A frailty index to predict the mortality risk in a population of senior Mexican adults.

Background: Frailty in the elderly can be regarded as nonspecific vulnerability to adverse health outcomes, caused by multiple factors. The aim was to analyze the relationships between the frailty index, age and mortality in a two year follow up study of Mexican elderly.
Methods: A frailty index was developed using 34 variables. To obtain the index, the mean of the total score for each individual was obtained. Survival analyses techniques were used to examine the risk ratios for the different levels of the frailty index. Kaplan-Meier estimates were obtained, adjusted for age and gender. Cox proportional hazards models were also built to obtain hazard ratio estimates.
Results: A total of 4082 participants was analyzed. Participants had an average age of 73 years and 52.5% were women. On average, participants were followed-up for 710 days (standard deviation = 111 days) and 279 of them died. Mortality increased with the frailty index level, especially in those with levels between .21 to .65, reaching approximately 17% and 21%, respectively. Cox proportional hazards models showed that participants with frailty index levels associated to increased mortality (.21 and higher) represent 24.0% of those aged 65-69 years and 47.6% of those 85 and older.
Conclusion: The frailty index shows the properties found in the other studies, it allows stratifying older Mexican into several groups different by the degree of the risk of mortality, and therefore the frailty index can be used in assessing health of elderly.