Cohort profile: Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

Time-varying exposure to anti-osteoporosis drugs and risk of first-time hip fracture: a population wide study within the Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

We investigated the association between bisphosphonate and denosumab use and risk of hip fracture in Norway. These drugs protect against fractures in clinical trials, but their population-level effect is unknown. Our results showed lowered risk of hip fracture for treated women. Treatment of high-risk individuals could prevent future hip fractures.

PURPOSE

To investigate whether bisphosphonates and denosumab reduced the risk of first-time hip fracture in Norwegian women when adjusting for a medication-based comorbidity index.

METHODS

Norwegian women aged 50-89 in 2005-2016 were included. The Norwegian prescription database (NorPD) supplied data on exposures to bisphosphonates, denosumab, and other drugs for the calculation of the Rx-Risk Comorbidity Index. Information on all hip fractures treated in hospitals in Norway was available. Flexible parametric survival analysis was used with age as time scale and with time-varying exposure to bisphosphonates and denosumab. Individuals were followed until hip fracture or censoring (death, emigration, age 90 years), or 31 December 2016, whichever occurred first. Rx-Risk score was included as a time-varying covariate. Other covariates were marital status, education, and time-varying use of bisphosphonates or denosumab with other indications than osteoporosis.

RESULTS

Of 1,044,661 women 77,755 (7.2%) were ever-exposed to bisphosphonate and 4483 (0.4%) to denosumab. The fully adjusted hazard ratios (HR) were 0.95 (95% confidence interval (CI): 0.91-0.99) for bisphosphonate use and 0.60 (95% CI: 0.47-0.76) for denosumab use. Bisphosphonate treatment gave a significantly reduced risk of hip fracture compared with the population after 3 years and denosumab after 6 months. Fracture risk was lowest in denosumab users who had previously used bisphosphonate: HR 0.42 (95% CI: 0.29-0.61) compared with the unexposed population.

CONCLUSIONS

In population-wide real-world data, women exposed to bisphosphonates and denosumab had a lower hip fracture risk than the unexposed population after adjusting for comorbidity. Treatment duration and treatment history impacted fracture risk.

Cause-specific excess mortality after hip fracture: the Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

BACKGROUND

Information on cause of death may help appraise the degree to which the high excess mortality after hip fracture reflects pre-existing comorbidities or the injury itself. We aimed to describe causes of death and cause-specific excess mortality through the first year after hip fracture.

METHODS

For studying the distribution of causes of death by time after hip fracture, we calculated age-adjusted cause-specific mortality at 1, 3, 6 and 12 months in patients hospitalized with hip fracture in Norway 1999-2016. Underlying causes of death were obtained from the Norwegian Cause of Death Registry and grouped by the European Shortlist for Causes of Death. For estimating excess mortality, we performed flexible parametric survival analyses comparing mortality hazard in patients with hip fracture (2002-2017) with that of age- and sex matched controls drawn from the Population and Housing Census 2001.

RESULTS

Of 146,132 Norwegians with a first hip fracture, a total of 35,498 (24.3%) died within one year. By 30 days post-fracture, external causes (mainly the fall causing the fracture) were the underlying cause for 53.8% of deaths, followed by circulatory diseases (19.8%), neoplasms (9.4%), respiratory diseases (5.7%), mental and behavioural disorders (2.0%) and diseases of the nervous system (1.3%). By one-year post-fracture, external causes and circulatory diseases together accounted for approximately half of deaths (26.1% and 27.0%, respectively). In the period 2002-2017, cause-specific one-year relative mortality hazard in hip fracture patients vs. population controls ranged from 1.5 for circulatory diseases to 2.5 for diseases of the nervous system in women, and correspondingly, from 2.4 to 5.3 in men.

CONCLUSIONS

Hip fractures entail high excess mortality from all major causes of death. However, the traumatic injury of a hip fracture is the most frequently reported underlying cause of death among older patients who survive less than one year after their fracture.

Characteristics of fallers who later sustain a hip fracture: a NOREPOS study

Fall prevention programs have shown inconclusive results concerning hip fracture reduction. We found that fallers with poor health, low societal participation, and use of psychotropics/painkillers had a threefold to fivefold increased hip fracture risk compared to non-fallers without these risk factors. This may help target fall prevention towards high-risk individuals.

INTRODUCTION

To investigate whether self-reported information on health, societal participation, and drug use in older people, easily obtainable by health care providers, contribute to predict future hip fracture beyond self-reported falls.

METHODS

We used data from 3801 women and 6439 men aged 70-79 years participating in population-based studies in five counties in Norway 2000-2003. Height and weight were measured. Socioeconomic status, lifestyle, health status, and history of falling were self-reported through questionnaires. Falls last year were dichotomized into one or more versus no falls. Hip fractures were identified by linkage to hospital data with follow-up through 2013. Hazard ratios (HR) with 95% confidence intervals (95% CI) for hip fracture by combinations of risk factors with history of falling were estimated using Cox proportional hazards regression.

RESULTS

More women (32.4%) than men (27.7%) reported one or more falls during the previous year, and 17.9% of women (n = 682) and 8.9% of men (n = 572) suffered a hip fracture during median 11.6 years of follow-up. Poor health, low societal participation, and use of psychotropics/analgesics among fallers were strong predictors of hip fracture. The presence of all three risk factors and history of falling was associated with HR 2.92 (95% CI 2.10-4.05) for hip fracture in women and HR 4.60 (95% CI 2.71-7.81) in men compared to non-fallers without these factors.

CONCLUSION

Our study indicates that self-assessment of health, information about activities outside home, and drug use among fallers far better identify high risk of hip fracture in older people than information about falls alone.

Impact of Total Hip Replacements on the Incidence of Hip Fractures in Norway During 1999-2019. A Norwegian Epidemiologic Osteoporosis Studies (NOREPOS) Study

The knowledge about why hip fracture rates in Norway have declined is sparse. Concurrent with decreasing hip fracture rates, the rates of total hip replacements (THRs) have increased. We wanted to investigate if hip fracture rates continued to decline, and whether the increase in THRs had any influence on this decline, assuming that living with a hip prosthesis precludes fracture of the operated hip. Information on hip fractures in Norway 1999-2019 was available from the Norwegian Epidemiologic Osteoporosis Studies (NOREPOS) hip fracture database and population size were available in official population tables from Statistics Norway. Primary THRs (for any cause except hip fracture) 1989-2019 were obtained from the Norwegian Arthroplasty Register. We calculated the annual age-standardized incidence rates of hip fracture by sex for the period 1999-2019. The hip fracture rates in a scenario with no hip prostheses were calculated by subtracting 0.5 persons from the population at risk for each prevalent hip prosthesis, considering that each person has two hips at risk of fracture. We estimated how much of the decline could be attributed to the increased prevalence of hip prostheses. From 1999 to 2019, age-standardized incidence rates of hip fracture decreased by 27% in women and 20% in men. The rates remained stable in those under 70 years and decreased in those 70 years and above. Excluding replaced hips from the population at risk led to higher incidence rates, and this impact was considerably larger at higher ages. The increased prevalence of hip prostheses over the period accounted for approximately 18% (20% in women and 11% in men) of the observed decline in hip fracture rates. In conclusion, the incidence of hip fractures continued to decline, and the increasing number of people living with hip prostheses contributed significantly to the observed declining time trends. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Contribution of an extensive medication-based comorbidity index (Rx-Risk) in explaining the excess mortality after hip fracture in older Norwegians: a NOREPOS cohort study

OBJECTIVES

Patients with hip fracture are typically characterised by extensive comorbidities and excess mortality. Methods that account for a wide range of comorbidities are needed when attempting to identify causal associations in registry-based studies. We aimed to study the association between the prescription-based Rx-Risk Comorbidity Index (abbreviated Rx-Risk) and mortality by history of hip fracture, and to quantify the contribution of Rx-Risk in explaining the excess mortality after hip fracture.

SETTING

In this prospective study, we used nationwide registry data from outpatient care. Rx-Risk was based on filled prescriptions recorded in the Norwegian Prescription Database. Medications were mapped to 46 comorbidity categories by Anatomical Therapeutic Chemical code. Information on hip fractures during 1994-2013 was available from the Norwegian Epidemiologic Osteoporosis Studies hip fracture database, and year of death was obtained from Statistics Norway. We estimated 1-year mortality risk (January through December 2014) according to Rx-Risk score based on dispensed prescriptions in 2013, history of hip fracture, age and sex using Poisson regression.

PARTICIPANTS

All individuals aged 65 years and older who were alive by the end of 2013 and had filled at least one prescription in an outpatient pharmacy in Norway in 2013 (n=735 968).

RESULTS

Mortality increased exponentially with increasing Rx-Risk scores, and it was highest in persons with a history of hip fracture across the major range of Rx-Risk scores. Age- and sex-adjusted mortality risk difference according to history of hip fracture (yes vs no) was 4.4 percentage points (7.8% vs 3.4%). Adjustment for Rx-Risk score further attenuated this risk difference to 3.3 percentage points.

CONCLUSIONS

History of hip fracture and comorbidity assessed by Rx-Risk are independent risk factors for mortality in the community-dwelling older population in Norway. Comorbidity explained a quarter of the excess mortality in persons with a history of hip fracture.

Increased Mortality in Hip Fracture Patients Living Alone: A NOREPOS Study

Hip fracture is associated with excess mortality, persisting for many years after the fracture. Several factors may affect survival; however, the role of social support has been less studied. Living situation could be an indicator of a person's social support, which predicts mortality in the general population. In this longitudinal cohort study, we considered whether living alone was a risk factor for post-hip fracture mortality compared with living with a partner. Information on hip fractures from all hospitals in Norway from 2002 to 2013 was combined with the 2001 National Population and Housing Census. The association between living situation and mortality during 12.8 years of follow-up in 12,770 men and 22,067 women aged 50 to 79 years at fracture was investigated using flexible parametric survival analysis. We also estimated relative survival of hip fracture patients compared with that of the non-fractured background population in the same living situation (alone or with a partner). Higher mortality after hip fracture was found in both men and women living alone versus with a partner (hazard ratio [HR] men = 1.37, 95% confidence interval [CI] 1.29-1.44; HR women = 1.23, 95% CI 1.18-1.28, adjusting for age, education level, urbanization degree, and number of children). We demonstrated the strongest association in male hip fracture patients aged <60 years (long-term mortality HR = 3.29, 95% CI 2.25-6.49). Compared with the general population, relative survival 8 years after a hip fracture was 43% in men and 61% in women living alone, whereas relative survival in those living with a partner was 51% in men and 67% in women. In conclusion, hip fracture patients who lived alone had higher mortality than those living with a partner and lower survival relative to the general population. © 2021 American Society for Bone and Mineral Research (ASBMR).

Ethnic differences in risk of hip fracture in Norway: a NOREPOS study

Hip fracture is a major public health problem, and the incidence rates vary considerably between countries. Ethnic differences in bone mineral density have been identified as a factor to explain some of the geographical differences in rates of hip fracture. In this Norwegian register-based study, we found that all immigrant groups experienced lower risk of hip fracture than individuals born in Norway.

INTRODUCTION

Norway is among the countries with the highest incidence rates. The aim of this study was to investigate differences in risk of hip fracture between ethnic groups living in Norway.

METHODS

We linked individuals in the Norwegian Population and Housing Census conducted in 2001 and a database consisting of all hip fractures in Norway in the period 2001-2013. Residents (n = 1,392,949) between 50 and 89 years and born in nine different geographical regions of the world were examined, and we computed age-standardized incidence rates for the different geographic regions-denoted ethnic groups in the paper. Gender-stratified Cox regression analysis, adjusted for age, was used to model risk of hip fracture as a function of region of birth.

RESULTS

Age-standardized incidence rates of hip fracture varied considerably between regions of birth living in Norway, in both genders. All immigrant groups had lower risk of hip fracture compared to the Norwegian-born population. Immigrants from Central and Southeast Asia had the lowest risk of hip fracture when compared to individuals born in Norway (HR = 0.2, 95% CI 0.1-0.3 and HR =0.2, 95% CI 0.2-0.4 in men and women, respectively).

CONCLUSION

Lower risk of hip fracture was found in all immigrant groups compared to the Norwegian-born majority population.

Urban-Rural Differences in Hip Fracture Mortality: A Nationwide NOREPOS Study

Higher hip fracture incidence in urban than in rural areas has been demonstrated, but urban–rural differences in posthip fracture mortality have been less investigated, and the results are disparate. Hence, the aims of the present register‐based cohort study were to examine possible urban–rural differences in short‐ and long‐term mortality in Norwegian hip fracture patients and their potential associations with sociodemographic variables, and to investigate possible urban–rural differences in excess mortality in hip fracture patients compared with the general population. Data were provided from the NOREPOS hip fracture database, the 2001 Population and Housing Census, and the National Registry. The urbanization degree in each municipality was determined by the proportion of inhabitants living in densely populated areas (rural: <1/3, semirural: 1/3 to 2/3, and urban: >2/3). Age‐adjusted mortality rates and standardized mortality ratios were calculated for hip fracture patients living in rural, semirural, and urban municipalities. A flexible parametric model was used to estimate age‐adjusted average and time‐varying HRs by category of urbanization with the rural category as reference. Among 96,693 hip fracture patients, urban residents had higher mortality than their rural‐dwelling counterparts. The HR of mortality in urban compared with rural areas peaked during the first 1 to 2 years postfracture with a maximum HR of 1.20 (95% CI, 1.10 to 1.30) in men and 1.15 (95% CI, 1.08 to 1.21) in women. The differences were significant during approximately 5 years after fracture. Adjusting for sociodemographic variables did not substantially change the results. However, absolute 30‐day mortality was not significantly different between urban and rural residents, suggesting that health‐care quality immediately postfracture does not vary by urbanization. The novel findings of a higher long‐term mortality in urban hip fracture patients might reflect disparities in health status or lifestyle, differences in posthip fracture health care or rehabilitation, or a combination of several factors. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

The association between alcohol consumption and risk of hip fracture differs by age and gender in Cohort of Norway: a NOREPOS study

The association between alcohol consumption and hip fracture differed by gender: Men aged 30-59 years drinking frequently or 14+ gl/week had higher risk than moderate drinkers. No significant association was seen in older men. Women not drinking alcohol had higher risk than those drinking moderately both regarding frequency and amount.

INTRODUCTION

We aimed to examine alcohol consumption and risk of hip fracture according to age and gender in the population-based Cohort of Norway (1994-2003).

METHODS

Socio-demographics, lifestyle, and health were self-reported and weight and height were measured in 70,568 men and 71,357 women ≥ 30 years. Information on subsequent hip fractures was retrieved from hospitals' electronic patient registries during 1994-2013. Frequency of alcohol consumption was categorized: never/seldom, moderate (≤ 2-3 times/week), or frequent (≥ 4 times/week), and amount as number of glasses per week: 0, 1-6, 7-13, 14-27, and 28+. Type of alcohol (wine vs. beer/hard liquor) was also examined. Cox's proportional hazards regression was used to estimate hazard ratios (HRs) stratified on gender and baseline age < 60 and ≥ 60 years.

RESULTS

During median 15-year follow-up, 1558 men and 2511 women suffered a hip fracture. Using moderate drinkers as reference, men < 60 years drinking frequently had multivariable adjusted HR = 1.73 (CI 1.02-2.96) for hip fracture and more than 2.5 times higher risk if they consumed 14+ glasses compared to 1-6 glasses per week. In other groups of age and gender, no statistically significant increased risk was found in those consuming the highest levels of alcohol. Compared to women with moderate or frequent alcohol use, never/seldom-drinking women had the highest fracture risk. In women, use of wine was associated with lower fracture risk than other types of alcohol.

CONCLUSIONS

Risk of hip fracture was highest in men < 60 years with the highest frequency and amount of alcohol consumption and in non-drinking women.

Does the Association of Comorbidity with 1-Year Mortality After Hip Fracture Differ According to Gender? The Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

BACKGROUND/OBJECTIVES

Excess mortality after hip fracture is higher in men than in women. The objective was to study whether comorbidity differs in men and women with hip fracture and to what degree differences in comorbidity according to gender may explain the higher excess mortality in men.

DESIGN

Population-based matched cohort covering the population aged 50 and older in Norway.

SETTING

Specialist healthcare (individuals with hip fracture) and general population (controls).

PARTICIPANTS

All individuals with hip fracture aged 50 and older from 2005 to 2008 (n = 32,175) and individuals without hip fracture matched 3:1 to those with hip fracture on gender, age, and county of residence (n = 96,410).

MEASUREMENTS

Comorbid diagnoses were recorded during the hospital stay. Relative and absolute excess 1-year mortality in individuals with hip fracture according to gender and Charlson Comorbidity Index (CCI) were investigated using Cox regression and linear regression, respectively.

RESULTS

Despite lower age (mean 78.7 vs 81.7), men had higher comorbidity than women. Compared with controls, women (hazard ratio (HR) = 6.5, 95% confidence interval (CI) = 6.2-6.9) and men (HR = 7.8, 95% CI = 7.3-8.3) with a CCI of 2 or greater were more likely to die. Women with a CCI of 2 or greater had an estimated 1-year risk of dying of 44%, and controls had an 11% risk; men with a CCI of 2 or greater had an estimated risk of dying of 53%, and controls had a 12% risk. Men were twice as likely as women to die within 1 year (HR = 2.0, 95% CI = 1.9-2.1). When adjusting for comorbidity, the difference was only slightly smaller (HR = 1.8, 95% CI = 1.7-1.8).

CONCLUSION

Men had greater comorbidity than women, but this did not explain the difference according to gender in excess mortality after hip fracture. Men who fracture a hip are an especially vulnerable subpopulation, even when there is no apparent comorbidity, and warrant special attention in follow-up and care.

Hip fracture incidence and social deprivation: results from a French ecological study

The association between socioeconomic status (SES) and hip fracture (HF) incidence was analyzed in France in 2008. In men and women, a decrease in HF incidence was observed as the social deprivation index increased. This result may be partly due to the protective effect of increasing body weight against HF.

INTRODUCTION

Regional variations in hip fracture (HF) incidence exist worldwide. Reasons for these variations remain unknown. As regional variations have also been observed for socioeconomic status, we analyzed the association between socioeconomic deprivation (SED) and HF incidence in France in 2008.

METHODS

From the French Hospital National Database, we selected all HF encoded as primary diagnosis in persons aged 30 years and over. The recently published French version of the European Deprivation Index (EDI) was used for SED analysis, and an EDI score was measured for the year 2007 in each French local municipality. The EDI score was categorized in quintiles. Poisson regression was performed to examine the association between HF incidence and EDI adjusted for age and sex. The population attributable fraction (PAF) was measured to calculate the proportion of excess cases of HF associated with social affluence.

RESULTS

In 2008, 83,538 HF were reported in France of which 59,143 were included in this study. Among them, 44,401 fractures occurred in women (75%) and 14,742 in men (25%). In both men and women, there was a decrease in the HF incidence with increasing SED index. In Poisson regression, the interaction of age class and sex was significant (p < 0.0001) and the EDI in quintiles was significantly associated with the incidence of HF (p < 0.0001). A higher number of people living in affluent residential areas corresponded to a higher risk of HF. The risk of HF is 2.42 times higher for those living in the most affluent group compared to those living in the most underprivileged group. The value of the PAF was calculated at 27.1%.

CONCLUSION

Social disparities in HF incidence exist in France with the most deprived municipalities having the lowest incidence. Prior knowledge demonstrates the strong relationships between body weight and HF risk as well as between body weight and the SED. The link found in our study between EDI and HF incidence as well as regional and temporal variations in HF incidence may be partly due to the protective effect of increased body weight against HF.

Protective Effect of Chokeberry (Aronia melanocarpa L.) Extract against Cadmium Impact on the Biomechanical Properties of the Femur: A Study in a Rat Model of Low and Moderate Lifetime Women Exposure to This Heavy Metal

The hypothesis that the consumption of Aronia melanocarpa berries (chokeberries) extract, recently reported by us to improve bone metabolism in female rats at low-level and moderate chronic exposure to cadmium (1 and 5 mg Cd/kg diet for up to 24 months), may increase the bone resistance to fracture was investigated. Biomechanical properties of the neck (bending test with vertical head loading) and diaphysis (three-point bending test) of the femur of rats administered 0.1% aqueous chokeberry extract (65.74% of polyphenols) or/and Cd in the diet (1 and 5 mg Cd/kg) for 3, 10, 17, and 24 months were evaluated. Moreover, procollagen I was assayed in the bone tissue. The low-level and moderate exposure to Cd decreased the procollagen I concentration in the bone tissue and weakened the biomechanical properties of the femoral neck and diaphysis. Chokeberry extract administration under the exposure to Cd improved the bone collagen biosynthesis and femur biomechanical properties. The results allow for the conclusion that the consumption of chokeberry products under exposure to Cd may improve the bone biomechanical properties and protect from fracture. This study provides support for Aronia melanocarpa berries being a promising natural agent for skeletal protection under low-level and moderate chronic exposure to Cd.

Hip fracture registries: utility, description, and comparison

Hip fractures (HF) are prevalent and involve high morbidity and mortality so improving their management is important. HF registries are a good way to improve knowledge about this condition and its quality of care, while at the same time reducing clinical variability, optimizing efficiency, improving outcomes, and reducing costs.

INTRODUCTION

Hip fractures (HF) are a prevalent fragility fracture secondary to osteoporosis that involves high morbidity and mortality. They are low-impact fractures, resulting from a fall from a standing or sitting height. Despite numerous Clinical Practice Guidelines that establish uniform recommendations for their care, great variability persists regarding clinical and healthcare outcomes. Fracture registries can help detect deficits and establish measures to improve care. The objective of this work is to analyze the contents that a HF registry should have and to compare the characteristics of some national HF registries.

METHODS

A literature search was conducted on several national hip fracture registries, and those that contain relevant information on the variables and their outcomes were selected.

RESULTS

The selected HF registries were compared using the parameters they measure as well as the outcomes in the different countries. The variables collected in the majority of the databases and those that give useful information are as follows: sociodemographic variables (age, sex, place of residence), clinical variables (function before and after HF, anesthesia risk as measured by the ASA score, type of fracture, type of surgery and anesthesia, and in-hospital and 1-month mortality), and healthcare variables (pre-operative and overall stay, presence of collaboration with orthogeriatrics or with any clinician in addition to the surgeon, secondary prevention of new fractures by assessing the fall risk, and need for osteoporosis treatment).

CONCLUSION

The recording of HF cases in different countries improves knowledge about handling this condition and its quality of care, while at the same time reducing clinical variability, optimizing efficiency, improving outcomes, and reducing costs. The debate on the variables that should be recorded is timely, such as organizing how to collect each measurement, and even trying to unify the national and international registries or using a current proposal such as the one from the Fragility Fracture Network.

Fracture incidence rates in Norwegian children, The Tromsø Study, Fit Futures

This study describes childhood fracture rates in Norway, a country known for high fracture rates in the adult population. Fracture rates correspond with other reports from Scandinavia, although with a slightly higher proportion in girls. Indications of increased vulnerability during stages of puberty require further exploration.

INTRODUCTION

Fractures are common injuries during childhood. Incidence rates and patterns vary, but population-based data are scarce. The aim of this study was to describe the sex-, age- and maturation-specific incidence of fractures in a representative population-based sample from a region in Norway.

METHODS

All fractures in the population based convenient cohort Fit Futures, comprising 961 adolescents under 18 years, were recorded retrospectively from the local hospital. Details on individual's age and fracture site were recorded. A radiologist confirmed all fractures.

RESULTS

In the period from birth to cohort scanning, the register recorded 316 fractures in 253 individuals. Fractures were more common in boys (35%) than in girls (31%). The overall annual fracture incidence was 204 per 10,000 persons-year under the age of 18 and 205 under the age of 16. The majority of fractures involved the upper extremities and the most common site of fracture was the forearm with 24% of the fractures followed by phalanges with 23% of the fractures. Fractures peaked in girls at sexual maturation stage 3. Boys had a peak in stage 2. Timing of subsequent fractures was also consistent with stages of sexual maturation.

CONCLUSIONS

The overall incidence of fractures in childhood in Northern Norway corresponds with other reports from Scandinavia, although the proportion of fractures in girls is higher than in other studies. Both sexes seem especially vulnerable at stages related to sexual maturation. Whether this reflects bone vulnerability or other changes related to puberty requires further investigation.

A combination of low serum concentrations of vitamins K1 and D is associated with increased risk of hip fractures in elderly Norwegians: a NOREPOS study

The present study investigated the risk of incident hip fractures according to serum concentrations of vitamin K1 and 25-hydroxyvitamin D in elderly Norwegians during long-term follow-up. The results showed that the combination of low concentrations of both vitamin D and K1 provides a significant risk factor for hip fractures.

INTRODUCTION

This case-cohort study aims to investigate the associations between serum vitamin K1 and hip fracture and the possible effect of 25-hydroxyvitamin D (25(OH)D) on this association.

METHODS

The source cohort was 21,774 men and women aged 65 to 79 years who attended Norwegian community-based health studies during 1994-2001. Hip fractures were identified through hospital registers during median follow-up of 8.2 years. Vitamins were determined in serum obtained at baseline in all hip fracture cases (n = 1090) and in a randomly selected subcohort (n = 1318). Cox proportional hazards regression with quartiles of serum vitamin K1 as explanatory variable was performed. Analyses were further performed with the following four groups as explanatory variable: I: vitamin K1 ≥ 0.76 and 25(OH)D ≥ 50 nmol/l, II: vitamin K1 ≥ 0.76 and 25(OH)D < 50 nmol/l, III: vitamin K1 < 0.76 and 25(OH)D ≥ 50 nmol/l, and IV: vitamin K1 < 0.76 and 25(OH)D < 50 nmol/l.

RESULTS

Age- and sex-adjusted analyses revealed an inverse association between quartiles of vitamin K1 and the risk of hip fracture. Further, a 50 % higher risk of hip fracture was observed in subjects with both low vitamin K1 and 25(OH)D compared with subjects with high vitamin K1 and 25(OH)D (HR 1.50, 95 % CI 1.18-1.90). The association remained statistically significant after adjusting for body mass index, smoking, triglycerides, and serum α-tocopherol. No increased risk was observed in the groups low in one vitamin only.

CONCLUSION

Combination of low concentrations of vitamin K1 and 25(OH)D is associated with increased risk of hip fractures.

Educational Inequalities in Post-Hip Fracture Mortality: A NOREPOS Study

Hip fractures are associated with high excess mortality. Education is an important determinant of health, but little is known about educational inequalities in post-hip fracture mortality. Our objective was to investigate educational inequalities in post-hip fracture mortality and to examine whether comorbidity or family composition could explain any association. We conducted a register-based population study of Norwegians aged 50 years and older from 2002 to 2010. We measured total mortality according to educational attainment in 56,269 hip fracture patients (NORHip) and in the general Norwegian population. Both absolute and relative educational inequalities in mortality in people with and without hip fracture were compared. There was an educational gradient in post-hip fracture mortality in both sexes. Compared with those with primary education only, the age-adjusted relative risk (RR) of mortality in hip fracture patients with tertiary education was 0.82 (95% confidence interval [CI] 0.77-0.87) in men and 0.79 (95% CI 0.75-0.84) in women. Additional adjustments for Charlson comorbidity index, marital status, and number of children did not materially change the estimates. Regardless of educational attainment, the 1-year age-adjusted mortality was three- to fivefold higher in hip fracture patients compared with peers in the general population without fracture. The absolute differences in 1-year mortality according to educational attainment were considerably larger in hip fracture patients than in the population without hip fracture. Absolute educational inequalities in mortality were higher after hip fracture compared with the general population without hip fracture and were not mediated by comorbidity or family composition. Investigation of other possible mediating factors might help to identify new targets for interventions, based on lower educational attainment, to reduce post-hip fracture mortality.

Population data on calcium in drinking water and hip fracture: An association may depend on other minerals in water. A NOREPOS study

BACKGROUND

The Norwegian population has among the highest hip fracture rates in the world. The incidence varies geographically, also within Norway. Calcium in drinking water has been found to be beneficially associated with bone health in some studies, but not in all. In most previous studies, other minerals in water have not been taken into account. Trace minerals, for which drinking water can be an important source and even fulfill the daily nutritional requirement, could act as effect-modifiers in the association between calcium and hip fracture risk. The aim of the present study was to investigate the association between calcium in drinking water and hip fracture, and whether other water minerals modified this association.

MATERIALS AND METHODS

A survey of trace metals in 429 waterworks, supplying 64% of the population in Norway, was linked geographically to the home addresses of patients with incident hip fractures (1994-2000). Drinking water mineral concentrations were divided into "low" (below and equal waterworks average) and "high" (above waterworks average). Poisson regression models were fitted, and all incidence rate ratios (IRRs) were adjusted for age, geographic region, urbanization degree, type of water source, and pH of the water. Effect modifications were examined by stratification, and interactions between calcium and magnesium, copper, zinc, iron and manganese were tested both on the multiplicative and the additive scale. Analyses were stratified on gender.

RESULTS

Among those supplied from the 429 waterworks (2,110,916 person-years in men and 2,397,217 person-years in women), 5433 men and 13,493 women aged 50-85 years suffered a hip fracture during 1994-2000. Compared to low calcium in drinking water, a high level was associated with a 15% lower hip fracture risk in men (IRR=0.85, 95% CI: 0.78, 0.91) but no significant difference was found in women (IRR=0.98, 95%CI: 0.93-1.02). There was interaction between calcium and copper on hip fracture risk in men (p=0.051); the association between calcium and hip fracture risk was stronger when the copper concentration in water was high (IRR=0.52, 95% CI: 0.35, 0.78) as opposed to when it was low (IRR=0.88, 95% CI: 0.81, 0.94). This pattern persisted also after including potential confounding factors and other minerals in the model. No similar variation in risk was found in women.

CONCLUSION

In this large, prospective population study covering two thirds of the Norwegian population and comprising 19,000 hip fractures, we found an inverse association between calcium in drinking water and hip fracture risk in men. The association was stronger when the copper concentration in the water was high.

Self-perceived memory loss is associated with an increased risk of hip fracture in the elderly: a population-based NOREPOS cohort study

Background

An early detection of memory loss may hold great value as a predictor for dementia. Dementia has already been associated with higher risk of hip fracture. Our aim was to examine the prospective association between self-reported memory-loss and the risk of subsequent hip fracture in the elderly.

Methods

A population-based prospective cohort study design was used. Information on four self-perceived memory loss questions was obtained from questionnaires in 3 health surveys performed in Norway during the years 2000–2001. A total of 7154 men and 2462 women aged 67–77 years old were followed for a median of 7.8 years. Hip fracture information (n = 287 in men, and n = 237 in women) was obtained from NORHip (a database including all hip fractures treated in Norway from year 1994). Cox survival analysis was performed to estimate HR (hazard ratio).

Results

The risk of sustaining a hip fracture were higher in those who reported to forget things they had just heard or read, with a HR of 1.52 (1.19--1.95) in men and HR 1.60 (1.23--2.07) in women after adjustment for relevant confounders. Women reporting to forget where they had put things also had higher risk of later hip fracture with a HR of 1.58 (1.20--2.07). Answering yes in both questions showed stronger association with sustaining a first hip fracture compared with those who gave a negative response in both questions, with a multivariate adjusted HR of 1.41 (IC 95 % 1.06--1.88) in men and 1.90 (IC 95 % 1.39--2.60) in women. The two last questions did not show a significant association with hip fracture.

Conclusions

There was a higher risk of hip fracture in elderly who reported self-perceived memory loss. Due to the serious implications of sustaining a hip fracture, early detection of risk groups is important for preventive interventions.