Readmission Rates After Total Hip Arthroplasty

Abstract

To the Editor: Dr Cram and colleagues reported a decrease in hospital length of stay (LOS) with an increase in readmission for the Medicare population undergoing total hip arthroplasty between 1991 and 2008. The authors concluded that modifications in reimbursement should be made to incentivize “the correct LOS, rather than perpetual reductions in LOS that seem to be occurring.” Although such reimbursement modifications may be beneficial, the results reported do not justify these conclusions. From 1991 to 2000, there was a rapid decrease in LOS (9.1 days to 4.5 days) and decreased rates of 30-day and 90day all-cause readmission rates (30-day: 5.9% to 4.8%). The later period (2001-2008) saw an increase in readmission rates (30-day: 4.6% to 8.5%) with a slight decrease in LOS (4.4 days to 3.7 days). During this time, the number of comorbidities for patients undergoing total hip arthroplasty increased. If the authors are correct in their assumption that the data set is not biased by changes in diagnostic coding practices, then the reported increase in obesity (1.4% to 4.7%) and renal failure (0.8% to 6.1%) may be a more probable explanation for the increased readmission rate. The authors missed an opportunity to perform a direct correlation of LOS and readmission rates. With the data set available, a multivariable analysis assessing the independent effects of LOS on readmission would have been interesting. The literature on the relationship of LOS and readmission rates in the Medicare population is sparse. The available reports provide evidence that current LOS practices do not increase readmission. Bozic et al reported that higher annual procedure volume among surgeons was associated with shorter LOS and lower readmission rates following total joint replacement surgery. In a multicenter analysis, Weingarten et al provided evidence that implementation of practice guidelines that shortened LOS did not increase 30-day readmission rates for knee or hip replacements. With a significant increase in total hip arthroplasty projected, the study by Cram et al was timely and necessary but not definitive. Because of the potential effect on quality and cost of care, future research is crucial to identify the causes of escalating rates of readmission.