Abstract
Background
Increasing national expenditures and use associated with TKA have resulted in pressure to reduce costs through various reimbursement cuts. However, within the arthroplasty literature, few studies have examined the association of medical comorbidities on resource use and length of stay after joint arthroplasty.
Questions/purposes
The purpose of this study was to examine the association between individual patient characteristics (including demographic factors and medical comorbidities) on resource allocation and length of stay (LOS) after TKA.
Methods
We queried the 2009 Nationwide Inpatient Sample dataset for International Classification of Diseases, 9th Revision code, 81.54, for TKAs. An initial 621,029-patient cohort was narrowed to 516,745 after inclusion of elective TKAs on patients aged between 40 and 95 years. Using generalized linear models, we estimated the effect of comorbidities on resource use (using cost-to-charge conversions to estimate hospital costs) and the LOS controlling for patient and hospital characteristics. Across the 2009 national cohort with TKAs, 12.7% had no comorbidities, whereas 32.6% had three or more. The most common conditions included hypertension (67.8%), diabetes (20.0%), and obesity (19.8%). Mean hospital costs were USD 14,491 (95% confidence interval [CI], 14,455–14,525) and mean hospital LOS was 3.3 days (95% CI, 3.29–3.31) in this data set.
Results
Patients with multiple comorbidities were associated with increased resource use and LOS. Higher marginal costs and LOS were associated with patients who had an inpatient death (USD +8017 [95% CI, 8006–8028], +2.3 [CI, 2.15–2.44] days over baseline), patients with recent weight loss (USD +4587 [95% CI, 4581–4593], +1.5 [CI, 1.45–1.61) days], minority race (USD +1037 [95% CI, 1035–1038], +0.3 [CI, 0.28–0.33] days), pulmonary-circulatory disorders (USD +3218 [95% CI, 3214–3221], +1.3 [CI, 1.25–1.34] days), and electrolyte disturbances (USD +1313 [95% CI, 1312–1314], +0.6 [CI, 0.57–0.60] days). All p values were < 0.001.
Conclusion
Multiple patient comorbidities were associated with additive resource use and LOS after TKA. Current reimbursement may not adequately account for these patient characteristics. To avoid potential loss of access to care for sicker patients, payment needs to be adjusted to reflect actual resource use.
Level of Evidence
Level IV, economic and decision analysis. See the Instructions for Authors for a complete description of levels of evidence.
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Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
The study examined inpatient admissions in 2009 using the National Inpatient Sample (NIS) Database, Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality. The HCUP and the hospitals participating in the NIS Program are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request.
Each author certifies that his or her institution approved or waived approval for the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
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Pugely, A.J., Martin, C.T., Gao, Y. et al. Comorbidities in Patients Undergoing Total Knee Arthroplasty: Do They Influence Hospital Costs and Length of Stay?. Clin Orthop Relat Res 472, 3943–3950 (2014). https://doi.org/10.1007/s11999-014-3918-x
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DOI: https://doi.org/10.1007/s11999-014-3918-x