Patients with lupus use healthcare resources at a higher rate and experience longer hospital stays after primary total knee arthroplasty (TKA), according to data published in Rheumatology.

Researchers identified patients with lupus who underwent primary TKA to determine whether these patients experience more complications or healthcare use compared with patients without lupus who undergo primary TKA.

Investigators collected data from the US National Inpatient Sample from 1998 to 2014. Primary study outcomes were healthcare use and in-hospital, postoperative complications; researchers assessed healthcare use by the length of hospital stay, total hospital charges, and discharge disposition. They evaluated postoperative complications as secondary diagnoses, including implant infection, implant revision, blood transfusion, and mortality.

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The study cohort included data from 8,127,282 primary TKA procedures; 30,912 of these were performed on patients with lupus. Mean cohort age was 66.4±0.03 years. Nearly two-thirds (63%) of patients were women, 68% were white, and 97% of patients had an underlying diagnosis of osteoarthritis.

Overall, complication rates were very low: 0.1%, for implant infection, 0.2% for implant revision, and 0.1% for death, respectively; 16% of patients required a blood transfusion.

Mean and median length of hospital stay was 3.53±0.01 days and 2.7 days, respectively; mean and median total hospital charges were $42,336±$235 and $35,891. Mean and median hospital charges and length of hospital stay were higher in patients with lupus.

Multivariable-adjusted analyses independently associated lupus with a significantly higher risk for transfusion (odds ratio [OR] 1.34; 95% CI, 1.25-1.42), but no significant differences in implant infection (OR 1.38; 95% CI, 0.73-2.6) or revision (OR 1.35; 95% CI, 0.83-2.19) or mortality (OR 0.83; 95% CI, 0.34-2.03) were noted.

In addition, patients with lupus were significantly more likely to have higher total hospital charges (OR 1.42; 95% CI, 1.22-1.66), a longer length of hospital stay (>3 days; OR 1.09; 95% CI, 1.04-1.15), and were more likely to be discharged to an inpatient facility (OR 1.34; 95% CI, 1.27-1.41).

Study limitations include an inability to perform a longitudinal data analysis, the exclusion of simultaneous bilateral TKA from the data, and a lack of data from military or Veteran’s Affairs hospitals, meaning that findings cannot be generalized to these patient populations.

“Future studies need to evaluate the reasons for higher health care utilization in patients with lupus and whether implant survival and pain/function outcomes differ at longer-term follow-up post-TKA,” concluded the researchers.

Singh reported several financial relationships, including consultancy fees and stock options.

Reference

Singh JA. Total knee arthroplasty outcomes in lupus: a study using the US National Inpatient Sample [published online May 23, 2019]. Rheumatology. doi:10.1093/rheumatology/kez176