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- Orsini, Nicola
(författare)
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Physical activity and health benefits
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical activity (PA), due to its role in health promotion and disease prevention, is of particular interest to be investigated. The aims of this thesis were: to assess the associations between PA and different health outcomes (lower urinary tract symptoms, cancer incidence, and mortality) in the Cohort of Swedish Men (COSM); to perform a dose-response meta- analysis of published associations between walking and incidence of coronary heart disease (CHD); and to provide user-friendly software packages for dose-response meta-analysis and for sensitivity analysis of biases in observational studies. The COSM is a population-based prospective cohort of 45,906 men between 45 to 79 years of age in central Sweden who were cancer-free and completed a questionnaire about current and historical PA, diet, and other life- style factors at enrollment in 1997. At baseline 6905 men reported moderate to severe lower urinary tract symptoms (LUTS). A significant inverse relationship was seen between total PA and moderate and severe LUTS (highest vs lowest quartile odds ratio=0.72; 95% confidence interval (CI)=0.66-0.79). Men who were physically active at work as well as during leisure-time showed 50% reduction in risk of moderate to severe LUTS (95% CI=0.40-0.60) compared to those who were sedentary. Conversely, men with long-term sedentary lifestyles (5 hours/day watching TV both at age 30 years and current) reported a 2-fold increase (95% CI=1.41-2.59) risk to these symptoms when compared to men more active at both time periods. After 7 years of study enrollment 3714 men of the COSM were diagnosed with cancer and 1153 of them died due to the disease. We observed a strong inverse linear association between total daily PA and death from any form of cancer. For each increment of 4 metabolic equivalent (MET)-hours/day of total PA (approximately 1 hour daily of moderate effort) cancer incidence tended to be decreased by 2% and cancer mortality decreased significantly by 12% (95% CI = 6-18%). During 9.7 years of follow-up, we identified a total of 4086 deaths from all causes. Compared to men who were lean and active (BMI < 25 kg/m2; top tertile total PA) the adjusted rate ratios of death from all causes were 1.44 (95% CI=1.11-1.86) for obese-active men (BMI 30 kg/m2), 1.54 (95% CI=1.34-1.77) for lean but inactive men (bottom tertile total PA), and 1.81 (95% CI=1.48-2.23) for obese-inactive men. After excluding the first 3 years of follow-up, current and former smokers, those who had lost weight from age 20 years to baseline, and heavy manual workers, the adjusted rate ratios of death from all causes were 1.65 (95% CI=1.20-2.27) for overweight-to-obese and active men, 2.15 (95% CI=1.59-2.91) for lean-inactive men, and 2.04 (95% CI=1.52-2.74) for overweight-to-obese and inactive men compared to lean-active men. During 10 years of follow-up a total of 2735 men were diagnosed with prostate cancer, of which 190 were fatal. We observed an inverse linear association between lifetime (average of age 30, 50 and baseline) walking/bicycling duration and incidence of total prostate cancer risk. The multivariable-adjusted rate ratio decreased by 8% (95% CI=2-13%) for every 30 min/day increment of lifetime walking/bicycling in the range of 30 to 120 min/day. The fatal prostate cancer rate among those men who hardly ever walked or biked was two-fold that of men in the highest average lifetime walking/bicycling of 120 min/day, although this increased rate was not significant. In the dose-response meta-analysis of eight epidemiological studies we found that every increment of 8 MET-hours/week of walking (moderate-intensity about 30 min/day on 5 days of the week) was associated with 19% decrease (95% CI=14-23%) of CHD risk. In conclusion, we observed that increased PA levels may lower the risk of LUTS, all-cause and cancer mortality, prostate cancer, and CHD. Furthermore, the two statistical components developed for Stata® software can greatly facilitate dose-response meta-analyses (glst) and support sensitivity analysis (episens) of epidemiological findings.
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- Orsini, Nicola
(författare)
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Total physical activity in middle-aged and elderly women from a population-based cohort
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Regularly performed physical activity (PA) is associated with a reduced risk of coronary heart disease, stroke, type 2 diabetes, some forms of cancer, osteoporosis, and all-cause mortality. Due to its role in health promotion and disease prevention, PA is a particularly important health behavior to be investigated. The first aim of this thesis was to investigate temporal trends and correlates of total PA using data from the Swedish Mammography Cohort (SMC). The second aim was to evaluate the reproducibility and validity of self-reported PA and to make a profile of PA behaviors using accelerometer data from a subset of the SMC. The SMC is a population-based prospective cohort established between 1987 and 1990 in Uppsala and Västmanland Counties. In our analyses among 38,988 women between the ages of 48 and 83 years, we observed a decreasing trend of total PA by calendar time between the 1930s and the 1990s. Total activity level decreased in all age groups (15, 30, and 50 years of age) by an average of 3 MET-hours/day corresponding to about 45 minutes of brisk walking. The likelihood of engaging in higher total daily PA levels linearly decreased with age (for 5-year increase: odds ratio (OR) = 0.87; 95% confidence interval (Cl): 0.85-0.89) and body mass index (for 5-unit, kg/m2, increase: OR= 0.81; 95% Cl: 0.79-0.84). Total PA levels were inversely associated with smoking (OR= 0.83; 95% Cl: 0.79-0,88), drinking (OR= 0.88 95% Cl: 0.82-0.94), educational level (university vs. primary: OR=0.54, 95% Cl: 0.51-0.58), and childhood environment (city vs. countryside: OR= O.62, 95% Cl: 0.59-0.65). Reproducibility, as measured among 303 women by intraclass correlation (ICC) for total current PA, was 0.69. For historical PA, the reliabilities for total activity were from 0.75 for age 50 to 0.81 for age 30 years, being substantial for occupational activities (ICC=0.73-0.75), and fair to moderate for inactivity (ICC=0.31-0.60). Validity, as measured among 116 women by de-attenuated concordance correlations comparing total daily activity estimated by the questionnaire with the accelerometers and the records were 0.72 and 0.67, respectively. According to the PA recommendation to accumulate at least 30 minutes per day (in either 1 continuous bout or several shorter bouts lasting 8-10 minutes) of moderate-to-vigorous activity 5 days per week or more, we found that among 133 women the proportion who met this recommendation was 31% which decreased to 18% among obese women. In conclusion, our findings from a large population-based prospective cohort of middle-aged and elderly women show that total PA has been decreasing by calendar time during the last 60 years of the 20th century. The likelihood of engaging in higher total daily PA levels decreased with age, body mass index, educational level, smoking, drinking, and growing up in urban places. Our short self-administered PA questionnaire was reasonably reproducible and valid. The fact that only a third of the women were not meeting the PA recommendation suggests that counselling messages may need to Place more emphasis on the correct number of days per week and in which way moderate activity should be obtained to achieve health benefits.
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