Evaluation of Multimorbidity Burden in Frailty Transitions in Costa Rican Older Adults Using Multistate Markov Models

The accumulation of non-communicable chronic diseases is recognized to play a crucial role in the deterioration of health in older adults, partly because it may impact frailty states. This study assessed the influence of multimorbidity on the phenotype transitions in frailty over time and frailty-related mortality risk.

Data from the Costa Rican Longevity and Healthy Aging Study Cohort (2005-2010) was used. A total of 2660 individuals aged 60 and above were included. Multimorbidity was defined as having three or more non-communicable diseases from 13 chronic conditions. Fried criteria were employed to assess frailty states (robust, pre-frail, frail). Markov-based multistate models were used to examine the impact of multimorbidity on frailty transitions and mortality over 5 years.

Multimorbidity accelerates the transition to frailty. Compared to those with fewer than three non-communicable diseases, individuals with both multimorbidity and a prefrail state had a lower chance of recovering to robustness (HR:0.73 [95% CI: 0.54-0.99]), and a higher risk of becoming frail (HR:1.83 [95% CI: 1.43-2.34]). This translates into a 30-month earlier onset of frailty compared to individuals without chronic diseases. Multimorbidity increased the risk of all-cause mortality in those who were pre-frail (HR:1.83 [95% CI: 1.43-2.34]) but did not affect mortality risk in those who were already frail (HR:0.88 [95% CI: 0.62-1.23]).

Multimorbidity is a predictor for dynamic transitions to frailty or death. It favors the transition to "Frailty" more than to death and impacts mortality mostly in people with a "Pre-frail" state, encouraging them to explore opportunities for intervention.