title: Trends in incidence and outcomes of revision total hip arthroplasty in Spain: a population based study.
abstract: BACKGROUND
  To analyze changes in incidence and outcomes of patients undergoing revision total hip arthroplasty (RTHA) over an 8-year study period in Spain.
  
  
  METHODS
  We selected all surgical admissions in individuals aged ≥ 40 years who underwent RTHA (ICD-9-CM procedure code 81.53) between 2001 and 2008 from the Spanish National Hospital Discharge Database. Age- and sex-specific incidence rates, Charlson co-morbidity index, length of stay (LOS), costs and in-hospital mortality (IHM) were estimated for each year. Multivariate analyses were conducted to asses time trends.
  
  
  RESULTS
  32,280 discharges of patients (13, 391 men/18, 889 women) having undergone RTHA were identified. Overall crude incidence showed a small but significant increase from 20.2 to 21.8 RTHA per 100, 000 inhabitants from 2001 to 2008 (p < 0.01).The incidence increased for men (17.7 to 19.8 in 2008) but did not vary for women (22.3 in 2001 and 22.2 in 2008). Greater increments were observed in patients older than 84 years and in the age group 75-84. In 2001, 19% of RTHA patients had a Charlson Index ≥ 1 and this proportion rose to 24.6% in 2008 (p < 0.001). The ratio RTHA/THA remained stable and around 20% in Spain along the entire period. The crude overall in-hospital mortality (IHM) increased from 1.16% in 2001 to 1.77% (p = 0.025) in 2008. For both sexes the risk of death was higher with age, with the highest mortality rates found among those aged 85 or over. After multivariate analysis no change was observed in IHM over time. The mean inflation adjusted cost per patient increased by 78.3%, from 9, 375 to 16, 715 Euros from 2001 to 2008.After controlling for possible confounders using Poisson regression models, we observed that the incidence of RTHA hospitalizations significantly increased for men and women over the period 2001 to 2008 (IRR 1.10, 95% CI 1.03-1.18 and 1.08, 95% CI 1.02-1.14 respectively).
  
  
  CONCLUSIONS
  The crude incidence of RTHA in Spain showed a small but significant increase from 2001 to 2008 with concomitant reductions in LOS, significant increase in co-morbidities and cost per patient.
authors.affiliation: Orthopedic Department, Hospital Gregorio Marañon, Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Villanueva-Martınez
authors.forename: Valentın
authors.initials: V
authors.lastname: Hernandez-Barrera
authors.forename: Francisco
authors.initials: F
authors.lastname: Chana-Rodríguez
authors.forename: José
authors.initials: J
authors.lastname: Rojo-Manaute
authors.forename: Antonio
authors.initials: A
authors.lastname: Rıos-Luna
authors.forename: Jesus
authors.initials: J
authors.lastname: San Roman Montero
authors.forename: Angel
authors.initials: A
authors.lastname: Gil-de-Miguel
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Jimenez-Garcia
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000191:economics / Q000401:mortality / Q000639:trends*; D016009:Chi-Square Distribution; D015897:Comorbidity; D017046:Cost Savings; D016208:Databases, Factual / Q000639:trends; D005260:Female; D017721:Hospital Costs / Q000639:trends; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D015994:Incidence; D007902:Length of Stay / Q000639:trends; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010043:Outcome and Process Assessment, Health Care / Q000639:trends*; D010351:Patient Discharge / Q000639:trends; D011183:Postoperative Complications / Q000453:epidemiology; D012086:Reoperation; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013030:Spain / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome