BackgroundDespite the advancements in knowledge about health care for older adults, essential gaps persist regarding the effects of chronic diseases as epidemiological markers of the state of functional dependence. This study aimed to identify the prevalence of moderate and severe functional dependence in Brazilian older adults and its association with chronic diseases and verify the multimorbidity patterns by dependence status.MethodsThis cross-sectional analytical study used data from 11,177 community-dwelling Brazilian older adults from the 2013 National Health Survey conducted in Brazil. The dependent variables were moderate and severe functional dependence in basic activities of daily living (BADLs) and instrumental ADLs (IADLs). The independent variables were defined based on the questions applied to measure each morbidity in a self-reported manner and asked, "Has a doctor ever diagnosed you as having (each disease)? Multimorbidity was simultaneously considered present for older adults with ≥ 2 chronic morbidities. The association between functional dependence on BADLs and IADLs separately by severity and the independent variables was verified from crude and adjusted estimates of the point prevalence ratios and their 95% confidence intervals using the regression model Poisson with robust variance. To group diseases into patterns, exploratory factor analysis was used.ResultsThe prevalences of moderate and severe BADL dependence were 10.2% (95% CI, 9.6–10.7) and 4.8% (95% CI, 4.4–5.2), respectively. Moderate and severe IADL dependence prevalences were 13.8% (95% CI, 13.1–14.4) and 15.6% (95% CI, 14.9%–16.2), respectively. When changing the condition from moderate to severe dependence in BADLs, in the presence of other mental illnesses and stroke, the probability of dependence increased more than four times in the case of other mental illnesses and more than five times for stroke. There was a linear trend for dependence severity, both moderate and severe, whereas, for severe dependence on IADLs, this same factor maintained a linear trend toward an increase in probability as the number of diseases simultaneously increased.ConclusionsChronic diseases are associated with functional dependence, with greater emphasis on mental illnesses and stroke in severe disability, considering their acute adverse effects.