Clinical characteristics and outcomes of Medicare patients undergoing total hip arthroplasty, 1991-2008.

CONTEXT: Total hip arthroplasty is a common surgical procedure but little is known about longitudinal trends.

OBJECTIVE: To examine demographics and outcomes of patients undergoing primary and revision total hip arthroplasty.

DESIGN, SETTING, AND PARTICIPANTS: Observational cohort of 1,453,493 Medicare Part A beneficiaries who underwent primary total hip arthroplasty and 348,596 who underwent revision total hip arthroplasty. Participants were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes for primary and revision total hip arthroplasty between 1991 and 2008.

MAIN OUTCOME MEASURES: Changes in patient demographics and comorbidity, hospital length of stay (LOS), mortality, discharge disposition, and all-cause readmission rates.

RESULTS: Between 1991 and 2008, the mean age for patients undergoing primary total hip arthroplasty increased from 74.1 to 75.1 years and for revision total hip arthroplasty from 75.8 to 77.3 years (P < .001). The mean number of comorbid illnesses per patient increased from 1.0 to 2.0 for primary total hip arthroplasty and 1.1 to 2.3 for revision (P < .001). For primary total hip arthroplasty, mean hospital LOS decreased from 9.1 days in 1991-1992 to 3.7 days in 2007-2008 (P = .002); unadjusted in-hospital and 30-day mortality decreased from 0.5% to 0.2% and from 0.7% to 0.4%, respectively (P < .001). The proportion of primary total hip arthroplasty patients discharged home declined from 68.0% to 48.2%; the proportion discharged to skilled care increased from 17.8% to 34.3%; and 30-day all-cause readmission increased from 5.9% to 8.5% (P < .001). For revision total hip arthroplasty, similar trends were observed in hospital LOS, in-hospital mortality, discharge disposition, and hospital readmission rates.

CONCLUSION: Among Medicare beneficiaries who underwent primary and revision hip arthroplasty between 1991 and 2008, there was a decrease in hospital LOS but an increase in the rates of discharge to postacute care and readmission.