Background: In settings in which diseases wax and wane, there is a need to measure disease dynamics in longitudinal studies. Traditional measures of disease occurrence (eg, cumulative incidence) do not address change or stability or are limited to stable cohorts (eg, incidence) and may thus lead to erroneous conclusions. To illustrate how different measures can be used to detect disease dynamics, we investigated sex differences in the occurrence of asthma and wheezing, using a population-based study cohort that covered the first 18 years of life. Methods: In the Isle of Wight birth cohort (n = 1456), prevalence, incidence, cumulative incidence, positive and negative transitions, and remission were determined at ages 1 or 2, 4, 10, and 18 years. Latent transition analysis was used to simultaneously identify classes of asthma and wheezing (related phenotypes) and characterize transition probabilities over time. Trajectory analysis was used to characterize the natural history of asthma and wheezing. Results: Regarding time-specific changes, positive and negative transition probabilities were more informative than other measures of associations because they revealed a sex switchover in asthma prevalence (P < 0.05). Transition probabilities were able to identify the origin of a sex-specific dynamic; in particular, prior wheezing transitioned to asthma at age 18 years among girls but not among boys. In comparison with latent transition analysis, trajectory analysis did not directly identify a switchover in prevalence among boys and girls. Conclusions: In longitudinal analyses, transition analyses that impose minimal restrictions on data are needed in order to produce appropriate information on disease dynamics.
Background: Physical activity (PA) is complex and a difficult behavior to assess as there is no ideal assessment tool(s) that can capture all contexts of PA. Therefore, it is important to understand how different assessment tools rank individuals. We examined the extent to which self-report and direct assessment PA tools yielded the same ranking of PA levels. Methods: PA levels were measured by the Modifiable Activity Questionnaire (MAQ) and pedometer at baseline among 855 white (W), African-American (AA), Japanese-American (JA), and Korean (K) men (mean age 45.3 years) in 3 geographic locations in the ERA JUMP study. Results: Korean men were more active than W, AA, and JA men, according to both the MAQ and pedometer (MAQ total PA [mean ± SD]: 41.6 ± 17.8, 20.9 ± 9.9, 20.0 ± 9.1, and 29.4 ± 10.3 metabolic equivalent [MET] hours/week, respectively; pedometer: 9584.4 ± 449.4, 8363.8 ± 368.6, 8930.3 ± 285.6, 8335.7 ± 368.6 steps/day, respectively). Higher levels of total PA in Korean men, as shown by MAQ, were due to higher occupational PA. Spearman correlations between PA levels reported on the MAQ and pedometer indicated positive associations ranging from rho = 0.29 to 0.42 for total activity, rho = 0.13 to 0.35 for leisure activity, and rho = 0.10 to 0.26 for occupational activity. Conclusions: The 2 assessment methods correlated and were complementary rather than interchangeable. The MAQ revealed why Korean men were more active. In some subpopulations it may be necessary to assess PA domains other than leisure and to use more than 1 assessment tool to obtain a more representative picture of PA levels.
Background: Recent studies indicate that ambient temperature could be a risk factor for infectious diarrhea, but evidence for such a relation is limited in China. Methods: We investigated the short-term association between daily temperature and physician-diagnosed infectious diarrhea during 2008–2010 in Shanghai, China. We adopted a time-series approach to analyze the data and a quasi-Poisson regression model with a natural spline-smoothing function to adjust for long-term and seasonal trends, as well as other time-varying covariates. Results: There was a significant association between temperature and outpatient visits for diarrhea. A 1°C increase in the 6-day moving average of temperature was associated with a 2.68% (95% CI: 1.83%, 3.52%) increase in outpatient visits for diarrhea. We did not find a significant association between rainfall and infectious diarrhea. Conclusions: High temperature might be a risk factor for infectious diarrhea in Shanghai. Public health programs should focus on preventing diarrhea related to high temperature among city residents.
Background: Few studies have assessed cause of death among patients with amyotrophic lateral sclerosis (ALS). We investigated underlying cause and place of death among patients with ALS in Taiwan during 2003–2008. Methods: The data source was the Taiwan National Health Insurance database for the period 2003–2008. In total, 751 patients older than 15 years with a primary diagnosis of ALS were included and followed until 2008 in the national mortality database. Crude mortality rates (per 100 person-years) and standardized mortality ratios (SMRs) were calculated in relation to cause of death, sex, and age group (15–44, 45–64, 65+ years). Results: In total, 297 (39.6%) patients died during the follow-up period, an age- and sex-standardized mortality rate 13 times (95% CI, 10.6–15.6) that of the Taiwanese general population. The leading cause of death among the patients was respiratory diseases, and the second most frequent cause was cardiovascular diseases. During the first year after an ALS diagnosis, suicide was much more frequent (SMR, 6.9; 95% CI, 1.9–17.6) than among the general population. Conclusions: During 2003–2008, respiratory diseases and cardiovascular diseases were the most frequent causes of death among Taiwanese patients with ALS. In addition, our findings indicate that suicide prevention is an urgent priority during the period soon after an ALS diagnosis.
Background: The long-term outcomes of Kawasaki disease (KD) are unknown. Methods: Fifty-two collaborating hospitals collected data on all patients who had received a new definite diagnosis of KD between July 1982 and December 1992. Patients were followed until December 31, 2009 or death. Standardized mortality ratios (SMRs) were calculated based on Japanese vital statistics data. Results: Of the 6576 patients enrolled, 46 (35 males and 11 females) died (SMR: 1.00; 95% CI: 0.73–1.34). Among persons without cardiac sequelae, SMRs were not high after the acute phase of KD (SMR: 0.65; 95% CI: 0.41–0.96). Among persons with cardiac sequelae, 13 males and 1 female died during the observation period (SMR: 1.86; 95% CI: 1.02–3.13). Conclusions: In this cohort, the mortality rate among Japanese with cardiac sequelae due to KD was significantly higher than that of the general population. In contrast, the rates for males and females without sequelae were not elevated.
Background: We investigated risk factors for fracture among young adults, particularly body mass index (BMI) and physical activity, which although associated with fracture in older populations have rarely been investigated in younger people. Methods: In 2009, 4 years after initial recruitment, 58 204 Thais aged 19 to 49 years were asked to self-report fractures incident in the preceding 4 years. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% CIs for associations of fracture incidence with baseline BMI and physical activity. Results: Very obese women had a 70% increase in fracture risk (OR = 1.73, 95% CI 1.21–2.46) as compared with women with a normal BMI. Fracture risk increased by 15% with every 5-kg/m2 increase in BMI. The effects were strongest for fractures of the lower limbs. Frequent purposeful physical activity was also associated with increased fracture risk among women (OR = 1.52, 95% CI 1.12–2.06 for 15 episodes/week vs none). Neither BMI nor physical activity was associated with fracture among men, although fracture risk decreased by 4% with every additional 2 hours of average sitting time per day (OR = 0.96, 95% CI 0.93–0.99). Conclusions: The increase in obesity prevalence will likely increase fracture burden among young women but not young men. While active lifestyles have health benefits, our results highlight the importance of promoting injury prevention practices in conjunction with physical activity recommendations, particularly among women.
Background: Occupational class differences in body mass index (BMI) have been systematically reported in developed countries, but the studies have mainly focused on white populations consuming a Westernized diet. We compared occupational class differences in BMI and BMI change in Japan and Finland. Methods: The baseline surveys were conducted during 1998–1999 among Japanese (n = 4080) and during 2000–2002 among Finnish (n = 8685) public-sector employees. Follow-up surveys were conducted among those still employed, in 2003 (n = 3213) and 2007 (n = 7086), respectively. Occupational class and various explanatory factors were surveyed in the baseline questionnaires. Linear regression models were used for data analysis. Results: BMI was higher at baseline and BMI gain was more rapid in Finland than in Japan. In Finland, baseline BMI was lowest among men and women in the highest occupational class and progressively increased to the lowest occupational class; no gradient was found in Japan (country interaction effect, P = 0.020 for men and P < 0.0001 for women). Adjustment for confounding factors reflecting work conditions and health behavior increased the occupational class gradient among Finnish men and women, whereas factors related to social life had no effect. No statistically significant difference in BMI gain was found between occupational classes. Conclusions: The occupational class gradient in BMI was strong among Finnish employees but absent among Japanese employees. This suggests that occupational class inequalities in obesity are not inevitable, even in high-income societies.
Background: Albuminuria is a risk factor for not only nephropathy progression but also cardiovascular disease. Oxidative stress may have a role in the positive association between albuminuria and cardiovascular disease. Methods: This cross-sectional study investigated the associations of serum levels of carotenoids, which are dietary antioxidants, with albuminuria among 501 Japanese adults (198 men, mean age ± SD: 66.4 ± 10.0 years; 303 women, mean age ± SD: 65.4 ± 9.8 years) who attended a health examination. Serum levels of carotenoids were determined by high-performance liquid chromatography. Logistic regression analysis was used to estimate odds ratios (ORs) with 95% CIs for albuminuria after adjustment for age, body mass index, smoking habits, drinking habits, hypertension, diabetes mellitus, and dyslipidemia. Results: Prevalence of albuminuria was 15.4% among men and 18.1% among women. Among women with albuminuria, geometric mean serum levels of canthaxanthin, lycopene, β-carotene, total carotenes, and provitamin A were significantly lower than those of normoalbuminuric women. Adjusted ORs for albuminuria among women in the highest tertiles of serum β-carotene (OR, 0.45; 95% CI, 0.20–0.98) and provitamin A (OR, 0.45; 95% CI, 0.20–0.97) were significantly lower as compared with those for women in the lowest tertile. There were no associations between serum carotenoids and albuminuria in men. Conclusions: An increased level of serum provitamin A, especially serum β-carotene, was independently associated with lower risk of albuminuria among Japanese women.
Background: Inflammatory gene polymorphisms are potentially associated with atherosclerosis risk, but their age-related effects are unclear. To investigate the age-related effects of inflammatory gene polymorphisms on arterial stiffness, we conducted cross-sectional and 5-year follow-up studies using the cardio-ankle vascular index (CAVI) as a surrogate marker of arterial stiffness. Methods: We recruited 1850 adults aged 34 to 69 years from the Japanese general population. Inflammatory gene polymorphisms were selected from NF-kB1, CD14, IL-6, IL-10, MCP-1, ICAM-1, and TNF-α. Associations of CAVI with genetic and conventional risk factors were estimated by sex and age group (34–49, 50–59, and 60–69 years) using a general linear model. The association with 5-year change in CAVI was examined longitudinally. Results: Glucose intolerance was associated with high CAVI among women in all age groups, while hypertension was associated with high CAVI among participants in all age groups, except younger women. Mean CAVI for the CD14 CC genotype was lower than those for the TT and CT genotypes (P for trend = 0.005), while the CD14 polymorphism was associated with CAVI only among men aged 34 to 49 years (P = 0.006). No association of the other 6 polymorphisms with CAVI was observed. No association with 5-year change in CAVI was apparent. Conclusions: Inflammatory gene polymorphisms were not associated with arterial stiffness. To confirm these results, further large-scale prospective studies are warranted.
Background: There is little information regarding the impact of diet on disease incidence and mortality in Switzerland. We assessed ecologic correlations between food availability and disease. Methods: In this ecologic study for the period 1970–2009, food availability was measured using the food balance sheets of the Food and Agriculture Organization of the United Nations. Standardized mortality rates (SMRs) were obtained from the Swiss Federal Office of Statistics. Cancer incidence data were obtained from the World Health Organization Health For All database and the Vaud Cancer Registry. Associations between food availability and mortality/incidence were assessed at lags 0, 5, 10, and 15 years by multivariate regression adjusted for total caloric intake. Results: Alcoholic beverages and fruit availability were positively associated, and fish availability was inversely associated, with SMRs for cardiovascular diseases. Animal products, meat, and animal fats were positively associated with the SMR for ischemic heart disease only. For cancer, the results of analysis using SMRs and incidence rates were contradictory. Alcoholic beverages and fruits were positively associated with SMRs for all cancer but inversely associated with all-cancer incidence rates. Similar findings were obtained for all other foods except vegetables, which were weakly inversely associated with SMRs and incidence rates. Use of a 15-year lag reversed the associations with animal and vegetal products, weakened the association with alcohol and fruits, and strengthened the association with fish. Conclusions: Ecologic associations between food availability and disease vary considerably on the basis of whether mortality or incidence rates are used in the analysis. Great care is thus necessary when interpreting our results.