Lipid Levels During Adult Lifetime in Men and Women With and Without a Subsequent Incident Myocardial Infarction: A Longitudinal Analysis of Data From the Tromsø Study 1974 to 2016.

Background The atherosclerotic effect of an adverse lipid profile is assumed to accumulate throughout life, leading to increased risk of myocardial infarction (MI). Still, little is known about age at onset and duration of unfavorable lipid levels before MI. Methods and Results Longitudinal data on serum lipid levels for 26 130 individuals (50.5% women, aged 20-89 years) were obtained from 7 population-based health surveys in Tromsø, Norway. Diagnoses of MI were obtained from national registers. A linear mixed model was applied to compare age- and sex-specific mean values of total cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglyceride concentration by MI status (MI versus non-MI). Already from young adulthood, 20 to 35 years before the incident MI, individuals with a subsequent incident MI had on average more adverse lipid levels than individuals of the same age and sex without MI. Analogous to a dose-response relationship, there was a clear trend toward more severe adverse lipid levels the lower the age at incident MI (P<0.001, test for trend through ordered categories <55, 55-74, ≥75 years). This trend was particularly pronounced for high-density lipoprotein cholesterol in percentage of total cholesterol (both sexes) and for the relative relationship between triglyceride, high-density lipoprotein cholesterol, and total cholesterol level (women). The difference in mean lipid level by MI status was just as large in women as in men, but the age pattern differed (P≤0.05, tests of 3-way interaction). Conclusions Compared with general population mean levels, adverse lipid levels were seen 20 to 35 years before the incident MI in both men and women.

Menopausal hormone therapy, oral contraceptives and risk of chronic low back pain: the HUNT Study.

BACKGROUND: There are indications that use of menopausal hormone therapy (MHT) and oral contraceptives (OC) increases the risk of low back pain (LBP), with higher oestrogen levels involved in the underlying mechanisms. The purpose of the present study was to investigate associations between use of systemic MHT or OC and risk of chronic LBP in a large population-based data set. METHODS: Data were obtained from two surveys in the Trøndelag Health Study in Norway, HUNT2 (1995-1997) and HUNT3 (2006-2008). A cross-sectional study of association between use of systemic MHT and prevalence of chronic LBP comprised 12,974 women aged 40-69 years in HUNT2, with 4007 women reporting chronic LBP. A cohort study involving MHT comprised 6007 women without chronic LBP at baseline in HUNT2, and after 11 years 1245 women reported chronic LBP at follow-up in HUNT3. The cross-sectional study of association with use of OC included 23,593 women aged 20-69 years in HUNT2, with 6085 women reporting chronic LBP. The corresponding cohort study included 10,586 women without chronic LBP at baseline in HUNT2, of whom 2084 women reported chronic LBP in HUNT3. Risk of chronic LBP was examined in both study designs in generalised linear models with adjustment for potential confounders. RESULTS: In the cohort study, current users of systemic MHT at baseline showed a greater risk of chronic LBP (relative risk (RR) 1.30; 95% CI: 1.14-1.49; compared with never users). The risk increased according to duration of MHT use (P for linear trend = 0.003). Known users of systemic MHT based exclusively on oestrogen experienced the highest risk (RR 1.49; 95% CI: 1.16-1.91), but an increased risk was also seen among known users of oestrogen-progestin combination MHT (RR 1.35; 95% CI: 1.16-1.57). A slight increase in risk of chronic LBP was found in the cohort study among former users of OC (RR 1.17; 95% CI: 1.06-1.30; compared with never users). CONCLUSIONS: Long-lasting use of systemic MHT, in particular therapy based on oestrogen only, is associated with greater risk of chronic LBP. Having been a user of OC most likely entails a minor increase in risk.

Does the risk of chronic low back pain depend on age at menarche or menopause? A population-based cross-sectional and cohort study: the Trøndelag Health Study.

OBJECTIVE: In most population-based studies of low back pain (LBP), women have a higher risk than men, possibly reflecting hormonal influences. The aim of this study was to explore associations between age at menarche and menopause and risk of chronic LBP. DESIGN: Population-based cross-sectional and cohort study designs. SETTING: The HUNT2 and HUNT3 medical surveys of the entire population of Nord-Trøndelag County in Norway. MAIN OUTCOME MEASURE: Prevalence or risk of chronic LBP, defined as LBP persisting at least 3 months continuously during last year. PARTICIPANTS: Associations between age at menarche and prevalence of chronic LBP were examined in cross-sectional data from HUNT2, comprising 27 697 women aged 20-69 years, with 7300 women reporting LBP. The corresponding cohort data included 11 659 women without LBP at baseline in HUNT2, with 2353 women reporting LBP at follow-up 11 years later in HUNT3. Cross-sectional data on age at menopause or premenopausal status included 11 332 women aged 40-69 years, with 3439 women reporting chronic LBP. Corresponding cohort data included 7893 women without LBP at baseline, of whom 1100 developed LBP. METHODS: Associations between age at menarche or menopause and risk of chronic LBP were examined by generalised linear modelling. RESULTS: A U-shaped association was indicated between age at menarche and risk of chronic LBP, both in the cross-sectional and cohort studies. Age at menarche ≤11 years was associated with an increased risk of chronic LBP, with a relative risk of 1.32 (95% CI 1.15 to 1.52), compared with age 14 years at menarche, after relevant adjustments. Corresponding cross-sectional crude absolute risks were 32% and 25%, respectively. No association was established between age at menopause and risk of LBP. Being premenopausal had no influence on risk. CONCLUSIONS: In contrast to results for age at menopause, the association with age at menarche suggests that hormonal factors affect the risk of LBP.

Socioeconomic and geographic differences in ablation of atrial fibrillation in Norway - a national cohort study.

BACKGROUND: The aim of this study was to analyse whether there are patient related or geographic differences in the use of catheter ablation among atrial fibrillation patients in Norway. METHODS: National population-based data on individual level of all Norwegians aged 25 to 75 diagnosed with atrial fibrillation from 2008 to 2017 were used to study the proportion treated with catheter ablation. Survival analysis, by Cox regression with attained age as time scale, separately by gender, was applied to examine the associations between ablation probability and educational level, income level, place of residence, and follow-up time. RESULTS: Substantial socioeconomic and geographic variation was documented. Atrial fibrillation patients with high level of education and high income were more frequently treated with ablation, and the education effect increased with increasing age. Patients living in the referral area of St. Olavs Hospital Trust had around three times as high ablation rates as patients living in the referral area of Finnmark Hospital Trust. CONCLUSIONS: Differences in health literacy, patient preference and demands are probably important causes of socioeconomic variation, and studies on how socioeconomic status influences the choice of treatment are warranted. Some of the geographic variation may reflect differences in ablation capacity. However, geographic variation related to differences in clinical practice and provider preferences implies a need for clearer guidelines, both at the specialist level and at the referring level.

Equitable access to cancer patient pathways in Norway - a national registry-based study.

BACKGROUND: In 2015, cancer patient pathways (CPP) were implemented in Norway to reduce unnecessary non-medical delay in the diagnostic process and start of treatment. The main aim of this study was to investigate the equality in access to CPPs for patients with either lung, colorectal, breast or prostate cancer in Norway. METHODS: National population-based data on individual level from 2015 to 2017 were used to study two proportions; i) patients in CPPs without the cancer diagnosis, and ii) cancer patients included in CPPs. Logistic regression was applied to examine the associations between these proportions and place of residence (hospital referral area), age, education, income, comorbidity and travel time to hospital. RESULTS: Age and place of residence were the two most important factors for describing the variation in proportions. For the CPP patients, inconsistent differences were found for income and education, while for the cancer patients the probability of being included in a CPP increased with income. CONCLUSIONS: The age effect can be related to both the increasing risk of cancer and increasing number of GP and hospital contacts with age. The non-systematic results for CPP patients according to income and education can be interpreted as equitable access, as opposed to the systematic differences found among cancer patients in different income groups. The inequalities between income groups among cancer patients and the inequalities based on the patients' place of residence, for both CPP and cancer patients, are unwarranted and need to be addressed.

Impact of parents' education on variation in hospital admissions for children: a population-based cohort study.

OBJECTIVES: To assess the impact of parental educational level on hospital admissions for children, and to evaluate whether differences in parents' educational level can explain geographic variation in admission rates. DESIGN: National cohort study. SETTING: The 18 hospital referral areas for children in Norway. PARTICIPANTS: All Norwegian children aged 1-16 years in the period 2008-2016 and their parents. MAIN OUTCOME MEASURES: Age- and gender-adjusted admission rates and probability of admission. RESULTS: Of 1 538 189 children, 156 087 (10.2%) had at least one admission in the study period. There was a nearly twofold (1.9) variation in admission rates between the hospital referral areas (3113 per 100 000 children, 95% CI: 3056 to 3169 vs 1627, 95% CI: 1599 to 1654). Area level variances in multilevel analysis did not change after adjusting for parental level of education. Children of parents with low level of education (maternal level of education, low vs high) had the highest admission rates (2016: 2587, 95% CI: 2512 to 2662 vs 1810, 95% CI: 1770 to 1849), the highest probability of being admitted (OR: 1.18, 95% CI: 1.16 to 1.20), the highest number of admissions (incidence rate ratio: 1.05, 95% CI: 1.01 to 1.10) and admissions with lower cost (-0.5%, 95% CI: -1.2% to 0.3%). CONCLUSIONS: Substantial geographic variation in hospital admission rates for children was found, but was not explained by parental educational level. Children of parents with low educational level had the highest admission probability, and the highest number of admissions, but the lowest cost of admissions. Our results suggest that the variation between the educational groups is not due to differences in medical needs, and may be characterised as unwarranted. However, the manner in which health professionals communicate and interact with parents with different educational levels might play an important role.

Associations between the number of children, age at childbirths and prevalence of chronic low back pain: the Nord-Trøndelag Health Study.

BACKGROUND: Associations between childbirths and subsequent risk of low back pain (LBP) have not been clarified. Changes in sex hormone levels or lumbar posture during pregnancy may have an impact on LBP later in life. The purpose of this study was to explore associations between the number of childbirths, age at childbirths and prevalence of chronic LBP in a general population of women. METHODS: Data were obtained from the Norwegian community-based Nord-Trøndelag Health Study, HUNT2 (1995-1997). Women aged 20-69 years indicated whether they suffered from chronic LBP, defined as LBP persisting at least 3 months continuously during last year. Information about LBP was collected from 3936 women who had experienced no childbirths, 3143 women who had delivered one child only and 20,584 women who had delivered 2 or more children. Of these, 7339 women reported chronic LBP. The 595 women who were pregnant when information was collected were considered separately, regardless of previous births, with 80 women reporting chronic LBP. Associations with prevalence of chronic LBP were examined by generalised linear modelling with adjustment for potential confounders in a cross-sectional design. RESULTS: Women who had delivered one child only showed a higher prevalence of chronic LBP than women with no childbirths (prevalence ratio (PR) 1.11; 95% CI: 1.01-1.22). Among women with one or more childbirths, no overall change in prevalence could be demonstrated with an increasing number of children in analyses adjusted for age at first delivery. In women with at least two childbirths, an age less than 20 years at first childbirth was associated with an increased prevalence of chronic LBP (PR 1.36; 95% CI: 1.25-1.49; compared with age 25-29 years). No association was observed between age at last delivery and chronic LBP. The lowest prevalence of chronic LBP was found among women who were currently pregnant (PR 0.80; 95% CI: 0.63-1.00; compared with women with no childbirths). CONCLUSIONS: Having experienced at least one childbirth seems to be associated with a higher prevalence of chronic LBP later in life. A young age at first childbirth is also associated with a long-lasting increased prevalence.

Effects of a Parent-Administered Exercise Program in the Neonatal Intensive Care Unit: Dose Does Matter-A Randomized Controlled Trial.

BACKGROUND: Despite the risk of delayed motor development in infants born preterm, knowledge about interventions in the neonatal intensive care unitt (NICU) and the effects of dosing is sparse. OBJECTIVE: The objectives of this study were to examine the effectiveness of a parent-administered exercise program in the NICU on motor outcome at 3 months corrected age (CA) and the effect of dosing on motor performance. DESIGN: This was a randomized clinical trial. SETTING: The study was conducted at 3 university hospitals in Tromsø, Trondheim, and Oslo, Norway. PARTICIPANTS: A total of 153 infants with gestational age <32 weeks at birth were randomly assigned to intervention or control groups. INTERVENTION: A 3-week parent-administered intervention designed to facilitate movements in preterm infants was performed in the NICU. Parents were asked to administer the intervention 10 minutes twice a day. MEASUREMENTS: Test of Infant Motor Performance (TIMP) was used to assess short-term outcome at 3 months CA. RESULTS: No significant difference in the TIMP z-score was found between intervention and control groups at follow-up 3 months CA, but a significant positive relationship was found between total intervention dose and TIMP z-scores. The adjusted odds of having a clinical z-score < 0 at 3 months CA was about 6 times higher for infants with less than median intervention time than for infants with a longer intervention time. LIMITATIONS: The number of infants born before 28 weeks was small. A spillover effect in favor of the control group was possible. We do not know if the infants received physical therapy after discharge from the hospital. CONCLUSIONS: There was no difference in motor performance between the intervention group and the control group at 3 months CA. However, an increased intervention dose was positively associated with improved motor outcome.

Does diabetes influence the probability of experiencing chronic low back pain? A population-based cohort study: the Nord-Trøndelag Health Study.

OBJECTIVE: Low back pain (LBP) is a major problem in modern society and it is important to study possible risk factors for this disorder. People with diabetes are often affected by LBP, but whether diabetes represents a risk factor for LBP has not been studied in detail. The aim of this study was to explore the association between diabetes and subsequent risk of chronic LBP. DESIGN: An 11-year follow-up study. SETTING: The Nord-Trøndelag Health Study (HUNT2; 1995-1997) and HUNT3 (2006-2008) surveys of Nord-Trøndelag County in Norway. MAIN OUTCOME MEASURE: Chronic LBP, defined as LBP persisting at least 3 months continuously during the last year. PARTICIPANTS: A total of 18 972 persons without chronic LBP at baseline in HUNT2, and 6802 persons who reported chronic LBP at baseline in HUNT2. METHODS: Associations between diabetes and risk of chronic LBP among individuals aged 30-69 years were examined by generalised linear modelling. RESULTS: Men without chronic LBP at baseline showed a significant association between diabetes and risk of chronic LBP (relative risk (RR) 1.43, 95% CI 1.04 to 1.96, p=0.043). In women, no association was found (RR 1.01, 95% CI 0.69 to 1.48, p=0.98). No association could be established between diabetes and recurrence or persistence of chronic LBP after 11 years in either sex. CONCLUSIONS: Men with a diagnosis of diabetes may have a higher risk of subsequently experiencing chronic LBP.

Is chronic low back pain a risk factor for diabetes? The Nord-Trøndelag Health Study.

OBJECTIVE: The purpose of this study was to examine the risk of diabetes associated with the presence or absence of chronic low back pain, considering both cross-sectional and cohort data. RESEARCH DESIGN AND METHODS: Analyses were based on the Norwegian HUNT2 and HUNT3 surveys of Nord-Trøndelag County. The prevalence of diabetes was compared in groups with and without chronic low back pain among 45 157 participants aged 30-69 years. Associations between low back pain at baseline and risk of diabetes were examined in an 11-year follow-up of 30 380 individuals with no baseline diagnosis of diabetes. The comorbidity between diabetes and low back pain was assessed at the end of follow-up. All analyses were carried out considering generalized linear models incorporating adjustment for other relevant risk factors. RESULTS: Cross-sectional analyses did not reveal any association between low back pain and diabetes. With adjustment for age, body mass index, physical activity and smoking, the cohort study of women showed a significant association between low back pain at baseline and risk of diabetes (RR 1.30; 95% CI 1.09 to 1.54, p=0.003). The association differed between age groups (p=0.015), with a stronger association in relatively young women. In men, no association was found in the whole age range (RR 1.02; 95% CI 0.86 to 1.21, p=0.82). No association was observed between diabetes and chronic low back pain at the end of follow-up. CONCLUSION: Among younger women, those with chronic low back pain may have an increased risk of diabetes.

Modelling memory decay after injuries using household survey data from Khartoum State, Sudan.

BACKGROUND: Injuries represent an important cause of morbidity and mortality worldwide. In retrospective epidemiological studies, estimated rates of reported injuries often decline considerably when information is included from periods more than a few months before the data collection. Such low rates are usually regarded as a consequence of memory decay. It is largely unknown whether the extent of memory decay depends on external factors otherwise affecting injury rates. METHODS: A statistical model was introduced to separate the influence of external factors on true injury rates from effects on memory decay. The relationship between apparent rates and time elapsed between injury occurrence and data collection was described by a parametric regression model. Relationships between memory decay and external factors were modelled by effect modification of the relationship with time. The procedure was applied to data collected in a retrospective household survey, carried out in Khartoum State in 2010, which elicited information about injuries that had occurred during the last year. The survey included 5661 individuals in 973 households, reporting a total of 481 non-fatal injuries. RESULTS: In the data from Khartoum State, differences in memory recall were observed between socioeconomic groups, with considerably faster memory decay in the lower socioeconomic tertile. In this tertile the estimated probability that an injury which occurred 6 months ago was reported was only 18%, compared to probabilities of about 35% in the remainder of the population. In the lower socioeconomic tertile, in contrast to other groups, a simple exponential model was not sufficient for describing memory decay. Memory decay did not depend on sex, age, urban/rural status or education. Road traffic injuries were subject to less memory decay than injuries due to falls, mechanical causes and burns. Memory decay seriously affected crude overall injury rates and also to some degree estimated relative rates. CONCLUSION: In the statistical analysis of retrospective injury data it is important to take into account the effects of memory decay.

Is there an association between vitamin D status and risk of chronic low back pain? A nested case-control analysis in the Nord-Trøndelag Health Study.

OBJECTIVES: To explore potential associations between vitamin D status and risk of chronic low back pain (LBP) in a Norwegian cohort, and to investigate whether relationships depend on the season of blood sample collection. DESIGN: A nested case-control study in a prospective data set. SETTING: The Norwegian community-based Nord-Trøndelag Health Study (HUNT). Data were collected in the HUNT2 (1995-1997) and HUNT3 (2006-2008) surveys. MAIN OUTCOME MEASURE: Chronic LBP, defined as LBP persisting at least 3 months continuously during the past year. PARTICIPANTS: Among individuals aged 19-55 years without LBP in HUNT2, a data set was generated including 1685 cases with LBP in HUNT3 and 3137 controls without LBP. METHODS: Blood samples from the participants collected in HUNT2 were analysed for serum 25-hydroxyvitamin D (25(OH)D) level. Associations with LBP in HUNT3 were evaluated by unconditional logistic regression analysis with adjustment for age, sex, work status, physical activity at work and in leisure time, education, smoking, and body mass index. RESULTS: No association between vitamin D status and risk of chronic LBP was found in the total data set (OR per 10 nmol/L 25(OH)D=1.01, 95% CI 0.97 to 1.06) or in individuals with blood samples collected in summer/autumn (OR per 10 nmol/L 25(OH)D=0.99, 95% CI 0.93 to 1.06). For blood samples drawn in winter/spring, associations differed significantly between women and men (p=0.004). Among women a positive association was seen (OR per 10 nmol/L 25(OH)D=1.11, 95% CI 1.02 to 1.20), but among men no significant association was observed (OR per 10 nmol/L 25(OH)D=0.90, 95% CI 0.81 to 1.01). CONCLUSIONS: Overall, no association between vitamin D status and risk of LBP was demonstrated. The association suggested in women for the winter/spring season cannot be regarded as established.

Data on gender contrasts in the risk of incident myocardial infarction by age. The Tromsø Study 1979-2012.

The data presented in this article relate to the research article entitled "Risk of incident myocardial infarction by gender: Interactions with serum lipids, blood pressure and smoking. The Tromsø Study 1979-2012" (Albrektsen et al., 2017) [1]. Data quantify the gender differences in the risk of myocardial infarction (MI) in terms of incidence rate ratios (IRR), in subgroups defined by serum lipids, blood pressure and smoking among persons aged 35-54 years, 55-74 years and 75-94 years, respectively. Data also describe the age- and gender-specific linear associations with the coronary heart disease (CHD) risk factors. IRRs for combined categories of age, gender and a CHD risk factor, with each category compared to the same reference group, are also shown. IRRs were calculated as estimates of relative risk in Poisson regression analyses of person-years at risk. Among 33,859 individuals at risk, a total of 622, 1308 and 816 were diagnosed with MI at ages 35-54, 55-74 and 75-94 years, respectively.

Physical activity level at work and risk of chronic low back pain: A follow-up in the Nord-Trøndelag Health Study.

BACKGROUND: Physical activity in leisure time seems to reduce the risk of low back pain, but it is not known whether occupational activity, as recorded in a representative working population, produces a higher or lower risk. OBJECTIVE: To study associations between physical activity level at work and risk of chronic low back pain. METHODS: Associations were examined in a Norwegian prospective study using data from the HUNT2 and HUNT3 surveys carried out in the whole county of Nord-Trøndelag. Participants were 7580 women and 7335 men who supplied information about physical activity level at work. Levels considered were sedentary work, work involving walking but no heavy lifting, work involving walking and heavy lifting, and particularly strenuous physical work. Nobody in the cohort was affected by chronic low back pain at baseline. After 11 years, participants reported whether they suffered from chronic low back pain. Generalized linear modelling with adjustment for potential confounders was applied to assess associations with risk factors. RESULTS: In age-adjusted analyses both women and men showed statistically significant associations between physical activity at work and risk of chronic low back pain, suggesting positive relationships. For particularly strenuous physical work the relative risk of chronic low back pain was 1.30 (95% CI: 1.00-1.71) in women and 1.36 (95% CI 1.17-1.59) in men, compared to sedentary work. Women still showed a general association with activity level after adjustment for education, leisure time physical activity, BMI, smoking and occupational category. In men, the higher risk was only maintained for particularly strenuous work. CONCLUSION: In this cohort, women had a higher risk of chronic low back pain with work involving walking and heavy lifting or particularly strenuous work, compared to sedentary work. Men participating in particularly strenuous work also experienced a higher risk of chronic low back pain.

Risk of incident myocardial infarction by gender: Interactions with serum lipids, blood pressure and smoking. The Tromsø Study 1979-2012.

BACKGROUND AND AIMS: Overall, men have roughly twice the risk of myocardial infarction (MI) compared to women, but what causes this contrast is unclear. Identification of subgroups where the gender contrast in risk is particularly low or high, may provide new insight. In the search for such subgroups, we focus on gender-specific effects of established coronary heart disease (CHD) risk factors. Heterogeneity across age groups is also explored. METHODS: Population-based prospective study from Tromsø, Norway, comprising 33,859 individuals (51% women); 2746 individuals (854 women) received a diagnosis of MI during follow-up at ages 35-94 years. Incidence rate ratios (IRR) were calculated as estimates of relative risk in Poisson regression analyses. RESULTS: The association between total cholesterol and risk of MI was stronger for men than women, and IRR for men vs. women accordingly increased with increasing cholesterol, but the risk was higher for men in all subgroups (IRR in range 1.63-3.27), except among older people with low cholesterol levels. The adverse effect of increasing blood pressure (BP) was stronger for women, and IRR for gender diminished with increasing systolic (from 3.90 to 1.38) and diastolic BP (from 2.87 to 1.54). The gender contrast in risk was also substantially reduced in smokers ≥75 years. Associations with high-density lipoprotein cholesterol (HDL-C) did not differ between genders. CONCLUSIONS: Gender heterogeneity in associations with total cholesterol but not HDL-C indicates gender differences in associations with non-HDL-C. The stronger association with BP in women may relate to more severe hypertension-induced left ventricular hypertrophy.

Lifelong Gender Gap in Risk of Incident Myocardial Infarction: The Tromsø Study.

Importance: It is not clear to what extent the higher incidence of coronary heart disease (CHD) in men vs women is explained by differences in risk factor levels because few studies have presented adjusted risk estimates for sex. Moreover, the increase in risk of CHD in postmenopausal women, possibly hormone related, may eventually eliminate the sex contrast in risk, but age-specific risk estimates are scarce. Objective: To quantify the difference in risk of incident myocardial infarction (MI) between men and women. Design, Setting and Participants: Population-based prospective study from Tromsø, Norway, comprising 33 997 individuals (51% women). Median follow-up time during ages 35 to 102 years was 17.6 years. Incidence rates (IRs) and incidence rate ratios (IRRs, relative risk) of MI were calculated in Poisson regression analysis of person-years at risk. The data analysis was performed in November 2015. Exposures: Sex, age, birth cohort, serum lipid levels, blood pressure, lifestyle factors, diabetes. Main Outcomes and Measures: Incident MI. Results: A total of 2793 individuals (886 women) received a diagnosis of MI during follow-up in the period 1979 through 2012. The IR increased with age in both sexes, with lower rates for women until age 95 years. Adjusted for age and birth cohort, the overall IRR for men vs women was 2.72 (95% CI, 2.50-2.96). Adjustment for high-density lipoprotein cholesterol and total cholesterol levels had the strongest impact on the risk estimate for sex, followed by diastolic blood pressure and smoking. However, the sex difference remained substantial even after adjustment for these factors (IRR, 2.07; 95% CI, 1.89-2.26). Men had higher risk throughout life, but the IRRs decreased with age (3.64 [95% CI, 2.85-4.65], 2.00 [95% CI, 1.76-2.28], and 1.66 [95% CI, 1.42-1.95] for age groups 35-54, 55-74, and 75-94 years, respectively). Adjustment for systolic blood pressure, diabetes, body mass index, and physical activity had no notable impact. Conclusions and Relevance: The observed sex contrast in risk of MI cannot be explained by differences in established CHD risk factors. The gender gap persisted throughout life but declined with age as a result of a more pronounced flattening of risk level changes in middle-aged men. The minor changes in IRs when moving from premenopausal to postmenopausal age in women make it unlikely that changes in female hormone levels influence the risk of MI.

Is there a U-shaped relationship between physical activity in leisure time and risk of chronic low back pain? A follow-up in the HUNT Study.

BACKGROUND: Physical activity in leisure time is often considered to have favourable effects on the risk of low back pain (LBP), but demonstrating a definite association in epidemiological studies has proven difficult. The purpose of the present study was to explore associations between physical activity and risk of chronic LBP in an adult population and to investigate whether relationships are limited to certain age groups or to females or males. A particular objective was to determine whether support could be found for a U-shaped relationship, with both low and high activity levels carrying greater risk. METHODS: The relationship between physical activity and risk of chronic LBP was examined in a Norwegian prospective study using data from the community-based HUNT2 and HUNT3 surveys. Participants were 9616 women and 8452 men without LBP at baseline, who reported after 11 years whether they suffered from LBP. Associations between baseline physical activity in leisure time and risk of chronic LBP at end of follow-up were evaluated by generalized linear modelling with adjustment for potential confounders. RESULTS: Significant associations between leisure time physical activity and risk were observed in both sexes after age adjustment, mainly suggesting inverse relationships. Women participating in hard physical activity 1-2 h per week had a relative risk (RR) of chronic LBP of 0.81 (95 % CI 0.71-0.93) compared to those with only light physical activity less than 1 h per week. The corresponding RR in men was 0.71 (95 % CI 0.60-0.85). After adjustment for education, employment, occupational activity, body mass index (BMI) and smoking, significant relationships could only be demonstrated in those aged 50 years or more at baseline. The associations differed between female educational groups, with more U-shaped relationships being observed among women with basic education only. CONCLUSION: No strong support was found overall for U-shaped relationships. However, no further general decrease in risk was seen among those with 3 h or more of hard physical activity per week. The contrasts observed between female educational groups may reflect different preferences regarding specific strenuous activities. Men aged 50 years or more seem in particular to benefit from hard physical activities.

A Comparison of Anthropometric Measures for Assessing the Association between Body Size and Risk of Chronic Low Back Pain: The HUNT Study.

BACKGROUND: Previous work indicates that overweight and obese individuals carry an increased risk of experiencing chronic low back pain (LBP). It is not known, however, how the association with body size depends on the choice of anthropometric measure used. OBJECTIVE: This work compares relationships with LBP for several measures of body size. Different results may indicate underlying mechanisms for the association between body size and risk of LBP. METHODS: In a cohort study, baseline information was collected in the community-based HUNT2 (1995-1997) and HUNT3 (2006-2008) surveys in Norway. Participants were 10,059 women and 8725 men aged 30-69 years without LBP, and 3883 women and 2662 men with LBP at baseline. Associations with LBP at end of follow-up were assessed by generalized linear modeling, with adjustment for potential confounders. RESULTS: Relationships between waist-hip-ratio and occurrence of LBP at end of follow-up were weak and non-significant after adjustment for age, education, work status, physical activity, smoking, lipid levels and blood pressure. Positive associations with LBP at end of follow-up were all significant for body weight, BMI, waist circumference and hip circumference after similar adjustment, both in women without and with LBP at baseline, and in men without LBP at baseline. After additional mutual adjustment for anthropometric measures, the magnitude of the association with body weight increased in women without LBP at baseline (RR: 1.130 per standard deviation, 95% CI: 0.995-1.284) and in men (RR: 1.124, 95% CI 0.976-1.294), with other measures showing weak associations only. CONCLUSION: Central adiposity is unlikely to play a major role in the etiology of LBP. Total fat mass may be one common factor underlying the associations observed. The association with body weight remaining after mutual adjustment may reflect mechanical or structural components behind the relationship between overweight or obesity and LBP.