Xiao-Mei Mai

Cross-Sectional and Prospective Cohort Study of Serum 25-Hydroxyvitamin D Level and Obesity in Adults The HUNT Study

Experimental studies suggest that vitamin D modulates the activity of adipocytes. The authors examined baseline serum 25-hydroxyvitamin D (25(OH)D) level in relation to prevalent and cumulative incident obesity in Norway. A cohort of 25,616 adults aged 19-55 years participated in both the second and third surveys of the Nord-Trøndelag Health Study (HUNT 2 (1995-1997) and HUNT 3 (2006-2008)). Serum 25(OH)D levels measured at baseline and anthropometric measurements taken at both baseline and follow-up were available for a random sample of 2,460 subjects. Overall, 40% of the 2,460 subjects had a serum 25(OH)D level less than 50.0 nmol/L, and 37% had a level of 50.0-74.9 nmol/L. The prevalence and cumulative incidence of obesity, defined as body mass index (weight (kg)/height (m)(2)) ≥30, were 12% and 15%, respectively. Lower serum 25(OH)D level was associated with a higher prevalence of obesity. In the 2,165 subjects with baseline BMI less than 30, a serum 25(OH)D level less than 50.0 nmol/L was associated with a significantly increased odds ratio for incident obesity during follow-up (adjusted odds ratio = 1.73, 95% confidence interval: 1.24, 2.41). When prevalent and incident obesity were classified according to waist circumference (≥88 cm for women, ≥102 cm for men), similar results were obtained. In addition to prevalent obesity, a serum 25(OH)D level less than 50.0 nmol/L was significantly associated with new-onset obesity in adults.

General and abdominal obesity and incident asthma in adults: the HUNT study

Measures of body mass index (BMI) and waist circumference define general obesity and abdominal obesity respectively. While high BMI has been established as a risk factor for asthma in adults, waist circumference has seldom been investigated. To determine the association between BMI, waist circumference and incident asthma in adults, we conducted a prospective study (n=23,245) in a population living in Nord-Trøndelag, Norway in 1995–2008. Baseline BMI and waist circumference were measured and categorised as general obesity (BMI ≥30.0 kg·m2) and abdominal obesity (waist circumference ≥88 cm in females and ≥102 cm in males). Incident asthma was self-reported new-onset cases during an 11-yr follow-up period. Odds ratios for asthma associated with obesity were calculated using multivariable logistic regression. General obesity was a risk factor for asthma in females (OR 1.96, 95% CI 1.52–2.52) and males (OR 1.84, 95% CI 1.30–2.59). In females, after additional adjustment for BMI, abdominal obesity remained a risk factor for asthma development (OR 1.46, 95% CI 1.04–2.05). Abdominal obesity seems to increase the risk of incident asthma in females in addition to BMI, indicating that using both measures of BMI and waist circumference in females may be a superior clinical assessment for asthma risk than any measure alone.

The associations of anxiety and depression symptoms with weight change and incident obesity: The HUNT Study

OBJECTIVE:To investigate the associations of anxiety and depression symptoms with weight change and incident obesity in men and women.DESIGN:We conducted a prospective cohort study using the Norwegian Nord-Trøndelag Health Study (HUNT).SUBJECTS:The study cohort included 25 180 men and women, 19–55 years of age from the second survey of the HUNT (1995–1997).MEASUREMENTS:Anxiety and depression symptoms were measured using the Hospital Anxiety and Depression Scale. Weight change was determined for the study period of an average 11 years. Incident obesity was new-onset obesity classified as having a body mass index of ⩾30.0 kg m2 at follow-up. The associations of anxiety or depression with weight change in kilograms (kg) was estimated using linear regression models. Risk ratios (RRs) for incident obesity associated with anxiety or depression were estimated using log-binomial regression.RESULTS:In men, any anxiety or depression was associated with an average 0.81 kg (95% confidence interval (CI) 0.27–1.34) larger weight change after 11 years compared with those without such symptoms (mean weight change: 5.04 versus 4.24 kg). Women with any anxiety or depression had an average 0.98 kg (95% confidence interval (CI) 0.49–1.47) larger weight change compared with those without such symptoms (mean weight change: 5.02 versus 4.04 kg). Participants with any anxiety or depression had a significantly elevated cumulative incidence of obesity (men: RR 1.37, 95% CI 1.13–1.65; women: RR 1.18, 95% CI 1.00–1.40).CONCLUSION:We found that symptoms of anxiety and depression were associated with larger weight change and an increased cumulative incidence of obesity in both men and women.

Metabolic syndrome and incidence of asthma in adults: the HUNT study

Obesity is a risk factor for incident asthma in adults, and obesity is a major component of metabolic syndrome. This study aimed to explore the associations of metabolic syndrome and its components with the cumulative incidence of asthma in adults. We conducted a prospective cohort study of participants who were asthma-free at baseline (n = 23 191) in the Nord-Trøndelag Health Study from 1995 to 2008. Baseline metabolic syndrome was categorised using the definition of the Joint Interim Statement from several international organisations. Incident asthma was self-reported at follow-up, which averaged 11 years. Metabolic syndrome was a risk factor for incident asthma (adjusted OR 1.57, 95% CI 1.31–1.87). This association was consistent in sensitivity analyses using a stricter asthma definition (adjusted OR 1.42, 95% CI 1.13–1.79). Among the components of metabolic syndrome, two remained associated with incident asthma after mutual adjustment for the other metabolic components: high waist circumference (adjusted OR 1.62, 95% CI 1.36–1.94) and elevated glucose or diabetes (adjusted OR 1.43, 95% CI 1.01–2.04). Metabolic syndrome and two of its components (high waist circumference and elevated glucose or diabetes) were associated with an increased risk of incident asthma in adults. Metabolic syndrome and two of its components were associated with an increased risk of incident asthma in adults http://ow.ly//p2RNy

GOLD classifications and mortality in chronic obstructive pulmonary disease: the HUNT Study, Norway

Background How different Global Initiative for Chronic Obstructive Lung Disease (GOLD) classifications of chronic obstructive pulmonary disease (COPD) predict mortality is unclear. Objective To examine the association of spirometric GOLD grades and the new ABCD groups with mortality, and to compare their informativeness in relation to mortality. Methods We studied 1540 people with post-bronchodilator COPD who participated in the Norwegian Nord-Trøndelag Health Study 1995–1997 and were followed up on all-cause mortality until May 2012. The associations of spirometric GOLD grades and ABCD groups with mortality were estimated by sex specific adjusted HRs from Cox regression and standardised mortality ratios. To assess the informativeness of spirometric GOLD grades and ABCD groups at predicting mortality we used the difference in twice the log-likelihood of a Cox regression model with and without each COPD classification. Results The distribution of participants was 28% in GOLD 1, 57% in GOLD 2, 13% in GOLD 3 and 2% in GOLD 4, in contrast to 61% in group A, 18% in group B, 12% in group C and 10% in group D. During a median of 14.6 years of follow-up, 837 people (54%) died. Mortality increased gradually from GOLD 1 to 4, while it was generally similar in groups A and B, and in groups C and D. Spirometric GOLD grades were substantially more informative than ABCD groups at predicting mortality. Conclusions Spirometric GOLD grades predicted mortality better than the new ABCD groups among people with COPD from a Norwegian general population.

Factors associated with vitamin D deficiency in a Norwegian population: the HUNT Study

Vitamin D deficiency occurs worldwide. Winter season and high Body Mass Index (BMI) are associated with low levels of serum 25-hydroxyvitamin D (25(OH)D). We estimated the prevalence of vitamin D deficiency in a Norwegian adult population and examined factors associated with vitamin D deficiency. A cohort of 25 616 adults (19–55 years) who participated in both the second and third Nord-Trøndelag Health Study (HUNT 2 (1995–1997) and HUNT 3 (2006–2008)) was established in a previous study. A 10% random sample of the cohort population was recruited for serum 25(OH)D measurements (n=2584), which was used for the current cross-sectional study. Vitamin D deficiency was defined as serum 25(OH)D level <50 nmol/L. The overall prevalence of vitamin D deficiency was 40%, but varied by season (winter: 64%; summer: 20%). Winter season (adjusted prevalence ratio (PR): 3.16, 95% CI 2.42 to 4.12) and obesity (BMI ≥30.0 kg/m2) (PR: 1.74, 95% CI 1.45 to 2.10) were strongly associated with prevalent vitamin D deficiency. Current smoking also demonstrated an increased PR (1.41, 95% CI 1.21 to 1.65). Daily intake of cod liver oil (PR: 0.60, 95% CI 0.41 to 0.77), increased physical activity (PR: 0.80, 95% CI 0.68 to 0.95) and more frequent alcohol consumption (PR: 0.76, 95% CI 0.60 to 0.95) were associated with a reduced PR. The prevalence of vitamin D deficiency was high in Norwegian adults. Winter season, high BMI and current smoking were positively associated, and intake of cod liver oil, increased physical activity and more frequent alcohol consumption were inversely associated with vitamin D deficiency.

Serum 25-Hydroxyvitamin D Levels and Incident Asthma in Adults The HUNT Study

The impact of low vitamin D status on asthma development is unclear. The authors investigated the relation between the baseline serum 25-hydroxyvitamin D (25(OH)D) level and incident asthma in adults, including possible effect modification by allergy status, using allergic rhinitis as a proxy measure. A cohort of 25,616 Norwegian adults aged 19-55 years participated in 2 surveys of the Nord-Trøndelag Health Study known as HUNT 2 (1995-1997) and HUNT 3 (2006-2008). Of this cohort, a nested case-control study included 584 new-onset asthma cases and 1,958 nonasthma controls whose baseline serum 25(OH)D levels were measured. After adjustment for potential asthma risk factors, the baseline serum level of 25(OH)D (<50 nmol/L) was not significantly associated with asthma in either women (adjusted odds ratio = 0.94, 95% confidence interval (CI): 0.67, 1.32) or men (adjusted odds ratio = 1.47, 95% CI: 0.93, 2.32). In men, allergic rhinitis modified the association with the adjusted odds ratio being 0.87 (95% CI: 0.36, 2.06) among men with allergic rhinitis and 2.32 (95% CI: 1.06, 5.10) among men without allergic rhinitis. The serum 25(OH)D level was not associated with incident asthma in women, regardless of allergy status. Low vitamin D status was not significantly associated with incident asthma in most adults, but it may have increased risk among men without allergy.

Serum 25-hydroxyvitamin D levels and self-reported allergic rhinitis in Norwegian adults – The HUNT Study

The role of low vitamin D status in the development of allergic rhinitis is unclear. We aimed to investigate the relationship between serum 25‐hydroxyvitamin D [25(OH)D] and incidence of allergic rhinitis in adults.

The joint association of anxiety, depression and obesity with incident asthma in adults: the HUNT Study

BACKGROUND Anxiety or depression symptoms may increase the risk of developing asthma, and their interaction with obesity is not known. We aimed to assess the association of anxiety or depression symptoms and the joint association of these symptoms and obesity with incident asthma. METHODS We conducted a prospective cohort study of 23 599 adults who were 19-55 years old and free from asthma at baseline in the Norwegian Nord-Trøndelag Health Study. The Hospital Anxiety and Depression Scale was used to measure anxiety or depression symptoms. Obesity was defined as a body mass index≥30.0 kg/m2. Incident asthma was self-reported new cases of asthma during the 11-year follow-up. RESULTS Having anxiety or depression symptoms was associated with incident asthma [odds ratio (OR) 1.39, 95% confidence interval (CI) 1.09-1.78). Obese participants with anxiety or depression symptoms had a substantially higher risk of incident asthma (OR 2.93, 95% CI 2.20-3.91) than any other group (non-obese participants without anxiety or depression symptoms [reference], non-obese participants with anxiety or depression symptoms (OR 1.20, 95% CI 1.00-1.45) and obese participants without anxiety or depression symptoms (OR 1.47, 95% CI 1.19-1.82)]. The relative excess risk for incident asthma due to interaction between anxiety or depression symptoms and obesity was 1.26 (95% CI 0.39-2.12). CONCLUSIONS This study suggests that having anxiety or depression symptoms contributes to the development of asthma in adults. The risk of asthma may be further increased by the interaction between anxiety or depression symptoms and obesity.

Cod liver oil intake and incidence of asthma in Norwegian adults—the HUNT study

Background Cod liver oil is an important source of vitamin D, but also contains other fat-soluble components such as vitamin A. Before 1999, the cod liver oil formula in Norway contained a high concentration of vitamin A (1000 µg per 5 ml). High vitamin A status is associated with increased risks of several chronic diseases. Objective To investigate the association between cod liver oil intake and asthma development. Methods In the Nord-Trøndelag Health Study, a total of 25 616 Norwegian adults aged 19–55 years were followed up from 1995–1997 to 2006–2008. Current analysis based on 17 528 subjects who were free of asthma and had complete information on cod liver oil intake at baseline. Cod liver oil intake was defined as daily intake ≥1 month during the year prior to baseline. Incident asthma was reported as new-onset asthma during the 11-year follow-up. Results Of the 17 528 subjects, 18% (n=3076) consumed cod liver oil daily for ≥1 month over the past year. Cod liver oil intake was significantly associated with incident asthma with an OR of 1.62 (95% CI 1.32 to 1.98) after adjustment for age, sex, daily smoking, physical activity, education, socio-economic status, family history of asthma, and body mass index (BMI). The positive association was consistent across age (<40/≥40 years), sex (men/women), family history of asthma (yes/no) and BMI subgroups (<25/≥25 kg/m2). Conclusions Intake of cod liver oil with high vitamin A content was significantly associated with increased incidence of adult-onset asthma.