Incidence and cost of rotavirus hospitalizations in Denmark.

In anticipation of licensure and introduction of rotavirus vaccine into the western market, we used modeling of national hospital registry data to determine the incidence and direct medical costs of annual rotavirus-associated admissions over >11 years in Denmark. Diarrhea-associated hospitalizations coded as nonspecified viral or presumed infectious have demonstrated a marked winter peak similar to that of rotavirus-associated hospitalizations, which suggests that the registered rotavirus-coded admissions are grossly underestimated. We therefore obtained more realistic estimates by 2 different models, which indicated 2.

Birth weight and risk of cancer.

Background: It is well established that prenatal biologic processes are important for the development of some childhood cancers, whereas less is known regarding their influence on adult cancer risk. High birth weight has been associated with risk of breast cancer, whereas studies of other specific cancers and all cancers together have been less conclusive.

Methods: The authors established a cohort of more than 200,000 men and women who were born between 1936 and 1975.

The Childcare Database: a valuable register linkage.

Rationale: To assess the impact of childcare attendance on morbidity for an entire country the Childcare Database was created by linking person-identifiable data from several Danish national data sources. The present paper describes the creation, characteristics, and potential of the Childcare Database.

Design And Measurement: Based on the unique Danish Civil Registration System (DCRS) identification number register data were linked regarding childcare attendance, child and family characteristics, childcare facility characteristics, and hospitalizations for children aged 0 to 5 years in the period from 1989 to 2004.

Strong combined gene-environment effects in anti-cyclic citrullinated peptide-positive rheumatoid arthritis: a nationwide case-control study in Denmark.

Objective: To study the role of shared epitope (SE) susceptibility genes, alone and in combination with tobacco smoking and other environmental risk factors, for risk of subtypes of rheumatoid arthritis (RA) defined by the presence or absence of serum antibodies against cyclic citrullinated peptides (CCPs).

Methods: To address these issues, a nationwide case-control study was conducted in Denmark during 2002-2004, comprising incident cases of RA or patients with recently diagnosed RA (309 seropositive and 136 seronegative for IgG antibodies against CCP) and 533 sex- and age-matched population controls. Associations were evaluated by logistic regression analyses, in which odds ratios (ORs) served as measures of relative risk.

Perinatal and crowding-related risk factors for invasive pneumococcal disease in infants and young children: a population-based case-control study.

Background: Denmark's systems of registry-based data offer a unique opportunity to examine, on a population basis, risk factors for invasive pneumococcal disease (IPD) relating to perinatal and crowding exposures among children. The main objective of this study was to identify the role of familial and day care factors in the risk of IPD among unvaccinated infants and children.

Methods: A total of 1381 children aged 0-5 years old who experienced IPD were identified from a national surveillance program of IPD in Denmark.

Reproductive history and cutaneous malignant melanoma: a comparison between women and men.

To evaluate whether previously observed associations between parity and cutaneous malignant melanoma (CMM) risk in women reflected a biologic mechanism or resulted from uncontrolled confounding by lifestyle factors associated with parity (e.g., patterns of sun exposure), the authors investigated the effect of reproductive history (parenthood) on CMM risk in both women and men.

Reproductive patterns and non-Hodgkin lymphoma risk in Danish women and men.

Reproductive patterns have been inconsistently linked to risk of non-Hodgkin lymphoma (NHL) in women, and fathering patterns in relation to NHL risk have not been studied. The authors conducted a register-based cohort study of 4.1 million Danes to investigate associations of livebirths with subsequent NHL incidence (85 million person-years, 3819 NHL cases).

Population-based study of the impact of childcare attendance on hospitalizations for acute respiratory infections.

Objectives: It is well known that children attending childcare have a higher risk of acute respiratory infections compared with children in home care; however, knowledge is sparse regarding how the excess risk of acute respiratory infection varies with age, time since enrollment, and other factors.

Methods: A national register-based study of 138,821 inpatient admissions to hospital for acute respiratory infection during 3,982,925 person-years of follow-up in Danish children aged 0 to 5 years. Data on child and family characteristics, childcare attendance, and hospitalizations were obtained from Danish registries.

Growth patterns and the risk of breast cancer in women.

Adult height and body mass index (BMI) influence the risk of breast cancer in women. Whether these associations reflect growth patterns of the fetus or growth during childhood and adolescence is unknown. We investigated the association between growth during childhood and the risk of breast cancer in a cohort of 117,415 Danish women.

Environmental risk factors differ between rheumatoid arthritis with and without auto-antibodies against cyclic citrullinated peptides.

The aim of this study was to evaluate new and previously hypothesised non-genetic risk factors for serologic subtypes of rheumatoid arthritis (RA) defined by the presence or absence of auto-antibodies to cyclic citrullinated peptides (CCP). In a national case-control study, we included 515 patients recently diagnosed with RA according to the American College of Rheumatology 1987 classification criteria and 769 gender- and age-matched population controls. Telephone interviews provided information about non-genetic exposures, and serum samples for patients were tested for anti-CCP-antibodies.

Type 1 diabetes and multiple sclerosis: A Danish population-based cohort study.

Background: Type 1 diabetes mellitus (T1D) and multiple sclerosis (MS) contribute considerably to the burden of autoimmune diseases in young adults. Although HLA patterns of T1D and MS are considered mutually exclusive, individual and familial co-occurrence of the 2 diseases has been reported.

Objective: To assess the co-occurrence of T1D and MS by estimating the risk for MS in patients with T1D and the risk for T1D in first-degree relatives of patients with MS.

Maternal serum alpha-fetoprotein level during pregnancy and isolated cryptorchidism in male offspring.

Cryptorchidism is thought to result from a disruption of the androgen-estrogen balance in utero. Alpha-fetoprotein (AFP) interacts with and may modulate fetal responses to estrogens. Using a cohort of boys born to women participating in a Danish maternal serum AFP screening program between 1980 and 1994, the authors explored whether AFP levels (as reflected by maternal serum AFP levels in gestational weeks 14-22) were associated with the risk of isolated cryptorchidism in male offspring.

No association between selected candidate gene polymorphisms and severe chronic periodontitis.

Background: Chronic periodontitis (CP) risk is influenced by environmental and genetic factors. Using a case-control design, we tested for associations between CP and selected DNA sequence variations (single nucleotide polymorphisms [SNPs]) in or near genes coding for proteins that play a role in the pathogenesis of this disease.

Methods: DNA was analyzed from 219 whites who were examined clinically.

Temporal trend in paediatric infections in Denmark.

Aim: To study temporal trends in the incidence of hospitalisations due to infection in children in Denmark.

Methods: A national register based cohort of 1 892 711 Danish children aged 0-5 years were studied from 1980 to 2001. Child and family characteristics were identified in the Danish Civil Registration System; hospitalisations were identified in the Danish National Patient Registry.

The impact of pre-school booster vaccination of 4--6-year-old children on pertussis in 0--1-year-old children.

Pertussis in young children is severe and relatively prevalent in vaccinated populations. We estimated the impact of pre-school booster vaccination of 4-6-year-old children on pertussis in 0-1-year-old children. We conducted a population-based historical cohort study of all children born in Denmark, 1977-2001 (N=1,536,717) using information on place of residence to identify household members and vaccination history from nationwide registers.

Cancer susceptibility in nasopharyngeal carcinoma families--a population-based cohort study.

Undifferentiated nasopharyngeal carcinoma is a result of environmental factors, in particular EBV infection, affecting genetically susceptible individuals. The familial risk of nasopharyngeal carcinoma is among the highest of any malignancy. Whether this susceptibility is restricted to nasopharyngeal carcinoma is unknown as information on the risk of other cancers in relatives is limited.

Risk factors for idiopathic congenital/infantile cataract.

Purpose: To investigate maternal, demographic, and pre- and perinatal risk factors for idiopathic congenital/infantile (ICI) cataract.

Methods: Based on national registries, a cohort of all children born in Denmark and aged 0 to 17 years during 1977 to 2001 was established, and congenital/infantile cataract cases were identified. Cases of unknown/idiopathic cause were included in the study.

Familial risk of multiple sclerosis: a nationwide cohort study.

Multiple sclerosis (MS) is known to accumulate within families. The magnitude of the familial risk, however, remains uncertain. Using a nationwide MS register and other national registers, the authors estimated relative and absolute risks of MS in a population-based cohort that included 19,615 first-degree relatives of 8,205 Danish MS patients followed from 1968 to 1997.

Childhood vaccination and nontargeted infectious disease hospitalization.

Context: It has been hypothesized that multiple-antigen vaccines, such as measles-mumps-rubella vaccine, or aggregated vaccine exposure could lead to immune dysfunction, resulting in nontargeted infectious diseases as a result of an "overload" mechanism.

Objective: To evaluate the relationship between routinely administered childhood vaccines (Haemophilus influenzae type b; diphtheria-tetanus-inactivated poliovirus; diphtheria-tetanus-acellular pertussis-inactivated poliovirus; whole-cell pertussis; measles-mumps-rubella; oral poliovirus) and hospitalization for nontargeted infectious diseases.

Design, Setting, And Participants: Population-based cohort comprising all children born in Denmark from 1990 through 2001 (N = 805 206).

A comparison of risk factors for wheeze and recurrent cough in preschool children.

In a study of 2,978 Danish children aged 5 years from two suburban counties of Copenhagen, carried out in 1998, the authors compared risk factor profiles for wheeze and recurrent cough without wheeze by using polytomous logistic regression to clarify whether the two conditions are likely to have the same etiology. Data were obtained 1) by a mailed parental questionnaire (International Study of Asthma and Allergies in Childhood questions and supplementary questions on cough, sociodemography, perinatal factors, and environmental exposure); 2) through general practitioners (familial allergic disease); and 3) from the National Medical Birth Register (birth weight). Wheeze (WH) was defined as more than one episode of wheeze within the last 12 months (irrespective of cough status) and recurrent cough without WH (RC) as cough occurring outside colds and usually lasting for periods of more than 1 week in children with no more than one attack of wheeze within the last 12 months.

Sibship characteristics and risk of allergic rhinitis and asthma.

Studying associations between sibship characteristics and allergic diseases in detail may contribute clues to their etiology. The authors studied associations between sibship characteristics and risk of self-reported allergic rhinitis and asthma among 31,145 pregnant women participating in a nationwide study in Denmark during 1997-2000. Increasing sibship size was associated with a decreased risk of allergic rhinitis and asthma with allergic rhinitis but not with asthma without allergic rhinitis.

Lung function in Greenlandic and Danish children and adolescents.

Respiratory morbidity in Inuit children is high. However, little is know regarding lung function measures in this population. The forced expiratory volumes in one second (FEV(1)) and forced vital capacity (FVC) in 888 Greenlandic Inuits (N=888) and Danes (N=477) aged 6-18 years were compared.

A nationwide Danish study of 1027 cases of congenital/infantile cataracts: etiological and clinical classifications.

Objective: To study the distribution of congenital/infantile cataract in the entire population of Denmark according to etiological and clinical classifications.

Design: Population-based cohort study with retrospective chart review.

Participants: All children (0 to 17 years old) who were born between 1959 and 2001 and registered with congenital/infantile cataract in Denmark during the period 1977 to 2001.

Reproductive factors and extreme levels of maternal serum alpha-fetoprotein: a population-based study.

Background: Levels of maternal alpha-fetoprotein (AFP) are increased during multiple gestations and preeclampsia but little is known regarding AFP levels in relation to other reproductive factors. Consequently, the objective of this work was to describe the possible relationship between AFP levels during pregnancy and maternal age at birth, maternal age at first birth, parity, time since previous birth and gender of the offspring.

Methods: Based on national registries we obtained the reproductive history on a population-based cohort of 44 227 women who had serum AFP levels determined in gestational weeks 14-21 and whose present and previous pregnancies resulted in live-born singletons.