Added Comorbidities Lengthens Hospitalization, Hikes TKA Costs

Research is linking additional patient comorbidities to increases in hospital length of stay and charges for total knee arthroplasty.

“We used the 2009 [National Inpatient Sample] NIS database to evaluate primary total knee arthroplasty (TKA) and found the average hospital costs were $14,500, mean charges were $49,000 and the mean hospital stay was 3.3 days. Both costs and length of stay rise dramatically with increases in patient comorbidity,” Andrew J. Pugely, M.D., said. “The current reimbursement schemes may not adequately account for these multiple comorbidity patients, and as payments continue to decline, it is imperative that policymakers look to provide fair adjustments to reimbursements after total knee arthroplasty. Otherwise, we fear restrictions in access to care may occur.”

Using ICD-9 codes, researchers identified 621,000 patients who underwent primary TKA in 2009. Pugely noted information in the database allows for conversion of hospital charges to hospital costs. After obtaining costs, the investigators used linear models to calculate the effect of patient characteristics on costs and length of stay.

They found 12 percent of patients had no comorbidities, while a third of patients had three or more comorbidities. The most common were hypertension, diabetes and obesity.

“Baseline costs were about $14,500, but patients with zero comorbidities cost less at $13,700 and those with seven or more comorbidities were $5,000 more with $17, 700,” Pugely said. “With each successive comorbidity, there was a statistically significant increase in cost. The same trend was true for hospital length of stay.”

He noted patients without comorbidities had a length of stay of 2.9 days, while patients with seven comorbidities or more stayed nearly two days longer.