Longitudinal association of sleep quality with physical performance measures: SABE cohort study, Brazil.

OBJECTIVES: The aim of this study was to investigate the longitudinal association of sleep with physical performance in a representative sample of non-institutionalised older adults residing in the municipality of São Paulo, Brazil. STUDY DESIGN: Prospective cohort study. METHODS: The current longitudinal study used data extracted from the Health, Well-being, and Aging Study (Estudo Saúde Bem-Estar e Envelhecimento [SABE]). The study population consisted of individuals aged ≥60 years who participated in the study in 2010 or 2015. Dependent variables included the Short Physical Performance Battery (SPPB) and gait speed. Independent variables of interest were self-reported sleep difficulty, daytime sleepiness and sleep quality. The longitudinal association between sleep variables and the outcomes was evaluated using Generalised Estimating Equations (GEE) Models adjusted for covariates. All the variables, except age, sex and schooling, were assessed at baseline and follow-up visits (2010 and 2015). RESULTS: The analyses included 2205 observations from 1559 individuals. The population mean age was 72 years in 2010 and 71 years in 2015, with a higher prevalence of women in both years. Between 2010 and 2015, there was a decline in the SPPB score and gait speed. Daytime sleepiness was negatively associated with the SPPB score [Coef.: -0.38 (95% confidence interval {CI}: -0.56, -0.21)] and gait speed [Coef.: -0.03 (95% CI: -0.05, -0.01)]. Poor sleep quality was negatively associated with the SPPB score [Coef.: -0.29 (95% CI: -0.57, -0.01)] and gait speed [Coef.: -0.03 (95% CI: -0.06, -0.00)]. CONCLUSIONS: Daytime sleepiness and poor sleep quality are associated with compromised physical performance in non-institutionalised older adults, and this association remained consistent over time.

Appendicular Lean Soft Tissue: Development and Cross-Validation of Predictive Models for Older Men and Women.

BACKGROUND: Sarcopenia may explain, in a large proportion, physical disability, falls and fractures, especially in aged elderly. However, a diagnosis in an operationally systematic, simple and low cost way is extremely important, particularly for home-based, epidemiological studies. OBJECTIVE: The purpose of this study was to develop and validate predictive equations of appendicular lean soft tissue (ALST) in elderly older than 80 years. DESIGN AND SETTINGS: A validation study was performed in 106 elderly (men and women) aged 80 years and older. MEASUREMENTS: Body weight, height, circumference (arm, midcalf, hip and waist) and triceps skinfold were measured in the elderly. ALST were measured using as the reference method dual-energy X-ray absorptiometry (DXA). RESULTS: Two models were predicted. The first model (ALST, in kg = 0.074*height + 0.277*weight - 0.144*triceps skinfold - 0.103*waist circumference + 1.831*gender -0.966), which considered all possible variables in stepwise multiple regression, presented better statistical performance (r2 = 0.82; SEE = 1.67 kg), compared to the second model (ALST, in kg = 0.138*height + 0.103*weight + 3.061*gender - 12.489), a more practical equation, due to a lesser quantity of predictive variables (r2 = 0.75; SEE = 1.94 kg). Both models were validated, however, it was verified trend (p<0.05) for overestimation of predicted ALST. CONCLUSION: In summary, two models for predicting ALST in men and women with age ≥ 80 years were developed and cross-validated. Model 1, with a greater number of predictive variables, presented a better accuracy than did the model with only three variables (height, weight, and gender). Validation studies are needed to test the usefulness of both models in other populations.