ASSOCIATION OF DEPRESSION WITH HOSPITAL LENGTH OF STAY AND 90-DAY READMISSION FOLLOWING TOTAL KNEE ARTHROPLASTY

Purpose: Hospital readmission and length of stay (LOS) following total knee arthroplasty (TKA) account for substantial resource consumption and may serve as measures of efficiency and care quality. Psychiatric comorbidities may impact post-surgical outcomes and potentially readmission. This study evaluated whether patients undergoing TKA were at increased risk for long LOSs or 90-day readmission if they had co-occurring depression.

Method(s): We analyzed cohort data from the population-based California Healthcare Cost and Utilization Project (HCUP) database from 2007-2010 (n=131,634) for primary TKA discharges in adults ages 50+. We evaluated predictors of hospital LOS, the difference in days between date of admission and date of discharge, using negative binomial regression to model effect(s) of covariates of interest on LOS; we also fit a logistic regression model to predict a binary outcome of “long stay” (top 5% of stays). Finally, we used logistic regression to predict odds of 90-day readmission following TKA. We included demographics (age, sex, race/ethnicity, Medicaid insurance as proxy for low income), comorbidities (including depression), and admission year.

Result(s): Median LOS was 3 days, with a mean of 3.4 days (sd=1.7 days). Overall 90-day readmission rate was almost 17%. A depression diagnosis was associated with a significantly longer LOS (1.05 times longer: 95% CI: 1.04-1.06) and odds of 90-day readmission (OR: 1.21 95%CI:1.13-1.29). LOS and odds of readmission increased with age, as high as 1.15 (95% CI: 1.14-1.17) times longer for those over age 80 than the reference category of 50-54 year olds. There was a significantly longer LOS and odds of readmission associated with being Black compared to White (OR: 1.11; 95% CI: 1.10-1.12 for LOS; OR:1.36, 95%CI: 1.10-1.66 for readmission) and being insured with Medicaid compared to other insurance types (OR: 1.22; 95% CI: 1.20-1.24 for LOS; OR:1.39; 95%CI:1.12-1.73 for readmission). 

Conclusion(s): Even after controlling for other chronic conditions and non-modifiable covariates, we found significant associations of depression with longer LOS and readmission rates. Promoting care coordination across disciplines for the management of patients’ non-orthopedic comorbidities prior to surgery, particularly in higher risk patients with depression, could have a positive influence on orthopedic surgery outcomes, patient overall well-being, and ultimately healthcare resource utilization.