One-year prevalence of cluster headache, hemicrania continua, paroxysmal hemicrania and SUNCT in Norway: a population-based nationwide registry study

BACKGROUND

There is lack of population-based studies evaluating the prevalence of paroxysmal hemicrania, hemicrania continua and short-lasting unilateral neuralgiform headache attacks.

OBJECTIVES

The aim of this study was to investigate the gender-specific 1-year prevalence of cluster headache, paroxysmal hemicrania, hemicrania continua, and short-lasting unilateral neuralgiform headache attacks.

METHODS

A nationwide study was conducted from January 1 2022 and December 31 2022 by linking diagnostic codes from Norwegian Patient Registry and prescription of relevant drugs from Norwegian Prescription Database on an individual basis. The 1-year prevalence with 95% confidence intervals (CI) of cluster headache, paroxysmal hemicrania, hemicrania continua and short-lasting unilateral neuralgiform headache attacks are estimated based on the combination of diagnostic codes, prescription of drugs and corresponding reimbursement codes.

RESULTS

Among 4,316,747 individuals aged ≥ 18 years, the 1-year prevalence per 100,000 was 14.6 (95% CI 13.5-15.8) for cluster headache, 2.2 (95% CI 1.8-2.7) for hemicrania continua, 1.4 (95% CI 1.0-1.8) for paroxysmal hemicrania, and 1.2 (95% CI 0.8-1.4) for short-lasting unilateral neuralgiform headache attacks. For all the trigeminal autonomic cephalalgies, cluster headache included, the prevalence was higher for women than men.

CONCLUSIONS

In this nationwide register-based study, we found a 1-year prevalence per 100,100 of 14.6 for cluster headache, 2.2 for hemicranias continua, 1.4 for paroxysmal hemicranias, and 1.2 for short-lasting unilateral neuralgiform headache attacks. This is the first study reporting higher prevalence of cluster headache for women than men.

Heart failure describing the underlying cause of death: a misconception, lack of information on the true underlying causes, or both?

AIM

The underlying cause of death represents the most important information on death certificates. Often, conditions that cannot represent a true underlying cause of death are listed as such. This phenomenon affects the quality of vital statistics and results of studies using cause-specific mortality as endpoints. We aimed at exploring the magnitude and factors associated with the use of heart failure to describe the underlying cause of death.

METHODS

In this cross-sectional, register based study we linked data from the Norwegian Cause of Death Registry and the Norwegian Patient Registry. We used logistic regression models to analyse the association between external factors and heart failure listed as the underlying cause of death.

RESULTS

Heart failure was listed as the underlying cause of death in 3.6% of all deaths. The odds of heart failure increased: (a) by 35% for 5-year increment in age; (b) by 78% for deaths occurring at nursing homes (compared with in-hospital deaths); and (c) by 602% for deaths not followed by an autopsy (compared with those followed by an autopsy). Deceased with a previous hospitalisation with heart failure as the discharge diagnosis had 514% higher odds of having heart failure listed as their underlying cause of death. Of the deceased with heart failure listed as the underlying cause of death, 9.4% did not have any, and 69.2% had only irrelevant additional information for assessing the true underlying cause of death in their death certificates.

CONCLUSIONS

Heart failure listed as the underlying cause of death was associated with age, place of death, autopsy and previous hospitalisations - all factors that should not influence coding procedures. Better completion of death certificates in accordance with the World Health Organization rules will help reduce the use of heart failure to describe the underlying cause of death.

Annual incidence of substance-induced psychoses in Scandinavia from 2000 to 2016

BACKGROUND

Substance-induced psychosis (SIP) is a serious condition and may predispose for schizophrenia. We know too little about SIP incidence over time and across countries, including substance-specific SIPs. We estimated annual incidence rate of SIP in Denmark, Norway, and Sweden according to substance, age, gender, and socioeconomic background.

METHODS

Data were drawn from registries covering the whole adult population in the countries. Annual incidence rate per 100 000 persons of SIPs was estimated for Denmark and Sweden from 2000 to 2016 and for Norway from 2010 to 2015.

RESULTS

The annual incidence rate of any SIP fluctuated between 9.3 and 14.1. The most commonly occurring SIPs were those induced by alcohol, cannabis, amphetamines, and multiple substances. There was a steady decrease in the incidence rate of alcohol-induced psychosis from the first to the last year of the observation period in Denmark (from 4.9 to 1.5) and Sweden (from 4.5 to 2.2). The incidence rate of cannabis-induced psychosis increased in all countries, from 2.6 to 5.6 in Denmark, from 0.8 to 2.7 in Sweden, and from 1.8 to 3.0 in Norway. Median age of any SIP decreased in Denmark (from 36 to 29 years) and Sweden (from 41 to 31 years). Incidence rates were higher in men and in individuals on disability pension, and increased more among those with high parental education.

CONCLUSIONS

We found similar and stable incidence rates of any SIP in all Scandinavian countries through the observation period. The incidence of alcohol-induced psychosis decreased. The incidence of cannabis-induced psychosis increased.

Association of Prenatal Exposure to Benzodiazepines and Z-Hypnotics With Risk of Attention-Deficit/Hyperactivity Disorder in Childhood

IMPORTANCE

Evidence is limited regarding the safety of prenatal benzodiazepine and z-hypnotic exposure and its association with long-term neurodevelopment in childhood.

OBJECTIVE

To quantify the associations of the timing and number of intervals of prenatal exposure to benzodiazepines and/or z-hypnotics with the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the 1999 to 2008 population-based Norwegian Mother, Father and Child Cohort Study, which are linked to the Medical Birth Registry of Norway, Norwegian Patient Registry, and Norwegian Prescription Database. Two populations of participants were created: a full sample and a mental health sample. The full sample included mothers and their live-born singletons, whereas the mental health sample was restricted to offspring of mothers who reported anxiety, depression, or sleeping problems during pregnancy or 6 months before pregnancy. Data were analyzed from September 2021 to February 2022.

EXPOSURES

Maternal self-report of benzodiazepine and/or z-hypnotic use during pregnancy was grouped into early pregnancy exposure and middle and/or late pregnancy exposure for analysis of the association with timing of exposure, and number of 4-week intervals of exposure was classified (single [1] vs multiple [≥2]) for analysis of the association with number of exposed intervals.

MAIN OUTCOME AND MEASURES

The outcome was ADHD, defined as time to ADHD diagnosis or filled prescription for ADHD medication. To control for confounding, inverse probability of treatment-weighted Cox proportional hazards regression models were used. Hazard ratios and 95% CIs were estimated. The weights were derived from propensity score modeling of the probability of benzodiazepine and/or z-hypnotic exposure as a function of potential confounders between the exposure and the outcome, including maternal symptoms of depression and anxiety.

RESULTS

The full sample comprised 82 201 pregnancies, and the mental health sample included 19 585 pregnancies. In total, 681 offspring (0.8%) in the full sample and 468 offspring (2.4%) in the mental health sample were prenatally exposed to benzodiazepines and/or z-hypnotics. After weighting, exposure in early (hazard ratio, 0.74; 95% CI, 0.39-1.94) and middle and/or late (hazard ratio, 0.76; 95% CI, 0.35-1.61) pregnancy was not associated with increased risk of childhood ADHD. There was no evidence of substantial association between the number of exposed intervals during pregnancy and childhood ADHD.

CONCLUSIONS AND RELEVANCE

Results of this study suggest that there may be no increased risk of childhood ADHD associated with prenatal exposure to benzodiazepines and/or z-hypnotics, regardless of timing of exposure and number of exposed intervals. However, these findings should be interpreted with caution due to low study power.

Relevant vs non-relevant subspecialist for patients hospitalised in internal medicine at a local hospital: which is better? A retrospective cohort study

Background

Studies of the treatment of patients in-hospital with a specific diagnosis show that physicians with a subspecialisation relevant to this diagnosis can provide a better quality of care. However, studies including patients with a range of diagnoses show a more negligible effect of being attended by a relevant subspecialist. This project aimed to study a more extensive set of patients and diagnoses in an environment where the subspecialist present could be controlled. Thus, this study investigated whether being attended by a physician with a subspeciality relevant to the patient’s primary diagnosis was prospectively associated with readmission, in-hospital mortality, or length of stay compared to a physician with a subspeciality not relevant to the patient’s primary diagnosis.

Methods

We have conducted a retrospective register-based study of 11,059 hospital admissions across 9 years at a local hospital in south-eastern Norway, where it was possible to identify the physician attending the patients at the beginning of the stay. The outcomes studied were emergency readmissions to the same ward within 30 days, any in-hospital mortality and the total length of stay. The patients admitted were matched with the consultant(s) responsible for their treatment. Then, the admissions were divided into two groups according to their primary diagnosis. Was their diagnosis within the subspeciality of the attending consultant (relevant subspecialist) or not (non-relevant subspecialist). The two groups were then compared using bivariable and multivariable models adjusted for patient characteristics, comorbidities, diagnostic group and physician sex.

Results

A relevant subspecialist was present during the first 3 days in 8058 (73%) of the 11,059 patient cases. Patients attended to by a relevant subspecialist had an odds ratio (OR) of 0.91 (95% confidence interval 0.76 to 1.09) for being readmitted and 0.71 (0.48 to 1.04) for dying in the hospital and had a length of stay that was 0.18 (− 0.07 to 0.42) days longer than for those attended to by a non-relevant subspecialist.

Conclusions

This study found that patients attended by a relevant subspecialist did not have a significantly different outcome to those attended by a non-relevant subspecialist.

Association of Maternal Use of Triptans During Pregnancy With Risk of Attention-Deficit/Hyperactivity Disorder in Offspring

Importance

Triptans are commonly used in the treatment of migraine. Prenatal exposure to triptans may be associated with adverse fetal neurodevelopment; however, there is limited information about the long-term safety of triptan use during pregnancy.

Objective

To examine the association between maternal use of triptans during pregnancy and diagnosis and symptoms of attention-deficit/hyperactivity disorder (ADHD) among offspring.

Design, Setting, and Participants

This study used data from the Norwegian Mother, Father and Child Cohort Study (recruitment 1999-2008), linked to national health registries. Live-born singleton children born to women with migraine before or during pregnancy were included. Two analytic samples were defined: one to assess ADHD diagnosis and one to assess ADHD symptoms. Data were analyzed from May 1 to November 30, 2021.

Exposure

Maternal self-report of triptan use during pregnancy. Exposed children were compared with 2 groups of unexposed children whose mothers reported migraine (1) during pregnancy and (2) before pregnancy only.

Main Outcomes and Measures

An ADHD diagnosis was defined as diagnosis of hyperkinetic disorder or receipt of dispensed ADHD medication. Symptoms of ADHD at 5 years were measured by the Conners' Parent Rating Scale, where a higher score indicates more symptoms of ADHD. Cox proportional hazards regression models and generalized linear models with inverse probability weights were used to estimate weighted hazard ratios (HRs) and standardized mean differences, respectively, with 95% CIs.

Results

The ADHD diagnosis sample comprised 10 167 children (mean [SD] maternal age, 30.2 [4.6] years; 5231 boys [51.5%]), and the ADHD symptoms sample comprised 4367 children (mean [SD] maternal age, 30.6 [4.4] years; 2191 boys [50.2%]). Children were followed up for a mean (SD) of 10.6 (2.2) years. Children with prenatal triptan exposure had no increased risk of ADHD diagnosis compared with unexposed children whose mothers had migraine during pregnancy (weighted HR, 1.16; 95% CI, 0.78-1.74) and compared with unexposed children whose mothers had migraine only before pregnancy (weighted HR, 1.28; 95% CI, 0.84-1.94). There were no differences in ADHD symptom scores between exposed and unexposed children.

Conclusions and Relevance

The findings of this study suggest that there is no increased risk of ADHD among offspring associated with prenatal exposure to triptans.

Prenatal exposure to nitrofurantoin and risk of childhood leukaemia: a registry-based cohort study in four Nordic countries

Background

Studies have suggested increased risks of childhood leukaemia after prenatal exposure to antibiotics, particularly nitrofurantoin. However, these findings may be related to the underlying maternal infection. This multinational study aimed to investigate the association between prenatal nitrofurantoin exposure and childhood leukaemia while accounting for maternal infection.

Methods

In a population-based cohort study of children born in Denmark, Finland, Norway or Sweden from 1997 to 2013, prenatal exposure to nitrofurantoin or pivmecillinam (active comparator) was ascertained from national Prescription Registries. Childhood leukaemia was identified by linkage to national Cancer Registries. Poisson regression was used to estimate incidence rate ratios (IRRs) and incidence rate differences (IRDs) with inverse probability of treatment weights applied to account for confounding.

Results

We included 44 091 children prenatally exposed to nitrofurantoin and 247 306 children prenatally exposed to pivmecillinam. The children were followed for 9.3 years on average (standard deviation 4.1). There were 161 cases of childhood leukaemia. The weighted IRR for prenatal nitrofurantoin exposure when compared with pivmecillinam was 1.34 (95% confidence interval 0.88, 2.06), corresponding to an IRD of 15 per million person-years. Higher point estimates were seen for first- and third-trimester exposure. There was no evidence of a dose–response relationship.

Conclusions

Prenatal exposure to nitrofurantoin was not substantially associated with childhood leukaemia, although a slightly elevated IRR with confidence intervals including the null was observed, corresponding to a small absolute risk. The lack of a dose–response relationship and a clear biological mechanism to explain the findings suggests against a causal association.

What are determinants of utilisation of pharmaceutical anticancer treatment during the last year of life in Norway? A retrospective registry study

OBJECTIVES

The objective of this study was to investigate the use of, and predictors for, pharmaceutical anticancer treatment (PACT) towards the end of a patient's life in a country with a public healthcare system.

DESIGN

Retrospective registry study.

SETTING

Secondary care in Norway.

PARTICIPANTS

All Norwegian patients with cancer (International Classification of Diseases tenth revision (ICD-10) codes C00-99, D00-09, D37-48) in contact with a somatic hospital in Norway between 2009 and 2017 (N=420 655). Analyses were performed on a subsample of decedents with follow-back time of more than 1 year (2013-2017, N=52 496).

INTERVENTIONS

N/A.

PRIMARY AND SECONDARY OUTCOME MEASURES

Proportion of patients receiving PACT during the last year and month of life. We calculated CIs with block bootstrapping, while predictors of PACT were estimated with logistic regression.

RESULTS

24.0% (95% CI 23.4% to 24.6%) of the patients received PACT during the last year of life and 3.2% (95% CI 3.0% to 3.5%) during their final month. The proportion during the last month was highest for multiple myeloma (12.7%) and breast cancer (6.5%) and lowest for urinary tract (1.1%) and prostate and kidney cancer (1.4%). Patients living in northern (OR 0.80, 95% CI 0.68 to 0.94) and western (OR 0.85, 95% CI 0.75 to 0.96) Norway had lower odds of PACT during the last month, while patients with myeloma (OR 3.0, 95% CI 2.5 to 3.7) and breast (OR 1.4, 95% CI 1.1 to 1.6) had higher odds. Kidney cancer (OR 0.25, 95% CI 0.2. to 0.4), urinary tract (OR 0.38, 95% CI 0.3 to 0.5) and prostate cancer (OR 0.4, 95% CI 0.3 to 0.5) were associated with lower probability of receiving PACT within the last month.

CONCLUSIONS

The proportion of patients receiving PACT in Norway is lower than in several other industrialised countries. Age, type of cancer and area of living are significant determinants of variation in PACT.

Association of Timing and Duration of Prenatal Analgesic Opioid Exposure With Attention-Deficit/Hyperactivity Disorder in Children

IMPORTANCE

Prior studies have reported that the use of illicit opioids during pregnancy is associated with increased risk of attention-deficit/hyperactivity disorder (ADHD) in offspring; however, evidence regarding the association of analgesic opioids is limited.

OBJECTIVE

To examine the association of timing and duration of prenatal analgesic opioid exposure with ADHD in children.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study uses data from the Norwegian Mother, Father and Child Cohort study (1999-2008), a nationwide birth cohort study linked to national health registries, with a mean (SD) follow-up of 10.8 (2.2) years. A total of 73 784 live-born singleton children born to 62 013 mothers who reported a pain-related condition before and/or during pregnancy were included, with 2 comparator groups: (1) mothers who did not use any opioids and (2) mothers who used opioids before pregnancy only. Data were analyzed from June to December 2020.

EXPOSURES

Maternal self-report of analgesic opioid use during pregnancy, by timing (early and middle and/or late) and duration (≥5 weeks vs ≤4 weeks).

MAIN OUTCOMES AND MEASURES

Diagnosis of ADHD or filled prescription for ADHD medication in children and symptoms of ADHD at child age 5 years, measured by Conners' Parent Rating Scale-Revised. Inverse probability of treatment weights were used to control for measured confounding. Cox regression was used to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

The analyses of ADHD diagnosis and ADHD symptoms included 73 480 children (35 996 [49.0%] girls; mean [SD] maternal age, 30.0 [4.6] years) and 31 270 children (15 377 [49.2%] girls; mean [SD] maternal age, 30.5 [4.4] years), respectively. Overall, 1726 children in the ADHD diagnosis sample (2.3%) and 667 children in the ADHD symptom sample (2.1%) were exposed to an analgesic opioid at least once during gestation. No associations between timing of prenatal analgesic opioid exposure and ADHD diagnosis or symptoms was found. Exposure for 5 or more weeks was associated with an increased risk of ADHD diagnosis (HR, 1.60, 95% CI, 1.04-2.47) compared with exposure for 4 weeks or less; however, there was no such association for the risk of ADHD symptoms.

CONCLUSIONS AND RELEVANCE

In this cohort study, a slightly elevated risk of ADHD diagnosis after prenatal analgesic opioid exposure for 5 or more weeks was found compared with exposure for 4 weeks or less. This result may be driven by longer duration of use; however, the role of residual or unmeasured confounding cannot be excluded. This finding needs to be replicated in other studies.

Men receive more end-of-life cancer hospital treatment than women: fact or fiction?

BACKGROUND

An important goal of health care systems is equitable access to health care. Previous research, however, indicates that men receive more cancer care and health care resources than women. The aim of this study was to investigate whether there is a gender difference in terms of end-of-life cancer treatment in hospitals in Norway.

MATERIAL AND METHODS

We used nationwide patient-level data from the Norwegian Patient Registry (2013-2017, n = 64,694), and aggregated data from the Norwegian Cause of Death Registry (2013-2018, n = 66,534). We described direct medical costs and utilization of cancer treatment in hospitals (in-patient stays and out-patient clinics) and specialized palliative home care teams by the means of the following variables: gender, type of cancer, age, region of residence, place of death, and use of pharmaceutical anti-cancer treatment last month before death. Generalized linear models with a gamma distribution and log-link function were fitted to identify determinants of direct medical costs in hospital's last year of life.

RESULTS

Women aged 0-69 years had an average direct medical cost in hospitals of €26,117 during the last year of life, compared to €29,540 for men, while they were respectively €19,889 and €22,405 for those aged 70 years or older. These gender differences were confirmed in regression models with gender as the only covariate. Adjusted additionally for the type of cancer, the difference was 11%, while including age as a covariate reduced the difference to 6%. When the place of death was also included, the difference was down to 4%.

DISCUSSION

The gender difference in hospital costs last year of life can largely be explained by age at death and the proportion dying in hospitals. When adjusting for confounding factors, the differences in end-of-life costs in hospitals are minimal.

Phase- and gender-specific, lifetime, and future costs of cancer: A retrospective population-based registry study

Valid estimates of cancer treatment costs are import for priority setting, but few studies have examined costs of multiple cancers in the same setting.We performed a retrospective population-based registry study to evaluate phase-specific (initial, continuing, and terminal phase) direct medical costs and lifetime costs for 13 cancers and all cancers combined in Norway. Mean monthly cancer attributable costs were estimated using nationwide activity data from all Norwegian hospitals. Mean lifetime costs were estimated by combining phase-specific monthly costs and survival times from the national cancer registry. Scenarios for future costs were developed from the lifetime costs and the expected number of new cancer cases toward 2034 estimated by NORDCAN.For all cancers combined, mean discounted per patient direct medical costs were Euros (EUR) 21,808 in the initial 12 months, EUR 4347 in the subsequent continuing phase, and EUR 12,085 in the terminal phase (last 12 months). Lifetime costs were higher for cancers with a 5-year relative survival between 50% and 70% (myeloma: EUR 89,686, mouth/pharynx: EUR 66,619, and non-Hodgkin lymphoma: EUR 65,528). The scenario analyses indicate that future cancer costs are highly dependent on future cancer incidence, changes in death risk, and cancer-specific unit costs.Gender- and cancer-specific estimates of treatment costs are important for assessing equity of care and to better understand resource consumption associated with different cancers.Cancers with an intermediate prognosis (50%-70% 5-year relative survival) are associated with higher direct medical costs than those with relatively good or poor prognosis.

Societal cost of cancer in Norway -Results of taking a broader cost perspective

BACKGROUND

The broader cost consequences of diseases may be of interest for a wide range of stakeholders. We aimed to estimate all relevant societal costs of cancer and to provide insight into the relative magnitude of the different cost categories.

METHOD

We used data from eight different health and work-related registries in Norway. Direct, indirect, and intangible costs (value of lost life years) were estimated over a period of one year with a combination of a top-down and a bottom-up costing approach.

RESULTS

The indirect costs (EUR 1,997 million per year) are almost as high as direct costs (EUR 2,154 million), and the value of lost life years and quality of life represents the greatest cost related to cancer (EUR 18,200 million). In addition, cancer is associated with other costs which are commonly omitted from cost-of-illness analyses, including informal nursing (EUR 306 million), patient time costs (EUR 85 million), and excess costs of using public funds (EUR 439 million). Breast and cervical cancer had relatively high work absenteeism costs, while pancreatic and lung cancer had relatively high production costs due to premature deaths.

DISCUSSION

Direct health care costs represent small proportions of the total societal costs of cancer. Costs commonly omitted in cost-of-illness analyses represent a significant cost and should be measured and valued in these analyses.

Attention-deficit/hyperactivity disorder in children following prenatal exposure to antidepressants: results from the Norwegian mother, father and child cohort study

OBJECTIVE

To determine the association between child attention-deficit/hyperactivity disorder (ADHD) and prenatal exposure to selective serotonin (SSRI) and serotonin-norepinephrine (SNRI) reuptake inhibitor antidepressants, by timing and duration, with quantification of bias due to exposure misclassification.

DESIGN

Norwegian Mother, Father and Child Cohort Study and national health registries.

SETTING

Nationwide, Norway.

POPULATION

A total of 6395 children born to women who reported depression/anxiety in pregnancy and were either medicated with SSRI/SNRI in pregnancy (n = 818) or non-medicated (n = 5228), or did not report depression/anxiety but used antidepressants 6 months before pregnancy (discontinuers, n = 349).

MAIN OUTCOME MEASURE

Diagnosis of ADHD or filled prescription for ADHD medication in children, and mother-reported symptoms of ADHD by child age 5 years.

RESULTS

When the hazard was averaged over the duration of the study follow up, there was no difference in ADHD risk between ever in utero SSRI/SNRI-exposed children and comparators (weighted hazard ratio [wHR] 1.07, 95% CI 0.76-1.51 versus non-medicated; wHR 1.53, 95% CI 0.77-3.07 versus discontinuers). Underestimation of effects due to exposure misclassification was modest. In early childhood, the risk for ADHD was lower with prenatal SSRI/SNRI exposure compared with no exposure, and so were ADHD symptoms (weighted β -0.23, 95% CI -0.39 to -0.08); this risk became elevated at child age 7-9 years (wHR 1.93, 95% CI 1.22-3.05). Maternal depression/anxiety before pregnancy was independently associated with child ADHD.

CONCLUSION

Prenatal SSRI/SNRI exposure is unlikely to considerably increase the risk of child ADHD beyond that posed by maternal depression/anxiety. The elevated risk at child age 7-9 years needs to be elucidated.

TWEETABLE ABSTRACT

Women with depression who use antidepressants in pregnancy do not have greater risk of having children with ADHD. Findings in school-age children needs follow up.

Prenatal exposure to non-steroidal anti-inflammatory drugs and risk of attention-deficit/hyperactivity disorder: A follow-up study in the Norwegian mother, father and child cohort

PURPOSE

To estimate the association between Attention-Deficit/Hyperactivity Disorder (ADHD) in children in preschool and primary school, and prenatal exposure to non-steroidal anti-inflammatory drugs (NSAIDs) by timing and duration.

METHODS

This study was based on the Norwegian Mother, Father and Child Cohort Study linked to the Medical Birth Registry of Norway, the Norwegian Patient Registry (NPR) and the Norwegian Prescription Database (NorPD). NSAID exposure was identified by maternal self-report in pregnancy. Child diagnosis of ADHD was obtained from NPR and NorPD. Symptoms of ADHD at age 5 years were measured using Conners' Parent Rating Scale-Revised, where higher scores correspond to more symptoms. To account for time-varying exposure and confounders, marginal structural models were fitted to estimate hazard ratios and mean difference in z-scores.

RESULTS

The analyses on ADHD diagnosis and ADHD symptoms included 56 340 and 34 961 children respectively. Children exposed to NSAIDs prenatally had no increased risk of ADHD diagnosis (first trimester: HR 1.12, 95% CI 0.86;1.45, second trimester: HR 0.98, 95% CI 0.69;1.38, third trimester: HR 0.68, 95% CI 0.31; 1.46) or ADHD symptoms (first trimester: standardized mean difference 0.03, 95% CI -0.03;0.09, second trimester: standardized mean difference 0.03, 95% CI -0.04;0.11, third trimester: standardized mean difference 0.11, 95% CI -0.03; 0.25). There was no duration-response relationship for either outcome.

CONCLUSION

Though non-differential misclassification of the exposure may have attenuated results, these findings are reassuring and suggest no substantially increased risk of ADHD diagnosis or symptoms in children prenatally exposed to NSAIDs, regardless of timing or duration.

Rethinking rehabilitation after percutaneous coronary intervention: a protocol of a multicentre cohort study on continuity of care, health literacy, adherence and costs at all care levels (the CONCARDPCI)

INTRODUCTION

Percutaneous coronary intervention (PCI) aims to provide instant relief of symptoms, and improve functional capacity and prognosis in patients with coronary artery disease. Although patients may experience a quick recovery, continuity of care from hospital to home can be challenging. Within a short time span, patients must adjust their lifestyle, incorporate medications and acquire new support. Thus, CONCARD^PCI will identify bottlenecks in the patient journey from a patient perspective to lay the groundwork for integrated, coherent pathways with innovative modes of healthcare delivery. The main objective of the CONCARD^PCI is to investigate (1) continuity of care, (2) health literacy and self-management, (3) adherence to treatment, and (4) healthcare utilisation and costs, and to determine associations with future short and long-term health outcomes in patients after PCI.

METHODS AND ANALYSIS

This prospective multicentre cohort study organised in four thematic projects plans to include 3000 patients. All patients undergoing PCI at seven large PCI centres based in two Nordic countries are prospectively screened for eligibility and included in a cohort with a 1-year follow-up period including data collection of patient-reported outcomes (PRO) and a further 10-year follow-up for adverse events. In addition to PROs, data are collected from patient medical records and national compulsory registries.

ETHICS AND DISSEMINATION

Approval has been granted by the Norwegian Regional Committee for Ethics in Medical Research in Western Norway (REK 2015/57), and the Data Protection Agency in the Zealand region (REG-145-2017). Findings will be disseminated widely through peer-reviewed publications and to patients through patient organisations.

TRIAL REGISTRATION NUMBER

NCT03810612.

The burden of herpes zoster disease in Norway

BACKGROUND

No national vaccination program against herpes zoster (HZ) is currently in place in Norway. We aimed to quantify the burden of medically attended HZ to assess the need for a vaccination program.

METHODS

We linked data from several health registries to identify medically attended HZ cases during 2008-2014 and HZ-associated deaths during1996-2012 in the entire population of Norway. We calculated HZ incidences for primary and hospital care by age, sex, type of health encounter, vaccination status, and co-morbidities among hospital patients. We also estimated HZ-associated mortality and case-fatality.

RESULTS

The study included 82,064 HZ patients, of whom none were reported as vaccinated against HZ. The crude annual incidence of HZ was 227.1 cases per 100,000 in primary healthcare and 24.8 cases per 100,000 in hospitals. Incidence rates were higher in adults aged ≥50 years (461 per 100,000 in primary care and 57 per 100,000 in hospitals), and women than in men both in primary healthcare (267 vs 188 per 100,000), and hospitals (28 vs 22 per 100,000). Among hospital patients, 47% had complicated zoster and 25% had comorbidities, according to the Charlson comorbidity index. The duration of hospital stay (median 4 days) increased with the severity of comorbidities. The estimated mortality rate was 0.18 per 100,000; and in-hospital case-fatality rate was 1.04%.

CONCLUSIONS

Medically attended HZ poses a substantial burden in the Norwegian healthcare sector. The majority of the zoster cases occurred among adults aged ≥50 years - the group eligible for zoster vaccination - and increased use of zoster vaccination may be warranted, especially among persons with co-morbidities.

Chronic immune thrombocytopenia in Denmark, Sweden and Norway: The Nordic Country Patient Registry for Romiplostim

BACKGROUND

Population-based cohorts of immune thrombocytopenia (ITP) are useful for understanding occurrence, clinical characteristics and long-term clinical course. This paper describes the content of the Nordic Country Patient Registry for Romiplostim (NCPRR) and provides prevalence and incidence estimates of chronic ITP (cITP).

METHODS

The NCPRR, a cohort study established in 2009, includes all adult (≥ 18 years) patients in Denmark, Sweden and Norway with cITP (defined as ITP lasting > 12 months and platelet count < 100 × 10⁹/L), combining data from national health registries and medical records. The NCPRR currently includes prevalent cITP patients diagnosed before 2009 and incident cITP patients diagnosed during 2009-2016. The registry obtains clinical information for cITP patients, including comorbidities, treatments, laboratory values, and complete follow-up for various outcomes.

FINDINGS

The NCPRR currently includes 3831 patients with cITP (1258 prevalent; 2573 incident). In 2009, the prevalence of registered cITP was 10 · 0/100,000 (95%CI:9 · 1-11 · 0) adult persons in Denmark and 10 · 7/100,000 (95% CI: 9 · 9-11 · 4) adults in Sweden. During 2009-2016, the incidence rates of cITP per 100,000 person-years were 2 · 8 (95%CI: 2 · 6-3 · 0), 1 · 8 (95%CI: 1 · 7-1 · 9) and 2 · 1 (95%CI: 1 · 9-2 · 2) in Denmark, Sweden and Norway, respectively. Fifty-eight percent of cITP patients were women. At NCPRR inclusion, 30.2% were aged ≥ 70 years, 23% had a platelet count < 50 × 10⁹/L, 17.4% were splenectomized, 41% had prior ITP therapy, and 8.6% had severe comorbidity.

INTERPRETATION

The NCPRR provides population-based data on the epidemiology and characteristics of almost 4000 cITP patients and is a valuable resource for research.

FUNDING

This study was partly funded by a research grant from Amgen to Aarhus University.

Mortality following first-time hospitalization with acute myocardial infarction in Norway, 2001-2014: Time trends, underlying causes and place of death

BACKGROUND

Trends on cause-specific mortality following acute myocardial infarction (AMI) are poorly described and no studies have analyzed where do AMI patients die. We analyzed trends in 28-day and one-year mortality following an incident AMI with focus on changes over time in the underlying cause and place of death.

METHODS

We identified in the 'Cardiovascular Disease in Norway' Project all patients 25+ years, hospitalized with an incident AMI in Norway, 2001-2014. Information on date, underlying cause and place of death was obtained from the Cause of Death Registry.

RESULTS

Of 144,473 patients included in the study, 11.4% died within first 28 days. The adjusted 28-day mortality declined by 5.2% per year (p_trend < 0.001). Of 118,881 patients surviving first 28 days, 10.1% died within one year. The adjusted one-year CVD mortality declined by 6.2% per year (p_trend < 0.001) while non-CVD mortality increased by 1.4% per year (p_trend < 0.001), mainly influenced by increased risk of dying from neoplasms. We observed a shift over time in the underlying cause of death toward more non-CVD deaths, and in the place of death toward more deaths occurring in nursing homes.

CONCLUSIONS

We observed a decline in 28-day mortality following an incident AMI hospitalization. One-year CVD mortality declined while one-year risk of dying from non-CVD conditions increased. The resulting shift toward more non-CVD deaths and deaths occurring outside a hospital need to be considered when formulating priorities in treating and preventing adverse events among AMI survivors.

The Norwegian Patient Registry and the Norwegian Registry for Primary Health Care: Research potential of two nationwide health-care registries

In Norway, the Directorate of Health is responsible for two nationwide registries – the Norwegian Patient Registry (NPR) and the Norwegian Registry for Primary Health Care (NRPHC) – which together cover all governmental-funded health care. The NPR (specialist health care) was established in 2008, while the NRPHC (primary health care) was established in 2017. Data from the NPR are extensively used in a large variety of studies. We expect that data from the NRPHC will increase in importance when the registry covers a longer time period. The NRPHC will be especially important for studying conditions mainly treated in primary care and for investigation of patient trajectories. The main aim of this paper is to give an overview of the history and content of the NPR and its research possibilities. In addition, we introduce the NRPHC as a possible future research tool and the potential for studying patient trajectories when combining data from the two registries.

Association Between Antibiotics in the First Year of Life and Celiac Disease

BACKGROUND & AIMS

The intestinal microbiota is believed to be involved in the pathogenesis of celiac disease, in addition to genetic variants and dietary gluten. The gut microbiota is strongly influenced by systemic antibiotics-especially in early life. We explored the association between exposure to a systemic antibiotic in the first year of life and risk of diagnosed celiac disease.

METHODS

We performed an observational nationwide register-based cohort study. We included all children born in Denmark from 1995 through 2012 or Norway from 2004 through 2012. Children born in Denmark were followed until May 8, 2015 (age at end of follow-up was 2.3-20.3 years) and children born in Norway were followed until December 31, 2013 (age at end of follow-up was 1-10 years). We collected medical information from more than 1.7 million children, including 3346 with a diagnosis of celiac disease. Exposure to systemic antibiotics was defined as a dispensed systemic antibiotic in the first year of life.

RESULTS

Exposure to systemic antibiotics in the first year of life was positively associated with diagnosed celiac disease in the Danish and Norwegian cohorts (pooled odds ratio 1.26, 95% confidence interval 1.16-1.36). We found a dose-dependent relation between an increasing number of dispensed antibiotics and the risk of celiac disease (pooled odds ratio for each additional dispensed antibiotic 1.08, 95% confidence interval 1.05-1.11). No specific type of antibiotic or age period within the first year of life was prominent. Adjustment for hospital admissions with an infectious disease in the first year of life did not change the estimates; adjustment for the number of maternally reported infections in the child in 2 large sub-cohorts decreased the association slightly (pooled odds ratio 1.18, 95% confidence interval 0.98-1.39).

CONCLUSION

In a nationwide study of children in Denmark and Norway, we found exposure to systemic antibiotics in the first year of life to be associated with a later diagnosis of celiac disease. These findings indicate that childhood exposure to systemic antibiotics could be a risk factor for celiac disease.

Trends in incident acute myocardial infarction in Norway: An updated analysis to 2014 using national data from the CVDNOR project

Background We updated the information on trends of incident acute myocardial infarction in Norway, focusing on whether the observed trends during 2001-2009 continued throughout 2014. Methods All incident (first) acute myocardial infarctions in Norwegian residents age 25 years and older were identified in the Cardiovascular Disease in Norway 1994-2014 project. We analysed overall and age group-specific (25-64 years, 65-84 years and 85 + years) trends by gender using Poisson regression analyses and report the average annual changes in rates with their 95% confidence intervals. Results During 2001-2014, 221,684 incident acute myocardial infarctions (59.4% men) were identified. Hospitalised cases accounted for 79.9% of all incident acute myocardial infarctions. Overall, incident acute myocardial infarction rates declined on average 2.6% per year (incidence rate ratio 0.974, 95% confidence interval 0.972-0.977) in men and 2.8% per year (incidence rate ratio 0.972, 95% confidence interval 0.971-0.974) in women, contributed by declining rates of hospitalisations (1.8% and 1.9% per year in men and women, respectively) and deaths (6.0% and 5.8% per year in men and women, respectively). Declining rates were observed in all three age groups. The overall acute myocardial infarction incidence rates continued to decline from 2009 onwards, with a steeper decline compared to 2001-2009. During 2009-2014, gender-adjusted acute myocardial infarction incidence among adults age 25-44 years declined 5.3% per year, contributed mostly by declines in hospitalisation rates (5.1% per year). Conclusion Acute myocardial infarction incidence rates continued to decline after 2009 in Norway in both men and women. The decline started to involve individuals aged 25-44 years, marking a turning point in the previously reported stagnation of rates during 2001-2009.

Epilepsy in Children After Pandemic Influenza Vaccination

OBJECTIVES

To determine if pandemic influenza vaccination was associated with an increased risk of epilepsy in children.

METHODS

Information from Norwegian registries from 2006 through 2014 on all children <18 years living in Norway on October 1, 2009 was used in Cox regression models to estimate hazard ratios for incident epilepsy after vaccination. A self-controlled case series analysis was used to estimate incidence rate ratios in defined risk periods after pandemic vaccination.

RESULTS

In Norway, the main period of the influenza A subtype H1N1 pandemic was from October 2009 to December 2009. On October 1, 2009, 1 154 113 children <18 years of age were registered as residents in Norway. Of these, 572 875 (50.7%) were vaccinated against pandemic influenza. From October 2009 through 2014 there were 3628 new cases of epilepsy (incidence rate 6.09 per 10 000 person-years). The risk of epilepsy was not increased after vaccination: hazard ratio: 1.07; 95% confidence interval: 0.94-1.23. Results from the self-controlled case series analysis supported the finding of no association between vaccination and subsequent epilepsy.

CONCLUSIONS

Pandemic influenza vaccination was not associated with increased risk of epilepsy. Concerns about pandemic vaccination causing epilepsy in children seem to be unwarranted.

Varicella-related Primary Health-care Visits, Hospitalizations and Mortality in Norway, 2008-2014

BACKGROUND

Norway does not currently implement universal varicella vaccination in childhood. We aimed to characterize health care burden of varicella in Norway in the prevaccine era.

METHODS

We linked individual patient data from different national registries to examine varicella vaccinations and varicella-coded primary care consultations, hospitalizations, outpatient hospital visits, deaths and viral infections of central nervous system in the whole population of Norway during 2008-2014. We estimated health care contact rates and described the epidemiology of medically attended varicella infection.

RESULTS

Each year approximately 14,600 varicella-related contacts occurred within primary health care and hospital sector in Norway. The annual contact rate was 221 cases per 100,000 population in primary health care and 7.3 cases per 100,000 in hospital care. Both in primary and hospital care, the highest incidences were observed among children 1 year of age: 2,654 and 78.1 cases per 100,000, respectively. The annual varicella mortality was estimated at 0.06 deaths per 100,000 and in-hospital case-fatality rate at 0.3%. Very few (0.2-0.5%) patients were vaccinated against varicella. Among hospitalized varicella patients, 22% had predisposing conditions, 9% had severe-to-very severe comorbidities and 5.5% were immunocompromised. Varicella-related complications were reported in 29.3% of hospitalized patients. Varicella zoster virus was the third most frequent virus found among 16% of patients with confirmed viral infections of central nervous system.

CONCLUSIONS

Varicella causes a considerable health care burden in Norway, especially among children. To inform the policy decision on the use of varicella vaccination, a health economic assessment of vaccination and mathematical modeling of vaccination impact are needed.

Comorbidities treated in primary care in children with chronic fatigue syndrome / myalgic encephalomyelitis: A nationwide registry linkage study from Norway

Background

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a complex condition. Causal factors are not established, although underlying psychological or immunological susceptibility has been proposed. We studied primary care diagnoses for children with CFS/ME, with children with another hospital diagnosis (type 1 diabetes mellitus [T1DM]) and the general child population as comparison groups.

Methods

All Norwegian children born 1992–2012 constituted the study sample. Children with CFS/ME (n = 1670) or T1DM (n = 4937) were identified in the Norwegian Patient Register (NPR) (2008-2014). Children without either diagnosis constituted the general child population comparison group (n = 1337508). We obtained information on primary care diagnoses from the Norwegian Directorate of Health. For each primary care diagnosis, the proportion and 99 % confidence interval (CI) within the three groups was calculated, adjusted for sex and age by direct standardization.

Results

Children with CFS/ME were more often registered with a primary care diagnosis of weakness/general tiredness (89.9 % [99 % CI 88.0 to 91.8 %]) than children in either comparison group (T1DM: 14.5 % [99 % CI: 13.1 to 16.0 %], general child population: 11.1 % [99 % CI: 11.0 to 11.2 %]). Also, depressive disorder and anxiety disorder were more common in the CFS/ME group, as were migraine, muscle pain, and infections. In the 2 year period prior to the diagnoses, infectious mononucleosis was registered for 11.1 % (99 % CI 9.1 to 13.1 %) of children with CFS/ME and for 0.5 % (99 % CI (0.2 to 0.8 %) of children with T1DM. Of children with CFS/ME, 74.6 % (1292/1670) were registered with a prior primary care diagnosis of weakness / general tiredness. The time span from the first primary care diagnosis of weakness / general tiredness to the specialist health care diagnosis of CFS/ME was 1 year or longer for 47.8 %.

Conclusions

This large nationwide registry linkage study confirms that the clinical picture in CFS/ME is complex. Children with CFS/ME were frequently diagnosed with infections, supporting the hypothesis that infections may be involved in the causal pathway. The long time span often observed from the first diagnosis of weakness / general tiredness to the diagnosis of CFS/ME might indicate that the treatment of these patients is sometimes not optimal.

The quality of denominator data in surgical site infection surveillance versus administrative data in Norway 2005-2010

Background

High quality of surveillance systems for surgical site infections (SSIs) is the key to their usefulness. The Norwegian Surveillance System for Antibiotic Consumption and Healthcare-Associated Infections (NOIS) was introduced by regulation in 2005, and is based largely on automated extraction of data from underlying systems in the hospitals.

Methods

This study investigates the quality of NOIS-SSI’s denominator data by evaluating completeness, representativeness and accuracy compared with de-identified administrative data for 2005–2010. Comparisons were made by region, hospital type and size, age and sex for 4 surgical procedures.

Results

The completeness of NOIS improved from 29.2 % in 2005 to 79.8 % in 2010. NOIS-SSI became representative over time for most procedures by hospital size and type, but not by region. It was representative by age and sex for all years and procedures. Accuracy was good for all years and procedures by all explanatory variables.

Conclusions

A flexible and incremental implementation strategy has encouraged the development of computer-based surveillance systems in the hospitals which gives good accuracy, but the same strategy has adversely affected the completeness and representativeness of the denominator data. For the purpose of evaluating risk factors and implementing prevention and precautionary measures in the individual hospitals, representativeness seems sufficient, but for benchmarking and/or public reporting it is not good enough.

Two age peaks in the incidence of chronic fatigue syndrome/myalgic encephalomyelitis: a population-based registry study from Norway 2008-2012

BACKGROUND

The aim of the current study was to estimate sex- and age-specific incidence rates of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) using population-based registry data. CFS/ME is a debilitating condition with large impact on patients and their families. The etiology is unknown, and the distribution of the disease in the general population has not been well described.

METHODS

Cases of CFS/ME were identified in the Norwegian Patient Register (NPR) for the years 2008 to 2012. The NPR is nationwide and contains diagnoses assigned by specialist health care services (hospitals and outpatient clinics). We estimated sex- and age-specific incidence rates by dividing the number of new cases of CFS/ME in each category by the number of person years at risk. Incidence rate ratios were estimated by Poisson regression with sex, age categories, and year of diagnosis as covariates.

RESULTS

A total of 5,809 patients were registered with CFS/ME during 2008 to 2012. The overall incidence rate was 25.8 per 100,000 person years (95% confidence interval (CI): 25.2 to 26.5). The female to male incidence rate ratio of CFS/ME was 3.2 (95% CI: 3.0 to 3.4). The incidence rate varied strongly with age for both sexes, with a first peak in the age group 10 to 19 years and a second peak in the age group 30 to 39 years.

CONCLUSIONS

Early etiological clues can sometimes be gained from examination of disease patterns. The strong female preponderance and the two age peaks suggest that sex- and age-specific factors may modulate the risk of CFS/ME.