Determinants of functional outcome in hip fracture: the role of comorbidity

Background and aims Executed studies did not clearly identify which index of comorbidity was an independent outcome determinant. The aim of this prospective observational cohort study was to address this issue. Methods We analyzed 200 consecutive patients with hip fracture. All patients underwent rehabilitation. At admission comorbidity was assessed through the cumulative severity, severity index, and comorbidity index of the Cumulative Illness Rating Scale. Discharge scores and effectiveness in the Functional Independence Measure motor subscale, and discharge destination were the outcome measures. Multivariate regression analyses were performed to identify determinants of outcome. Results Mini Mental State Examination and comorbidity index of the Cumulative Illness Rating Scale were important independent determinants of final (respectively, β = 0.46 and −0.25) and effectiveness (respectively, β = 0.47 and −0.25) in motor Functional Independence Measure scores, while hip strength and Rankin score were determinants of final motor Functional Independence Measure score (respectively, β = 0.21 and −0.20). Comorbidity index of the Cumulative Illness Rating Scale (odds ratio 8.18 for ≥3 versus < 3 comorbidity score; 95% confidence interval, 1.03–64.7) and Geriatric Depression Scale (odds ratio 4.02 for ≥6 versus ≤5 depression scale score; 95% confidence interval, 1.52–10.63) were risk indicators for nursing home. Conclusions Among the indices of the Cumulative Illness Rating Scale, comorbidity index is the sole independent determinant of both motor Functional Independence Measure scores and discharge destination in hip fracture patients. This suggests to specifically evaluate this index to identify the patients who may be admitted to a rehabilitation program.