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.

Genome-wide association study identifies RNF123 locus as associated with chronic widespread musculoskeletal pain.

BACKGROUND AND OBJECTIVES: Chronic widespread musculoskeletal pain (CWP) is a symptom of fibromyalgia and a complex trait with poorly understood pathogenesis. CWP is heritable (48%-54%), but its genetic architecture is unknown and candidate gene studies have produced inconsistent results. We conducted a genome-wide association study to get insight into the genetic background of CWP. METHODS: Northern Europeans from UK Biobank comprising 6914 cases reporting pain all over the body lasting >3 months and 242 929 controls were studied. Replication of three independent genome-wide significant single nucleotide polymorphisms was attempted in six independent European cohorts (n=43 080; cases=14 177). Genetic correlations with risk factors, tissue specificity and colocalisation were examined. RESULTS: Three genome-wide significant loci were identified (rs1491985, rs10490825, rs165599) residing within the genes Ring Finger Protein 123 (RNF123), ATPase secretory pathway Ca2+transporting 1 (ATP2C1) and catechol-O-methyltransferase (COMT). The RNF123 locus was replicated (meta-analysis p=0.0002), the ATP2C1 locus showed suggestive association (p=0.0227) and the COMT locus was not replicated. Partial genetic correlation between CWP and depressive symptoms, body mass index, age of first birth and years of schooling were identified. Tissue specificity and colocalisation analysis highlight the relevance of skeletal muscle in CWP. CONCLUSIONS: We report a novel association of RNF123 locus and a suggestive association of ATP2C1 locus with CWP. Both loci are consistent with a role of calcium regulation in CWP. The association with COMT, one of the most studied genes in chronic pain field, was not confirmed in the replication analysis.

The joint effect of insomnia symptoms and lifestyle factors on risk of self-reported fibromyalgia in women: longitudinal data from the HUNT Study.

OBJECTIVES: To investigate the association between insomnia symptoms and risk of self-reported fibromyalgia in women, and to explore whether leisure time physical activity and body mass index (BMI) modify this association. DESIGN: Prospective cohort study. SETTING: We used longitudinal data from the Norwegian Nord-Trøndelag Health Study collected in 1995-1997 (baseline) and 2006-2008 (follow-up). PARTICIPANTS: A total of 14 172 women who reported to be free from fibromyalgia at baseline. PRIMARY OUTCOME MEASURES: We estimated adjusted risk ratios (RRs) with 95% CI for self-reported fibromyalgia at follow-up associated with baseline insomnia symptoms, leisure time physical activity and BMI. RESULTS: Overall, 466 incident cases of fibromyalgia were reported during the follow-up period of approximately 11 years, corresponding to a crude absolute risk (AR) of 3.3%. Compared with women without insomnia symptoms (crude AR=2.8%), women who reported one, two or three symptoms had RRs of fibromyalgia of 1.39 (95% CI: 1.08 to 1.80), 1.86 (95% CI: 1.33 to 2.59) and 2.66 (95% CI: 1.75 to 4.06), respectively. Compared with highly physically active women without insomnia symptoms (crude AR=2.7%), women with one or more insomnia symptoms had a RR of fibromyalgia of 1.90 (95% CI: 1.30 to 2.79) if they reported low physical activity and a RR of 1.55 (95% CI: 1.12 to 2.13) if they reported high physical activity. We found no synergistic effect between insomnia symptoms and BMI on risk of fibromyalgia; however, overweight and obese women with one or more insomnia symptoms had RRs of 2.35 (95% CI: 1.73 to 3.21) and 2.18 (95% CI: 1.42 to 3.35) compared with the reference group of normal weight women without insomnia symptoms (crude AR=2.3%). CONCLUSIONS: Insomnia symptoms are strongly and positively associated with risk of fibromyalgia in adult women. Leisure time physical activity may compensate for some of the adverse effect of insomnia symptoms on risk of fibromyalgia.

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.

Lifestyle factors and risk of migraine and tension-type headache. Follow-up data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008.

AIMS: The aim of this population-based historical cohort study was to investigate the influence of lifestyle factors on the risk of developing migraine or tension-type headache (TTH). METHODS: Data from the Nord-Trøndelag Health Study performed in 1995-1997 and 2006-2008 was used. A total of 15,276 participants without headache at baseline were included. A Poisson regression was used to evaluate the associations between lifestyle factors and risk ratios (RRs) of migraine and TTH 11 years later. Precision of the estimates was assessed by 95% confidence interval (CIs). RESULTS: Increased risk of migraine (RR 1.30, 95% CI 1.11-1.52) was found in smokers (past or current) compared to those who had never smoked. Hard physical exercise 1-2 hours per week reduced the risk of migraine (OR 0.71, 95% CI 0.54-0.94) compared to inactivity, and the risk of migraine was also lower among those who consumed alcohol (RR 0.73, 95% CI 0.57-0.94) compared to abstainers. No association was found between smoking, physical activity, alcohol use and risk of TTH. CONCLUSIONS: The main finding was that current and previous smoking was associated with increased risk of migraine, but not of TTH.

Headache following head injury: a population-based longitudinal cohort study (HUNT).

BACKGROUND: Headache is the most frequent symptom following head injury, but long-term follow-up of headache after head injury entails methodological challenges. In a population-based cohort study, we explored whether subjects hospitalized due to a head injury more often developed a new headache or experienced exacerbation of previously reported headache compared to the surrounding population. METHODS: This population-based historical cohort study included headache data from two large epidemiological surveys performed with an 11-year interval. This was linked with data from hospital records on exposure to head injury occurring between the health surveys. Participants in the surveys who had not been hospitalized because of a head injury comprised the control group. The head injuries were classified according to the Head Injury Severity Scale (HISS). Multinomial logistic regression was performed to investigate the association between head injury and new headache or exacerbation of pre-existing headache in a population with known pre-injury headache status, controlling for potential confounders. RESULTS: The exposed group consisted of 294 individuals and the control group of 25,662 individuals. In multivariate analyses, adjusting for age, sex, anxiety, depression, education level, smoking and alcohol use, mild head injury increased the risk of new onset headache suffering (OR 1.74, 95% CI 1.05-2.87), stable headache suffering (OR 1.70, 95% CI 1.15-2.50) and exacerbation of previously reported headache (OR 1.93, 95% CI 1.24-3.02). The reference category was participants without headache in both surveys. CONCLUSION: Individuals hospitalized due to a head injury were more likely to have new onset and worsening of pre-existing headache and persistent headache, compared to the surrounding general population. The results support the entity of the ICHD-3 beta diagnosis "persistent headache attributed to traumatic injury to the head".

Inverse relationship between type 1 diabetes mellitus and migraine. Data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008.

Aims The aim of this cross-sectional population-based study was to investigate the associations between migraine and type 1 and type 2 diabetes mellitus (DM). Methods We used data from the second (1995-1997) and third survey (2006-2008) in the Nord-Trøndelag Health Study. Analyses were made for the 26,121 participants (30-97 years of age, median 58.3 years) with known headache and DM status in both surveys, and for the 39,584 participants in the third survey (20-97 years, median 54.1 years). The diagnosis of migraine was given to those who fulfilled the questionnaire-based migraine diagnosis in the second and/or third survey. Associations were assessed using multiple logistic regression, estimating prevalence odds ratio (OR) with 95% confidence intervals (CIs). Results In the multivariate analysis of the 26,121 participants in both surveys, adjusting for age, gender, years of education, and smoking, classical type 1 DM (n = 81) was associated with a lower prevalence of any headache (OR = 0.55, 95% CI 0.34-0.88),and migraine (OR = 0.47, 95% CI 0.26-0.96) compared to those without DM (n = 24,779). Correspondingly, the merged group of classical type 1 DM and latent autoimmune diabetes of adults (LADA) (n = 153) were less likely to have migraine (OR = 0.53, 95% CI 0.31-0.91). Similarly, an inverse relationship between type 1 DM and migraine was found in analyses of 39,584 participants in the third survey. No clear association was found between headache and type 2 DM. Conclusions In this cross-sectional population-based study of mainly middle-aged participants, type 1 DM was inversely associated with headache, in particular migraine.

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.

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.

Paranasal sinus opacification in headache sufferers: A population-based imaging study (the HUNT study-MRI).

Background The association between headache and paranasal sinus disease is still unclear. Because of symptom overlap, the two conditions are not easily studied on the basis of symptoms alone. The aim of the present study was to investigate whether paranasal sinus opacification on magnetic resonance imaging (MRI) was associated with migraine, tension-type headache (TTH) or unclassified headache. Methods This was a cross-sectional study of 844 randomly selected participants (442 women, age range 50-65 years, mean age 57.7 years). Based on 14 headache questions, participants were allocated to four mutually exclusive groups: migraine, TTH, unclassified headache or headache free. On MRI, opacifications as mucosal thickening, polyps/retention cysts and fluid in the five paired sinuses were measured and recorded if ≥1 mm. For each participant, opacification thickness was summed for each sinus and, in addition, a total sum of all sinuses was calculated. Opacification in each sinus was compared between headache-free participants and the headache groups using non-parametric tests, and the total sum was compared by logistical regression. Results No significant association was found between paranasal sinus opacification and headache in general, nor when headache was differentiated into migraine, TTH and unclassified headache. This was also true in separate analyses of mucosal thickening and fluid and of opacification from each paranasal sinus. Conclusion Migraine, TTH and unclassified headache were found not to be associated with an increased degree of paranasal sinus opacification at MRI.

The Mortality Associated With Chronic Widespread Musculoskeletal Complaints: A Systematic Review of the Literature.

BACKGROUND: Chronic widespread musculoskeletal complaints (CWMSC) are a prevalent condition with a large impact on quality of life and with a large burden on society. Studies investigating the relationship between CWMSC and mortality have yielded inconsistent results. The present study aimed to clarify this relationship through a systematic review of the existing literature, including meta-analyses, to estimate pooled results and heterogeneity. METHODS: The MEDLINE, EMBASE and Science Citation Index Expanded databases were searched in February 2016. Broad search terms were used to identify as many observational studies as possible that investigated the association between CWMSC and mortality. The identified studies were evaluated according to predetermined inclusion criteria. RESULTS: Six studies fulfilled the inclusion criteria. In pooled unadjusted analyses of three studies evaluating CWMSC, a non-significant tendency of increased overall mortality was found [mortality risk ratio (MRR) 1.69, 95% confidence interval (CI) 0.91-3.14]. However, in pooled analyses of all six studies reporting adjusted results, the non-significant tendency for higher mortality rates in those with CWMSC was nearly eliminated (MRR 1.13, 95% CI 0.95-1.34). Heterogeneity between studies was moderate to high, particularly regarding the use of confounding factors. CONCLUSIONS: In this systematic review, based on a limited number of studies, pooled data gave no evidence of a higher mortality rate among individuals with CWMSC. The non-significant tendency for a higher mortality rate in unadjusted pooled analyses was nearly eliminated in the adjusted pooled analyses, considering lifestyle factors such as physical activity smoking. In population-based studies evaluating the relationship between CWMSC and mortality rates, we recommend that both unadjusted and adjusted analyses should be presented. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Chronic musculoskeletal complaints as a predictor of mortality-The HUNT study.

The impact of chronic musculoskeletal complaints (CMSC) and chronic widespread chronic musculoskeletal complaints (CWMSC) on mortality is controversial. The aim of this study was to investigate the relationship between these conditions and mortality. In this prospective population-based cohort study from Norway, baseline data from the second Nord-Trøndelag Health Survey (HUNT2, performed 1995-1997) were linked to the comprehensive National Cause of Death Registry in Norway with follow-up through the year 2011. A total of 65,026 individuals (70%) participated and were categorized based on their response to CMSC questions in HUNT2 (no CMSC, CMSC, or CWMSC). Hazard ratios (HRs) of mortality during a mean of 14.1 years of follow-up were estimated using Cox regression. During the follow-up period, 12,521 subjects died, 5162 from cardiovascular diseases, 3478 from cancer, and 3881 from all other causes. In the multivariate-adjusted analyses, there was no difference in all-cause mortality between individuals with or without CMSC (HR 1.01, confidence interval, 0.97-1.05) and CWMSC (HR 1.01, confidence interval, 0.96-1.05). Similarly, there was no association between CMSC or CWMSC and cardiovascular mortality, mortality from cancer, or mortality from all other causes. Therefore, from this study, we conclude that there is no evidence for a higher mortality rate among individuals with CMSC or CWMSC.

Intracranial abnormalities and headache: A population-based imaging study (HUNT MRI).

BACKGROUND: Most studies on intracranial abnormalities among headache sufferers were performed in selected clinical populations. The aim of this study was to evaluate the relationship between intracranial abnormalities and headache among middle-aged adults in the general population. METHODS: Participants in a large epidemiological study (the HUNT 3 study; 2006-2008) who answered a headache questionnaire and participated in a population-based imaging study of the head (HUNT MRI; 2007-2009) were included (n = 864; age, 50-65 at enrollment). Based on the responses to the HUNT 3 questionnaire, respondents were categorized as having migraine, tension-type headache, or unclassified headache. Logistic regression was used to compare the occurrence of intracranial abnormalities between groups. RESULTS: Intracranial abnormalities were more common in headache sufferers than in headache-free individuals (29% vs. 22%, respectively; p = 0.041). Adjusted multivariate analyses revealed that those with tension-type headache had higher odds of having minor abnormalities (odds ratio, 2.13; 95% confidence interval = 1.18-3.85). This association disappeared when those with only white matter hyperintensities were removed from the analysis. CONCLUSIONS: Headache sufferers had increased odds of minor intracranial abnormalities. The increased odds were primarily related to the presence of white matter hyperintensities.

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.

Headache as a predictor for dementia: The HUNT Study.

BACKGROUND: The impact of headache on dementia is largely unknown. This study examined the association between headache and dementia using data from a large population-based study. METHODS: This population-based study used data from the Nord-Trøndelag Health Surveys performed in 1995-1997 (HUNT2) and 2006-2008 (HUNT3). The reference group (controls) was participants aged ≥55 years who answered the headache questions in HUNT2 and later participated in HUNT3 (n = 15,601). The association with headache status in HUNT2 was investigated in sample of confirmed non-demented elderly evaluated with psychometric tests after HUNT3 (n = 96), and HUNT2 participants later diagnosed with dementia during 1997-2011 (n = 746). The association with headache was evaluated by logistical regression with adjustment for age, gender, level of education, comorbidity, smoking, and anxiety and depression. RESULTS: Any headache was more likely to be reported in HUNT2 among those who later were included in the dementia registry (OR 1.24; 95 % CI 1.04-1.49) compared to the reference group, but less likely among the confirmed non-demented individuals (OR 0.62; 95 % CI 0.39-0.98). This relationship was even stronger for non-migrainous headache, whereas such association was not found for migraine. CONCLUSIONS: Compared to the reference group, individuals with dementia were more likely to report non-previous migrainous headache in HUNT2, whereas a sample of confirmed non-demented were less likely to report previous non-migrainous headache.

Association between body height and chronic low back pain: a follow-up in the Nord-Trøndelag Health Study.

OBJECTIVE: To study potential associations between body height and subsequent occurrence of chronic low back pain (LBP). DESIGN: Prospective cohort study. SETTING: The North-Trøndelag Health Study (HUNT). Data were obtained from a whole Norwegian county in the HUNT2 (1995-1997) and HUNT3 (2006-2008) surveys. PARTICIPANTS: Altogether, 3883 women and 2662 men with LBP, and 10,059 women and 8725 men without LBP, aged 30-69 years, were included at baseline and reported after 11 years whether they suffered from LBP. MAIN OUTCOME MEASURE: Chronic LBP, defined as pain persisting for 3 months during the previous year. RESULTS: Associations between body height and risk and recurrence of LBP were evaluated by generalised linear modelling. Potential confounders, such as BMI, age, education, employment, physical activity, smoking, blood pressure and lipid levels were adjusted for. In women with no LBP at baseline and body height ≥ 170 cm, a higher risk of LBP was demonstrated after adjustment for other risk factors (relative risk 1.19, 95% CI 1.03 to 1.37; compared with height <160 cm). No relationship was established among men or among women with LBP at baseline. CONCLUSIONS: In women without LBP, a body height ≥ 170 cm may predispose to chronic LBP 11 years later. This may reflect mechanical issues or indicate a hormonal influence.

Do abnormal serum lipid levels increase the risk of chronic low back pain? The Nord-Trøndelag Health Study.

BACKGROUND: Cross-sectional studies suggest associations between abnormal lipid levels and prevalence of low back pain (LBP), but it is not known if there is any causal relationship. OBJECTIVE: The objective was to determine, in a population-based prospective cohort study, whether there is any relation between levels of total cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides and the probability of experiencing subsequent chronic (LBP), both among individuals with and without LBP at baseline. METHODS: Information was collected in the community-based HUNT 2 (1995-1997) and HUNT 3 (2006-2008) surveys of an entire Norwegian county. Participants were 10,151 women and 8731 men aged 30-69 years, not affected by chronic LBP at baseline, and 3902 women and 2666 men with LBP at baseline. Eleven years later the participants indicated whether they currently suffered from chronic LBP. RESULTS: Among women without LBP at baseline, HDL cholesterol levels were inversely associated and triglyceride levels positively associated with the risk of chronic LBP at end of follow-up in analyses adjusted for age only. Adjustment for the baseline factors education, work status, physical activity, smoking, blood pressure and in particular BMI largely removed these associations (RR: 0.96, 95% CI: 0.85-1.07 per mmol/l of HDL cholesterol; RR: 1.16, 95% CI: 0.94-1.42 per unit of lg(triglycerides)). Total cholesterol levels showed no associations. In women with LBP at baseline and men without LBP at baseline weaker relationships were observed. In men with LBP at baseline, an inverse association with HDL cholesterol remained after complete adjustment (RR: 0.83, 95% CI: 0.72-0.95 per mmol/l). CONCLUSION: Crude associations between lipid levels and risk of subsequent LBP in individuals without current LBP are mainly caused by confounding with body mass. However, an association with low HDL levels may still remain in men who are already affected and possibly experience a higher pain intensity.

Migraine, headache and development of metabolic syndrome: an 11-year follow-up in the Nord-Trøndelag Health Study (HUNT).

Migraine with aura is associated with an increased incidence of stroke and cardiovascular disease, but the biological mechanisms are poorly understood. This study examined the incidence of metabolic syndrome and its relationship to migraine with and without aura and to nonmigraine headache. In the population-based the Nord-Trøndelag Health Study (HUNT), 19,895 individuals were followed for the development of metabolic syndrome, with a median follow-up time of 11.3 years. Headache diagnoses were based on a validated headache questionnaire, and metabolic syndrome was based on a modified version of the National Cholesterol Education Program's Adult Treatment Panel (ATP) III criteria, using objective anthropometric measurements and blood biochemistry. Using the Poisson regression model, migraine with aura was associated with an increased risk for developing metabolic syndrome. The effect was modified by smoking, with an adjusted incident risk ratio (IRR) among smokers of 2.10 (95% CI 1.53-2.89) and among nonsmokers of 1.39 (95% CI 1.03-1.86), when compared to headache-free controls. A moderate risk increase was seen for migraine without aura (IRR 1.26, 95% CI 1.12-1.42) and nonmigraine headache (IRR 1.22, 95% CI 1.13-1.32), not modified by smoking. The results suggest that traditional risk factors may be one of the mechanisms through which migraine with aura is linked to an increased risk for cardiovascular disease. A heightened vigilance concerning cardiovascular risk factors in this patient group may be warranted.

Smoking as a risk factor for chronic musculoskeletal complaints is influenced by age. The HUNT study.

Chronic musculoskeletal complaints (MSCs) are among the major health problems, and cross-sectional studies suggest an association between smoking and MSCs. The causal relationship, however, is not known. The present study is designed to assess the association between smoking and chronic MSCs, and is based on data from a large longitudinal cohort study of all inhabitants ⩾20years in Nord-Trøndelag County (Helse Undersøkelsen i Nord-Trøndelag -HUNT), conducted in 1995-97 (HUNT 2) and 2006-08 (HUNT 3). The study population consisted of 15,134 subjects without chronic MSCs and valid exposure data on smoking at baseline (HUNT 2). The outcome was defined as presence of chronic MSCs at follow-up (HUNT 3). The results show that smoking at baseline represents a 20% increased risk (IRR=1.20, 95% CI 1.14-1.27, P=0.0001) for chronic MSCs at follow-up. The risk for chronic MSCs by daily smoking decreased with increasing age up to 50years; after this, there was no significant association. The results show that modifiable risk factors like smoking should be included in public health intervention programs for MSCs.