Siri Forsmo

Maternal recall of breastfeeding duration twenty years after delivery

BackgroundStudies on the health benefits from breastfeeding often rely on maternal recall of breastfeeding. Although short-term maternal recall has been found to be quite accurate, less is known about long-term accuracy. The objective of this study was to assess the accuracy of long-term maternal recall of breastfeeding duration.MethodsIn a prospective study of pregnancy and birth outcome, detailed information on breastfeeding during the child’s first year of life was collected from a cohort of Norwegian women who gave birth in 1986–88. Among 374 of the participants, data on breastfeeding initiation and duration were compared to recalled data obtained from mailed questionnaires some 20 years later. Intraclass correlation coefficient (ICC), Bland-Altman plot, and Kappa statistics were used to assess the agreement between the two sources of data. Logistic regression was used to assess predictors of misreporting breastfeeding duration by more than one month.ResultsRecorded and recalled breastfeeding duration were strongly correlated (ICC=0.82, p < 0.001). Nearly two thirds of women recalled their breastfeeding to within one month. Recall data showed a modest median overestimation of about 2 weeks. There were no apparent systematic discrepancies between the two sources of information, but recall error was predicted by the age when infants were introduced to another kind of milk. Across categories of breastfeeding, the overall weighted Kappa statistic showed an almost perfect agreement (κ = 0.85, 95% confidence interval [CI] 0.82 – 0.88).ConclusionBreastfeeding duration was recalled quite accurately 20 years after mothers gave birth in a population where breastfeeding is common and its duration long.

Physical activity, body mass index and bone mineral density-associations in a prospective population-based cohort of women and men: the Canadian Multicentre Osteoporosis Study (CaMos).

BACKGROUND Physical activity (PA) is an important modifiable risk factor for both bone mineral density (BMD) and body mass index (BMI). However, BMI is itself strongly predictive of BMD. Our aim was to determine the association between PA and BMD, with consideration of BMI as a potential mediating factor. METHODS The Canadian Multicentre Osteoporosis Study (CaMos) is a population-based prospective cohort study of Canadian women and men. PA was determined from interviewer-administered questionnaires at baseline and Year 5 and summarized as daily energy expenditure in total metabolic equivalents of the task multiplied by minutes/day (MET*m/d). Height, weight, and total hip and lumbar spine BMD were measured at baseline and Year 5. General linear models assessed relationships between PA and BMD, both cross-sectionally (baseline PA with baseline BMD) and longitudinally (average PA and change in PA with change in BMD). BMI was considered as a mediating factor. Potential confounders included age, center, education, caffeine intake, alcohol exposure, smoking history, history of weight-cycling, age at menarche, past use of oral contraceptives, history of >3 months missed menstruation, menopausal status, and antiresorptive use, as relevant. RESULTS The study included 2855 men and 6442 women. PA was inversely associated with BMI at baseline, and an increase in PA between baseline and Year 5 was associated with a decrease in BMI, with 0.41 (95% CI: 0.22, 0.60) kg/m(2) loss per 1000 MET*m/d increase (in men) and 0.40 (95% CI: 0.23, 0.57) kg/m(2) loss per 1000 MET*m/d increase (in women). BMI was strongly associated with BMD, both cross-sectionally and longitudinally. However, increased PA was associated with a small increase in total hip BMD, 0.004 (95% CI: 0.000-0.008) g/cm(2) per 1000 MET*m/d (in men) and 0.003 (95% CI: 0.000-0.007) g/cm(2) per 1000 MET*m/d (in women). Average PA was associated with an increase in lumbar spine BMD in women, but not in men; it was not associated with change in total hip BMD in either sex. CONCLUSION Increased PA is associated with an increase in BMD and a concomitant decrease in BMI. These findings suggest that population-level interventions to increase PA would favorably impact bone and other health outcomes.

Mortality following the first hip fracture in Norwegian women and men (1999-2008). A NOREPOS study

Hip fractures are associated with increased mortality and their incidence in Norway is one of the highest worldwide. The aim of this nationwide study was to examine short- and long-term mortality after hip fractures, burden of disease (attributable fraction and potential years of life lost), and time trends in mortality compared to the total Norwegian population. Information on incident hip fractures between 1999 and 2008 in all persons aged 50 years and older was collected from Norwegian hospitals. Death and emigration dates of the hip fracture patients were obtained through 31 December 2010. Standardized mortality ratios (SMRs) were calculated and Poisson regression analyses were used for the estimation of time trends in SMRs. Among the 81,867 patients with a first hip fracture, the 1-year excess mortality was 4.6-fold higher in men, and 2.8-fold higher in women compared to the general population. Although the highest excess mortality was observed during the first two weeks post fracture, the excess risk persisted for twelve years. Mortality rates post hip fracture were higher in men compared to women in all age groups studied. In both genders aged 50 years and older, approximately 5% of the total mortality in the population was related to hip fractures. The largest proportion of the potential life-years lost was in the relatively young-old, i.e. less than 80 years. In men, the 1-year absolute mortality rates post hip fracture declined significantly between 1999 and 2008, by contrast, the mortality in women increased significantly relatively to the population mortality.

Hyperthyroid levels of TSH correlate with low bone mineral density: the HUNT 2 study

OBJECTIVE To study the relationship between TSH and forearm bone mineral density (BMD) in a general female population. Design Cross-sectional, population-based study. METHODS In a substudy of the Nord-Trøndelag Health Study 1995-1997 (HUNT 2), 5778 women without and 944 with self-reported thyroid disease aged > or =40 years had their serum TSH and distal and ultra-distal forearm BMD measured. In range-based categories of TSH, excluding women with previous thyroid disease, a general linear model was used to calculate adjusted mean BMD, and a logistic regression model to compute adjusted odds ratio (OR) for osteopenia and osteoporosis. Corresponding models were used to compare BMD in women with self-reported hypothyroidism or hyperthyroidism to euthyroid women. RESULTS In women without self-reported thyroid disease, those with TSH <0.5 mU/l had 10.7 mg/cm(2) (95% confidence interval (CI) 0.2-21.1) lower distal and 9.1 mg/cm(2) (95% CI -0.7-18.9) lower ultra-distal BMD than women in the reference category (TSH 0.50-1.49 mU/l). No differences were found between the categories with TSH > or =0.50 mU/l. Compared to self-reported euthyroid women, self-reported hyperthyroid women had increased odds for osteoporosis both distally (OR 1.35, 95% CI 1.00-1.82) and ultra-distally (OR 1.48, 95% CI 1.10-1.99). CONCLUSION Women with the lowest TSH (<0.5 mU/l) had lower forearm BMD than the reference category. No differences were observed between the TSH categories > or =0.50 mU/l. The prevalence of osteoporosis was higher in women who reported hyperthyroidism than in women without self-reported thyroid disease.

How do reproductive and lifestyle factors influence bone density in distal and ultradistal radius of early postmenopausal women? The Nord-Trøndelag Health Survey, Norway

Abstract: In a population-based health survey, densitometry was performed at the distal and ultradistal radius with single-energy X-ray absorptiometry. Bone mineral density (BMD) data and self-reported reproductive and lifestyle data from 1652 randomly selected peri- and postmenopausal women aged 50–59 years were analyzed. A total of 893 (54.1%) postmenopausal women reported no prior use of hormone replacement therapy (HRT) and constituted the principal group of study. These women were more frequently smokers, consumed less alcohol, more coffee and had made less use of oral contraceptives (OC) than women in the HRT group. The strongest association with both distal and ultradistal radius bone densities was found for age, weight, time since menopause and a history of bilateral oophorectomy. Among reproductive factors, nulliparous women had lower BMD than parous women; however, no linear relationship was found between parity and bone density. A weak, positive relationship was found for OC and BMD in bivariate, but not in multivariate analyses. A history of hysterectomy was positively associated with BMD, stronger at the ultradistal than distal radius. A positive relationship between alcohol consumption and BMD was found at the ultradistal radius. Present or prior smokers had lower BMD than never smokers. In the multivariate model, interaction between pack-years of smoking and daily coffee intake was observed at the distal radius, and both factors had a stronger negative influence on distal than ultradistal radius bone density. In perimenopausal women, most reproductive and lifestyle risk factors found to be associated with BMD of the radius may be explained by different levels of estrogen.

Incidence and seasonal variation in hip fracture incidence among elderly women in Norway. The HUNT Study

There is a substantial variation in hip fracture incidence between populations. The Scandinavian countries have the highest incidence of hip fractures worldwide, and latitude and seasonal variation have been discussed as possible reasons for the high fracture incidences. The purpose of this study was to investigate time dependent and seasonal variation of hip fractures in a population based cohort of women aged 65+ residing in a rural county in Norway and followed for 9.3 years. Information at baseline was collected as part of The Nord-Trøndelag Health Study (HUNT) during 1995-97, and 8362 women with no previous hip fracture and with a mean age of 74.3 years were included in the study. All hip fractures occurring after inclusion in the health study were registered (mean follow-up: 9.3 years) by medical journals and x-ray reports. A total of 5661 of the women had their forearm bone mineral density (BMD) measured by single energy x-ray bone densitometers (SXA) as part of HUNT. In total, 782 women sustained a first hip fracture during follow-up, and the overall hip fracture incidence rate per 1000 person-years was 13.1 (95 % CI: 12.2-14.1). The hip fracture incidence increased exponentially by age from 2.1 (95% CI: 1.2-3.8) in the age group 65-69 years to 49.7 (95% CI: 41.2-59.8) among the women aged 90+, respectively. In age-stratified analyses no changes in the incidence of hip fractures were observed during the nine years of follow up. The occurrence of fractures varied by season of the year, characterized by higher fracture rates during the winter months. In conclusion, the hip fracture rates in this population of elderly women are highest in the winter months. There was, however, no indication of an increasing hip fracture incidence in this rural area. Compared to similar studies from more urban areas in Norway, the hip fracture rates in this population seem somewhat lower.

Association between the candidate susceptibility gene ACVR2A on chromosome 2q22 and pre-eclampsia in a large Norwegian population-based study (the HUNT study).

Genome-wide scans in Icelandic, Australian/New Zealand and Finnish pedigrees have provided evidence for maternal susceptibility loci for pre-eclampsia on chromosome 2, although at different positions (Iceland: 2p13 and 2q23, Australia/New Zealand: 2p11–12 and 2q22, Finland: 2p25). In this project, a large population-based (n=65 000) nested case–control study was performed in Norway to further explore the association between positional candidate genes on chromosome 2q and pre-eclampsia, using single-nucleotide polymorphisms (SNPs). DNA samples from 1139 cases (women with one or more pre-eclamptic pregnancies) and 2269 controls (women with normal pregnancies) were genotyped using the Applied Biosystems SNPlex high-throughput genotyping assay. In total, 71 SNPs within positional candidate genes at 2q22–23 locus on chromosome 2 were genotyped in each individual. Genotype data were statistically analysed with the sequential oligogenic linkage analysis routines (SOLAR) computer package. Nominal evidence of association was found for six SNPs (rs1014064, rs17742134, rs1424941, rs2161983, rs3768687 and rs3764955) within the activin receptor type 2 gene (ACVR2A) (all P-values <0.05). The non-independence of statistical tests due to linkage disequilibrium between SNPs at a false discovery rate of 5% identifies our four best SNPs (rs1424941, rs1014064, rs2161983 and rs3768687) to remain statistically significant. The fact that populations with different ancestors (Iceland/Norway–Australia/New Zealand) demonstrate a common maternal pre-eclampsia susceptibility locus on chromosome 2q22–23, may suggest a general role of this locus, and possibly the ACVR2A gene, in pre-eclampsia pathogenesis.

Low Serum Levels of 25-Hydroxyvitamin D Predict Hip Fracture in the Elderly: A NOREPOS Study

BACKGROUND Despite considerable interest, the relationship between circulating 25-hydroxyvitamin D and the risk of hip fracture is not fully established. OBJECTIVE The objective of the study was to study the association between serum 25-hydroxyvitamin D concentrations [s-25(OH)D] and the risk of hip fracture in Norway, a high-latitude country that has some of the highest hip fracture rates worldwide. METHODS A total of 21 774 men and women aged 65-79 years attended 4 community-based health studies during 1994-2001. Information on subsequent hip fractures was retrieved from electronic hospital discharge registers, with a maximum follow-up of 10.7 years. Using a stratified case-cohort design, s-25(OH)D was determined by HPLC-atmospheric pressure chemical ionization-mass spectrometry in stored serum samples in hip fracture cases (n = 1175; 307 men, 868 women) and in gender-stratified random samples (n = 1438). Cox proportional hazards regression adapted for the case-cohort design was performed. RESULTS We observed an inverse association between s-25(OH)D and hip fracture; those with s-25(OH)D in the lowest quartile (<42.2 nmol/L) had a 38% [95% confidence interval (CI) 9-74%] increased risk of hip fracture compared with the highest quartile (≥67.9 nmol/L) in a model accounting for age, gender, study center, and body mass index. The association was stronger in men than in women: hazard ratio 1.65 (95% CI 1.04-2.61) vs hazard ratio 1.25 (95% CI 0.95-1.65). CONCLUSION In this prospective case-cohort study of hip fractures, the largest ever reported, we found an increased risk of hip fracture in subjects in the lowest compared with the highest quartile of serum 25-hydroxyvitamin D. In accordance with the findings of previous community-based studies, low vitamin D status was a modest risk factor for hip fracture.

Lactation and cardiovascular risk factors in mothers in a population-based study: the HUNT-study

BackgroundLactation has beneficial short term effects on maternal metabolic health, but the long term effects are less well known.MethodsWe studied the association between lifetime duration of lactation and cardiovascular risk factors in mothers later in life among 21,368 parous women aged 20 to 85 years attending the second Nord-Trøndelag Health Study (HUNT2) in 1995–1997, Norway, a cross-sectional population-based study. General linear modelling was used to calculate mean values of known cardiovascular risk factor levels in five categories of lifetime duration of lactation. Logistic regression was conducted to estimate odds ratios of hypertension, obesity and diabetes.ResultsAmong women aged 50 years or younger, lifetime duration of lactation was significantly and inversely associated with body mass index (P-trend, < 0.001), waist circumference (P-trend, < 0.001), systolic and diastolic blood pressure (both P-trends, < 0.001), and serum levels of triglycerides, total cholesterol and low density lipoprotein cholesterol (all P-trends, < 0.001) after adjustment for covariates. Parous women aged 50 years or younger who had never lactated had higher prevalence of hypertension, obesity and diabetes. In this age group, compared to women who had lactated for 24 months or more, parous women who had never lactated had an OR for hypertension of 1.88 (95% CI 1.41, 2.51), an OR for obesity of 3.37 (95% CI 2.51, 4.51) and an OR for diabetes of 5.87 (95% CI 2.25, 15.3). Among women older than 50 years there were no clear associations.ConclusionLifetime duration of lactation was associated with long term reduced cardiovascular risk levels in mothers aged 50 years or younger.

A low COMT activity haplotype is associated with recurrent preeclampsia in a Norwegian population cohort (HUNT2)

The etiology of preeclampsia is complex, with susceptibility being attributable to multiple environmental factors and a large genetic component. Although many candidate genes for preeclampsia have been suggested and studied, the specific causative genes still remain to be identified. Catechol-O-methyltransferase (COMT) is an enzyme involved in catecholamine and estrogen degradation and has recently been ascribed a role in development of preeclampsia. In the present study, we have examined the COMT gene by genotyping the functional Val108/158Met polymorphism (rs4680) and an additional single-nucleotide polymorphism, rs6269, predicting COMT activity haplotypes in a large Norwegian case/control cohort (ncases= 1135, ncontrols= 2262). A low COMT activity haplotype is associated with recurrent preeclampsia in our cohort. This may support the role of redox-regulated signaling and oxidative stress in preeclampsia pathogenesis as suggested by recent studies in a genetic mouse model. The COMT gene might be a genetic risk factor shared between preeclampsia and cardiovascular diseases.