PopulationsHumans1,299 individualsCohort study

Comorbidity link to hospital disability fades with frailty

Comorbidity was linked to hospital disability in nonfrail patients (OR 1.44), but the association attenuated with mild frailty (OR 1.11) and disappeared in frail adults (OR 0.98).

Figure 1 from Journal of the American Medical Directors Association — Figure 1Umegaki et al.

Journal of the American Medical Directors Association4 Oct 2026, 08:05 BST

Researchers analyzed data from 1,299 hospitalized older adults aged 65 years and older admitted to acute care hospitals in Japan. The retrospective multicenter cohort study evaluated comorbidity burden using the Charlson Comorbidity Index and categorized baseline frailty with the Clinical Frailty Scale. Hospital-associated disability was defined as a decline of at least 5 points on the Barthel Index during hospitalization. After adjusting for age, sex, and cognitive function, higher comorbidity was associated with higher odds of disability in nonfrail patients (OR, 1.44; 95% CI, 1.20–1.73). However, this association attenuated in the mildly frail group (OR, 1.11; 95% CI, 0.91–1.35) and was not observed in the frail group (OR, 0.98; 95% CI, 0.90–1.06).

Why it matters

The findings suggest that multimorbidity loses its predictive relevance for acute functional decline as physiological vulnerability increases. This supports incorporating frailty assessments into risk frameworks rather than relying solely on comorbidity counts.

Caveats

The study used a retrospective observational design, which cannot establish causality. Additionally, the analysis was limited to older patients in acute care hospitals in Japan, and 300 of the original 1,599 individuals were excluded from the final analytic sample.