Mortality after primary total hip arthroplasty has declined somewhat over time, and mortality after revision arthroplasty has remained stable, according to a report in the April 20 issue of JAMA.
In the 18-year longitudinal study of Medicare data, both of these reassuring trends occurred despite a substantial increase in patient complexity, said Dr. Peter Cram of the University of Iowa, Iowa City.
However, two concerning trends also were noted: The number of total hip arthroplasty patients discharged to postacute care facilities (such as nursing homes and rehabilitation centers) instead of to home increased substantially, and the number of hospital readmissions following total hip arthroplasty rose markedly.
Dr. Cram and his colleagues noted that objective evaluations of total hip arthroplasty outcomes are lacking in the literature. It is generally assumed that increasing experience with the procedure has inevitably produced better patient outcomes, "but rigorous empirical data documenting such improvement are limited."
They assessed trends in patient outcomes using data on Medicare fee-for-service beneficiaries who underwent primary (1,453,493 patients) or revision (348,596 patients) total hip arthroplasties over an 18-year period. "More than 60% of all total hip arthroplasty procedures are performed on Medicare enrollees, making this an appropriate data set for studying" the surgery.
During 1991-2008, the medical complexity of patients who underwent these procedures increased. For primary arthroplasty, the mean patient age rose from 74 to 75 years, the prevalence of diabetes more than doubled from 7% to 15%, and the prevalence of obesity more than tripled from 2% to 7%. The prevalence of heart failure climbed from just under 3% to just over 4%, and that of renal failure rose tenfold, from 0.4% to 4%. The mean number of comorbid conditions doubled from one to two.
Despite the increasing patient complexity, the mean 30-day mortality for primary total hip arthroplasty dropped from 0.7% to 0.3% during this interval, and mean 90-day mortality decreased from 1.3% to 0.7%, the investigators said (JAMA 2011;305:1560-7).
For revision hip arthroplasty, which often is done in an emergent setting, 30-day mortality remained steady at approximately 2% and 90-day mortality was steady at 4.5% throughout the study period.
For primary hip arthroplasty, hospital length of stay also decreased approximately 60% over time, from 9.1 days to 3.7 days. But this trend is not as encouraging as it appears to be at first glance, because the number of patients discharged to home declined dramatically, whereas the proportion discharged to skilled or intermediate care facilities approximately doubled.
In addition, the 30-day readmission rate, which some consider a gauge of the inappropriateness of a short length of stay (LOS), also rose markedly from 5.9% to 8.5%. The patterns were similar for revision hip arthroplasty, Dr. Cram and his associates said.
These LOS findings "may have policy implications." Hospitals clearly are motivated "to reduce LOS under the Medicare prospective payment system," but these results indicate that the practice is not benefiting patients.
This study was supported by the National Center for Research Resources, the Robert Wood Johnson Physician Faculty Scholars Program, and the National Heart, Lung, and Blood Institute. No financial conflicts of interest were reported.