2012 Annual Conference

Galloway, Rebecca

University of Texas Medical Branch, Galveston, TX

Although most patients with debility, or deconditioning, return to the community after inpatient rehabilitation, 11% discharge to acute care and 19% are re-hospitalized within 30 days (Medicare data, 2006 – 2009).  Comorbidity, a relevant and complex risk factor, can be measured by different methods.  The purpose of this study was to compare common comorbidity variables by discharge setting for older adults with deconditioning. 

73,821 patients were from 1,240 inpatient rehabilitation facilities. Mean age was 81 years (SD 7.1), 59% were female, and 88% were white. Mean length of stay (LOS) was 12 days (SD 5.0).

This retrospective study utilized Centers for Medicare and Medicaid Services data from 2006 through 2009.  Criteria included: inpatient rehabilitation admission for debility, age 66 to 100 years, LOS 3 to 30 days, and fee-for service Medicare.  Comorbidity variables included: Charlson Comorbidity Index (CCI), Case Mix Group (CMG) Comorbidity Tier, and total comorbidity count.  Discharge setting was grouped as acute, sub-acute, or community (reference group). 

Components of comorbidity measures were examined for face validity in the context of an older adult population with deconditioning.  Analyses included: univariate statistics and frequency distributions for comorbidity measures, Kruskal-Wallis and rank-sum tests for discharge group differences, logistic regression for odds of discharge to acute care, and Spearman correlations among comorbidity measures.

Maximum total comorbidity count of 10 was documented for 28% of cases.  There were significant differences in comorbidity among discharge groups (p < .0001).  Those discharged to acute care had the highest comorbidity.  Higher quartiles were associated with higher odds of discharge to acute care for CCI and CMG Comorbidity Tier.  Comorbidity measures were weakly correlated (r_s = 0.14 – 0.28, p < .0001).

Patients with deconditioning who discharged to acute care had higher comorbidity than those who returned to community living.  CCI and CMG Comorbidity Tier are standardized comorbidity measures that can be incorporated into multivariate risk models.

Selection of appropriate comorbidity variables is fundamental for comprehensive risk factor analysis, particularly for older adults with multiple medical conditions.