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Marginal structural models (MSMs) allow estimating the causal effect of a time-varying exposure on an outcome in the presence of time-dependent confounding. The parameters of MSMs can be estimated utilizing an inverse probability of treatment weight estimator under certain assumptions. One of these assumptions is that the proposed causal model relating the outcome to exposure history is correctly specified. However, in practice, the true model is unknown. We propose a test that employs the observed data to attempt validating the assumption that the model is correctly specified. The performance of the proposed test is investigated with a simulation study. We illustrate our approach by estimating the effect of repeated exposure to psychosocial stressors at work on ambulatory blood pressure in a large cohort of white-collar workers in Québec City, Canada. Code examples in SAS and R are provided to facilitate the implementation of the test. [ABSTRACT FROM AUTHOR]

Objective: The Canadian province of Quebec has recently legalized medical aid in dying (MAID) for competent patients who satisfy strictly defined criteria. The province is considering extending the practice to incompetent patients. We compared the attitudes of four groups of stakeholders toward extending MAID to incompetent patients with dementia.Methods: We conducted a province-wide postal survey in random samples of older adults, informal caregivers of persons with dementia, nurses, and physicians caring for patients with dementia. Clinical vignettes featuring a patient with Alzheimer's disease were used to measure the acceptability of extending MAID to incompetent patients with dementia. Vignettes varied according to the stage of the disease (advanced or terminal) and type of request (written or oral only). We used the generalized estimating equation (GEE) approach to compare attitudes across groups and vignettes.Results: Response rates ranged from 25% for physicians to 69% for informal caregivers. In all four groups, the proportion of respondents who felt it was acceptable to extend MAID to an incompetent patient with dementia was highest when the patient was at the terminal stage, showed signs of distress, and had written a MAID request prior to losing capacity. In those circumstances, this proportion ranged from 71% among physicians to 91% among informal caregivers.Conclusion: We found high support in Quebec for extending the current MAID legislation to incompetent patients with dementia who have reached the terminal stage, appear to be suffering, and had requested MAID in writing while still competent. [ABSTRACT FROM AUTHOR]

Objective: The NIH-developed Diabetes Prevention Program (DPP) is successful in achieving clinically significant weight loss in individuals with overweight/obesity when delivered one-on-one. The group-based DPP is less effective, with average weight losses of only 3.5%. The objective of this study was to increase weight loss outcomes of the group-based DPP by integrating habit formation tools (i.e., if-then plans). This two-arm randomized controlled trial tested the efficacy of the habit formation-enhanced group-based DPP compared with the standard group-based DPP on changes in body weight (primary outcome). This study presents the 3- and 12-month results of this 24-month trial.Methods: A total of 208 participants were randomly assigned to the standard or enhanced DPP, and 172 participated. Participants were men and women with overweight/obesity who self-reported less than 200 min/wk of exercise.Results: Both groups achieved high weight losses at 3 (5.76%) and 12 (9.98%) months, with no differences between groups (χ2  < 1). Both groups improved in blood pressure and physical activity.Conclusions: If-then plans did not result in higher weight loss. Both program versions resulted in higher weight loss than the group-based DPP. This may suggest that cognitive behavioral therapy skills of the coaches (clinical psychology doctoral students) was a key factor in treatment outcome. [ABSTRACT FROM AUTHOR]

The search for an empirically based personality typology has regained the interest of researchers. To date, however, empirical inquiries have mainly been cross-sectional. In this study, an empirically based developmental typology of personality was identified using data from a prospective longitudinal study of a sample of men adjudicated during their adolescence and assessed on four occasions until midlife. Cluster analyses were performed on measures of disinhibition, negative emotionality, and extraversion. Four developmental types of personality were identified. The first was characterized by average scores in the three traits in adolescence that decreased linearly until midlife (39%). The second type displayed very high scores in disinhibition and negative emotionality in adolescence that decreased rapidly during early adulthood (24%). The third type was characterized by very high scores in disinhibition and negative emotionality that remained stable until midlife, while extraversion was average during adolescence and then decreased rapidly until midlife (17%). The fourth type was characterized by high scores in disinhibition and negative emotionality in adolescence that was followed by cycles of decreases and increases until midlife (20%). These four developmental types of personality seemed to be related to known antisocial behaviour trajectories. [ABSTRACT FROM AUTHOR]