Bente Morseth

Prevalence of vertebral fractures in women and men in the population-based Tromsø Study

BackgroundOsteoporotic vertebral fractures are, as the hip fractures, associated with increased morbidity and mortality. Norway has one of the highest reported incidences of hip fractures in the world. Because of methodological challenges, vertebral fractures are not extensively studied. The aim of this population based study was to describe, for the first time, the age- and sex specific occurrence of osteoporotic vertebral fractures in Norway.MethodsData was collected in the Tromso Study, 2007/8 survey. By the use of dual x-ray absorptiometry (GE Lunar Prodigy) vertebral fracture assessments were performed in 2887 women and men aged from 38 to 87 years, in addition to measurements of bone mineral density at the femoral sites. Information on lifestyle was collected through questionnaires. Comparisons between fractures and non-fractures were done sex stratified, by univariate analyses, adjusting for age when relevant.ResultsThe prevalence of vertebral fractures varied from about 3% in the age group below 60 to about 19% in the 70+ group in women, and from 7.5% to about 20% in men, with an overall prevalence of 11.8% in women and 13.8% in men (p = 0.07). Among those with fractures, only one fracture was the most common; two and more fractures were present in approximately 30% of the cases. Fractures were seen from the fourth lumbar to the fifth thoracic vertebrae, most common between first lumbar and sixth thoracic vertebrae. The most common type of fracture was the wedge type in both sexes. Bone mineral density at the hip differed significantly according to type of fracture, being highest in those with wedge fractures and lowest in those with compression fractures.ConclusionsThe prevalence of vertebral fractures increased by age in women and men, but the overall prevalence was lower than expected, considering the high prevalence of hip and forearm fractures in Norway. In both sexes, the wedge type was the fracture type most frequently observed and most common in the thoracic region.

Physical activity, resting heart rate, and atrial fibrillation: the Tromsø Study

AIMS The objective was to examine the association of physical activity and resting heart rate (RHR) with hospital-diagnosed atrial fibrillation (AF) in a Norwegian cohort. METHODS AND RESULTS This prospective study included 20 484 adults (50.3% men) who participated in the third Tromsø Study survey in 1986-87. At baseline, physical activity was assessed by a validated questionnaire, and RHR was objectively measured. Participants were followed from baseline through 2010 with respect to incident cases of hospital-diagnosed AF documented on an electrocardiogram. During a mean follow-up period of 20 years (409 045 person-years), 750 participants (70.5% men) were diagnosed with AF. Compared with the low physical activity group, moderately active individuals had a 19% lower risk of any AF [adjusted hazard ratio (HR) 0.81, 95% confidence interval (CI) 0.68-0.97], whereas highly active had similar risk of AF. Vigorously active individuals showed a non-significantly higher risk of AF (adjusted HR 1.37, 95% CI 0.77-2.43). Risk of AF increased with decreasing RHR (adjusted HR 0.92, 95% CI 0.86-0.98 for each 10 b.p.m. increase in RHR), and RHR < 50 b.p.m. was a risk factor for AF (P < 0.05). CONCLUSION In this prospective cohort study, leisure time physical activity was associated with AF in a J-shaped pattern. Moderate physical activity was associated with a reduced risk of AF, whereas higher activity levels attenuated the benefits of moderate activity. Low RHR was a risk factor for AF. Our results support the hypothesis that moderate and vigorous physical activity may affect AF risk via different pathophysiological mechanisms.

Tracking of Leisure Time Physical Activity during 28 yr in Adults: The Tromsø Study

PURPOSE Physical activity plays an important role in the prevention of many serious diseases. To develop targeted strategies that encourage physical activity, knowledge of stability of physical activity levels over time is essential. The aim of this study was to examine tracking of leisure time physical activity in adults in Northern Norway during three decades. METHODS We followed 5432 women and men who attended the Tromsø Study in 1979-1980, as well as repeated examinations after 7 and 28 yr. Baseline age was 20-54 yr (mean age=35.8 yr). Physical activity was assessed by self-administered questionnaires. Tracking of physical activity, defined as maintenance of relative rank of physical activity level, was estimated by Spearman correlation coefficient and by weighted κ statistics. Tracking in terms of predictability of later values from earlier measurements was analyzed by generalized estimating equations. RESULTS A higher-than-expected proportion of subjects maintained their physical activity level from examination 1 to 2 (58%) and 3 (53%). κ statistics showed agreement of 0.41 and 0.29, respectively. Belonging to a specific physical activity level at baseline increased the odds of belonging to the same category at later examinations (sedentary odds ratio (OR)=3.9 (95% confidence interval (CI)=3.5-4.4), moderately active OR=2.2 (95% CI=2.0-2.4), active OR=2.9 (95% CI=2.6-3.3), and highly active OR=14.0 (95% CI=8.7-22.5)). Being physically active in young adulthood increased the odds of being physically active later in life (moderately active OR=3.4 (95% CI=3.0-3.9), active OR=5.4 (95% CI=4.6-6.4), and highly active OR=13.0 (95% CI=7.4-22.8)). CONCLUSIONS This study showed tracking of leisure time physical activity during 28 yr in a cohort of adults.

Important risk factors and attributable risk of vertebral fractures in the population-based Tromsø study

BackgroundVertebral fractures, the most common type of osteoporotic fractures, are associated with increased risk of subsequent fracture, morbidity, and mortality. The aim of this study was to examine the contribution of important risk factors to the variability in vertebral fracture risk.MethodsVertebral fracture was ascertained by VFA method (DXA, GE Lunar Prodigy) in 2887 men and women, aged between 38 and 87 years, in the population-based Tromsø Study 2007/2008. Bone mineral density (BMD; g/cm2) at the hip was measured by DXA. Lifestyle information was collected by questionnaires. Multivariable logistic regression model, with anthropometric and lifestyle factors included, was used to assess the association between each or combined risk factors and vertebral fracture risk. Population attributable risk was estimated for combined risk factors in the final multivariable model.ResultsIn both sexes, age (odds ratio [OR] per 5 year increase: 1.32; 95% CI 1.19-1.45 in women and 1.21; 95% CI 1.10-1.33 in men) and BMD (OR per SD decrease: 1.60; 95% CI 1.34-1.90 in women and1.40; 95% CI 1.18-1.67 in men) were independent risk factors for vertebral fracture. At BMD levels higher than 0.85 g/cm2, men had a greater risk of fracture than women (OR 1.52; 95% CI 1.14-2.04), after adjusting for age. In women and men, respectively, approximately 46% and 33% of vertebral fracture risk was attributable to advancing age (more than 70 years) and low BMD (less than 0.85 g/cm2), with the latter having a greater effect than the former.ConclusionsThese data confirm that age and BMD are major risk factors for vertebral fracture risk. However, in both sexes the two factors accounted for less than half of fracture risk. The identification of individuals with vertebral fracture is still a challenge.

The ambiguity of physical activity, exercise and atrial fibrillation

Although commonly associated with cardiovascular disease or other medical conditions, atrial fibrillation may also occur in individuals without any known underlying conditions. This manifestation of atrial fibrillation has been linked to extensive and long-term exercise, as prolonged endurance exercise has shown to increase prevalence and risk of atrial fibrillation. In contrast, more modest physical activity is associated with a decreased risk of atrial fibrillation, and current research indicates a J-shaped association between atrial fibrillation and the broad range of physical activity and exercise. This has led to the hypothesis that the mechanisms underlying an increased risk of atrial fibrillation with intensive exercise are different from those underlying a reduced risk with moderate physical activity, possibly linked to distinctive characteristics of the population under study. High volumes of exercise over many years performed by lean, healthy endurance trained athletes may lead to cardiac (patho)physiological alterations involving the autonomic nervous system and remodelling of the heart. The mechanisms underlying a reduced risk of atrial fibrillation with light and moderate physical activity may involve a distinctive pathway, as physical activity can potentially reduce the risk of atrial fibrillation through favourable effects on cardiovascular risk factors.

Comments to Emaus et al. Does a variation in self-reported physical activity reflect variation in objectively measured physical activity, resting heart rate, and physical fitness? Results from the Tromsø study

In a recent study of 313 men and women aged 40–44 years, Emaus et al. [1] examined the associations between answers to a widely used simple question concerning leisure-time physical activity and objectively measurements of physical activity (accelorometer) and physical fitness (VO2max). They found that the question had acceptable validity. The question concerning leisure physical activity has four response options as detailed in the footnote to Table I, and the participants are asked to indicate their usual level of leisure activity in the past year choosing only one of the categories. The reported results [1] are interesting and are supported by our data from 1471 women and 1389 men, 18–69 years old, randomly selected from the population register of the county of Nordland, Norway. In our study, we examined the relationship between this simple question and a detailed questionnaire concerning 22 different leisure-time activities. The participants gave information about how often, how long, and the intensity (light, moderate, hard) of the activities during the last year. From the detailed questionnaire, metabolic equivalent of task (MET) was calculated. MET is the ratio of metabolic rate during a specific physical activity to a reference rate of metabolic rate at rest, and give a rough indication of the intensity of the activity. One MET is the resting metabolic rate obtained during quiet sitting and a MET value of 2, such as walking at a slow pace means that a person requires twice the energy than at rest. Ainsworth et al. have provided a coding scheme that classifies specific physical activity by rate of energy expenditure, and by use of the updated (2002) scheme [2], we estimated the sum of metabolic equivalent hours per week (METh/week) for each participant. As displayed in Table I, we found a strong relationship between the response to the simple question and the METh/week estimated from the more detailed questionnaire (Table), with Spearman’s correlation coefficient1⁄4 0.5 (p<0.001) for both gender. In conclusion, our results and previous studies show that this simple question on physical activity is reliable, has acceptable validity and is strongly related to METh/week as estimated from a comprehensible detailed questionnaire.

Are Physical Activity and Benefits Maintained After Long-Term Telerehabilitation in COPD?

This study investigated whether physical activity levels and other outcomes were maintained at 1-year from completion of a 2-year telerehabilitation intervention in COPD. During the post-intervention year, nine patients with COPD (FEV1 % of pred. 42.4±19.8%; age 58.1±6 years) were encouraged to exercise on a treadmill at home and monitor daily symptoms and training sessions on a webpage as during the intervention. Participants were not provided supervision or motivational support. Physical activity levels decreased from 3,806 steps/day to 2,817 steps/day (p= 0.039). There was a decline in time spent on light physical activity (p=0.009), but not on moderate-to-vigorous activity (p=0.053). Adherence to registration of symptoms and training sessions decreased significantly. Other outcomes including health status, quality of life, anxiety and depression, self-efficacy, and healthcare utilization did not change significantly. In conclusion, provision of equipment for self-management and unsupervised home exercise might not be enough to maintain physical activity levels.

The independent and joint associations of physical activity and body mass index with myocardial infarction: The Tromsø Study

Physical activity and overweight are associated with myocardial infarction (MI). However, their joint association with MI remains unclear. Our objective was to examine the independent and joint association between leisure-time physical activity (LTPA), body mass index (BMI) and MI. This prospective cohort study included 16,572 men and women (47.5% women) aged 20-54 years who took part in the second Tromsø Study. At baseline in 1979-80 LTPA was assessed by questionnaire. Data on MI was collected and adjudicated through hospital and causes of death registries between 1979 and 2013. Cox proportional hazards models were used to examine the independent and joint associations between LTPA, BMI and MI. The final sample included 16,104 individuals. During a median follow up of 34 years, 1613 incident cases of MI were recorded. Physical inactivity and elevated BMI were both independently associated with MI (p for trend 0.02 and <0.001). In joint analyses, normal weight, inactive individuals had a 20% higher risk of MI compared to their active counterparts (hazard ratio (HR) 1.20 (1.02-1.41)). The highest risk of MI was seen in obese, inactive individuals when compared to normal weight, active individuals (HR 3.20 (2.30-4.44)). The risk of MI increased with increasing BMI regardless of the activity level. HRs were lower for active compared to inactive individuals within the same BMI category. The findings suggest that LTPA and BMI are independently associated with risk of MI. LTPA seems to attenuate but not eliminate the risk of MI associated with excess bodyweight.

Sex Differences in the Impact of Body Mass Index on the Risk of Future Atrial Fibrillation: Insights From the Longitudinal Population‐Based Tromsø Study

Background Atrial fibrillation (AF) prevalence is increasing, and body mass index (BMI) is a risk factor for AF. However, sex differences in the impact of BMI on AF risk have not been fully elucidated. Methods and Results Data from the fourth survey (1994–1995) of the Tromsø Study (Norway) were used to investigate the association of single‐measurement BMI on future AF risk. To analyze the influence of BMI changes on AF risk, data from individuals who attended the third and fourth study surveys were used. AF diagnosis was derived from record linkage and end point adjudication. Cox regression analysis was conducted using fractional polynomials of BMI and BMI change with models adjusted for age, baseline BMI (change analyses), risk factors, comorbidities, and antihypertensive medications. Data were available for 24 799 individuals from the fourth survey (mean age, 45.5±14.2 years; 52.9% women). Over 15.7±5.5 years, 811 women (6.2%) and 918 men (7.9%) developed AF. In men, lower BMI decreased AF risk and higher BMI increased risk (hazard ratios [95% confidence intervals] for BMI 18 or 40 kg/m2 compared with 23 kg/m2 were 0.75 [0.70–0.81] and 4.42 [3.00–6.53], respectively). The same pattern was identified in women. Two surveys were attended by 14 652 individuals. In men and women, a decrease in BMI over time was associated with decreased AF risk and an increase in BMI was associated with increased AF risk. Conclusions Within a population cohort, BMI was positively associated with AF risk. Change in BMI over time influenced AF risk in both men and women.

The impact of changes in leisure time physical activity on changes in cardiovascular risk factors: results from The Finnmark 3 Study and SAMINOR 1, 1987–2003

ABSTRACT Objective: The aim of this study was to examine the associations between changes in leisure time physical activity and changes in cardiovascular risk factors over 16 years and whether they differ between two ethnic groups in Norway. Methods: Data were extracted from two population-based studies. Altogether, 3671 men and women participated in both surveys, and 30% reported being of Sami ethnicity. Leisure time physical activity was self-reported, and cardiovascular risk factors were measured. ANCOVA analysis was used to examine associations between changes in physical activity and changes in cardiovascular risk factors. Results: After adjustment for age, sex, smoking, ethnicity and respective baseline values, favourable changes in body mass index (BMI) and levels of triglycerides were most pronounced in those who were active in both surveys (p < 0.05) whereas the opposite was the situation for cholesterol levels (p = 0.003). Changes in systolic blood pressure, diastolic blood pressure and resting heart rate were not significantly associated with change in physical activity. Ethnicity did not influence the associations between physical activity and cardiovascular risk factors. Conclusion: Traditional cardiovascular risk factors were to a small extent associated with change in leisure time physical activity. Persistent physical activity was associated with beneficial changes in BMI and triglycerides.