Generalizability of cognitive results from clinical trial participants to an older adult population: Addressing external validity

Introduction

Study inclusion criteria and recruitment practices limit the generalizability of randomized-controlled trial (RCT) results. Statistical modeling could enhance generalizability of outcomes. To illustrate this, the cognition-depression relationship was assessed with and without adjustment relative to the target population of older women.

Methods

Randomized participants from four RCTs and non-randomized participants from two cohorts were included in this study. Prediction models estimated probability of being randomized into trials from target populations. These probabilities were used for inverse odds weighting relative to target populations. Weighted linear regression was used to assess the depression-cognition relationship.

Results

There was no depression-cognition relationship in the combined randomized sample. After applying weights relative to a representative cohort, negative relationships were observed. After applying weights relative to a non-representative cohort, bias of estimates increased.

Discussion

Quantitative approaches to transportability using representative samples may explain the absence of a-priori established relationships in RCTs.

The Influence of Lifestyle Behaviors on the Incidence of Frailty

BACKGROUND

Frailty is a clinical state defined as an increase in an individual's vulnerability to developing adverse health-related outcomes.

OBJECTIVES

We propose that healthy behaviors could lower the incidence of frailty. The aim is to describe the association between healthy behaviors (physical activity, vaccination, tobacco use, and cancer screening) and the incidence of frailty.

DESIGN

This is a secondary longitudinal analysis of the Mexican Health and Aging Study (MHAS) cohort.

SETTING

MHAS is a population-based cohort, of community-dwelling Mexican older adults. With five assessments currently available, for purposes of this work, 2012 and 2015 waves were used.

PARTICIPANTS

A total of 6,087 individuals 50-year or older were included.

MEASUREMENTS

Frailty was defined using a 39-item frailty index. Healthy behaviors were assessed with questions available in MHAS. Individuals without frailty in 2012 were followed-up three years in order to determine their frailty incidence, and its association with healthy behaviors. Multivariate logistic regression models were used to assess the odds of frailty occurring according to the four health-related behaviors mentioned above.

RESULTS

At baseline (2012), 55.2% of the subjects were male, the mean age was 62.2 (SD ± 8.5) years old. The overall incidence (2015) of frailty was 37.8%. Older adults physically active had a lower incidence of frailty (48.9% vs. 42.2%, p< 0.0001). Of the activities assessed in the adjusted multivariate models, physical activity was the only variable that was independently associated with a lower risk of frailty (odds ratio: 0.79, 95% confidence interval 0.71-0.88, p< 0.001).

CONCLUSIONS

Physically active older adults had a lower 3-year incidence of frailty even after adjusting for confounding variables. Increasing physical activity could therefore represent a strategy for reducing the incidence of frailty. Other so-called healthy behaviors were not associated with incident frailty, however there is still uncertainty on the interpretation of those results.

Clinical and epidemiological variability in severe sepsis: an ecological study

BACKGROUND

To assess clinical and epidemiological trends of severe sepsis.

METHODS

Ecological study of patients presenting to the emergency department with severe sepsis or septic shock between 2005 and 2013. Patients were identified using the state-wide hospital administrative database. Key outcomes included incidence rates (IRs) and mortality rates (per 1000 population) by age and medically underserved areas (MUAs), sepsis case fatality rate (deaths per 100 sepsis cases), and proportions of transfer and comorbidities.

RESULTS

There were 154 019 sepsis cases identified. In 2005, 85+ yo in non-MUAs had a 44% increase in IR compared with those in MUAs, and this difference rose to 74% by 2013. Mortality rates were 1.6 (95% CI 1.3 to 1.8) times greater among 85+ yo in non-MUAs. Mortality rates increased by 1.8% annually, while the sepsis case fatality rate decreased by 7.7%. The proportion of transfer among sepsis cases decreased by 2.1% per year (3.8% in non-MUAs, 0.7% in MUAs).

CONCLUSIONS

Sepsis incidence varies geographically, and access to healthcare is one proposed mechanism that may explain heterogeneity. Over time, we may be capturing higher acuity sepsis cases with better recognition and management, as well as observing differential diagnostic coding documentation by location.

Association of Healthy Habits Beliefs and Mortality in Older Adults: A Longitudinal Analysis of the Mexican Health and Aging Study

OBJECTIVE

The aim of this article is to establish the association between beliefs about healthy habits and mortality in a group of Mexican older adults.

METHOD

This is an 11-year follow-up secondary analysis of the Mexican Health and Aging Study.

RESULTS

There was a significant difference ( p < .001) in survival rate between those participants who believed that healthy habits have the potential to improve health compared with those who did not. After adjustment for confounders, Cox regression models showed a hazard ratio (HR) of 0.17 (95% confidence interval [CI] [0.07, 0.38], p < .001) for the group that believed in healthy habits.

DISCUSSION

Although the mechanism is not completely clear, according to our results, believing that healthy habits can improve health was associated with lower rates of mortality. Further research should elucidate potential strategies for changing beliefs in older adults with the goal of improving their overall health.