Predictors of Frailty Transitions in Mexican Older Adults.

BACKGROUND: Frailty is a dynamic state in older adults. Current evidence, mostly in high-income countries, found that improving frailty is more likely in mild states (prefrailty). We aimed to determine the probability of frailty transitions and their predictors. METHODS: Participants were adults aged 50 years or over from the Study on Global Ageing and Adult Health in Mexico during 4 waves (2009, 2014, 2017, and 2021). We defined frailty with the frailty phenotype and we used multinomial logistic models to estimate the probabilities of frailty transitions and determine their predictors. RESULTS: For the 3 analyzed periods (2009-2014, 2014-2017, and 2017-2021), transition probabilities from frail to robust were higher for the younger age group (50-59 years) at 0.20, 0.26, and 0.20, and lower for the older age group (≥80 years), 0.03, 0.08 and 0.04. Transitioning from prefrail to robust had probabilities of 0.38, 0.37, and 0.35, for the younger age group, and 0.09, 0.18, and 0.10, for the older age group. The probabilities of transitioning to frail and to death were lower for the younger age group and for the robust at baseline; but higher for the older age group and for the frail at baseline. We identified age, disability, and diabetes as the most significant predictors of frailty transitions. CONCLUSIONS: These findings show that frailty has a dynamic nature and that a significant proportion of prefrail and frail individuals can recover to a robust or prefrail state. They also emphasize that prefrailty should be the focus of interventions.

Bayesian Analysis of Finite Populations under Simple Random Sampling.

Statistical methods to produce inferences based on samples from finite populations have been available for at least 70 years. Topics such as Survey Sampling and Sampling Theory have become part of the mainstream of the statistical methodology. A wide variety of sampling schemes as well as estimators are now part of the statistical folklore. On the other hand, while the Bayesian approach is now a well-established paradigm with implications in almost every field of the statistical arena, there does not seem to exist a conventional procedure-able to deal with both continuous and discrete variables-that can be used as a kind of default for Bayesian survey sampling, even in the simple random sampling case. In this paper, the Bayesian analysis of samples from finite populations is discussed, its relationship with the notion of superpopulation is reviewed, and a nonparametric approach is proposed. Our proposal can produce inferences for population quantiles and similar quantities of interest in the same way as for population means and totals. Moreover, it can provide results relatively quickly, which may prove crucial in certain contexts such as the analysis of quick counts in electoral settings.

GENEHUNTER versus SimWalk2 in the context of an extended kindred and a qualitative trait locus.

GENEHUNTER and SimWalk2 are among the most commonly used software for parametric multipoint linkage analysis. In the context of extended kindred analysis, GENEHUNTER has a limitation in terms of the number of individuals it can handle. One solution is to manually split the kindred into smaller pedigrees. SimWalk2 can handle a much larger number of individuals. However, its major drawback is the time it takes to process the data when compared to GENEHUNTER. Aside from the limitations of each program, when studying extended kindreds researchers are typically confronted with missing data. In this work we used simulated genotype data based on the structure of a real extended pedigree in order to compare the results obtained through GENEHUNTER and SimWalk2, evaluate the effect of discarding individuals and splitting the kindred on the logarithm of odds (lod) score, and to assess how missing data affect the performance of each program. Our results show that (1) for pedigrees of a moderate size, GENEHUNTER and SimWalk2 produce nearly the same results; (2) when using GENEHUNTER, either splitting the kindred into smaller sub-pedigrees or discarding individuals has an adverse effect when compared to the results obtained when using SimWalk2 with the whole pedigree; and (3) the performance of both programs is qualitatively similar in the missing data scenario. These conclusions are based on the sample distributions of the lod score values and of the estimates of the recombination fraction.