Cannabis use in pregnancy and maternal and infant outcomes: A Canadian cross-jurisdictional population-based cohort study.

BACKGROUND: With the recent legalization of cannabis in Canada, there is an urgent need to understand the effect of cannabis use in pregnancy. Our population-based study investigated the effects of prenatal cannabis use on maternal and newborn outcomes, and modification by infant sex. METHODS: The cohort included 1,280,447 singleton births from the British Columbia Perinatal Data Registry, the Better Outcomes Registry & Network Ontario, and the Perinatal Program Newfoundland Labrador from April 1st, 2012 to March 31st, 2019. Logistic regression determined the associations between prenatal cannabis use and low birth weight, small-for-gestational age, large-for-gestational age, spontaneous and medically indicated preterm birth, very preterm birth, stillbirth, major congenital anomalies, caesarean section, gestational diabetes and gestational hypertension. Models were adjusted for other substance use, socio-demographic and-economic characteristics, co-morbidities. Interaction terms were included to investigate modification by infant sex. RESULTS: The prevalence of cannabis use in our cohort was approximately 2%. Prenatal cannabis use is associated with increased risks of spontaneous and medically indicated preterm birth (1.80[1.68-1.93] and 1.94[1.77-2.12], respectively), very preterm birth (1.73[1.48-2.02]), low birth weight (1.90[1.79-2.03]), small-for-gestational age (1.21[1.16-1.27]) and large-for-gestational age (1.06[1.01-1.12]), any major congenital anomaly (1.71[1.49-1.97]), caesarean section (1.13[1.09-1.17]), and gestational diabetes (1.32[1.23-1.42]). No association was found for stillbirth or gestational hypertension. Only small-for-gestational age (p = 0.03) and spontaneous preterm birth (p = 0.04) showed evidence of modification by infant sex. CONCLUSIONS: Prenatal cannabis use increases the likelihood of preterm birth, low birth weight, small-for-gestational age and major congenital anomalies with prenatally exposed female infants showing evidence of increased susceptibility. Additional measures are needed to inform the public and providers of the inherent risks of cannabis exposure in pregnancy.

Health Behaviours and Awareness of Canada's Food Guide: A Population-based Study.

PURPOSE: Lifestyle behaviours among adults reporting awareness of Canada's Food Guide (CFG) are described. METHODS: Data from a cross-sectional survey of adults from Alberta were used to estimate the prevalence of reported health behaviours among respondents aware of the CFG. RESULTS: Respondents (n = 1044) reported general awareness of CFG (mean age 50.3 years; 54.2% female) of whom 82.2% reported awareness of specific CFG recommendations. Respondents reported frequently reading food labels (>58.0%), reading the number of calories (45.5%), the amount of sodium (49.5%), the amount of fat (46.7%), and the type of fat (45.5%) on the food label. Most respondents (90.0%) reported frequently selecting foods to promote health. Approximately one-third of the respondents (35.8%) reported frequently consuming ≥5 portions of vegetables and fruit per day and regularly participating in physical activity (55.3%). Body weight was perceived as healthy by 63.4% of the respondents. Most engaged in 2 health behaviours frequently. Adjusting for important socio-demographic characteristics, those who reported frequently consuming ≥5 portions of vegetables and fruit per day were more likely to engage in a second health behaviour outlined in CGF (OR: 23.6, 95% CI (16.2-34.4)). CONCLUSION: Awareness of CFG did not translate to positive health behaviours. More proactive population level strategies to support specific health behaviours as outlined in CFG might be warranted.

Multimorbidity in a prospective cohort: prevalence and associations with weight loss and health status in severely obese patients.

OBJECTIVE: To examine the prevalence of multimorbidity (≥2 chronic conditions) in severely obese patients and its associations with weight loss and health status over 2 years. METHODS: In a prospective cohort including 500 severely obese adults, self-reported prevalence of 20 chronic conditions was calculated at baseline and 2 years. Multivariable logistic regression models were fitted to test the covariate-adjusted associations between ≥5% weight reduction and reduction in multimorbidity and the association between health status (visual analogue scale [VAS]) and reduction in multimorbidity over 2 years. RESULTS: After 2 years, mean weight change was -12.9 ±18.7 kg, 53% had ≥5% weight reduction, mean change in VAS was 11.5 ± 21.2, and 53.5% had ≥10% increase in VAS. Multimorbidity was reported in 95.4% and 92.8% patients at baseline and 2 years, respectively. Weight loss (≥5%) over 2 years was associated with reduction in multimorbidity (adjusted OR = 1.7, 95% CI 1.1-2.7). Reduction in multimorbidity was associated with clinically important improvements (≥10% increase in VAS) in health status (adjusted OR = 2.5, 95% CI 1.6, 4.0). CONCLUSIONS: Multimorbidity is common in severely obese patients. Having ≥5% weight reduction over 2 years was associated with a reduction in multimorbidity, which was also associated with improvements in health status.

Weight loss required by the severely obese to achieve clinically important differences in health-related quality of life: two-year prospective cohort study.

BACKGROUND: Guidelines and experts describe 5% to 10% reductions in body weight as 'clinically important'; however, it is not clear if 5% to 10% weight reductions correspond to clinically important improvements in health-related quality of life (HRQL). Our objective was to calculate the amount of weight loss required to attain established minimal clinically important differences (MCIDs) in HRQL, measured using three validated instruments. METHODS: Data from the Alberta Population-based Prospective Evaluation of Quality of Life Outcomes and Economic Impact of Bariatric Surgery (APPLES) study, a population-based, prospective Canadian cohort including 150 wait-listed, 200 medically managed and 150 surgically treated patients were examined. Two-year changes in weight and HRQL measures (Short-Form (SF)-12 physical (PCS; MCID = 5) and mental (MCS; MCID = 5) component summary score, EQ-5D Index (MCID = 0.03) and Visual Analog Scale (VAS; MCID = 10), Impact of Weight on Quality of Life (IWQOL)-Lite total score (MCID = 12)) were calculated. Separate multivariable linear regression models were constructed within medically and surgically treated patients to determine if weight changes achieved HRQL MCIDs. Pooled analysis in all 500 patients was performed to estimate the weight reductions required to achieve the pre-defined MCID for each HRQL instrument. RESULTS: Mean age was 43.7 (SD 9.6) years, 88% were women, 92% were white, and mean initial body mass index was 47.9 (SD 8.1) kg/m2. In surgically treated patients (two-year weight loss = 16%), HRQL MCIDs were reached for all instruments except the SF-12 MCS. In medically managed patients (two-year weight loss = 3%), MCIDs were attained in the EQ-index but not the other instruments. In all patients, percent weight reductions to achieve MCIDs were: 23% (95% confidence interval (CI): 17.5, 32.5) for PCS, 25% (17.5, 40.2) for MCS, 9% (6.2, 15.0) for EQ-Index, 23% (17.3, 36.1) for EQ-VAS, and 17% (14.1, 20.4) for IWQOL-Lite total score. CONCLUSIONS: Weight reductions to achieve MCIDs for most HRQL instruments are markedly higher than the conventional threshold of 5% to 10%. Surgical, but not medical treatment, consistently led to clinically important improvements in HRQL over two years. TRIAL REGISTRATION: Clinicaltrials.gov NCT00850356.

Comparing the EQ-5D 3L and 5L: measurement properties and association with chronic conditions and multimorbidity in the general population.

BACKGROUND: Studies comparing the measurement properties of EQ-5D 3L (3L) and EQ-5D 5L (5L) are limited to specific patient populations with small sample sizes. Using a general population sample, we compared 3L and 5L in terms of their measurement properties and association with number of chronic conditions, including multimorbidity--the concurrent occurrence of two or more chronic conditions. METHODS: Data were available from two consecutive cycles of a cross-sectional telephone interview survey using 3L (2010 cycle) and 5L (2012 cycle), in the general population of adults (age ≥ 18 years) in Alberta, Canada. Measurement properties were compared by determining their feasibility, ceiling effect, and discriminatory power (Shannon indices) for 3L and 5L. Linear regression models were fitted to test the associations between multimorbidity and EQ-5D index score. RESULTS: Data were available for 4946 (2010) and 4752 (2012) survey respondents with information on HRQL. Compared to 3L, 5L showed lower ceiling effect (32.3% versus 42.1%), higher absolute discriminatory power (Shannon index, mean 0.79 versus 0.52) and higher relative discriminatory power (Shannon Evenness index, mean 0.09 versus 0.06 for 3L). Despite these differences, similar relationships of lower HRQL with greater multimorbidity were observed for the 3L (ß = -0.13, 95% CI -0.15; -0.11) and 5L (ß = -0.12, 95% CI -0.13; -0.11). CONCLUSIONS: Using a general population sample, the EQ-5D 5L showed better measurement properties than the EQ-5D 3L. Nonetheless, clinically important differences in HRQL associated with multimorbidity were similar in magnitude using both versions of EQ-5D.

Mental health and the relationship between health promotion counseling and health outcomes in chronic conditions: cross-sectional population-based study.

OBJECTIVE: To explore the relationship between health promotion counseling (HPC) provided by FPs and health-related quality of life (HRQL) and the use of health care services among patients with chronic conditions, while assessing the effect of mental health on these relationships. DESIGN: Telephone survey using random-digit dialing. SETTING: Alberta. PARTICIPANTS: A total of 1615 participants with chronic conditions. MAIN OUTCOME MEASURES: Health promotion counseling provided by FPs, which was assessed using 4 questions; HRQL using the Euro quality of life 5-dimensions (EQ-5D) questionnaire; and the use of health care services assessed with self-reported emergency department (ED) visits and hospitalizations. RESULTS: Of the 1615 participants with chronic conditions, 55% were female and more than two-thirds were older than age 45 years. Less than two-thirds of participants received HPC from their FPs. In patients without anxiety or depression, those who needed help from their FPs in making changes to prevent illness had a 0.05 lower EQ-5D score than those who did not (P < .001); and those who received diet counseling had a 0.03 higher EQ-5D score than their counterparts did (P = .048). However, these associations were not observed in patients with anxiety or depression. Patients were more likely to have visited EDs if they needed their physicians' help in making changes to prevent illness (odds ratio 1.43, 95% CI 1.08 to 1.89) and less likely to visit EDs if they had been encouraged by their physicians to talk about their health concerns (odds ratio 0.69, 95% CI 0.52 to 0.91). None of the HPC items was associated with hospitalizations. CONCLUSION: Not all patients with chronic conditions are receiving HPC from their FPs. Also, there is an association between HPC and important health outcomes (ie, HRQL and ED visits), but this association is not apparent for those with anxiety or depression.

Predictors of health-related quality of life in 500 severely obese patients.

OBJECTIVE: To characterize health-related quality of life (HRQL) impairment in severely obese subjects, using several validated instruments. METHODS: A cross-sectional analysis of 500 severely obese subjects was completed. Short-Form (SF)-12 [Physical (PCS) and Mental (MCS) component summary scores], EuroQol (EQ)-5D [Index and Visual Analog Scale (VAS)], and Impact of Weight on Quality of Life (IWQOL)-Lite were administered. Multivariable linear regression models were performed to identify independent predictors of HRQL. RESULTS: Increasing BMI was associated with lower PCS (-1.33 points per 5 kg/m(2) heavier; P < 0.001), EQ-index (-0.02; P < 0.001), EQ-VAS (-1.71; P = 0.003), and IWQOL-Lite (-3.72; P = 0.002), but not MCS (P = 0.69). The strongest predictors (all P < 0.005) for impairment in each instrument were: fibromyalgia for PCS (-5.84 points), depression for MCS (-7.49 points), stroke for EQ-index (-0.17 points), less than full-time employment for EQ-VAS (-7.06 points), and coronary disease for IWQOL-Lite (-10.86 points). Chronic pain, depression, and sleep apnea were associated with reduced HRQL using all instruments. CONCLUSION: The clinical impact of BMI on physical and general HRQL was small, and mental health scores were not associated with BMI. Chronic pain, depression, and sleep apnea were consistently associated with lower HRQL.

Weight loss and outcomes in wait-listed, medically managed, and surgically treated patients enrolled in a population-based Bariatric program: prospective cohort study.

BACKGROUND: Multidisciplinary bariatric care is increasingly being delivered in Canada within publicly funded regional programs. Demand is high, wait lists are long, and clinical effectiveness is unknown. OBJECTIVE: To examine the "real-world" outcomes associated with a publicly funded, population-based regional bariatric (medical and surgical) program. RESEARCH DESIGN: Prospective observational cohort. SUBJECTS: Five hundred consecutive patients (150 wait-listed, 200 medically treated, 150 surgically treated) from the Edmonton Weight Wise program were enrolled. MEASURES: The primary outcome was weight change (kg). Between-group changes were analyzed using multivariable regression adjusted for age, sex, and baseline weight and "last-observation-carried-forward" was used for missing data. Subjects transitioning between groups (wait-list to medical or medical to surgery) were censored when crossing over. RESULTS: At baseline, mean age was 43.7 ± 9.6 years, mean body mass index was 47.9 ± 8.1 kg/m, and 88% were female. A total of 412 subjects (82%) completed 2-year follow-up and 143 (29%) subjects crossed over to the next treatment phase. Absolute and relative (% of baseline) mean weight reductions were 1.5 ± 8.5 kg (0.9 ± 6.1%) for wait-listed, 4.1 ± 11.6 kg (2.8 ± 8.1%) for medically treated, and 22.0 ± 19.7 kg (16.3 ± 13.5%) for surgically treated (P<0.001) subjects. For surgery, weight reductions were 7.0 ± 9.7 kg (5.8 ± 7.9%) with banding, 21.4 ± 16.0 kg (16.4 ± 11.6%) with sleeve gastrectomy, and 36.6 ± 19.5 kg (26.1 ± 12.2%) with gastric bypass (P<0.001). Rates of hypertension, diabetes, and dyslipidemia decreased to a significantly greater degree with surgery than medical management (P<0.001) and stayed the same or increased in wait-listed subjects. CONCLUSIONS: Population-based bariatric care, particularly bariatric surgery, was clinically effective. Weight and cardiometabolic risk was relatively stable wait-listed patients receiving "usual care."

Multimorbidity prevalence in the general population: the role of obesity in chronic disease clustering.

BACKGROUND: The role of obesity in the prevalence and clustering of multimorbidity, the occurrence of two or more chronic conditions, is understudied. We estimated the prevalence of multimorbidity by obesity status, and the interaction of obesity with other predictors of multimorbidity. METHODS: Data from adult respondents (18 years and over) to the Health Quality Council of Alberta 2012 Patient Experience Survey were analyzed. Multivariable regression models were fitted to test for associations. RESULTS: The survey sample included 4803 respondents; 55.8% were female and the mean age was 47.8 years (SD, 17.1). The majority (62.0%) of respondents reported having at least one chronic condition. The prevalence of multimorbidity, including obesity, was 36.0% (95% CI, 34.8 - 37.3). The prevalence of obesity alone was 28.1% (95% CI 26.6 - 29.5). Having obesity was associated with more than double the odds of multimorbidity (odds ratio = 2.2, 95% CI 1.9 - 2.7) compared to non-obese. CONCLUSIONS: The prevalence of multimorbidity in the general population is high, but even higher in obese than non-obese persons. These findings may be relevant for surveillance, prevention and management strategies for multimorbidity.

Self-monitoring of blood glucose in type 2 diabetes: Results of the 2011 Survey on Living with Chronic Diseases in Canada.

BACKGROUND: For insulin-treated patients with type 2 diabetes mellitus (T2DM), self-monitoring of blood glucose (SMBG) may be vital in adjusting insulin dosages. For patients who do not use insulin, evidence supporting the use of SMBG is inconclusive. METHODS: The prevalence, frequency and correlates of SMBG are examined. Data pertain to 2,682 individuals aged 20 or older with T2DM who responded to the 2011 Survey on Living with Chronic Diseases in Canada. Multivariate prevalence rate ratios for associations between respondents' characteristics and their use of SMBG were derived using binomial regression models. RESULTS: A large majority of the study population (87.8%) reported SMBG. No difference in the prevalence of SMBG was observed between oral medication users compared with insulin users; however, the frequency of SMBG was lower for those taking oral medication only. Significant determinants of SMBG were a health professional's recommendation, having insurance coverage, and receiving an A1C test from a health professional. INTERPRETATION: The use of SMBG by adults with T2DM is common, and does not differ between those taking oral medication only and those treated with insulin.

Determinants of lifestyle behavior in type 2 diabetes: results of the 2011 cross-sectional survey on living with chronic diseases in Canada.

BACKGROUND: Lifestyle behavior modification is an essential component of self-management of type 2 diabetes. We evaluated the prevalence of engagement in lifestyle behaviors for management of the disease, as well as the impact of healthcare professional support on these behaviors. METHODS: Self-reported data were available from 2682 adult respondents, age 20 years or older, to the 2011 Survey on Living with Chronic Diseases in Canada's diabetes component. Associations with never engaging in and not sustaining self-management behaviors (of dietary change, weight control, exercise, and smoking cessation) were evaluated using binomial regression models. RESULTS: The prevalence of reported dietary change, weight control/loss, increased exercise and smoking cessation (among those who smoked since being diagnosed) were 89.7%, 72.1%, 69.5%, and 30.6%, respectively. Those who reported not receiving health professional advice in the previous 12 months were more likely to report never engaging in dietary change (RR = 2.7, 95% CI 1.8 - 4.2), exercise (RR = 1.7, 95% CI 1.3 - 2.1), or weight control/loss (RR = 2.2, 95% CI 1.3 - 3.6), but not smoking cessation (RR = 1.0; 95% CI: 0.7 - 1.5). Also, living with diabetes for more than six years was associated with not sustaining dietary change, weight loss and smoking cessation. CONCLUSION: Health professional advice for lifestyle behaviors for type 2 diabetes self-management may support individual actions. Patients living with the disease for more than 6 years may require additional support in sustaining recommended behaviors.

Health-related quality of life and healthcare utilization in multimorbidity: results of a cross-sectional survey.

PURPOSE: We assessed the associations between multimorbidity and health-related quality of life (HRQL), and healthcare utilization, based on 16 common self-reported chronic conditions. METHODS: A cross-sectional questionnaire survey including the EQ-5D was conducted in a sample of the general population of adults (≥18 years) living in Alberta, Canada. Multiple linear and logistic regressions were used to assess the association between multiple chronic conditions and HRQL, hospitalization and emergency department (ED) use. RESULTS: A total of 4,946 respondents reported their HRQL, noting problems mostly with pain or discomfort (48.0%). All chronic conditions were associated with a clinically important reduction in HRQL, the highest burden with anxiety or depression (-0.19, 95% CI -0.21, -0.16) and chronic pain (-0.19, 95% CI -0.21, -0.17). Multimorbidity was associated with a clinically important reduction in the EQ-5D index score (-0.12, 95% CI -0.14, -0.11) and twice the likelihood of being hospitalized (OR = 2.2, 95% CI 1.7, 2.9) or having an ED visit (OR = 1.8, 95% CI 1.4, 2.2). CONCLUSIONS: Pain or discomfort is a common problem in people living with chronic conditions, and the existence of multimorbidity in these individuals is associated with a reduction in the HRQL as well as frequent hospitalization and emergency department visits.

Multimorbidity prevalence and patterns across socioeconomic determinants: a cross-sectional survey.

BACKGROUND: Studies on the prevalence of multimorbidity, defined as having two or more chronic conditions, have predominantly focused on the elderly. We estimated the prevalence and specific patterns of multimorbidity across different adult age groups. Furthermore, we examined the associations of multimorbidity with socio-demographic factors. METHODS: Using data from the Health Quality Council of Alberta (HQCA) 2010 Patient Experience Survey, the prevalence of self reported multimorbidity was assessed by telephone interview among a sample of 5010 adults (18 years and over) from the general population. Logistic regression analyses were performed to determine the association between a range of socio-demographic factors and multimorbidity. RESULTS: The overall age- and sex-standardized prevalence of multimorbidity was 19.0% in the surveyed general population. Of those with multimorbidity, 70.2% were aged less than 65 years. The most common pairing of chronic conditions was chronic pain and arthritis. Age, sex, income and family structure were independently associated with multimorbidity. CONCLUSIONS: Multimorbidity is a common occurrence in the general adult population, and is not limited to the elderly. Future prevention programs and practice guidelines should take into account the common patterns of multimorbidity.

Population-level response shift: novel implications for research.

OBJECTIVES: Response shift is a change in perceived HRQL that occurs as a result of recalibration, reprioritization, or reconceptualization of an individual respondent's internal standards, values, or conceptualization of HRQL. In this commentary, we suggest that response shift may also occur at the population level, triggered by causes that affect the distribution of individual-level risk. METHODS: We illustrated the nature and consequences of potential population-level response shift with two examples: the September 11 terror attacks, and the recent denormalization of smoking. RESULTS: Response shift may occur at the population-level, when a large proportion of the population experiences the shift simultaneously, as a unit, and when the cause of the response shift is a socially significant event or trend. Such catalysts are of a qualitatively different nature than the causes leading to health status changes among individuals, and speak to the determinants affecting the underlying distribution of risk in the population. CONCLUSIONS: We do not know if population-level causes have actually resulted in response shifts. Nonetheless, response shifts at the population-level may be worthwhile to investigate further, both to assess the validity of research evidence based on the measurement of HRQL in large populations, and as a desirable intermediate outcome in evaluations of population health programs.

Association between Epstein-Barr virus infection and risk for development of pregnancy-associated breast cancer: joint effect with vitamin D?

BACKGROUND: Few studies have evaluated the role of the ubiquitous Epstein-Barr virus (EBV) infection, together with levels of the immunomodulator, vitamin D, in different breast cancer entities. We studied, prospectively, the association of EBV and vitamin D status with the risk of pregnancy-associated breast cancer (PABC), breast cancer diagnosed during pregnancy or 1 year post-partum, using a nested case-control study. METHODS: Serum vitamin D and antibodies to EBV were measured for 108 PABC cases of the Finnish Maternity Cohort, and 208 controls matched for date of birth, date of sampling and parity. The joint effect of vitamin D and EBV on the risk of PABC was evaluated. RESULTS: EBV seropositivity was generally not associated with the risk of PABC. Among individuals with sufficient (≥75 nmol/l) levels of vitamin D, we, however, found similar increased risk estimates for PABC associated with serum immunoglobulin G (IgG) antibodies to EBV early antigens [odds ratio (OR)=7.7, 95% (confidence interval) CI 1.4-42.3] and the viral reactivator protein, ZEBRA (OR=7.8, 95% CI 1.1-61.2). CONCLUSION: Immunological markers of EBV reactivation status among individuals with sufficient vitamin D levels were consistently associated with increased risk of the disease. This suggests that EBV reactivation may be an indicator of the progression of breast cancer occurring soon after pregnancy, while the virus probably is not the aetiological agent.

The effects of storage time and sampling season on the stability of serum 25-hydroxy vitamin D and androstenedione.

Knowledge of the stability of serum samples stored in large biobanks is pivotal for reliable assessment of hormone-dependent disease risks. We studied the effects of sample storage time and season of serum sampling on the stability of 25-hydroxy vitamin D (25-OHD) and androstenedione in a stratified random sample of 402 women, using paired sera from the Finnish Maternity Cohort. Serum samples selected were donated between 6 and 24 yr ago. The storage time did not affect serum 25-OHD and androstenedione levels. However, there was a significant mean difference in the 25-OHD levels of sera withdrawn during winter (first sample) vs. during summer (second sample; -18.4 nmol/l, P

Serum 25-hydroxyvitamin D and the risk of ovarian cancer.

INTRODUCTION: Ecological and experimental studies suggest that vitamin D may be associated with a reduced risk of ovarian cancer. In this study, we sought to determine the risk of developing ovarian cancer according to serum 25-hydroxyvitamin D (25-OHD) concentrations assessed on average 5 years before the diagnosis. METHODS: We conducted a population-based longitudinal case-control study nested within the Finnish Maternity Cohort (FMC) which contains serum samples of virtually all pregnant women in Finland since 1983. Among them, 201 ovarian cancers diagnosed within 10 years of serum sampling were randomly selected as cases for this study. For each case, we selected two controls matched for age, parity and sampling season (+/-4 weeks) and one control matched for age and parity but for the opposite sampling season (6 months+/-4 weeks). RESULTS: The relative risks (estimated as odds ratio, OR) for ovarian cancer comparing the lowest quintile to the highest quintile of serum 25-OHD concentration were 1.8 (95% CI 0.9-3.5) among controls matched for the same season, and 1.1 (95% CI 0.6-2.2) among controls matched for the opposite season. The OR among women with insufficient (<75 nmol/L) serum 25-OHD concentration was 2.7 (95% CI 1.0-7.9, lower limit, 0.95) compared to that among those with sufficient (75 nmol/L) serum 25-OHD concentration. No differences in the point estimates were observed between serous or mucinous histological subtypes of ovarian cancer. CONCLUSION: Overall, we did not observe a significant association between serum 25-OHD concentrations and the risk of ovarian cancer. However, we found evidence suggestive of an increased risk among women with low to insufficient serum 25-OHD concentrations.

Serum 25-hydroxyvitamin D at pregnancy and risk of breast cancer in a prospective study.

BACKGROUND: Several laboratory and epidemiological studies have inversely linked endogenous vitamin D and the risk of breast cancer. The acquisition of vitamin D over time on the relative risk (RR) of the disease development is not known. In a longitudinal study, we evaluated the association between vitamin D levels at pregnancy over time with the risk of breast cancer, and pregnancy-associated breast cancer. METHOD: The risk for subsequent development of breast cancer associated with serum 25-hydroxyvitamin (25-OHD) levels was assessed for consecutive (1st and 2nd pregnancy) samples of 100 cases, with mean lag times (micro(t)) of 7.4 and 4.6 years between sampling and the diagnosis, and matched (parity, age, year, season) controls. Pregnancy-associated breast cancer (PABC, 111 case-control pairs, micro(t)=1 year) risk was also studied. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated using the lowest quintile as the reference. RESULTS: Serum 25-OHD level was not associated with an increased risk neither at the 1st nor at the 2nd pregnancy samples (OR=1.4, 95%CI 0.6-3.4; OR 1.4, 95%CI 0.7-2.8, respectively), but was associated with an increased risk of PABC (OR=2.7, 95%CI 1.04-6.7). CONCLUSION: Generally, vitamin D may not be related to breast cancer risk but the increased PABC risk fits the association of vitamin D with the most aggressive cancers, and warrants caution with vitamin D supplementation during pregnancy.