The effect of gestational age on major neurodevelopmental disorders in preterm infants.

BACKGROUND: Preterm infants have an increased risk of neurodevelopmental disorders. We established a direct quantitative comparison of the association between the degree of prematurity and three different neurodevelopmental disorders. METHODS: In this cohort study, we combined data from 995,498 children in the Danish Medical Birth Register, from birth years 1997-2013, with information on cerebral palsy, epilepsy, and special educational needs. We estimated the gestational week-specific prevalence and risk for each of the disorders. RESULTS: The risk ratio of cerebral palsy at gestational weeks 21-24, compared to term birth, was more than ten times higher than for the two other disorders. The prevalence of epilepsy and special educational needs declined almost parallel, with 9.2% (4.6%-13.5%) and 12.5% (11.2%-13.7%), respectively, per week of gestation toward term birth. Cerebral palsy did not decline similarly: from gestational weeks 21-24 until week 29 the prevalence declined insignificantly by 0.6% (-11.1%-11.0%) per week; whereas from week 29 until term, the prevalence declined markedly by 36.7% (25.9%-45.9%) per week. CONCLUSIONS: The prevalence and risk of cerebral palsy are affected differently by the degree of prematurity compared with epilepsy and special educational needs, possibly reflecting important differences in cerebral pathophysiology. IMPACT: For each week of gestation toward term birth, there was a clear log-linear decline in the prevalence of early childhood epilepsy and special educational needs. In contrast, the risk of cerebral palsy was high at the earliest gestational age, and the prevalence did not decline significantly until gestational week 29, from where it declined notably by nearly 40% for each week of gestation until term birth. Our results indicate important differences in the pathophysiological processes that associate preterm birth with these three neurodevelopmental disorders.

Declining prevalence of cerebral palsy in children born at term in Denmark.

AIM: To investigate reasons for the declining prevalence of cerebral palsy (CP) in children born at term in Denmark by evaluating obstetric and neonatal factors associated with CP, and their changes over time. METHOD: In this cohort study, we included 987 495 children (504 600 [51.1%] males and 482 895 [48.9%] females) born after 37 completed gestational weeks during birth years 1997 to 2013. Risk ratios of CP for each factor were calculated with log-binominal regression analyses. Significant factors were evaluated concerning their development in prevalence over time. RESULTS: In the antenatal period, there were significant associations with an increased risk of CP and high maternal body mass index (BMI), smoking during pregnancy, nulliparity, male sex, gestational age, and low birthweight. In the study period, fewer females smoked during pregnancy and fewer children were born post-term, dropping from 22.6% to 11.4% and 9.4% to 2.5% respectively. Conversely, the proportion of females with high BMI increased. Most significant risk factors were found in the neonatal period, with an increase in children with diagnosed birth defects and children admitted to neonatal care. INTERPRETATION: Reasons for the declining prevalence of CP appear to be multifactorial and likely include the decline in maternal smoking and children born post-term along with centralization and advances in neonatal treatment.

Disparities in postpartum depression screening participation between immigrant and Danish-born women.

BACKGROUND: Qualitative studies suggest that immigrant women experience barriers for postpartum depression (PPD) screening. This study examines the prevalence of participation in PPD screening in the universal home-visiting programme in Denmark, in relation to migrant status and its association with acculturation factors, such as length of residence and age at migration. METHODS: The sample consists of 77 694 births from 72 292 mothers (2015-18) that participated in the programme and were registered in the National Child Health Database. Lack of PPD screening using the Edinburgh Postpartum Depression Scale (EPDS) was examined in relation to migrant group and acculturation factors. We used Poisson regression with cluster robust standard errors to estimate crude and adjusted relative risk. RESULTS: In total, 27.8% of Danish-born women and 54.7% of immigrant women lacked screening. Compared with Danish-born women, immigrant women in all groups were more likely to lack PPD screening (aRR ranging from 1.81 to 1.90). Women with low acculturation were more likely to lack screening. Women who migrated as adults [aRR = 1.27 (95% CI 1.16, 1.38)] and women who had resided in Demark for <5 years [aRR = 1.37 (95% CI 1.28, 1.46)] were more likely to lack screening. CONCLUSIONS: Immigrant women in Denmark, particularly recent immigrants, are at increased risk of not being screened for PPD using the EPDS. This can lead to under-recognition of PPD among immigrant women. More work is needed to understand how health visitors recognize the mental health needs of immigrant women who are not screened, and whether this gap results in reduced use of mental health services.

Using both electromyography and movement disorder assessment improved the classification of children with dyskinetic cerebral palsy.

AIM: Children with dyskinetic cerebral palsy (CP) are often severely affected and effective treatment is difficult, due to different underlying disease mechanisms. Comprehensive systematic movement disorder evaluations were carried out on patients with this disorder. METHODS: Patients born from 1995 to 2007 were identified from the Danish Cerebral Palsy Register and referrals to the neuropaediatric centre, Rigshospitalet, Copenhagen. They were classified by gross motor function, manual functional ability, communication ability, dystonia and spasticity. Electromyography was carried out on the upper and lower limbs. Magnetic resonance imaging scans were revised, and aetiological searches for underlying genetic disorders were performed. RESULTS: We investigated 25 patients with dyskinetic CP at a mean age of 11.7 years. Dystonia, spasticity and rigidity were found in the upper limbs of 21, four and six children, respectively, and in the lower limbs of 18, 18 and three children. The mean total Burke-Fahn-Marsden score for dystonia was 45.02, and the mean Disability Impairment Scale level was 38% for dystonia and 13% for choreoathetosis. Sustained electromyography activity was observed in 20/25 children. Stretching increased electromyography activity more in children with spasticity. There were 10 re-classifications. CONCLUSION: The children had heterogenic characteristics, and 40% were reclassified after systematic movement disorder evaluation.

Parental education, parent-child relations and diagnosed mental disorders in childhood: prospective child cohort study.

BACKGROUND: Mental disorder in childhood is an important public health issue. We aimed to examine the prospective association between parental education at childbirth and diagnosed mental disorders in young children and explore whether this association was mediated or modified by parent-child relations in infancy. METHODS: Prospective cohort study of all newborn was from 2002 to 2010 from 16 municipalities in the capital region of Copenhagen, Denmark, with follow-up until their 8th birthday, N = 40 762. Baseline data included information from national population registers and from health visitors' records at child aged 0 to 10 months. Outcome variable: any mental disorder diagnosed at hospital from age 11 months to 8 years. RESULTS: Low parental education was predictive of diagnosed child mental disorder, adjusted odds ratio (AOR) = 1.83 (95% CI 1.49-2.23). Problematic parent-child relation at age 8-10 months was also predictive of mental disorder, AOR = 2.06 (1.57-2.70) but did not mediate the association between parental education and mental disorder. AOR for mental disorders was 3.24 (2.03-5.16 for the combination vocational training and problematic parent-child relation and 2.49 (1.42-4.38) for the combination primary school and problematic parent-child relation. CONCLUSIONS: Low parental education and problematic parent-child relation were independent risk factors for diagnosed mental disorders in the age span of 11 months to 8 years.

Reproductive history of the Danish multiple sclerosis population: A register-based study.

BACKGROUND: A diagnosis of multiple sclerosis (MS) may impact the choice of parenthood. OBJECTIVE: To investigate the number of live births, abortions and ectopic pregnancies among persons with MS. METHODS: From the Danish Multiple Sclerosis Registry, we extracted data from all persons diagnosed with MS from 1960 to 1996 and matched each MS person with four reference persons. We used a negative binomial regression model for the live births and Poisson regression model for abortions and ectopic pregnancies. The total fertility rate (TFR) during 1960-2016 and the annual number of live births in the MS population were analysed. RESULTS: Persons with MS had fewer children than reference persons. Fewer women with MS had elective abortions after diagnosis (incidence rate ratio (IRR) = 0.88; 95% confidence interval (CI) = 0.78-1.00) than reference persons. There was no difference regarding the number of elective abortions, spontaneous abortions or ectopic pregnancies after onset. The TFR was lower for women with MS than for reference persons, and the number of annual live births by MS persons increased during 1960-2016. CONCLUSION: MS seems to considerably impact reproductive choices, especially after clinical diagnosis, resulting in the MS population having fewer children than the general population.

Study protocol of the Healthy High School study: a school-based intervention to improve well-being among high school students in Denmark.

BACKGROUND: The prevalence of low well-being, perceived stress and unhealthy behaviours is high among high school students, but few interventions have addressed these problems. The aim of this paper is to present a study protocol of a cluster randomised controlled trial evaluating the Healthy High School (HHS) intervention programme. The intervention programme is designed to improve well-being (primary outcome) by preventing 1) stress and promoting 2) sleep, 3) sense of community, 4) physical activity (PA) and 5) regular and healthy meals among high school students in Denmark. METHODS: The development of the HHS study was guided by the Intervention Mapping protocol. The intervention comprises four components: 1) a teaching material, 2) a smartphone app, 3) a catalogue focusing on environmental changes, and 4) a peer-led innovation workshop aiming at inspiring students to initiate and participate in various movement activities. The HHS study employs a cluster-randomised controlled trial design. Thirty-one high schools across Denmark were randomly allocated to intervention (16 schools) or control (15 schools) groups. The study included all first-year students (~ 16 years of age) (n = 5976 students). Timeline: Intervention: August 2016 - June 2017. Collection of questionnaire data: Baseline (August 2016), 1st follow-up (May 2017) and 2nd follow-up (April 2018). All students were invited to participate in a monthly sub-study about perceived stress using text messages for data collection (September 2016 - June 2017). PA was objectively assessed among a sub-sample of students using accelerometers (Axivity, AX3) in August 2016 and May 2017. PRIMARY OUTCOME MEASURES: Student well-being measured by the Cantril Ladder and the five item World Health Organisation Well-being Index (individual level outcomes). SECONDARY OUTCOME MEASURES: Stress (10-item Perceived Stress Scale), sleep (quantity and quality), PA (hours of moderate-to-vigorous PA per week, hours of daily sedentary time and average daily PA), meal habits (daily intake of breakfast, lunch, snacks and water), and strong sense of community in class and at school, respectively (individual level outcomes). The study encompasses process and effect evaluation as well as health economic analyses. TRIAL REGISTRATION: ISRCTN ISRCTN43284296, 28 April 2017, retrospectively registered.

Children with dyskinetic cerebral palsy are severely affected as compared to bilateral spastic cerebral palsy.

AIM: We aimed at describing clinical findings in children with dyskinetic as compared to bilateral spastic cerebral palsy (CP). METHODS: Data were extracted from the Danish nationwide CP register. Participants were born in 1999-2007 and were 5-6 years at ascertainment. RESULTS: The total number of CP cases was 1165 of which 92 had dyskinetic and 540 bilateral spastic CP. Prevalence of dyskinetic CP was 0.16 per 1000 live births. In participants with dyskinetic compared to bilateral spastic CP, there was more frequently an Apgar level less than five at five minutes (22.7% vs. 11.2%) and neonatal seizures (43.5% vs. 28.5%), but less respiratory deficiency, hyperbilirubinaemia and sepsis. Impairment based on gross motor function classification was more severe in dyskinetic CP (level III-V 90.0% vs. 66.0%). In dyskinetic CP, there was a high rate of reduced developmental quotient (68.1%), visual impairment (39.3%) and epilepsy (51.6%). Basal ganglia lesions were more prevalent in dyskinetic compared to bilateral spastic CP (27.7% vs. 12.8%). CONCLUSION: Cases of dyskinetic CP had overlapping clinical features with cases of bilateral spastic CP, but differed significantly in several perinatal risk factors. The children with dyskinetic CP had experienced more peri- or neonatal adverse events, and neurodevelopmental impairment was severe.

Excess mortality among patients with multiple sclerosis in Denmark has dropped significantly over the past six decades: a population based study.

BACKGROUND: Lifetime expectancy in multiple sclerosis (MS) is reduced. Few studies have had sufficient follow-up or sufficient number of patients to assess if survival has improved with time. However, a recent meta-analysis found no time-dependent change in MS excess mortality across studies over recent decades. OBJECTIVE: To investigate whether short-term all-cause excess mortality in patients with MS in the total Danish population has changed over the last six decades. PATIENTS AND METHODS: We included all patients with MS recorded in the nationwide Danish MS Registry with definite or probable MS and onset from 1950 through 1999. The Danish Civil Registration System provided date of death for all deceased patients with follow-up in 2015, and Statistics Denmark supplied specific population mortality. We calculated excess number of death per 1000 person-years (EDR) and standardised mortality ratio (SMR). RESULTS: We included 18 847 patients among whom 6102 had died as opposed to 2492 expected deaths. EDR was 10.63 (95% CI 10.19 to 11.09) and a SMR was 2.45 (95% CI 2.39 to 2.51). The 15-year EDR dropped gradually from 11.29 (95% CI 9.95 to 12.73) in the 1950-1959 onset cohort to 2.56 (95% CI 1.98 to 3.18) in the 1990-1999 onset cohort, and SMR dropped from 4.48 (95% CI 4.06 to 4.92) to 1.80 (95% CI 1.62 to 1.99). CONCLUSION: The decline in short-term excess mortality in MS started decades before disease-modifying treatment of MS became available, before use of MRI became widespread, and before the McDonald diagnostic criteria were introduced. A change in the MS cohorts with fewer malignant cases may be a significant contributor.

Employment, disability pension and income for children with parental multiple sclerosis.

BACKGROUND: Little is known about the consequences of parental multiple sclerosis (MS) on offspring's socioeconomic circumstances. OBJECTIVE: To investigate employment, disability pension and income in offspring of parents with MS compared with matched reference persons in a nationwide register-based cohort study. METHODS: All Danish-born persons with onset of MS during 1950-1986 were retrieved from the Danish Multiple Sclerosis Registry. Their offspring were identified using the Civil Registration System. One random offspring from each sibship was matched by sex and year of birth with eight random reference persons. RESULTS: We included 2456 MS offspring and 19,648 reference persons. At age 30, employment was lower among MS offspring than reference children (odds ratio (OR): 0.89; 95% confidence interval (CI): 0.84-0.95; p = 0.0003), and they more often received disability pension (OR: 1.31; 95% CI: 1.15-1.50; p < 0.0001) at ages 30 and 40 but not at age 50. Although the mean income was not significantly lower for the MS offspring cohort, most of them attained an annual personal income below 250,000 DKK (Danish krone), that is, ~33,650 EUR (OR: 0.91; 95% CI: 0.84-0.99; p = 0.04). CONCLUSION: Having had a parent with MS may affect employment and increase the risk of disability pension and low income in adult life.

High-dose erythropoietin in patients with progressive multiple sclerosis: A randomized, placebo-controlled, phase 2 trial.

BACKGROUND: Erythropoietin (EPO) is a part of an endogenous neuroprotective system in the brain and may address pathophysiological mechanisms in progressive multiple sclerosis (MS). OBJECTIVE: To evaluate a treatment effect of EPO on progressive MS. METHODS: This was a single-center, randomized, double-blind, placebo-controlled phase 2 trial, in which 52 patients with secondary or primary progressive MS were allocated to treatment with recombinant EPO (48,000 IU) or placebo, administered intravenously 17 times during 24 weeks. Patients had an Expanded Disability Status Score (EDSS) from 4 to 6.5 and clinical progression without relapses in the 2 preceding years. The primary outcome was the change in a composite measure of maximum gait distance, hand dexterity, and cognition from baseline to 24 weeks. RESULTS: A total of 50 patients completed the study. Venesection was performed often but no thromboembolic events occurred. We found no difference in the primary outcome between the EPO and the placebo group using the intention-to-treat principle ( p = 0.22). None of the secondary outcomes, neither clinical nor magnetic resonance imaging (MRI) measures showed any significant differences. CONCLUSION: This study provides class II evidence that treatment with high-dose EPO is not an effective treatment in patients with moderately advanced progressive MS.

Psychiatric co-morbidity in multiple sclerosis: The risk of depression and anxiety before and after MS diagnosis.

BACKGROUND: Studies of depression and anxiety in multiple sclerosis (MS) patients have reported higher rates in MS patients than the general population. OBJECTIVE: To estimate the risk of depression and anxiety and the use of tricyclic antidepressant and selective serotonin reuptake inhibitors (SSRI) prescriptions, in the pre-diagnostic and the post-diagnostic period of MS compared to the background population. METHODS: A cohort of 5084 MS patients was included and matched with a control population of 24,771 persons linked to nationwide registers. Logistic regression analyses were performed estimating odds ratios (OR). RESULTS: In the pre-diagnostic period, the OR for having a diagnosis of depression and anxiety is 1.4 (95% confidence interval (CI) =1.05-1.88), and the OR of redemption prescriptions of TCAs is 1.90 (CI=1.54-2.34) and OR is 1.34 (CI= 1.20-1.51) for SSRI. In the post-diagnostic period the OR is 1.23 (CI= 0.92-1.64) for depression and anxiety diagnosis. The OR is 6.70 (CI=5.81-7.72) for TCA and OR is 2.46 (CI= 2.25-2.69) for SSRI. CONCLUSION: During both the pre- diagnostic and post-diagnostic period, MS patient have increased risk of depression and anxiety diagnoses and redemption of antidepressant and anxiolytic prescriptions, compared to the background population.

Problem Gambling Associated with Violent and Criminal Behaviour: A Danish Population-Based Survey and Register Study.

This study compares the number of criminal charges among problem gamblers (N = 384) and non-problem gamblers including non-gamblers (N = 18,241) and examines whether problem gambling is more strongly associated with income-generating crimes like theft, fraud and forgery than other types of crimes such as violent crimes. A cohort study was carried out, based on data from the Danish Health and Morbidity Surveys in 2005 and 2010, which were linked at the individual level with data from The Danish National Criminal Register. Multiple logistic regression analyses were used to determine the association between problem gambling and charges for different categories of crime. We found that problem gamblers had significantly higher odds of being charged than non-problem gamblers (adjusted odds ratio 1.5; 95 % confidence interval 1.1-1.9). The odds ratio for economic crime charges was 2.6 (1.5-4.5), for violence charges 2.2 (1.1-4.5), and for drug charges 3.7 (1.7-8.0). For road traffic charges the odds ratio was 1.3 (1.0-1.8). Hence, there was a strong association between problem gambling and being charged except for road traffic charges; however the association was not stronger for economic charges than for violence and drug charges.

Shaping the Social: design of a settings-based intervention study to improve well-being and reduce smoking and dropout in Danish vocational schools.

BACKGROUND: The social environment at schools is an important setting to promote educational attainment, and health and well-being of young people. However, within upper secondary education there is a need for evidence-based school intervention programmes. The Shaping the Social intervention is a comprehensive programme integrating social and educational activities to promote student well-being and reduce smoking and dropout in upper secondary vocational education. The evaluation design is reported here. METHODS/DESIGN: The evaluation employed a non-randomised cluster controlled design, and schools were selected to either implement the intervention or continue with normal practice for comparison. In the baseline survey conducted 2011-2012, 2,329 students from four intervention schools and 3,371 students from six comparison schools answered a computer-based questionnaire during class, representing 73% and 81% of eligible students, and 22% of all technical/agricultural vocational schools in Denmark. Follow-up assessment was conducted 10 weeks after baseline and at the same time teachers of the intervention classes answered a questionnaire about implementation. School dropout rates will be tracked via national education registers through a 2-year follow-up period. DISCUSSION: Shaping the Social was designed to address that students at Danish vocational schools constitute a high risk population concerning health behaviour as well as school dropout by modifying the school environment, alongside developing appropriate evaluation strategies. To address difficulties in implementing settings-based interventions, as highlighted in prior research, the strategy was to involve intervention schools in the development of the intervention. Baseline differences will be included in the effectiveness analysis, so will the impact of likely mediators and moderators of the intervention. TRIALS REGISTRATION: ISRCTN57822968. Date of registration: 16/01/2013.

Childhood body mass index and multiple sclerosis risk: a long-term cohort study.

BACKGROUND: Obesity in late adolescence has been associated with an increased risk of multiple sclerosis (MS); however, it is not known if body size in childhood is associated with MS risk. METHODS: Using a prospective design we examined whether body mass index (BMI) at ages 7-13 years was associated with MS risk among 302,043 individuals in the Copenhagen School Health Records Register (CSHRR). Linking the CSHRR with the Danish MS registry yielded 774 MS cases (501 girls, 273 boys). We used Cox proportional hazards models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Among girls, at each age 7-13 years, a one-unit increase in BMI z-score was associated with an increased risk of MS (HR(age 7)=1.20, 95% CI: 1.10-1.30; HR(age 13)=1.18, 95% CI: 1.08-1.28). Girls who were ≥95(th) percentile for BMI had a 1.61-1.95-fold increased risk of MS as compared to girls <85(th) percentile. The associations were attenuated in boys. The pooled HR for a one-unit increase in BMI z-score at age 7 years was 1.17 (95% CI: 1.09-1.26) and at age 13 years was 1.15 (95% CI: 1.07-1.24). CONCLUSION: Having a high BMI in early life is a risk factor for MS, but the mechanisms underlying the association remain to be elucidated.

Are there differences in injury mortality among refugees and immigrants compared with native-born?

BACKGROUND: The authors studied injury mortality in Denmark among refugees and immigrants compared with that among native Danes. METHOD: A register-based, historical prospective cohort design. All refugees (n=29, 139) and family reunited immigrants (n=27, 134) who between 1 January 1993 and 31 December 1999 received residence permission were included and matched 1:4 on age and sex with native Danes. Civil registration numbers were cross-linked to the Register of Causes of Death, and fatalities due to unintentional and intentional injuries were identified based on ICD-10 diagnosis. Sex-specific mortality ratios were estimated by migrant status and region of birth, adjusting for age and income and using a Cox regression model after a median follow-up of 11-12 years. RESULTS: Compared with native Danes, both female (RR=0.44; 95% CI 0.23 to 0.83) and male (RR=0.40; 95% CI 0.29 to 0.56) refugees as well as female (RR=0.40; 95% CI 0.21 to 0.76) and male (RR=0.22; 95% CI 0.12 to 0.42) immigrants had significantly lower mortality from unintentional injuries. Suicide rates were significantly lower for male refugees (RR=0.38; 95% CI 0.24 to 0.61) and male immigrants (RR=0.24; 95% CI 0.10 to 0.59), whereas their female counterparts showed no significant differences. Only immigrant women had a significantly higher homicide rate (RR=3.09; 95% CI 1.11 to 8.60) compared with native Danes. CONCLUSIONS: Overall results were advantageous to migrant groups. Research efforts should concentrate on investigating protective factors among migrants, which may benefit injury prevention in the majority population.

Absence from work due to occupational and non-occupational accidents.

AIMS: The aim of the present study was to investigate absence from work in Denmark due to occupational and non-occupational accidents. BACKGROUND: Since the beginning of the last decade, political focus has been placed on the population's working capacity and the scope of absence due to illness. Absence from work is estimated at between 3% and 6% of working hours in the EU and costs are estimated at approximately 2.5% of GNP. METHODS: Victims of accidents treated at two emergency departments were interviewed regarding absence for the injured, the family and others. All answers were linked to the hospital information on the injury, so that it was possible to examine the relation between absence and injury type, and cause of the accident. RESULTS: In total, 1,479 injured persons were interviewed. 36% of these reported absence from work by themselves or others. In mean, an injury caused 3.21 days of absence. Based on this the total absence due to injuries in Denmark was estimated to 1,822,000 workdays, corresponding to approximately 6% of the total absence from work due to all types of illness. Non-occupational injuries resulted in more absence than did occupational injuries. CONCLUSIONS: Absence due to accidents contributed to a considerable part of the total absence from work, and non-occupational accidents caused more absence than did occupational accidents.

Effects of individual and parental educational levels on multimorbidity classes: a register-based longitudinal study in a Danish population.

OBJECTIVES: To assess the effects of individual educational level in adulthood and parental educational level during childhood, as well as combinations of individual and parental educational levels, on multimorbidity classes. DESIGN AND SETTING: In this longitudinal study, we used data from a random sample of the Danish population aged 32-56 years without multimorbidity in 2010 (n=102 818). The study population was followed until 2018. Information on individual and parental educational levels and chronic conditions was obtained from national registers. Multinomial logistic regression analyses were adjusted for sex, age and ethnicity. OUTCOME MEASURE: Seven multimorbidity classes were identified using latent class analysis based on 47 chronic conditions. Persons deceased during follow-up comprised a separate class. RESULTS: We found an independent effect of individual educational level on five multimorbidity groups and death, most pronounced for the multimorbidity group 'Many conditions' (OR=1.89, 95% CI 1.58 to 2.26 for medium and OR=3.22, 95% CI 2.68 to 3.87 for short compared with long educational level) and of parental education on four groups and death, most pronounced for the multimorbidity group 'Many conditions' (OR=1.36, 95% CI 1.07 to 1.73 for medium and OR=1.48, 95% CI 1.15 to 1.89 for short compared with long educational level). Odds of belonging to four multimorbidity classes increased with lower combination of individual and parental educational levels, most pronounced for the multimorbidity group 'Many conditions'. CONCLUSION: As both individual and parental educational levels contribute to the risk of multimorbidity, it is important to address inequality throughout the life course to mitigate multimorbidity. Future studies could adopt a life course approach to investigate the mediating role of behavioural, clinical, environmental and other social factors.

The Danish Injury Register.

INTRODUCTION: The Danish Injury Register was established in 1988 and is based on injury case records from four Danish hospitals (five hospitals until 2007). CONTENT: In total, 1.76 million cases were recorded during 1990-2008. Data items include the place of the accident, mechanism of injury, involved products, type of sports, and description of the accident. VALIDITY AND COVERAGE: The register covers approximately 15% of the Danish population and is roughly representative for the whole Denmark in terms of age, sex, and social groups. CONCLUSION: The Danish Injury Register is a valuable source of information on injuries in Denmark, in particular product-related injuries and sports injuries. Further, the possibility to link to other registers increases the use of the data.

The Danish Multiple Sclerosis Registry.

OBJECTIVES: The Danish Multiple Sclerosis Registry is the oldest operative and nationwide MS registry. We present The Danish Multiple Sclerosis Registry with its history, data collection, scientific contribution, and national and international research collaboration. MATERIALS AND METHODS: Detailed description of data collection, completeness, quality optimizing procedures, funding, and legal, ethical and data protection issues are provided. RESULTS: The total number of registered cases with clinical isolated syndrome and multiple sclerosis since 1956 was by start of May 2020 30,023 of whom 16,515 cases were alive and residing in Denmark, giving a prevalence rate of about 284 per 100,000 population. The mean annual number of new cases receiving an MS diagnosis was 649 per year in the period 2010 to 2019. In total, 7,945 patients (48.1%) are receiving disease modifying therapy at the start of May 2020. CONCLUSIONS: Multiple Sclerosis registers are becoming increasingly important, not only for epidemiological research but also by quantifying the burden of the disease for the patients and society and helping health care providers and regulators in their decisions. The Danish Multiple Sclerosis Registry has served as data source for a number of scientific publications including epidemiological studies on changes in incidence and mortality, cohort studies investigating risk factors for developing MS, comorbidities and socioeconomic outcomes in the MS population, and observational studies on effectiveness of disease modifying treatments outside the narrow realms of randomized clinical trials.