Assessment of Comorbidity Burden and its Association With Functional Rehabilitation Outcome After Stroke or Hip Fracture: A Systematic Review and Meta-Analysis.

BACKGROUND: A well-grounded functional prognosis during triage for rehabilitation is important, especially in older patients who experience the burden of comorbidity. However, it remains unclear what impact comorbidity has on functional outcome after rehabilitation. AIM: To investigate the associations between comorbidity indexes and functional outcome after inpatient stroke or hip fracture rehabilitation. Furthermore, to identify which method of comorbidity assessment best reveals this relationship. DESIGN: Systematic review and meta-analysis. METHODS: An extensive search in PubMed, EMBASE, COCHRANE, Web of Science, and CINAHL of cited references and gray literature was carried out on March 4, 2016. This meta-analysis was conducted in agreement with the guidelines for Preferred Reporting Items for Systematic reviews and Meta-Analyses. Studies were included if participants were adult patients with a stroke or hip fracture, participants received inpatient rehabilitation, comorbidity was assessed with a valid index, and functional status was an outcome measure. Two reviewers independently extracted data; according to the predefined data extraction plan, included studies were independently evaluated on risk of bias. RESULTS: Twenty studies were eligible for review, and 7 studies were included in the meta-analysis. The pooled correlation between comorbidity and functional status at discharge was -0.43 [-0.69; -0.06]. Presence and strength of correlations differed between comorbidity indexes. Charlson index: range = 0.0 to -0.88 and 0%-1% explained variance (%var). Cumulative illness rating scale (CIRS) total or cumulative: range = -0.02 to -0.34 and unknown %var. CIRS-severity index: range = -0.25 to -0.40 and 12-16 %var. Comorbidity-severity index: range = -0.39 and -0.47 and 5 %var. Liu index: range = -0.28 to -0.50 and 4-7 %var. When the index contained a severity weighting, the associations were more evident. CONCLUSIONS: An association between comorbidity burden and functional outcome exists, albeit modest. Assessment of severity weighted comorbidity is preferred for estimating the functional prognosis after stroke and hip fracture rehabilitation.