A comorbidity prognostic effect on post-hospitalization outcome in a geriatric rehabilitation setting: the pivotal role of functionality, assessed by mediation model, and association with the Brass index

Background Discharge planning is a critical feature of hospital’s care in geriatric rehabilitation centers. The aim of this study was to evaluate the effects of comorbidity and functionality in identifying patients who are at risk of discharge problems. We also evaluate the association between Blaylock Risk Assessment Screening Score, BRASS index (BI), and post-hospitalization outcome (PHO). Methods Eighty patients (58 women and 22 men, with mean age equal to 83.28 ± 6.77 years) at geriatric rehabilitation division admission were screened with Geriatric Multidimensional Assessment (GMA). Then, BI and PHO were evaluated (mean follow-up time was 205.1 ± 95.8 days). By Structural Equation Model, we evaluated the existing causal relationships between comorbidity, functionality and PHO, elements of GMA, and the association between PHO and BI. Results Comorbidity acted on PHO through functionality with indirect effect only (+0.703, P = 0.019). So, the functionality assumes a pivotal role of the causal relationship comorbidity to PHO. BI is positively associated with PHO: correlation returned was equal to +0.313 ( P = 0.019). Conclusions The comorbidity has a role in getting worse PHO, but its effect is possible only through the mediation of functional status. The study also demonstrated the positive association between BI and PHO.