially explain risk ratio changes.