Blood pressure and smoking: observations on a national cohort

Trends in blood pressure in 9 to 11-year-old children in the United Kingdom 1980-2008: the impact of obesity

OBJECTIVES

High blood pressure (BP) is a major public health issue, both in the United Kingdom and worldwide. Although BP levels in UK adults are declining, there is little published information on BP trends in children, a particular concern in the context of the rising levels of childhood adiposity. Our aims are to determine whether BP in children has changed over time and whether the change reflected trends in adiposity.

METHODS

We collated data from seven population-based BP studies conducted in the United Kingdom between 1980 and 2008. Children of white European origin were included (9-11 years, mean 10.3 years). Adjustments were made to account for differences in mean ages, BP devices and cuff sizes used in different studies.

RESULTS

Mean SBP increased over time both in boys and girls: annual increases were 0.45 mmHg (95% CI: 0.43, 0.48) for boys; 0.51 mmHg (0.49, 0.53) for girls. Mean BMI increased by 0.064 kg/m(2) (0.060, 0.068) per year for boys; 0.070 kg/m(2) (0.065, 0.074) for girls; the prevalence of overweight/obesity increased from 5.7 to 21.1% and from 9.7 to 24.1%, respectively. The SBP trends occurred both in children with low and high BMI, but were more marked in low BMI group; BMI explained only 15.3% (15.1%, 15.6%) of increases in SBP for boys and 14.9% (14.6%, 15.1%) for girls. The BMI/SBP association appeared to become weaker over time (P < 0.001 for negative interaction from 1984). There was only a modest annual increase in DBP (<0.1 mmHg).

CONCLUSIONS

SBP levels have increased with time, but the increase is not explained by increased BMI. Further research is needed to identify the factors responsible.

Life style related to blood pressure and body weight in adolescence: cross sectional data from the Young-HUNT study, Norway

BACKGROUND

The associations between physical activity, unhealthy dietary habits and cigarette smoking and blood pressure, overweight and obesity are well established in adulthood. This is not the case for similar associations in adolescence. Thus, the purpose of this study is to examine how physical activity, smoking status and dietary habits were related to overweight, obesity and blood pressure in a population of Norwegian adolescents.

METHODS

Weight, height, systolic (SBP) and diastolic blood pressure (DBP) were measured, and body mass index (BMI) was calculated among 8408 adolescents who participated in a population based study in 1995-97 in the county of Nord-Trøndelag. Internationally accepted cut-off values were used to determine if the adolescents were overweight or obese. The adolescents also completed a detailed questionnaire including dietary habits, physical activity and smoking habits. We calculated adjusted mean blood pressures and odds ratios for being overweight or obese for different exposure categories of life style variables.

RESULTS

Low levels of physically activity were associated with increased odds of being overweight (odds ratio (OR), 1.4; 95% confidence interval (CI), 1.1-1.8 in girls and OR, 2.0; 95% CI, 1.6-2.5 in boys) or obese (girls: OR, 3.1; 95% CI, 1.6-6.0; boys: OR, 3.7; 95% CI, 2.1-6.4). In addition, the least physically active girls had a 1.5 mmHg higher mean DBP compared with the most active (p-trend <0.001), and among boys this difference was 1.0 mmHg (p-trend < 0.001). Smokers were more likely to be obese (OR, 1.6; 95% CI, 1.1-2.5 in girls and 1.4; 95% CI, 0.9-2.1 in boys) compared with non-smokers. Smokers also had lower mean SBP than non-smokers; however, this finding was restricted to smokers with the lowest smoking exposure. Associations between dietary habits and weight status largely disappeared after adjusting for weight losing behaviour.

CONCLUSION

In this population of adolescents low levels of physical activity were associated with higher mean DBP and higher odds of overweight or obesity. Smoking was also associated with higher odds of overweight and obesity. The paradoxical associations between healthy dietary habits and overweight and obesity are most likely an effect of reverse causality.

Smoking and diabetes in Chinese men

Smoking is a major cardiovascular risk factor and cause of death. Diabetes mellitus is also associated with an increased mortality and morbidity. Evidence concerning whether smoking increases the incidence of diabetes remains conflicting. Glycaemic status and smoking habits were analysed in 3718 Chinese subjects in order to assess the possible association between smoking and risk of diabetes in the Chinese population. The World Health Organisation 1998 criteria were used for the diagnosis of glucose intolerance. Smoking was defined as current cigarette smoking or ex-smoking without regard to daily consumption. The smoking habits of the studied subjects were correlated with glycaemic status. There were 3003 (80.8%) women and 715 (19.2%) men. The mean age (SD) was 38.4 (12.8) years (median 35.0, range 12-88 years). Of the 3718 subjects, 786 (21.1%) had diabetes, 708 (19.1%) had impaired glucose tolerance, and 2224 (59.8%) had normal results. Of the 3003 women, only 87 (2.9%) were smokers. The female smokers were younger, heavier, and had higher alcohol consumption than non-smokers. The prevalence of diabetes was similar between female smokers and non-smokers after adjustment for age, body mass index, family history of diabetes, and alcohol. Of the 715 men, 175 (24.5%) were smokers. The male smokers were younger, had lower blood pressure, and higher alcohol consumption. After adjustment for age, body mass index, family history of diabetes and alcohol, the male smokers had lower blood pressure, higher one hour plasma glucose, and more diabetes. Using logistic regression analysis (stepwise forward) with age, body mass index, alcohol, smoking, and family history of diabetes as independent variables to predict the risk of having diabetes, age and body mass index are independently associated with diabetes in both men and women. In addition, smoking is independently associated with the risk of diabetes in men, the odds ratio (95% confidence interval, CI) being 1.705 (1.106 to 2.630). Family history of diabetes is independently associated with the risk of diabetes in women, and the odds ratio (95% CI) is 1.643 (1.314, to 2.053). In conclusion, it was found that smoking is independently associated with diabetes after adjustment for age, body mass index, alcohol, and family history of diabetes in Hong Kong Chinese men, the odds ratio being 1.7. The prevalence of smoking in Hong Kong Chinese women is low and its association with diabetes is inconclusive.