Register-based Prospective Study Research Articles

Association between dementia risk and ulcerative colitis, with and without colectomy: a Swedish population-based register study

ObjectiveThis study aims to investigate the association of ulcerative colitis (UC) with all-cause dementia and assess differences in those with and without a total colectomy.Design, setting and participantsThis Swedish prospective...

Contraceptive plans and purchase after an induced abortion: A nationwide register study from Finland

ObjectivesTo examine the types of hormonal contraceptive methods chosen at the time of the abortion, and how they correspond to post-abortion hormonal contraceptive purchase. Study designThis was a prospective register-based study. We identified the present cohort of 8428 women undergoing induced abortion between July 1, 2017 and December 31, 2018, using the Prescription Centre, Social Insurance Institution database and the Finnish National Register of Induced Abortions. From the Register of Induced Abortions, we gathered information on planned post-abortion contraception. The redeemed prescriptions of hormonal contraception were identified from the Prescription Centre until December 31, 2019. We analyzed the hormonal contraceptive methods planned at the time of the abortion, and how they corresponded to hormonal contraceptive purchase during the 1-year follow-up. We also assessed factors (age, socioeconomic status, education, civil status, and reproductive history) affecting post-abortion contraceptive purchase by using Poisson regression models. ResultsAt the time of the abortion, 83% (n = 7023) of the women were planning to start using hormonal contraception. Planning any hormonal contraception at the time of the abortion was associated with a higher probability to purchase hormonal contraception after the abortion (incidence rate ratio [IRR] 2.30, 95% confidence intervals [CI] 2.07–2.55), especially in cases of the vaginal ring (IRR 42.66, 95% CI 33.89–53.71) and contraceptive patch (IRR 156.33, 95% CI 111.31–219.55). The following variables were associated with lower incidence rates for purchasing hormonal contraception after the abortion: educational level of bachelor at the highest or missing information on education, civil status as married or divorced, and history of delivery or induced abortion. ConclusionsThe majority of women undergoing abortion plan to use hormonal contraceptive method for post-abortion contraception. Planning any hormonal contraceptive method at the time of an induced abortion is an important predictor of purchasing the method within the year after the abortion. ImplicationsHormonal contraceptive purchase after an abortion is associated with pre-abortion contraceptive planning. Many background factors for not purchasing hormonal contraception can be identified, which may guide counseling dedicated to these groups.

Indicators of quality of diabetes care in persons with type 2 diabetes with and without severe mental illness: a Danish nationwide register-based cohort study.

This study aims to examine quality of diabetes care in persons with type 2 diabetes with and without severe mental illness (SMI). In a nationwide prospective register-based study, we followed persons with type 2 diabetes in Denmark with and without SMI including schizophrenia, bipolar disorder, or major depression. Quality of care was measured as receipt of care (hemoglobin A1c, low-density lipoprotein-cholesterol and urine albumin creatinine ratio assessment and eye and foot screening) and achievement of treatment targets between 2015 and 2019. Quality of care was compared in persons with and without SMI using generalized linear mixed models adjusted for key confounders. We included 216,537 persons with type 2 diabetes. At entry 16,874 (8%) had SMI. SMI was associated with lower odds of receiving care, with the most pronounced difference in urine albumin creatinine ratio assessment and eye screening (OR: 0.55, 95% CI: 0.53-0.58 and OR: 0.37 95% CI: 0.32-0.42, respectively). Among those with an assessment, we found that SMI was associated with higher achievement of recommended hemoglobin A1c levels and lower achievement of recommended low-density lipoprotein-cholesterol levels. Achievement of recommended low-density lipoprotein-cholesterol levels was similar in persons with versus without schizophrenia. Compared to persons without SMI, persons with SMI were less likely to receive process of care, with the most pronounced differences in urine albumin creatinine ratio assessment and eye screening. This study was funded by Steno Diabetes Center Copenhagen through an unrestricted grant from Novo Nordisk Foundation.

Differences between the dispatch priority assessments of emergency medical dispatchers and emergency medical services: a prospective register-based study in Finland

BackgroundResponsive and efficient emergency medical services (EMS) require accurate telephone triage. In Finland, such services are provided by Emergency Response Centre Agency (ERC Agency). In 2018, a new Finnish computer-assisted emergency dispatch system was introduced: the Emergency Response Integrated Common Authorities (ERICA). After the introduction of ERICA, the appropriateness of EMS dispatch has not been investigated yet. The study´s objective is to determine the consistency between the priority triage of the emergency medical dispatcher (EMD) and the on-scene priority assessment of the EMS, and whether the priority assessment consistency varied among the dispatch categories.MethodsThis was a prospective register-based study. All EMS dispatches registered in the Tampere University Hospital area from 1 August 2021 to 31 August 2021 were analysed. The EMD’s mission priority triaged during the emergency call was compared with the on-scene EMS’s assessment of the priority, derived from the pre-set criteria. The test performance levels were measured from the crosstabulation of true or false positive and negative values of the priority assessment. Statistical significance was analysed using the chi-square test and the Kruskal–Wallis H test, and p-values < 0.05 were considered significant.ResultsOf the 6416 EMS dispatches analysed in this study, 36% (2341) were urgent according to the EMD’s dispatch priority, and of these, only 29% (688) were urgent according to the EMS criteria. On the other hand, 64% (4075) of the dispatches were non-urgent according to the EMD’s dispatch priority, of which 97% (3949) were non-urgent according to the EMS criteria. Moreover, there were differences between the EMD and EMS priority assessments among the dispatch categories (p < 0.001). The overall efficiency was 72%, sensitivity 85%, specificity 71%, positive predictive value 29%, and negative predictive value 97%.ConclusionWhile the EMD recognised the non-urgent dispatches with high consistency with the EMS criteria, most of the EMD’s urgent dispatches were not urgent according to the same criteria. This may diminish the availability of the EMS for more urgent missions. Thus, measures are needed to ensure more accurate and therefore, more efficient use of EMS resources in the future.

Overqualification at work and risk of hospitalization for psychiatric and somatic diseases among immigrants in Sweden - a prospective register-based study.

This study aimed to (i) describe the prevalence of overqualification at work among immigrants in Sweden and (ii) analyze any association between overqualification and the risk of hospitalization for somatic and psychiatric disease among refugees and labor immigrants. We performed a prospective register study in a cohort of 120 339 adults who immigrated to Sweden in 1991-2005 and were employed in 2006. Education-occupation status was defined as the combination of an individual's highest level of education and their occupation skill level. Individuals were followed from 2007 to 2016 with regard to hospitalization for a psychiatric, cardiovascular, respiratory or musculoskeletal disease or diabetes. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated in a multivariate Cox regression analysis adjusted for age, gender, reason for residence and duration of residence. The overall prevalence of overqualification among immigrants with an academic education was 39%. Overqualified individuals had an increased risk of hospitalization for any disease (HR 1.33, 95% CI 1.21-1.46) compared to "job-matched with an academic education". However, the risk estimates were lower than that of "job-matched with no academic education" (HR 1.56, 1.46-1.68). The increased risk of hospitalization for a psychiatric disease of overqualified individuals did not differ from that of job-matched with no academic education. Our study showed that being overqualified was associated with poorer health outcomes than job-matched individuals with an academic education. Considering the high prevalence of overqualification in immigrants, this constitutes a concern, for both society and individuals.

Does occupational forward bending of the back increase long-term sickness absence risk? A 4-year prospective register-based study using device-measured compositional data analysis.

Forward bending of the back is common in many jobs and a risk factor for sickness absence. However, this knowledge is based on self-reported forward bending that is generally imprecise. Thus, we aimed to investigate the dose-response relation between device-measured forward bending at work and prospective register-based risk of long-term sickness absence (LTSA). At baseline, 944 workers (93% from blue-collar jobs) wore accelerometers on their upper back and thigh over 1-6 workdays to measure worktime with forward bending (>30˚ and >60˚) and body positions. The first event of LTSA (≥6 consecutive weeks) over a 4-year follow-up were retrieved from a national register. Compositional Cox proportional hazard analyses were used to model the association between worktime with forward bending of the back in an upright body position and LTSA adjusted for age, sex, body mass index (BMI), occupational lifting/carrying, type of work, and, in an additional step, for leisure time physical activity (PA) on workdays. During a mean worktime of 457 minutes/day, the workers on average spent 40 and 10 minutes on forward bending >30˚ and >60˚ in the upright position, respectively. Five more minutes forward bending >30˚ and >60˚ at work were associated with a 4% [95% confidence interval (CI) 1.01-1.07] and 8% (95% CI 1.01-1.16) higher LTSA risk, respectively. Adjustment for leisure-time PA did not influence the results. We found a dose-response association between device-measured forward bending of the back and prospective LTSA risk. This knowledge can be integrated into available feasible methods to measure forward bending of the back for improved workplace risk assessment and prevention.

Health care utilisation in treatment-resistant depression: a Swedish population-based cohort study

Objective To investigate the health care utilisation (HCU) among patients with treatment-resistant depression (TRD) compared to patients with depression not meeting TRD criteria. Methods Nationwide Swedish registers were used to identify patients 18–69 years old with incident depression and antidepressant treatment. Patients were followed prospectively and defined as having TRD at start of the third distinct consecutive treatment episode. Each of the 16,329 identified TRD patients were matched with five comparators with depression not meeting criteria for TRD. Main outcome measure was total number of inpatient days and outpatient visits, and secondary outcome was HCU in connection with a main diagnosis of depression or suicide attempt. Results TRD patients had a significantly higher risk of all-cause inpatient care than comparators (first year adjusted risk ratio [aRR] 3.03 [95%CI 3.01–3.05], years 1–3 aRR 2.15 [2.13–2.16]). This was more pronounced when the main diagnosis was depression (first year aRR 4.41 [4.36–4.45]), and after suicide attempt (first year aRR 4.43 [4.26–4.60]). Outpatient visits were also markedly more frequent for patients with TRD (first year aRR 2.05 [2.03–2.07]). Higher HCU among TRD patients persisted throughout follow-up. Conclusions Patients with TRD may have a twofold to fourfold higher HCU than other patients with depression. KEYPOINTS This register-based prospective study investigated health care utilisation (HCU) among patients with treatment-resistant depression (TRD) compared to other patients with depression. Patients with TRD had a two to fourfold higher HCU regarding all measured outcomes, including inpatient hospital days and outpatient visits. The elevated HCU persisted for more than three years, although decreasing gradually. This should correspond to increased costs and individual burden for patients with TRD.

Drinking Water Disinfection by-Products and Congenital Malformations: A Nationwide Register-Based Prospective Study.

Background:Drinking water chlorination by-products have been associated with adverse reproductive outcomes, although the findings for congenital malformations are still inconclusive.Objective:We conducted a nationwide register-based prospective study to assess whether first trimester maternal exposure to the four most common trihalomethanes [total trihalomethanes (TTHM)] via municipal drinking water was associated with risk of congenital malformation among newborns.Methods:We included all births during 2005–2015 (live and stillbirths) of mothers residing in Swedish localities having inhabitants, two or fewer operating water works, and sufficient municipal TTHM monitoring data. Individual maternal first trimester exposure was obtained by linking TTHM measurements to residential information, categorized into no chlorination and , 5–15, and TTHM/L. We also made chlorination treatment-specific analyses (exclusive use of chloramine or hypochlorite). Outcomes and covariates were obtained via linkage to health care and administrative registers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression.Results:Based on 623,468 births and a prevalence of congenital malformation of cases/100 births, we observed associations between TTHM exposure in areas using chloramine and malformations of the nervous system (; 95% CI: 1.07, 3.12), urinary system (; 95% CI: 1.53, 2.78), genitals (; 95% CI: 1.38, 2.26), and limbs (; 95% CI: 1.10, 1.64), comparing the highest exposed category with the unexposed. No associations were observed in areas using exclusively hypochlorite as the primary water treatment method. By contrast, for malformations of the heart, a significant inverse association was observed only in areas using hypochlorite.Discussion:TTHM exposure was associated with the increased risk of malformations of the nervous system, urinary system, genitals, and limbs in areas exclusively using chloramine. An association between chloramine-related chlorination by-products and congenital malformations has not previously been highlighted and needs further attention. https://doi.org/10.1289/EHP9122

Associations between exposure to drinking water chlorination by-products and congenital malformations–a nation-wide register-based prospective study including 600,000 births

BACKGROUND AND AIM: Chlorination is globally used as a drinking water disinfectant, but chlorination by-products, like trihalomethanes (THM), are easily formed. There are indications that THM may increase the risk of certain adverse reproductive outcomes, although the results are inconsistent. We conducted a nation-wide register-based prospective study to assess whether gestational exposure to THM via drinking water was associated with risk of congenital malformations. METHODS: We included all births during 2005-2015 of mothers residing in Swedish localities with 10,000 inhabitants, ≤ two operating water treatment plants, adequate information on chlorination procedures and sufficient number of THM measurements from the municipal monitoring. Individual maternal exposure was obtained by linking THM measurements to residential history, and categorized into no chlorination, 5, 5-15 and 15 µg THM/L. We also stratified the analyses by chlorination procedure. Outcomes and covariates were obtained via linkage of several Swedish health and administrative registers. Odds ratios (OR) and 95% confidence interval (CI) were estimated by logistic regression. RESULTS:Based on ~600,000 births and after full multivariable adjustment, we observed indications of associations between prenatal THM exposure in areas using chloramine and malformations of the nervous system (OR 1.82, 95% CI: 1.07-3.12), urinary system (2.06: 1.53-2.78), genitals (1.77: 1.38-2.26) and limbs (1.34: 1.10-1.64), comparing the population exposed to 15 µg THM/L with the unexposed. No associations were observed in areas using hypochlorite alone. CONCLUSIONS:This is one of the largest studies assessing chlorination by-products and congenital malformations. In areas using chloramine, we observed that THM was associated with an increased the risk of malformations of the nervous system, urinary system, genitals, and limb. An association between chloramine related chlorination by-products and congenital malformations has not previously been highlighted and needs attention. KEYWORDS: Water quality, Birth outcomes

Hospital Presentation for Self-Harm in Youth as a Risk Marker for Later Psychotic and Bipolar Disorders: A Cohort Study of 59 476 Finns.

Expanding clinical strategies to identify high risk groups for psychotic and bipolar disorders is a research priority. Considering that individuals diagnosed with psychotic and bipolar disorder are at high risk of self-harm, we hypothesised the reverse order relationship would also be true (ie, self-harm would predict psychotic/bipolar disorder). Specifically, we hypothesised that hospital presentation for self-harm would be a marker of high risk for subsequent development of psychotic/bipolar disorder and sought to test this hypothesis in a large population sample. This prospective register-based study included everyone born in Finland in 1987, followed until age 28 years (N = 59 476). We identified all hospital records of self-harm presentations, as well as all ICD-10 healthcare registrations of first diagnoses of psychotic and bipolar disorders. Cox proportional hazards models were used to assess the relationship between self-harm and psychotic/bipolar disorders. Of all individuals who presented to hospital with self-harm (n = 481), 12.8% went on to receive a diagnosis of psychosis (hazard ratio [HR] = 6.03, 95% confidence interval [CI] 4.56–7.98) and 9.4% a diagnosis of bipolar disorder (HR = 7.85, 95% CI 5.73–10.76) by age 28 years. Younger age of first self-harm presentation was associated with higher risk—for individuals who presented before age 18 years, 29.1% developed a psychotic or bipolar disorder by age 28 years. Young people who present to hospital with self-harm are at high risk of future psychotic and bipolar disorders. They represent an important cohort for the prevention of serious mental illness.

Parental income and mental disorders in children and adolescents: prospective register-based study.

BackgroundChildren with low-income parents have a higher risk of mental disorders, although it is unclear whether other parental characteristics or genetic confounding explain these associations and whether it is true for all mental disorders.MethodsIn this registry-based study of all children in Norway (n = 1 354 393) aged 5–17 years from 2008 to 2016, we examined whether parental income was associated with childhood diagnoses of mental disorders identified through national registries from primary healthcare, hospitalizations and specialist outpatient services.ResultsThere were substantial differences in mental disorders by parental income, except for eating disorders in girls. In the bottom 1% of parental income, 16.9% [95% confidence interval (CI): 15.6, 18.3] of boys had a mental disorder compared with 4.1% (95% CI: 3.3, 4.8) in the top 1%. Among girls, there were 14.2% (95% CI: 12.9, 15.5) in the lowest, compared with 3.2% (95% CI: 2.5, 3.9) in the highest parental-income percentile. Differences were mainly attributable to attention-deficit hyperactivity disorder in boys and anxiety and depression in girls. There were more mental disorders in children whose parents had mental disorders or low education, or lived in separate households. Still, parental income remained associated with children’s mental disorders after accounting for parents’ mental disorders and other factors, and associations were also present among adopted children.ConclusionsMental disorders were 3- to 4-fold more prevalent in children with parents in the lowest compared with the highest income percentiles. Parents’ own mental disorders, other socio-demographic factors and genetic confounding did not fully explain these associations.

Cost-of-illness trajectories among people with multiple sclerosis by comorbidity: A register-based prospective study in Sweden.

BackgroundComorbidities are common among people with multiple sclerosis (PwMS); yet, their impact on the cost-of-illness (COI) in MS is unknown.ObjectiveExplore the heterogeneity in COI trajectories among newly diagnosed PwMS in relation to type of comorbidity.MethodsA nationwide longitudinal cohort study, using prospectively collected Swedish register data for seven years. The COI/year of 639 PwMS diagnosed in 2006, when aged 25–60, was estimated until 2013. Using healthcare data, PwMS were categorised into six comorbidity groups: ocular; cardiovascular, genitourinary or cancer disease; musculoskeletal; mental; neurological other than MS; and injuries. One group of PwMS without comorbidity was also created. Group-based trajectory modelling was applied, examining different COI trajectories within each comorbidity group.ResultsAcross the seven follow-up years, PwMS with mental comorbidities had the highest COI overall (€36,482). Four COI trajectories were identified within each comorbidity group; the largest trajectory had high healthcare costs and productivity losses (36.3%–59.6% of PwMS, across all comorbidity groups). 59.6% of PwMS with mental comorbidity had high healthcare costs and productivity losses.ConclusionHigh COI and heterogeneity in COI trajectories could be partly explained by the presence of chronic comorbidities in the year around MS diagnosis, including the presence of mental comorbidity.

Dropout at Danish vocational schools: does the school\u2019s health promotion capacity play a role? A survey- and register-based prospective study

BackgroundSchool dropout rates and risky health behavior is common among students in vocational education and training (VET) schools. Students with poor physical and mental health are more likely to drop out, and as such VET schools may be an important setting for health promotion initiatives, not only to support a healthy lifestyle, but also to assure completion of education. A common feature of successful health promotion at VET schools is a high health promotion capacity at the school level. This study aimed to investigate the association between VET school’s health promotion capacity and later student dropout rates. Secondary, we explored other school characteristics associated with student dropout rates.MethodsThis prospective study comprised 58 Danish VET schools offering basic programs. Health promotion capacity was assessed using questionnaire data from 2017 from school managers and teachers, and this was combined with register-based data on student dropouts the following year. Health promotion capacity was assessed using six scales, representing six underlying domains, and managers and teachers’ ratings of these were compared using t-test. Associations between health promotion capacity and student dropout rates as well as associations between school characteristics and student dropout rates were analyzed using multiple linear regression.ResultsNo associations between VET schools’ health promotion capacity and student dropout rates were observed, neither for the schools’ overall health promotion capacity or for any of the six underlying domains (p = 0.17–0.84). School managers assessed health promotion capacity significantly higher than teachers overall and within all domains (p < 0.05). Moreover, student dropout rates were significantly lower at schools with a higher proportion of ethnic Danish students, VET-students at higher educational level and schools located in the Western part of Denmark (p < 0.05).ConclusionNo associations between VET schools’ health promotion capacity and student dropout rates were observed. This may be due to a relatively short follow-up time in our study and future research may reveal if VET school health promotion capacity may affect dropout rates over a longer time period. Moreover, more work is needed to further develop instruments for measuring health promotion capacity in a VET school context as well as other contexts.

Exposure to Drinking Water Chlorination by-Products and Fetal Growth and Prematurity: A Nationwide Register-Based Prospective Study.

Background:Chlorination is globally used to produce of safe drinking water. Chlorination by-products are easily formed, and there are indications that these are associated with adverse reproductive outcomes.Objectives:We conducted a nationwide register-based prospective study to assess whether gestational exposure to the four most common chlorination by-products [total trihalomethanes (TTHMs)] via tap water was associated with risk of small for gestational age (SGA), preterm delivery, and very preterm delivery. To date, this is one of the largest studies assessing drinking water TTHM-associated adverse reproductive outcomes.Methods:We included all singleton births 2005–2015 (live and stillbirths) of mothers residing in Swedish localities having inhabitants, operating waterworks, adequate information on chlorination treatment, and a sufficient number of routine TTHM measurements in tap water. Individual maternal second and third trimester exposure was obtained by linking TTHM measurements to residential history, categorized into no chlorination, , 5–15, and TTHM/L. Outcomes and covariates were obtained via the linkage to Swedish health and administrative registers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression using inverse probability weighting. We stratified the analyses by chlorination treatment (chloramine, hypochlorite).Results:Based on approximately 500,000 births, we observed a TTHM dose-dependent association with increased risk of SGA, confined to treatment with hypochlorite, corresponding to a multivariable-adjusted (95% CI: 1.08, 1.33) comparing drinking water TTHM to the unexposed. Similar results were obtained when, instead of unexposed, the lowest exposure category ( TTHM) was used as reference. No clear associations were observed for preterm delivery and very preterm delivery.Discussion:Chlorination by-products exposure via drinking water was associated with increased risk of SGA in areas with hypochlorite treatment. https://doi.org/10.1289/EHP6012

Incidence of advanced-stage breast cancer in regular participants of a mammography screening program: a prospective register-based study

BackgroundThe European Guidelines for breast cancer screening suggest that the impact of population-based mammography screening programmes (MSP) may be assessed using the relative reduction in the incidence of advanced breast cancer (ABC, that is, stage UICC II and higher) as a surrogate indicator of screening effectiveness.MethodsThis prospective, population register-based study contained individual data of 1,200,246 women (aged 50–69 years) who attended the initial prevalence screening between 2005 and 2009. Of them, 498,029 women returned for the regular (i.e., within 24 months) first subsequent, and 208,561 for the regular second subsequent incidence screenings. The incidence rate of ABC was calculated for the 24-months period following, but not including, the initial screening by incorporating all interval ABCs and all ABCs detected at the regular first incidence screening; the ABC rate for the second 24-months period was determined in the same way, including ABCs detected in the interval after the first and, respectively, at the second incidence screening. The relative reduction in the ABC incidence was derived by comparing the age-standardized rates in these two periods with an age-standardized reference incidence rate, observed in the target population before the MSP implementation. The strengths and weaknesses of this particular study design were contrasted with a recently published checklist of main methodological problems affecting studies of the effect of MSP on ABC incidence.ResultsThe age-standardized ABC incidence rate was 291.6 per 100,000 women for the 24-months period subsequent to the initial screening, and 275.0/100,000 for the 24-months period following the first subsequent screening. Compared to the 2-year incidence of 349.4/100,000 before the start of the MSP, this amounted to a relative reduction of 16.5 and 21.3%, respectively, in the incidence of ABC among regular MSP participants.ConclusionsThe design employed in this study avoids some of the substantial methodological limitations that compromised previous observational studies. Nevertheless, specific limitations prevail that demand a cautious interpretation of the results. Therefore, the study findings, indicating a reduction in ABC for regular MSP participants, need to be followed with respect to potential impacts on breast cancer mortality rates.

Midlife socioeconomic position and old-age dementia mortality: a large prospective register-based study from Finland

ObjectivesTo assess the association between multiple indicators of socioeconomic position and dementia-related death, and to estimate the contribution of dementia to socioeconomic differences in overall mortality at older ages.DesignProspective population-based...

Role of Maternal Age and Pregnancy History in Risk of Miscarriage: Prospective Register-based Study

(BMJ. 2019;364:I869) Miscarriage is unfortunately a relatively common pregnancy outcome. Various studies have reported that 12% to 15% of pregnancies end in miscarriage. However, these rates may not be accurate as some women experience miscarriage without ever realizing they were pregnant and differences exist among studies regarding the definition of miscarriage versus stillbirth. Several risk factors for miscarriage have been reported, but maternal age seems to have the strongest association. The youngest mothers have a slightly increased risk while older women have a much greater risk than younger women. There might also be an association between previous pregnancy complications and miscarriage risk. This population-based study aimed to evaluate the rate of miscarriage and its association with maternal age and pregnancy history among Norwegian women.

Dog Ownership and Survival After a Major Cardiovascular Event: A Register-Based Prospective Study.

Dog ownership is associated with increased physical activity levels and increased social support, both of which could improve the outcome after a major cardiovascular event. Dog ownership may be particularly important in single-occupancy households where ownership provides substitutive companionship and motivation for physical activity. We used the Swedish National Patient Register to identify all patients aged 40 to 85 presenting with an acute myocardial infarction (n=181 696; 5.7% dog ownership) or ischemic stroke (n=154 617; 4.8% dog ownership) between January 1, 2001 and December 31, 2012. Individual information was linked across registers for cause of death, sociodemographic, and dog ownership data. We evaluated all-cause mortality and risk of recurrent hospitalization for the same cause until December 31, 2012. Models were adjusted for socioeconomic, health, and demographic factors at study inclusion such as age, marital status, the presence of children in the home, area of residence, and income, as well as all registered comorbidities and hospitalization for cardiovascular disease in the past 5 years. Dog owners had a lower risk of death after hospitalization for acute myocardial infarction during the full follow-up period of 804 137 person-years, with an adjusted hazard ratio (HR) of 0.67 (95% CI, 0.61 to 0.75) for those who lived alone, and HR of 0.85 (95% CI, 0.80 to 0.90) for those living with a partner or a child. Similarly, after an ischemic stroke, dog owners were at lower risk of death during the full follow-up of 638 219 person-years adjusted HR of 0.73 (95% CI, 0.66 to 0.80) for those who lived alone and HR of 0.88 (95% CI, 0.83 to 0.93) for those living with a partner or a child. We further found an association of dog ownership with reduced risk of hospitalization for recurrent myocardial infarction (HR, 0.93; 95% CI, 0.87 to 0.99). We found evidence of an association of dog ownership with a better outcome after a major cardiovascular event. Although our models are adjusted for many potential confounders, there are also unmeasured confounders such as smoking that prevent us from drawing conclusions regarding a possible causal effect.

Associations between exposure to drinking water chlorination by-products and being born small or preterm - a nation-wide register-based prospective study including 500,000 singleton births

OPS 24: Drinking water contamination and children’s health, Room 411, Floor 4, August 27, 2019, 10:30 AM - 12:00 PM Background: Chlorination is used globally for the production of clean drinking water, but by-products such as trihalomethanes (THM) are easily formed. There are indications that chlorination by-products may increase the risk of some adverse reproductive outcomes, but results are inconsistent. We conducted a nation-wide register-based prospective study to assess whether gestational exposure to THM via drinking water was associated with risk of small-for-gestational-age (SGA), preterm birth (PTB) and very preterm birth (VPTB). Methods: We included all singleton births 2005-2015 of mothers residing in Swedish localities having >10,000 inhabitants, ≤ two operating water treatment plants, adequate information on chlorination procedures and sufficient number of routine THM measurements in tap water. Individual maternal exposure was obtained by linking THM measurements to residential history, categorized into no chlorination, <5, 5-15 and >15 µg THM/L. We also stratified by chlorination procedure. Outcomes and covariates were obtained via the linkage to Swedish health and administrative registers. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression using inverse probability weighting. Results: Based on ~500,000 births and after full multivariable adjustment, we observed no clear association between THM exposure and risk of SGA based on all assessments. Stratifying by chlorination procedure revealed dose-dependent increased risk of SGA for hypochlorite (OR, 1.20; 95% CI, 1.08-1.33), comparing highest THM exposure with no chlorination, but not for monochloramine. For PTD and VPTD, we observed ORs 0.94 (95% CI, 0.88-1.00) and 0.83 (95% CI, 0.70-0.98), respectively comparing highest THM exposure with no chlorination. Conclusions: This is one of the largest studies assessing drinking water THM-associated adverse reproductive outcomes and we were able to consider time-specific windows of exposure and all relevant individual confounders. After considering the chlorination procedure we observed indications of increased risk of SGA which occurred at a lower exposure than previously observed.

Cohort profile: the DANish LIFE course (DANLIFE) cohort, a prospective register-based cohort of all children born in Denmark since 1980

PurposeThe DANish LIFE course (DANLIFE) cohort is a prospective register-based study set up to investigate the complex life course mechanisms linking childhood adversities to health and well-being in childhood, adolescence...