• Article

Comparing Comorbidity Indices to Predict Post-Acute Rehabilitation Outcomes in Older Adults

Objective: Compare 5 comorbidity indices to predict community discharge and functional status following postYacute rehabilitation.

Design: This was a retrospective study of Medicare beneficiaries with stroke, lower-extremity fracture, and joint replacement discharged from inpatient rehabilitation in 2011 (N = 105,275). Community discharge and self-care, mobility, and cognitive function were compared using the Charlson, Elixhauser, Tier, Functional Comorbidity, and Hierarchical Condition Category comorbidity indices.

Results: Of the patients, 64.4% were female, and 84.6% were non-Hispanic white. Mean age was 79.3 (SD, 7.5) years. Base regression models including sociodemographic and clinical variables explained 56.6%, 42.2%, and 23.0% of the variance (R-2) for discharge self-care; 47.4%, 30.9%, and 18.6% for mobility; and 62.0%, 55.3%, and 37.3% for cognition across the 3 impairment groups. R2 values for self-care, mobility, and cognition increased by 0.2% to 3.3% when the comorbidity indices were added to the models. The base model C statistics for community discharge were 0.58 (stroke), 0.61 (fracture), and 0.62 (joint replacement). The C statistics increased more than 25% with the addition of discharge functional status to the base model. Adding the comorbidity indices individually to the base model resulted in C-statistic increases of 1% to 2%.

Conclusion: Comorbidity indices were poor predictors of community discharge and functional status in Medicare beneficiaries receiving inpatient rehabilitation.


Kumar, A., Graham, J. E., Resnik, L., Karmarkar, A. M., Tan, A., Deutsch, A., & Ottenbacher, K. J. (2016). Comparing Comorbidity Indices to Predict Post-Acute Rehabilitation Outcomes in Older Adults. American Journal of Physical Medicine & Rehabilitation, 95(12), 889-898. DOI: 10.1097/PHM.0000000000000527, 10.1097/phm.0000000000000527