Independent Effects of Stable and Changing Body Weight on Total Mortality

Abstract

To evaluate the impact of parental smoking on childhood asthma and wheezing, we studied two random samples of subjects ages 6-7 and 13-14 years in ten areas of northern and central Italy. Standardized questionnaires were completed by parents of 18,737 children and 21,068 adolescents (response rates, 92.8% and 96.3%, respectively) about their smoking habits and the respiratory health of their children. Adolescents were asked about their respiratory health and personal smoking. We compared two groups of cases with healthy subjects: (1) "current asthma" (children, 5.2%; adolescents, 6.2%) and (2) "current wheezing" not labeled as asthma (children = 4.5%, adolescents = 8.5%). Exposure to smoke of at least one parent increased the relative risk of current asthma among children [odds ratio (OR) = 1.34; 95% confidence interval (CI) = 1.11-1.62] and of current wheezing among adolescents (OR = 1.24; 95% CI = 1.07-1.44). Maternal smoking had a stronger effect than paternal smoking. Maternal smoking during pregnancy was associated with current asthma (OR = 1.62; 95% CI = 1.34-1.96) and current wheezing in children (OR = 1.31; 95% CI = 1.06-1.62); the effects were lower among adolescents. Among subjects with a negative history of parental asthma, maternal smoking was associated with current wheezing in both age groups, whereas among those with a positive history of parental asthma it was associated with current asthma in children, but not in adolescents. We estimated that 15% (95% CI = 12-19) of the current asthma cases among children and 11% (95% CI = 8.3-14) of the current wheezing cases among adolescents are attributable to parental smoking in Italy.

Combined effects of weight loss and physical activity on all-cause mortality of overweight men and women

“…In agreement with numerous other studies, 10,11,15,35,36 our study showed that weight loss among overweight or obese men and women was associated with excess mortality. Weight loss among subjects remaining or becoming inactive (PAPI or PIPI) seemed more hazardous than weight loss among subjects who remained or became active (PAPA or (1976-1978 and 1981-1983).…”

“…[1][2][3][4] Although weight loss is generally associated with improvement in metabolic and cardiovascular risk factor levels, [5][6][7] weight loss has also been associated with increased all-cause and cardiovascular mortality in observational studies. [8][9][10][11][12][13][14][15] However, the results are not consistent. 16,17 Variations in occurrence of pre-existing disease, sub-clinical disease, smoking, changes in body composition or fat distribution have been suggested to explain, in part, the elevated risk among those who lose weight.…”

“…16,17 Variations in occurrence of pre-existing disease, sub-clinical disease, smoking, changes in body composition or fat distribution have been suggested to explain, in part, the elevated risk among those who lose weight. 10,11,18,19 Although studies have shown that even after careful confounder control and exclusion of subjects with preexisting disease, weight loss still seems an independent risk factor for premature death. 11,15 Some of the variation in the health risk associated with weight loss may be explained by the balance between loss of lean body mass and fat mass and the type of fat mass lost.…”

“…10,11,18,19 Although studies have shown that even after careful confounder control and exclusion of subjects with preexisting disease, weight loss still seems an independent risk factor for premature death. 11,15 Some of the variation in the health risk associated with weight loss may be explained by the balance between loss of lean body mass and fat mass and the type of fat mass lost. 19 Some studies have shown that exercise-induced weight loss may result in a lower and more favourable ratio of fat to lean body mass than diet-induced weight loss, as muscle mass is kept or even elevated.…”

A simple estimate of mortality attributable to excess weight in the European Union

“…This may be due to RRs of death related to excess weight being about 0.1 -0.2 points lower for the whole population than when controlling for smoking and pre-existing illness (see Table 2). However, uncontrolled confounding by other factors (such as early disease (Mikkelsen et al, 1999), recent unintentional weight loss (Stevens et al, 1998), long-term weight loss (Calle et al, 1999), weight level (Mikkelsen et al, 1999), etc) may still be present, meaning that estimation of the true adverse effect of excess weight might be biased to a certain extent. Moreover, aside from any possible confounding, effect modification by covariates might also be in evidence (Seidell, 1995b).…”