Relationship Between Diabetes Codes That Affect Medicare Reimbursement (Tier Comorbidities) and Outcomes in Stroke Rehabilitation

Graham JE, Ripsin CM, Deutsch A, Kuo Y-F, Markello S, Granger CV, Ottenbacher KJ. Relationship between diabetes codes that affect Medicare reimbursement (tier comorbidities) and outcomes in stroke rehabilitation. Objectives: To examine the extent to which diabetes codes that increase reimbursement (tier comorbidities) under the prospective payment system are related to length of stay and functional outcomes in stroke rehabilitation. Design: Secondary data analysis. Setting: Inpatient rehabilitation facilities (N=864) across the United States. Participants: Patients (N=135,097) who received medical rehabilitation for stroke in 2002-2003. Intervention: None. Main Outcome Measures: Length of stay, FIM instrument, and discharge setting. Diabetes status was assigned to 1 of 3 categories: tier (increases reimbursement), nontier (no reimbursement effect), and no diabetes. Results: Mean ± standard deviation age of the sample was 70.4±13.4 years, and 31% had diabetes (6% tier, 25% nontier). Diabetes status by age demonstrated significant (P<.05) interaction effects, which lead to the following age-specific findings. In younger stroke patients (60y), tier diabetes was associated with shorter lengths of stay compared with both groups, lower FIM discharge scores compared with both groups, and lower odds of discharge home relative to the no-diabetes group. In older stroke patients (80y), tier diabetes was associated with longer lengths of stay compared with both groups and with higher FIM discharge scores compared with the nontier group. Conclusions: The diabetes-related conditions identified as tier comorbidities under the prospective payment system are significant predictors of stroke rehabilitation outcomes, but these relationships are moderated by patient age.