Trends in primary total hip arthroplasty in Spain from 2001 to 2008: Evaluating changes in demographics, comorbidity, incidence rates, length of stay, costs and mortality

Background: Hip arthroplasties is one of the most frequent surgical procedures in Spain and are conducted mainly in elderly subjects. We aim to analyze changes in incidence, co-morbidity profile, length of hospital stay (LOHS), costs and in-hospital mortality (IHM) of patients undergoing primary total hip arthroplasty (THA) over an 8-year study period in Spain. Methods: We selected all surgical admissions in individuals aged >= 40 years who had received a primary THA (ICD-9-CM procedure code 81.51) between 2001 and 2008 from the National Hospital Discharge Database. Age-and sex-specific incidence rates, LOHS, costs and IHM were estimated for each year. Co-morbidity was assessed using the Charlson comorbidity index. Multivariate analysis of time trends was conducted using Poisson regression. Logistic regression models were conducted to analyze IHM. Results: We identified a total of 161,791 discharges of patients having undergone THA from 2001 to 2008. Overall crude incidence had increased from 99 to 105 THA per 100.000 inhabitants from 2001 to 2008 (p < 0.001). In 2001, 81% of patients had a Charlson Index of 0, 18.4% of 1-2, and 0.6% > 2 and in 2008, the prevalence of 1-2 or > 2 had increased to 20.4% and 1.1% respectively (p < 0.001). The mean LOHS was 13 days in 2001 and decreased to 10.45 days in 2008 (p < 0.001). During the period studied, the mean cost per patient increased from 6,634 to 9,474 Euros. Multivariate analysis shows that from 2001 to 2008 the incidence of THA hospitalizations has significantly increased for both sexes and only men showed a significant reduction in IHM after THA. Conclusions: The current study provides clear and valid data indicating increased incidence of primary THA in Spain from 2001 to 2008 with concomitant reductions in LOHS, slight reduction IHM, but a significant increase in cost per patient. The health profile of the patient undergoing a THA seems to be worsening in Spain.