Total Hip Arthroplasty or Hemiarthroplasty for Hip Fracture

BACKGROUND

Globally, hip fractures are among the top 10 causes of disability in adults. For displaced femoral neck fractures, there remains uncertainty regarding the effect of a total hip arthroplasty as compared with hemiarthroplasty.

METHODS

We randomly assigned 1495 patients who were 50 years of age or older and had a displaced femoral neck fracture to undergo either total hip arthroplasty or hemiarthroplasty. All enrolled patients had been able to ambulate without the assistance of another person before the fracture occurred. The trial was conducted in 80 centers in 10 countries. The primary end point was a secondary hip procedure within 24 months of follow-up. Secondary end points included death, serious adverse events, hip-related complications, health-related quality of life, function, and overall health end points.

RESULTS

The primary end point occurred in 57 of 718 patients (7.9%) who were randomly assigned to total hip arthroplasty and 60 of 723 patients (8.3%) who were randomly assigned to hemiarthroplasty (hazard ratio, 0.95; 95% confidence interval [CI], 0.64 to 1.40; P = 0.79). Hip instability or dislocation occurred in 34 patients (4.7%) assigned to total hip arthroplasty and 17 patients (2.4%) assigned to hemiarthroplasty (hazard ratio, 2.00; 99% CI, 0.97 to 4.09). Function, as measured with the total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score, pain score, stiffness score, and function score, modestly favored total hip arthroplasty over hemiarthroplasty. Mortality was similar in the two treatment groups (14.3% among the patients assigned to total hip arthroplasty and 13.1% among those assigned to hemiarthroplasty, P = 0.48). Serious adverse events occurred in 300 patients (41.8%) assigned to total hip arthroplasty and in 265 patients (36.7%) assigned to hemiarthroplasty.

CONCLUSIONS

Among independently ambulating patients with displaced femoral neck fractures, the incidence of secondary procedures did not differ significantly between patients who were randomly assigned to undergo total hip arthroplasty and those who were assigned to undergo hemiarthroplasty, and total hip arthroplasty provided a clinically unimportant improvement over hemiarthroplasty in function and quality of life over 24 months. (Funded by the Canadian Institutes of Health Research and others; ClinicalTrials.gov number, NCT00556842.).

The crossover design for studies of infertility employing in-vitro fertilization: A methodological survey

Background

Infertility has become increasingly common worldwide. There is a need for the infertility literature to evaluate new interventions with IVF. The crossover design presents many methodological advantages for IVF trials. In addition to providing a within-person comparison of outcomes, it offers participants the opportunity to potentially benefit from more than one available treatment. However, infertility studies present a unique challenge in terms of bias: successful participants do not cross over to the second treatment group.

Objectives

The main objective of our study was to survey the methodological features of crossover trials for infertility with in-vitro fertilization (IVF) based interventions. A secondary focus was reporting key results.

Study design & setting

We conducted a methodological survey by systematically searching Medline and Embase databases. The capture-recapture technique was used to estimate the number of relevant studies that were not retrieved by our search strategy. We employed the Cochrane risk of bias tool to assess methodological rigour. Crossover-specific methods features were summarized. Treatment effects for pregnancy outcomes across studies are also presented.

Results

15 studies met inclusion criteria. Most studies were deemed to have high or unclear risks of bias, usually because of incomplete reporting of outcome data and assessment procedures. 13 studies did not employ crossover-specific methods to analyze outcome data by period, which may bias treatment effect estimates. Four studies reported pregnancy outcome data with sample sizes from both treatment periods. Of these four studies, three reported that the control intervention was favoured.

Conclusions

The main limitation of our survey was the small sample size of studies. Future reviews should be larger and seek to encompass a broader range of the infertility literature. Despite the issues identified in the included trials, consideration should still be given to using the crossover design in future infertility research. Employing crossover-specific analysis methods, such as accounting for participant non-completion, along with strict adherence to CONSORT reporting guidelines, may significantly reduce the risk of bias in individual studies.

Accounting for health literacy and intervention preferences when reducing unhealthy snacking: protocol for an online randomised controlled trial

INTRODUCTION

Health literacy describes the cognitive and social skills that individuals use to access, understand and act on health information. Health literacy interventions typically take the 'universal precautions approach' where all consumers are presented with simplified materials. Although this approach can improve knowledge and comprehension, its impact on complex behaviours is less clear. Systematic reviews also suggest that health literacy interventions underuse volitional strategies (such as planning) that play an important role in behaviour change. A recent study found volitional strategies may need to be tailored to the participant's health literacy. The current study aims to replicate these findings in a sample of people who have diabetes and/or are overweight or obese as measured by body mass index, and to investigate the most effective method of allocating an action plan to a participant to reduce unhealthy snacking.

METHODS AND ANALYSIS

We plan to recruit approximately 2400 participants at baseline. Participants will receive one of two alternative online action plans intended to reduce unhealthy snacking ('standard' action plan or 'literacy-sensitive' action plan). Participants will be randomised to a method of allocation to an action plan: (1) random allocation; (2) allocation by health literacy screening tool or (3) allocation by participant selection. Primary outcome is self-reported serves of unhealthy snacks during the previous month. Multiple linear regression will evaluate the impact of health literacy on intervention effectiveness. The analysis will also identify independent contributions of each action plan, method of allocation, health literacy and participant selections on unhealthy snacking at 4-week follow-up.

ETHICS AND DISSEMINATION

This study was approved by the University of Sydney Human Research Ethics Committee (2017/793). Findings will be disseminated through peer-reviewed international journals, conferences and updates with collaborating public health bodies (Diabetes New South Wales (NSW) & Australian Capital Territory (ACT), and Western Sydney Local Health District).

TRIAL REGISTRATION NUMBER

ACTRN12618001409268; Pre-results.

Estimates of the current and future burden of melanoma attributable to ultraviolet radiation in Canada

Exposure to ultraviolet radiation (UVR) is an established cause of cutaneous melanoma. The purpose of this study was to estimate the current attributable and future avoidable burden of melanoma related to exposure to UVR and modifiable UVR risk behaviors (sunburn, sunbathing, and indoor tanning). The population attributable risk (PAR) associated with UVR in 2015 was estimated by comparing Canadian melanoma incidence rates in 2015 to estimated incidence rates of a 1920 birth cohort. Rates were adjusted for changes in reporting and ethnicity. We estimated PARs for modifiable UVR risk behaviors using Caucasian prevalence data from the Second National Sun Survey and relative risks that are generalizable to Canada from meta-analyses of relevant studies. Attributable cases apply to 98.9% of melanomas in Canada that occur in Caucasians. We also estimated the future burden of UVR risk behaviors using the potential impact fraction framework and potential reductions in prevalence of 10% to 50% from 2018 to 2042. Adult sunburn and sunbathing were associated with increased risks of melanoma of 1.28 (95% CI: 1.15, 1.43) and 1.44 (95% CI: 1.18, 1.76), respectively. In 2015, we estimate that 62.3% of melanomas in Canada were attributable to exposure to UVR and that 29.7% were attributable to the combination of sunburn (7.4%), sunbathing (17.8%), and indoor tanning (7.0%). A 50% reduction in modifiable UVR behaviors could avoid an estimated 11,980 melanoma cases by 2042. Prevention strategies aimed at modifiable UVR behaviors are crucial to reduce the growing burden of melanoma in Canada.

Estimates of the current and future burden of cancer attributable to red and processed meat consumption in Canada

Red meat and processed meat have been consistently associated with an increased risk of colorectal, stomach, pancreatic cancer and esophageal cancer (processed meat only). The purpose of this analysis was to estimate the current attributable and future avoidable burden of cancer related to red and processed meat consumption in Canada. We estimated the population attributable risk of cancer separately for red meat consumption (beef, lamb, and pork, excluding processed meat) and processed meat consumption (sausage and bacon) incorporating current cancer incidence data, relative risks, and exposure prevalence. We also estimated the future avoidable burden of cancer from 2015 to 2042 for Canada and by province using the potential impact fraction associated with various potential intervention scenarios intended to reduce consumption, ranging from a decrease of 0.2 servings/week to 2.0 servings/week among the adult Canadian population aged 20 and over. The estimated mean red meat consumption in the Canadian population in 2007 to 2011 was approximately 3.2 times per week. In addition, Canadians consume an average of 1.2 times of processed meat per week. In 2015, an estimated 5.9% of associated cancers and 0.9% of all cancers were attributable to red meat consumption. An estimated 4.5% of associated cancers and 0.7% of all cancers were attributable to processed meat consumption. A mean decrease of 0.5 servings/week of red meat or processed meat could prevent about 8700 or 16,600 cancer cases, respectively, between 2015 and 2042. In conclusion, a small but meaningful cancer burden is associated with red and processed meat consumption. Interventions aimed at reducing consumption at the population level have the potential in the prevention of many cancers in Canada.

Estimates of the current and future burden of cancer attributable to lack of physical activity in Canada

Physical activity reduces the risk of many cancers, yet the prevalence of inadequate physical activity among Canadians remains high. Here we estimated the current attributable and future avoidable burden of cancer related to inadequate physical activity among Canadian adults. Population attributable risk (PAR) for all cancers associated with inadequate physical activity were estimated using relative risks obtained from comprehensive reports, meta-analyses and pooled analyses. Cancer incidence data were acquired from the Canadian Cancer Registry. Physical activity data were taken from Canadian Community Health Survey (Cycle 2.1, 2003), in which respondents were classified as "physically inactive" (<1.5 kcal/kg/day), "moderately active" (1.5-2.9 kcal/kg/day) or "physically active (≥3.0 kcal/kg/day). We defined "inadequate physical activity" as being either "physically inactive" or "moderately active" to determine the PAR of cancer due to inadequate physical activity. We estimated the future burden of inadequate physical activity using potential impact fractions and a series of intervention scenarios, including 10% to 50% reductions in inadequate physical activity from 2015 to 2042. For 2015, the total attributable burden due to inadequate physical activity for associated cancers was 10.6% and 4.9% for all cancers. A 50% reduction in inadequate physical activity could avoid 39,877 cumulative cases of cancer by 2042. Over 9000 cancer cases in 2015 were estimated to be attributable to inadequate physical activity and 5170 incident cases of cancer could be prevented with increases in physical activity levels by 2042. Policies aimed at increasing physical activity among Canadian could have a meaningful impact for cancer prevention.

Estimates of the current and future burden of cancer attributable to excess body weight and abdominal adiposity in Canada

The increasing prevalence of obesity among Canadians has important implications for newly diagnosed cases of cancer given that excess body weight and abdominal adiposity are known to increase the risk of several cancers. The purpose of this analysis was to estimate the current attributable and future avoidable burden of cancer related to excess body weight and abdominal adiposity among Canadian adults. We estimated the population attributable risk (PAR) for all cancers associated with excess body weight and abdominal adiposity using contemporary cancer incidence, relative risk and exposure prevalence data for body mass index (BMI), waist circumference and waist-to-hip-ratio. Using the partial impact fraction (PIF), we also estimated the future avoidable burden of cancer from 2015 to 2042 in Canada, and by province, through various hypothetical intervention scenarios. In 2003, approximately half (50.5%) of the Canadian population was estimated to be overweight (BMI 25.0-29.9) or obese (BMI ≥30.0), 56.5% to have excess abdominal adiposity and 56.8% with a high waist-to-hip ratio. In 2015, the estimated PARs of all incident cancers associated with excess body weight, excess abdominal adiposity and high waist-to-hip ratio were 7.2%, 8.9% and 10.0%, respectively. If the population BMI could revert to its 1994 distribution, 72,157 associated cancer cases could be prevented cumulatively by 2042. A reduction in excess body weight and abdominal adiposity has the potential to decrease the future cancer burden in Canada substantially, and hence efforts to reverse increasing trends in obesity should be prioritized.

Estimates of the current and future burden of cancer attributable to alcohol consumption in Canada

Alcohol consumption is associated with elevated risk of oropharyngeal, laryngeal, esophageal, colon, rectal, breast, liver, pancreatic and stomach cancers. The purpose of this analysis was to provide national and provincial estimates of the number and proportion of cancers attributable to alcohol consumption in Canada and to project the numbers of potentially avoidable cancers using possible intervention scenarios. We estimated the population attributable risk (PAR) for cancers associated with alcohol consumption levels (drinks/day) using: i) relative risks obtained from the World Cancer Research Fund/(WCRF) reports or meta-analyses, ii) alcohol consumption (prevalence) data from the 2003 Canadian Community Health Survey, and iii) cancer incidence data from the 2015 Canadian Cancer Registry. We used potential impact fractions (PIFs) to estimate the future avoidable cancer burden under four counterfactual scenarios: (1) lowering alcohol consumption to meet the WCRF low risk guidelines, (2) meeting the Canada's Low-Risk Drinking Guidelines, (3) reducing daily intake by one drink/day, and (4) decreasing consumption to 50% of the 2003 levels by 2032. We estimated that 3282 incident cancer cases (5.2% of alcohol-associated cancers and 1.8% of all cancers) diagnosed in Canada in 2015 were attributable to alcohol consumption. At the current consumption levels, alcohol-attributable cancers are expected to increase to 10,122 (8.8% of cases among alcohol-associated cancers) by 2042. Under the best case scenario, reducing alcohol consumption to 50% of 2003 levels by 2032, could prevent 70,261 cases by 2042. Strategies that effectively reduce alcohol consumption at a population level can have a meaningful impact on reducing the cancer burden in Canada.

The burden of cancer attributable to modifiable risk factors in Canada: Methods overview

Up-to-date estimates of current and projected future cancer burden attributable to various exposures are essential for planning and implementing cancer prevention initiatives. The Canadian Population Attributable Risk of Cancer (ComPARe) study was conducted to: i) estimate the number and proportion of cancers diagnosed among adults in Canada in 2015 that are attributable to modifiable risk factors and ii) project the future avoidable cancers by 2042 under various intervention targets. We estimated the population attributable risk (with 95% confidence intervals) and the potential impact fraction of cancers associated with selected lifestyle, environmental, and infectious factors. Exposure-specific sensitivity analyses were also completed where appropriate. Several exposures of interest included active and passive smoking, obesity and abdominal adiposity, leisure-time physical inactivity, sedentary behaviour, alcohol consumption, insufficient fruit and vegetable intake, red and processed meat consumption, air pollution (PM2.5, NO₂), indoor radon gas, ultraviolet radiation (UVR), hepatitis B and C virus, Helicobacter pylori, Epstein-Barr virus, human papillomavirus, human herpesvirus type 8 and human T-cell lymphotropic virus type 1. We used the 2015 cancer incidence data for 35 cancer sites from the Canadian Cancer Registry and projected cancer incidence to 2042 using historical data from 1983 to 2012. Here, we provide an overview of the data sources and methods used in estimating the current and future cancer burden in Canada. Specific methodologic details for each exposure are included in the individual articles included as part of this special issue.

Estimates of the current and future burden of cancer attributable to low fruit and vegetable consumption in Canada

Low fruit and vegetable consumption is associated with colorectal cancer and may be associated with lung, breast, bladder, pancreatic, ovarian, liver, stomach, esophageal, head and neck cancers. We estimated the current attributable and future avoidable burden of cancer associated with low fruit and vegetable consumption in Canada. Using data on cancer incidence, exposure prevalence and risk effects, we estimated the population attributable risk (PAR) for cancers associated with low fruit and vegetable consumption as well as the future avoidable burden. The prevalence of fruit and vegetable consumption was projected to 2032 and cancer incidence was projected to 2042 to estimate the future potential impact fraction of cancer attributable to low fruit and vegetable consumption. Based on estimates from the Canadian Community Health Survey, the prevalence of low fruit (<4 servings/day) and vegetable (<4 servings/day) consumption in the Canadian population was 80.5% and 86.6%, respectively. The PARs for colorectal cancer associated with low fruit and vegetable consumption were 6.1% (1, 371 cases) and 2.2% (487 cases), respectively. For all incident cancers in 2015, 0.7% and 0.3% were attributable to low fruit and vegetable consumption, respectively. An increase of one serving/week of fruit could prevent 20,710 colorectal cancer cases cumulatively by 2042, and the same increase in vegetable consumption could prevent 10,185 cases. Although more research on the association between fruit and vegetable consumption and cancer risk is needed, our results demonstrate that with reasonable increases in current fruit and vegetable consumption by Canadians, over 30,000 colorectal cancer cases could be prevented by 2042.

Estimates of the current and future burden of cancer attributable to active and passive tobacco smoking in Canada

Although previous studies have examined the burden of cancer attributable to tobacco smoking, updated estimates are needed given the dramatic changes in smoking behaviours over the last 20 years. In this study, we estimate the proportion of cancer cases in 2015 attributable to past tobacco smoking and passive exposure in Canada and the proportion of cancers in the future that could be prevented through the implementation of interventions targeted at reducing tobacco use. Data from the Canadian Community Health Survey (2003) were used to estimate the prevalence of active tobacco smoking and passive exposure. Population attributable risk estimates were employed to estimate the proportion of cancers attributable to tobacco in 2015. The prevalence of active tobacco smoking and passive exposure was projected to 2032 and cancer incidence was projected from 2016 to 2042 to estimate the future burden of cancer attributable to tobacco. In 2003, 30% and 24% of Canadians were former and current smoker, respectively and 24% had been exposed to tobacco smoke in the past. We estimated that 17.5% (32,655 cases; 95% CI: 31,253-34,034) of cancers were attributable to active tobacco smoking and 0.8% (1408 cases; 95% CI: 1048-1781) to passive tobacco exposure in never smokers. Between 41,191 and 50,696 cases of cancer could be prevented by 2042 under various prevention scenarios. By decreasing passive tobacco exposure by 10-50%, between 730 and 3650 cancer cases could be prevented by 2042. Strategies focused on reducing the prevalence of tobacco smoking are crucial for cancer control in Canada.

Optimising the two-stage randomised trial design when some participants are indifferent in their treatment preferences

Outcomes in a clinical trial can be affected by any underlying preferences that its participants have for the treatments under comparison and by whether they actually receive their preferred treatment. These effects cannot be evaluated in standard trial designs but are estimable in the alternative two-stage randomised trial design, in which some patients can choose their treatment, while the rest are randomly assigned. We have previously shown that, when all two-stage trial participants have a preferred treatment, the preference effects can be evaluated, in addition to the usual direct effect of treatment. We also determined criteria by which to optimise how many participants should be given a choice of treatment vs being randomised. More recently, we extended our methodology to allow for participants who are unable or unwilling to express a treatment preference if they are assigned to the choice group. In this paper, we show how to optimise the two-stage design when some participants are undecided about their treatment. We demonstrate that the undecided group should be regarded as distinct in the analysis, to obtain valid estimates of the preference effects. We derive the optimal proportion of participants who should be offered a choice of treatment, which in many cases will be close to 50%. More generally, the optima depend on the preference rates for treatments and the proportion of undecided participants, and the parameters of primary interest. We discuss some advantages and disadvantages of the two-stage trial design in this situation and describe a practical example.

Estimation of the benefit and harms of including clinical breast examination in an organized breast screening program

BACKGROUND

There is controversy about the value of clinical breast examination (CBE) in addition to mammography for breast screening. The study investigates the associations between risk factors such as mammographic density, hormone therapy use and family history and the effectiveness of screening mammography with or without CBE.

METHODS

The cohort consists of women 50-69 years old screened at the Ontario Breast Screening Program. The associations of the risk factors were investigated using a joint logistic regression model that accommodates the partially unobserved disease status, clustered data structures, individual risk factors, and the dependence between true and false detection.

RESULTS

Having high mammographic density, a first degree relative with breast cancer and using hormone therapy generally increased a woman's probability of being referred correctly. For low risk group (defined as without dense breasts, family history, and not currently using hormone therapy), the average loss of specificity ranged from 3.6% to 5.7% and the gain of sensitivity was between 10.6% and 21.2% with the addition of CBE.

CONCLUSIONS

The addition of CBE to mammography would increase the overall sensitivity and decrease the specificity. CBE can be targeted to those women in which it has the highest net benefit.

GRADE approach to rate the certainty from a network meta-analysis: avoiding spurious judgments of imprecision in sparse networks

When direct and indirect estimates of treatment effects are coherent, network meta-analysis (NMA) estimates should have increased precision (narrower confidence or credible intervals compared with relying on direct estimates alone), a benefit of NMA. We have, however, observed cases of sparse networks in which combining direct and indirect estimates results in marked widening of the confidence intervals. In many cases, the assumption of common between-study heterogeneity across the network seems to be responsible for this counterintuitive result. Although the assumption of common between-study heterogeneity across paired comparisons may, in many cases, not be appropriate, it is required to ensure the feasibility of estimating NMA treatment effects. This is especially the case in sparse networks, in which data are insufficient to reliably estimate different variances across the network. The result, however, may be spuriously wide confidence intervals for some of the comparisons in the network (and, in the Grading of Recommendations Assessment, Development, and Evaluation approach, inappropriately low ratings of the certainty of the evidence through rating down for serious imprecision). Systematic reviewers should be aware of the problem and plan sensitivity analyses that produce intuitively sensible confidence intervals. These sensitivity analyses may include using informative priors for the between-study heterogeneity parameter in the Bayesian framework and the use of fixed effects models.

Estimating the current and future cancer burden in Canada: methodological framework of the Canadian population attributable risk of cancer (ComPARe) study

INTRODUCTION

The Canadian Population Attributable Risk of Cancer project aims to quantify the number and proportion of cancer cases incident in Canada, now and projected to 2042, that could be prevented through changes in the prevalence of modifiable exposures associated with cancer. The broad risk factor categories of interest include tobacco, diet, energy imbalance, infectious diseases, hormonal therapies and environmental factors such as air pollution and residential radon.

METHODS AND ANALYSIS

Using a national network, we will use population-attributable risks (PAR) and potential impact fractions (PIF) to model both attributable (current) and avoidable (future) cancers. The latency periods and the temporal relationships between exposures and cancer diagnoses will be accounted for in the analyses. For PAR estimates, historical exposure prevalence data and the most recent provincial and national cancer incidence data will be used. For PIF estimates, we will model alternative or 'counterfactual' distributions of cancer risk factor exposures to assess how cancer incidence could be reduced under different scenarios of population exposure, projecting incidence to 2042.

DISSEMINATION

The framework provided can be readily extended and applied to other populations or jurisdictions outside of Canada. An embedded knowledge translation and exchange component of this study with our Canadian Cancer Society partners will ensure that these findings are translated to cancer programmes and policies aimed at population-based cancer risk reduction strategies.

Wound irrigation does not affect health-related quality of life after open fractures: results of a randomized controlled trial

AIMS

The Fluid Lavage in Open Fracture Wounds (FLOW) trial was a multicentre, blinded, randomized controlled trial that used a 2 × 3 factorial design to evaluate the effect of irrigation solution (soap versus normal saline) and irrigation pressure (very low versus low versus high) on health-related quality of life (HRQL) in patients with open fractures. In this study, we used this dataset to ascertain whether these factors affect whether HRQL returns to pre-injury levels at 12-months post-injury.

PATIENTS AND METHODS

Participants completed the Short Form-12 (SF-12) and the EuroQol-5 Dimensions (EQ-5D) at baseline (pre-injury recall), at two and six weeks, and at three, six, nine and 12-months post-fracture. We calculated the Physical Component Score (PCS) and the Mental Component Score (MCS) of the SF-12 and the EQ-5D utility score, conducted an analysis using a multi-level generalized linear model, and compared differences between the baseline and 12-month scores.

RESULTS

We found no clinically important differences between irrigating solutions or pressures for the SF-12 PCS, SF-12 MCS and EQ-5D. Irrespective of treatment, participants had not returned to their pre-injury function at 12-months for any of the three outcomes (p < 0.001).

CONCLUSION

Neither the composition of the irrigation solution nor irrigation pressure applied had an effect on HRQL. Irrespective of treatment, patients had not returned to their pre-injury HRQL at 12 months post-fracture. Cite this article: Bone Joint J 2018;100-B:88-94.

Dupuytren's contracture and handwork: A case-control study

OBJECTIVE

The objective of this study was to examine the association between Dupuytren's contracture (DC), repetitive handwork (RHW), heavy handwork (HHW), and/or vibration exposure.

METHODS

Frequency and intensity of the three types of handwork were collected and compared between DC patients and controls. Hours of work were weighted by average "frequency," for RHW, and average "intensity," for HHW and use of vibrating tool. Logistic regression was used to evaluate risk of developing DC associated with the above-mentioned factors.

RESULTS

Data from 129 cases (74 clinical, 106 controls) was analyzed. Family history, male gender and age (decades) were associated with increased risk of DC. Results indicate that the risk becomes substantial after about 30 years of steady RHW. Independent effects of intensity-weighted HHW and vibrating exposure were not established.

CONCLUSIONS

Frequency-weighted RHW increases DC risk. Additionally, a strong association between DC, male gender and heredity was found.

Prevalence and predictors of low serum 25-hydroxyvitamin D levels in rural Canadian children

Objectives

Studies in Canada have reported varying prevalences of low serum 25-hydroxyvitamin D (25(OH)D) levels, but none have been conducted in rural paediatric populations. The purpose of this study was to determine the prevalence and predictors of low vitamin D levels in rural communities.

Methods

We conducted a cross-sectional study of children aged 3 to 15 living in Canadian Hutterite communities. Serum 25(OH)D levels were measured between October 2008 and April 2009 using a chemiluminescence assay. Predictors of vitamin D levels were evaluated using multivariable linear regression. A multilevel model was used to evaluate the impact of individual, household and colony factors on the variation in vitamin D levels.

Results

Serum 25(OH)D levels were available on 743 children/adolescents. The median was 62.0 nmol/L (interquartile range 51.0, 74.0). Levels lower than 50 nmol/L and 75 nmol/L were found in 152 (20.5%) and 565 (76%) children, respectively. Adolescents were at highest risk for levels <75 nmol/L (odds ratio 3.38, 95% confidence interval 2.00, 5.80). Age and latitude were negatively correlated with serum 25(OH)D level. In the multilevel model, most of the variation in levels was associated with individual children.

Conclusion

Low vitamin D levels are a significant problem in rural Hutterite communities in Canada. Adolescents were at greatest risk for low levels and represent an important target group for supplementation. Variation in serum 25(OH)D levels was explained mostly at the individual level. Additional studies are needed to explore factors associated with individuals (e.g., genetics) leading to lower 25(OH)D levels.