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Valdimarsdottir, Unnur

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Valdimarsdottir

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Valdimarsdottir, Unnur

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  • Publication

    Consumption of Fish Products across the Lifespan and Prostate Cancer Risk

    (Public Library of Science, 2013) Torfadottir, Johanna E.; Valdimarsdottir, Unnur; Mucci, Lorelei; Kasperzyk, Julie L.; Fall, Katja; Tryggvadottir, Laufey; Aspelund, Thor; Olafsson, Orn; Harris, Tamara B.; Jonsson, Eirikur; Tulinius, Hrafn; Gudnason, Vilmundur; Adami, Hans-Olov; Stampfer, Meir; Steingrimsdottir, Laufey

    Objective: To examine whether fish and fish oil consumption across the lifespan is associated with a lower risk of prostate cancer. Design: The study was nested among 2268 men aged 67–96 years in the AGES-Reykjavik cohort study. In 2002 to 2006, dietary habits were assessed, for early life, midlife and later life using a validated food frequency questionnaire. Participants were followed for prostate cancer diagnosis and mortality through 2009 via linkage to nationwide cancer- and mortality registers. Adjusting for potential confounders, we used regression models to estimate odds ratios (ORs) and hazard ratios (HRs) for prostate cancer according to fish and fish oil consumption. Results: Among the 2268 men, we ascertained 214 prevalent and 133 incident prostate cancer cases, of which 63 had advanced disease. High fish consumption in early- and midlife was not associated with overall or advanced prostate cancer. High intake of salted or smoked fish was associated with a 2-fold increased risk of advanced prostate cancer both in early life (95% CI: 1.08, 3.62) and in later life (95% CI: 1.04, 5.00). Men consuming fish oil in later life had a lower risk of advanced prostate cancer [HR (95%CI): 0.43 (0.19, 0.95)], no association was found for early life or midlife consumption. Conclusions: Salted or smoked fish may increase risk of advanced prostate cancer, whereas fish oil consumption may be protective against progression of prostate cancer in elderly men. In a setting with very high fish consumption, no association was found between overall fish consumption in early or midlife and prostate cancer risk.

  • Publication

    Low Birth Weight, Small for Gestational Age and Preterm Births before and after the Economic Collapse in Iceland: A Population Based Cohort Study

    (Public Library of Science, 2013) Eiríksdóttir, Védís Helga; Ásgeirsdóttir, Tinna Laufey; Bjarnadóttir, Ragnheiður Ingibjörg; Kaestner, Robert; Cnattingius, Sven; Valdimarsdottir, Unnur

    Objective: Infants born small for gestational age (SGA) or preterm have increased rates of perinatal morbidity and mortality. Stressful events have been suggested as potential contributors to preterm birth (PB) and low birth weight (LBW). We studied the effect of the 2008 economic collapse in Iceland on the risks of adverse birth outcomes. Study design The study population constituted all Icelandic women giving birth to live-born singletons from January 1st 2006 to December 31st 2009. LBW infants were defined as those weighing <2500 grams at birth, PB infants as those born before 37 weeks of gestation and SGA as those with a birth weight for gestational age more than 2 standard deviations (SD's) below the mean according to the Swedish fetal growth curve. We used logistic regression analysis to estimate odds ratios [OR] and corresponding 95 percent confidence intervals [95% CI] of adverse birth outcomes by exposure to calendar time of the economic collapse, i.e. after October 6th 2008. Results: Compared to the preceding period, we observed an increased adjusted odds in LBW-deliveries following the collapse (aOR = 1.24, 95% CI [1.02, 1.52]), particularly among infants born to mothers younger than 25 years (aOR = 1.85, 95% CI [1.25, 2.72]) and not working mothers (aOR = 1.61, 95% CI [1.10, 2.35]). Similarly, we found a tendency towards higher incidence of SGA-births (aOR = 1.14, 95% CI [0.86, 1.51]) particularly among children born to mothers younger than 25 years (aOR = 1.87, 95% CI [1.09, 3.23]) and not working mothers (aOR = 1.86, 95% CI [1.09, 3.17]). No change in risk of PB was observed. The increase of LBW was most distinct 6–9 months after the collapse. Conclusion: The results suggest an increase in risk of LBW shortly after the collapse of the Icelandic national economy. The increase in LBW seems to be driven by reduced fetal growth rate rather than shorter gestation.

  • Publication

    Selective serotonin reuptake inhibitors and venlafaxine in early pregnancy and risk of birth defects: population based cohort study and sibling design

    (BMJ Publishing Group Ltd., 2015) Furu, Kari; Kieler, Helle; Haglund, Bengt; Engeland, Anders; Selmer, Randi; Stephansson, Olof; Valdimarsdottir, Unnur; Zoega, Helga; Artama, Miia; Gissler, Mika; Malm, Heli; Nørgaard, Mette

    Objective: To assess whether use of specific selective serotonin reuptake inhibitors (SSRIs) or venlafaxine in early pregnancy is associated with an increased risk of birth defects, with emphasis on cardiovascular birth defects even when accounting for lifestyle or other familial confounding. Design: Multicountry population based cohort study, including sibling controlled design. Setting: Nordic population (Denmark, Finland, Iceland, Norway, and Sweden) identified from nationwide health registers at different periods in 1996-2010. Population The full study cohort included women giving birth to 2.3 million live singletons. The sibling cohort included 2288 singleton live births. The sibling controlled analyses included sibling pairs who were discordant for exposure to SSRIs or venlafaxine and birth defects. Main outcome measure Prevalence of birth defects, including subtypes of cardiac defects. Odds ratio of birth defects from logistic and conditional logistic regression. Results: Among 36 772 infants exposed to any SSRI in early pregnancy, 3.7% (n=1357) had a birth defect compared with 3.1% of 2 266 875 unexposed infants, yielding a covariate adjusted odds ratio of 1.13 (95% confidence interval 1.06 to 1.20). In the sibling controlled analysis the adjusted odds ratio decreased to 1.06 (0.91 to 1.24). The odds ratios for any cardiac birth defect with use of any SSRI or venlafaxine were 1.15 (95% confidence interval 1.05 to 1.26) in the covariate adjusted analysis and 0.92 (0.72 to 1.17) in the sibling controlled analysis. For atrial and ventricular septal defects the covariate adjusted odds ratio was 1.17 (1.05 to 1.31). Exposure to any SSRI or venlafaxine increased the prevalence of right ventricular outflow tract obstruction defects, with a covariate adjusted odds ratio of 1.48 (1.15 to 1.89). In the sibling controlled analysis the adjusted odds ratio decreased to 0.56 (0.21 to 1.49) for any exposure to SSRIs or venlafaxine and right ventricular outflow tract obstruction defects. Conclusions: In this large Nordic study no substantial increase was found in prevalence of overall cardiac birth defects among infants exposed to SSRIs or venlafaxine in utero. Although the prevalence of septal defects and right ventricular outflow tract defects was higher in exposed infants, the lack of an association in the sibling controlled analyses points against a teratogenic effect of these drugs.

  • Publication

    Waiting time for cancer treatment and mental health among patients with newly diagnosed esophageal or gastric cancer: a nationwide cohort study

    (BioMed Central, 2017) Song, Huan; Fang, Fang; Valdimarsdottir, Unnur; Lu, Donghao; Andersson, Therese M.-L.; Hultman, Christina; Ye, Weimin; Lundell, Lars; Johansson, Jan; Nilsson, Magnus; Lindblad, Mats

    Background: Except for overall survival, whether or not waiting time for treatment could influences other domains of cancer patients’ overall well-being is to a large extent unknown. Therefore, we performed this study to determine the effect of waiting time for cancer treatment on the mental health of patients with esophageal or gastric cancer. Methods: Based on the Swedish National Quality Register for Esophageal and Gastric Cancers (NREV), we followed 7,080 patients diagnosed 2006–2012 from the time of treatment decision. Waiting time for treatment was defined as the interval between diagnosis and treatment decision, and was classified into quartiles. Mental disorders were identified by either clinical diagnosis through hospital visit or prescription of psychiatric medications. For patients without any mental disorder before treatment, the association between waiting time and subsequent onset of mental disorders was assessed by hazard ratios (HRs) with 95% confidence interval (CI), derived from multivariable-adjusted Cox model. For patients with a preexisting mental disorder, we compared the rate of psychiatric care by different waiting times, allowing for repeated events. Results: Among 4,120 patients without any preexisting mental disorder, lower risk of new onset mental disorders was noted for patients with longer waiting times, i.e. 18–29 days (HR 0.86; 95% CI 0.74-1.00) and 30–60 days (HR 0.79; 95% CI 0.67-0.93) as compared with 9–17 days. Among 2,312 patients with preexisting mental disorders, longer waiting time was associated with more frequent psychiatric hospital care during the first year after treatment (37.5% higher rate per quartile increase in waiting time; p for trend = 0.0002). However, no such association was observed beyond one year nor for the prescription of psychiatric medications. Conclusions: These data suggest that waiting time to treatment for esophageal or gastric cancer may have different mental health consequences for patients depending on their past psychiatric vulnerabilities. Our study sheds further light on the complexity of waiting time management, and calls for a comprehensive strategy that takes into account different domains of patient well-being in addition to the overall survival. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-3013-7) contains supplementary material, which is available to authorized users.

  • Publication

    Obstetric Outcomes of Mothers Previously Exposed to Sexual Violence

    (Public Library of Science, 2016) Gisladottir, Agnes; Luque-Fernandez, Miguel Angel; Harlow, Bernard L.; Gudmundsdottir, Berglind; Jonsdottir, Eyrun; Bjarnadottir, Ragnheidur I.; Hauksdottir, Arna; Aspelund, Thor; Cnattingius, Sven; Valdimarsdottir, Unnur

    Background: There is a scarcity of data on the association of sexual violence and women's subsequent obstetric outcomes. Our aim was to investigate whether women exposed to sexual violence as teenagers (12–19 years of age) or adults present with different obstetric outcomes than women with no record of such violence. Methods: We linked detailed prospectively collected information on women attending a Rape Trauma Service (RTS) to the Icelandic Medical Birth Registry (IBR). Women who attended the RTS in 1993–2010 and delivered (on average 5.8 years later) at least one singleton infant in Iceland through 2012 formed our exposed cohort (n = 1068). For each exposed woman's delivery, nine deliveries by women with no RTS attendance were randomly selected from the IBR (n = 9126) matched on age, parity, and year and season of delivery. Information on smoking and Body mass index (BMI) was available for a sub-sample (n = 792 exposed and n = 1416 non-exposed women). Poisson regression models were used to estimate Relative Risks (RR) with 95% confidence intervals (CI). Results: Compared with non-exposed women, exposed women presented with increased risks of maternal distress during labor and delivery (RR 1.68, 95% CI 1.01–2.79), prolonged first stage of labor (RR 1.40, 95% CI 1.03–1.88), antepartum bleeding (RR 1.95, 95% CI 1.22–3.07) and emergency instrumental delivery (RR 1.16, 95% CI 1.00–1.34). Slightly higher risks were seen for women assaulted as teenagers. Overall, we did not observe differences between the groups regarding the risk of elective cesarean section (RR 0.86, 95% CI 0.61–1.21), except for a reduced risk among those assaulted as teenagers (RR 0.56, 95% CI 0.34–0.93). Adjusting for maternal smoking and BMI in a sub-sample did not substantially affect point estimates. Conclusion: Our prospective data suggest that women with a history of sexual assault, particularly as teenagers, are at increased risks of some adverse obstetric outcomes.

  • Publication

    Body Mass Index, Smoking and Hypertensive Disorders during Pregnancy: A Population Based Case-Control Study

    (Public Library of Science, 2016) Gudnadóttir, Thuridur A.; Bateman, Brian; Hernádez-Díaz, Sonia; Luque-Fernandez, Miguel Angel; Valdimarsdottir, Unnur; Zoega, Helga

    While obesity is an indicated risk factor for hypertensive disorders of pregnancy, smoking during pregnancy has been shown to be inversely associated with the development of preeclampsia and gestational hypertension. The purpose of this study was to investigate the combined effects of high body mass index and smoking on hypertensive disorders during pregnancy. This was a case-control study based on national registers, nested within all pregnancies in Iceland 1989–2004, resulting in birth at the Landspitali University Hospital. Cases (n = 500) were matched 1:2 with women without a hypertensive diagnosis who gave birth in the same year. Body mass index (kg/m2) was based on height and weight at 10–15 weeks of pregnancy. We used logistic regression models to calculate odds ratios and corresponding 95% confidence intervals as measures of association, adjusting for potential confounders and tested for additive and multiplicative interactions of body mass index and smoking. Women’s body mass index during early pregnancy was positively associated with each hypertensive outcome. Compared with normal weight women, the multivariable adjusted odds ratio for any hypertensive disorder was 1.8 (95% confidence interval, 1.3–2.3) for overweight women and 3.1 (95% confidence interval, 2.2–4.3) for obese women. The odds ratio for any hypertensive disorder with obesity was 3.9 (95% confidence interval 1.8–8.6) among smokers and 3.0 (95% confidence interval 2.1–4.3) among non-smokers. The effect estimates for hypertensive disorders with high body mass index appeared more pronounced among smokers than non-smokers, although the observed difference was not statistically significant. Our findings may help elucidate the complicated interplay of these lifestyle-related factors with the hypertensive disorders during pregnancy.

  • Publication

    Use of SSRI and SNRI Antidepressants during Pregnancy: A Population-Based Study from Denmark, Iceland, Norway and Sweden

    (Public Library of Science, 2015) Zoega, Helga; Kieler, Helle; Nørgaard, Mette; Furu, Kari; Valdimarsdottir, Unnur; Brandt, Lena; Haglund, Bengt

    Background: The purpose was to describe utilization of selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs), including trends in prevalence, characteristics of users, drug switching and changes in prescribed doses in a large group of pregnant women across four Nordic countries. Methods: A drug utilization study based on linked individual-level data from the nationwide prescription- and medical birth registers in Denmark, Iceland, Norway and Sweden. The study population comprised all pregnancies in these countries, resulting in a live birth or stillbirth after gestational week 22 from January 1st 2008 to December 31st 2012 (N = 1 162 470). In addition to the main study drugs SSRIs and SNRIs, we included (concurrent) use of other antidepressants, antipsychotics, anxiolytics and hypnotics. Results: A total of 38 219 (3.3%) pregnancies were exposed to SSRIs and 5 634 (0.5%) to SNRIs. Prevalence of SSRI and SNRI use varied by country (1.8% in Norway to 7.0% in Iceland). Use and prescribed dosages decreased with each passing trimester of pregnancy; prevalence was 2.7% at conception, and 2.1%, 1.7% and 1.3% respectively in 1st, 2nd and 3rd trimester. In 0.6% of pregnancies women filled a prescription before pregnancy and in every trimester. In one third of exposed pregnancies, women were also dispensed anxiolytics, hypnotics or sedatives. Conclusion: Use of SSRI and SNRI use during pregnancy varied between the Nordic countries, but the overall prevalence remained low and relatively stable from 2008 to 2012. The low prevalence of use and high proportion of women who discontinue treatment in pregnancy raise questions about adequate treatment of depression in pregnant women.

  • Publication

    Sixteen-year follow-up of childhood avalanche survivors

    (Co-Action Publishing, 2016) Thordardottir, Edda Bjork; Valdimarsdottir, Unnur; Hansdottir, Ingunn; Hauksdóttir, Arna; Dyregrov, Atle; Shipherd, Jillian C.; Elklit, Ask; Resnick, Heidi; Gudmundsdottir, Berglind

    Background: Every year a substantial number of children are affected by natural disasters worldwide. However, data are scarce on long-term psychological impact of natural disasters on children's health. Identifying risk factors and outcomes associated with the long-term sequelae of posttraumatic stress disorder (PTSD) can provide a gateway to recovery as well as enhancement of preventive measures. Objective: Among childhood avalanche survivors, we aimed to investigate risk factors for PTSD symptoms and the relationship between socioeconomic status (SES) and PTSD symptoms in adulthood. Methods: Childhood survivors (aged 2–19 at the time of exposure) of two avalanches were identified through nationwide registers 16 years later. The Posttraumatic Diagnostic Scale was used to assess current PTSD symptoms. One-way ANOVA was used to explore PTSD symptoms by background and trauma-specific factors, as well as associations with current SES. Predictors of PTSD symptoms were examined by multivariable regression analysis. Results: Response rate was 66% (108/163). Results from univariate ANOVA analysis revealed that female sex was associated with PTSD symptoms (F=5.96, p<0.05). When adjusted for age and sex, PTSD symptoms were associated with lower education (F=7.62, p<0.001), poor financial status (F=12.21, p<0.001), and unemployment and/or disability (F=3.04, p<0.05). In a multivariable regression model, when adjusting for age and sex, lack of social support (t=4.22, p<0.001) and traumatic reactions of caregivers (t=2.49, p<0.05) in the aftermath of the disaster independently predicted PTSD 16 years post-trauma. Conclusions: Lingering PTSD symptoms after childhood exposure to a disaster may negatively influence socioeconomic development in adulthood. Strengthening children's support systems post-disaster may prevent the long-term sequelae of symptoms. Highlights of the article PTSD symptoms following avalanche exposure during childhood were associated with poorer socioeconomic status in adulthood. Lack of social support and traumatic reactions of caregivers in the aftermath of avalanches predicted PTSD symptoms among childhood survivors 16 years later. Findings underscore the importance of strengthening children's support systems in the aftermath of disasters.

  • Publication

    Sexually transmitted infections after bereavement – a population-based cohort study

    (BioMed Central, 2016) Bond, Emily; Lu, Donghao; Herweijer, Eva; Sundström, Karin; Valdimarsdottir, Unnur; Fall, Katja; Arnheim-Dahlström, Lisen; Sparén, Pär; Fang, Fang

    Background: Loss of a loved one has consistently been associated with various health risks. Little is however known about its relation to sexually transmitted infections (STIs). Methods: We conducted a population-based cohort study during 1987–2012 using the Swedish Multi-Generation Register, including 3,002,209 women aged 10-44 years. Bereavement was defined as death of a child, parent, sibling or spouse (N = 979,579, 33 %). STIs were defined as hospital visits with an STI as main or secondary diagnosis. Poisson regression and negative binomial regression were used to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) of STIs, comparing incidence rates of women who had experienced loss to those who had not. Results: Bereaved women were at significantly higher risk of nearly all STIs studied. The relative risk of any STI was highest during the first year after loss (IRR: 1.45, 95 % CI: 1.27–1.65) and predominantly among women with subsequent onset of psychiatric disorders after bereavement (IRR: 2.61, 95 % CI: 2.00–3.34). Notably, a consistent excess risk, persisting for over five years, was observed for acute salpingitis (IRR: 1.28, 95 % CI: 1.13–1.44), a severe complication of bacterial STIs. Conclusion: These data suggest that women who have experienced bereavement are at increased risk of STIs. Electronic supplementary material The online version of this article (doi:10.1186/s12879-016-1705-x) contains supplementary material, which is available to authorized users.

  • Publication

    Pregnancy-Induced Hypertensive Disorders before and after a National Economic Collapse: A Population Based Cohort Study

    (Public Library of Science, 2015) Eiríksdóttir, Védís Helga; Valdimarsdottir, Unnur; Ásgeirsdóttir, Tinna Laufey; Hauksdóttir, Arna; Lund, Sigrún Helga; Bjarnadóttir, Ragnheiður Ingibjörg; Cnattingius, Sven; Zoëga, Helga

    Background: Data on the potential influence of macroeconomic recessions on maternal diseases during pregnancy are scarce. We aimed to assess potential change in prevalence of pregnancy-induced hypertensive disorders (preeclampsia and gestational hypertension) during the first years of the major national economic recession in Iceland, which started abruptly in October 2008. Methods and Findings: Women whose pregnancies resulted in live singleton births in Iceland in 2005–2012 constituted the study population (N = 35,211). Data on pregnancy-induced hypertensive disorders were obtained from the Icelandic Medical Birth Register and use of antihypertensive drugs during pregnancy, including β-blockers and calcium channel blockers, from the Icelandic Medicines Register. With the pre-collapse period as reference, we used logistic regression analysis to assess change in pregnancy-induced hypertensive disorders and use of antihypertensives during the first four years after the economic collapse, adjusting for demographic and pregnancy characteristics, taking aggregate economic indicators into account. Compared with the pre-collapse period, we observed an increased prevalence of gestational hypertension in the first year following the economic collapse (2.4% vs. 3.9%; adjusted odds ratio [aOR] 1.47; 95 percent confidence interval [95%CI] 1.13–1.91) but not in the subsequent years. The association disappeared completely when we adjusted for aggregate unemployment rate (aOR 1.04; 95% CI 0.74–1.47). Similarly, there was an increase in prescription fills of β-blockers in the first year following the collapse (1.9% vs.3.1%; aOR 1.43; 95% CI 1.07–1.90), which disappeared after adjusting for aggregate unemployment rate (aOR 1.05; 95% CI 0.72–1.54). No changes were observed for preeclampsia or use of calcium channel blockers between the pre- and post-collapse periods. Conclusions: Our data suggest a transient increased risk of gestational hypertension and use of β-blockers among pregnant women in Iceland in the first and most severe year of the national economic recession.