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Morten Frydenberg

Publications and source records attributed to Morten Frydenberg.

16 recordsLinked to original sources
PubMed2006

Does low participation in cohort studies induce bias?

BACKGROUND: Participation rates in large cohort studies have decreased during the last 2 decades. The consequences of this trend for relative risk estimation are unknown. METHODS: The impact of a low participation rate (30%) on the Danish National Birth Cohort was examined among 49,751 women from the source population, including 15,373 participants in the cohort study. On the basis of independent data collection, we estimated odds ratios (ORs) in the source population and among participants for 3 exposure-risk associations: (a) in vitro fertilization and preterm birth, (b) smoking during pregnancy and birth of a small-for-gestational-age infant, and (c) prepregnancy body mass index and antepartum stillbirth. The effect of nonparticipation was described by a relative odds ratio (ROR), calculated as the OR(participants)/OR(source population). Two methods for calculation of confidence intervals for the relative odds ratio also were assessed. RESULTS: The effect of nonparticipation on the selected ORs was small. The relative ORs were close to one and the bias was never larger than 16%, although some of the confidence intervals were wide. The 2 methods for calculation of confidence intervals gave very similar results and a small simulation study showed that the coverage probabilities were close to the 95% nominal level. CONCLUSION: For the 3 chosen associations, the ORs were not biased by nonparticipation. The results are reassuring for studies based on the Danish cohort and similar cohorts of pregnant women. The methodology used to compute confidence intervals for the relative odds ratios performed well in the scenarios considered.

Adult↗
PubMed2006

Incidence of GH deficiency - a nationwide study.

OBJECTIVE: Data on incidence rates are scarce in GH deficiency (GHD). Here, we estimate the incidence rate in childhood onset (CO) and adult onset (AO) GHD in Denmark. DESIGN: We used three national registries to identify 9131 cases with an increased risk of GHD. Date of entry was defined using the date when a registration had taken place and when a date of sufficient information could be defined from a thorough examination of a record of a GHD patient, which ever came last. We considered date of entry as the incident date. METHODS: Sex-specific incidence rates of GHD in children and adults using the background population as reference. RESULTS: During 1980-1999, 1823 patients were incident. Three-hundred and three males and 191 females had CO, 744 males and 585 females had AO GHD. The incidence rate over time was stable for females with AO GHD and increasing for the other three subgroups. Average incidence rate for CO males, 2.58 (95% confidence interval (CI), 2.30-2.88), CO females, 1.70 (95% CI, 1.48-1.96), AO males, 1.90 (95% CI, 1.77-2.04), and AO females, 1.42 (95% CI, 1.31-1.54) all per 100 000. The incidence rate was significantly higher in males compared to females in the CO GHD group (P < 0.001) and in the AO GHD group in the age ranges of 45-64 and 65+years (P < 0.001). There was no significant difference in the 18-44 years age group. CONCLUSIONS: In conclusion, we have identified the incidence rates of GHD in a nationwide study of Denmark. In this population-based study, we have identified in CO GHD and in the two oldest age groups of AO GHD, a statistically significant higher incidence rate in males when compared with females.

Adolescent↗
PubMed2005

The Children's Depression Inventory and classification of major depressive disorder: validity and reliability of the Danish version.

The study examines the validity and reliability of the Danish version of the Children's Depression Inventory (CDI) in a child psychiatric population. Participants were 149 child psychiatric patients aged 8-13 and their parents. After diagnostic interview with the Kiddie-Schedule for Affective Disorders and Schizophrenia, the children completed the CDI. A subgroup of 44 children repeated the CDI after 2 weeks. The psychometric properties of the Danish CDI were similar to those reported for the English version. CDI is moderately correlated with other measures for depressive disorder, but the instrument is not sufficiently reliable or valid to be used as a single diagnostic or screening measure in a child psychiatric population.

Adolescent↗
PubMed2005

Prepregnancy obesity and fetal death: a study within the Danish National Birth Cohort.

OBJECTIVE: To examine the association between high prepregnancy body mass index and fetal death, allowing for the effects of gestational age, weight gain, and maternal diseases in pregnancy. METHODS: Prepregnancy body mass index (BMI) and fetal death were examined in the Danish National Birth Cohort among 54,505 pregnant women who participated in a comprehensive interview during the second trimester. Pregnancy outcomes were obtained from registers and medical records. Cox regression analyses with delayed entry and time-dependent covariates were used to estimate the risk of fetal death. RESULTS: Compared with normal-weight women (18.5 < or = BMI < 25), the risks of fetal death among obese women (BMI > or = 30), expressed as adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were as follows: before week 14: 0.8 (0.5-1.4), weeks 14-19: 1.6 (1.0-2.5), weeks 20-27: 1.9 (1.1-3.3), weeks 28-36: 2.1 (1.0-4.4), weeks 37-39: 3.5 (1.9-6.4), and weeks 40+: 4.6 (1.6-13.4). Overweight women (25 < or = BMI < 30) also experienced a higher risk after 28 weeks, and especially after 40 weeks of gestation (HR 2.9, 95% CI 1.1-7.7). Analysis of stillbirth (fetal death at 28+ completed weeks of gestation) indicated that the effects were not due to obesity-related diseases in pregnancy, nor was weight gain associated with stillbirth. The increased risk of stillbirth among overweight and obese women was partly attributable to inadequate placental function (crude odds ratios 2.1, 95% CI 1.0-4.4, and 5.2, 95% CI 2.5-10.9, respectively). CONCLUSION: Prepregnancy obesity was associated with an increasing excess risk of fetal death with advancing gestation, and placental dysfunction may be a possible contributing factor.

Adult↗
PubMed2005

Two definitions of "small size at birth" as predictors of motor development at six months.

BACKGROUND: Small babies are known to be at increased risk for a wide range of difficulties. In predicting risk, it may be more informative to estimate smallness in relation to family norm (using the birth weight of an older sibling) rather than to use the standard "small-for-gestational-age" (SGA z-score) measure. METHODS: For 10,577 babies born to women enrolled in the Danish National Birth Cohort, we calculated a "birth-weight ratio" (actual birth weight/expected birth weight predicted from older sibling x 100). We identified babies in the lowest decile of the birth-weight ratio (</=87.7% for boys and </=87.6% for girls) and compared them with babies in the lowest decile of the sex- and gestational age-specific distribution (SGA z-score). We evaluated how these definitions predicted motor development. We also compared how selected predictors of birth weight influenced the classification of the baby according to the birth-weight ratio and according to the SGA z-score. RESULTS: Birth-weight ratio and SGA identified 1058 and 1059 babies, respectively, with 738 identified by both methods. A low birth-weight ratio predicted delayed motor development slightly better than did SGA. Babies classified as too small solely by the SGA criterion were more often born to small or smoking mothers than those identified solely by the birth-weight ratio. CONCLUSIONS: The combined use of the birth-weight ratio and SGA may provide a more sensitive tool for identifying babies at risk. The birth-weight ratio is less likely to classify babies as small based on their mothers' body size, identifying instead babies who were substantially smaller than their sibling.

Adult↗
PubMed2004

Binge drinking during pregnancy--is it possible to obtain valid information on a weekly basis?

It has been suggested that future research into the adverse effects of binge drinking in pregnancy should take into account the time of binge drinking, and a method has been proposed. In a representative sample of 1,311 pregnant Danish women in 2000, the agreement between two different measures of binge drinking during the first half of pregnancy obtained from interviews and questionnaires was assessed. Compared with self-administered questionnaires, the interview provided an overall higher response rate and a higher response rate to the specific questions about binge drinking. Furthermore, a higher proportion of women admitted to binge episodes, and the internal consistency was better in the interviews compared with the questionnaires. The percent agreement between the methods ranged between 76% and 100% irrespective of the definition of binge drinking. Self-administered questionnaires are generally easier and cheaper to administer than interviews and, for descriptive purposes, the questionnaires may be sufficient to get an overall impression of the distribution of binge drinking. However, if the goal is to obtain data on the association of binge episodes during specific weeks of pregnancy and adverse pregnancy outcomes, the present results seem to suggest that personal interviews should be conducted if at all possible, particularly because of high internal consistency.

Adult↗
PubMed2004

Developmental profiles on the basis of the FTF (Five to Fifteen) questionnaire-clinical validity and utility of the FTF in a child psychiatric sample.

The Five to Fifteen parent questionnaire (FTF) was developed to offer a neuropsychological dimension to the assessment of children with Attention Deficit/Hyperactivity Disorder and other child psychiatric disorders. The domains included in the FTF were motor skills, executive functions, perception, memory, language, social skills and learning, in addition to a domain for emotional and behavioural problems. The aim of the present study was to test the clinical validity and utility of the FTF with a main focus on discriminant and criterion validity. The clinical sample consisted of 155 clinically diagnosed children (ICD-10 criteria), 102 were tested with WISC-III. The parents rated their children independent of the diagnostic evaluation. The results were presented as profiles. These clinical profiles were compared to those of a Swedish norm sample consisting of 854 children from the age of five to fifteen. Results demonstrated that the profiles for the clinical groups were similar in forms and levels to those of the upper 10 percent of the norm sample (those with most difficulties). Five out of eight FTF domains discriminated significantly between diagnostic groups in the clinical sample. Influence of IQ, gender and age on the results were low. Three out of four relevant FTF domains correlated significantly with corresponding WISC-III indexes/measures. The clinical utility of individual children's profiles were demonstrated. On the whole, the findings supported the clinical validity and utility of the FTF.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Multiple sclerosis in women having children by multiple partners. A population-based study in Denmark.

We investigated whether having children with multiple men is a risk factor for being diagnosed with multiple sclerosis (MS). We studied a cohort of 151,328 women, of whom 64,704 had different men fathering their children and 86,624 the same partner for all births. Women were included if they had a second or higher parity child between 1973 and 1996. The follow-up for MS ended in 1997. There were a total of 213 cases of MS diagnosed during the study period. We analysed data through Poisson regression models. Women having children with different men were not at higher risk of being diagnosed with MS, with the possible exception of a short period after having a baby with a new partner. Women having children with more than one man may have a higher risk of a pregnancy accelerating the diagnosis of MS but are probably not at an overall higher risk of MS.

Adult↗
PubMed2003

Studying health consequences of microchimerism: methodological problems in studying health effects of procreation with multiple partners.

A pregnancy requires a reasonably good health and may have positive as well as negative health consequences for the woman. Part of these health effects may depend on the immune response to the exchange of fetal cells (microchimerism). The number of biological fathers to a woman's children may thus have a health effect beyond the parity effect. A possible design for studying this is to compare health effects for women with or without multiple partners but with the same parity. We compared total and cause specific mortality in these two groups in order to estimate their comparability and thus the problem of confounding. By using population registries we identified all women who had children with at least two different partners from 1973 to 1996 in Denmark (64,704 exposed women). Among all women who had at least two births in the above mentioned time period, we selected a random sample of 100,000 women to obtain information on women having one father for their children. We linked this cohort to a number of registries, including the Cause of Death Registry. We studied cause-specific mortality up to 1997. Altogether 1373 women died during follow-up. Women who had children with more than one partner had a higher relative mortality rate, which was even higher if she had more than two partners. This finding persisted after excluding unnatural deaths and did not depend on time from exposure. Although some of the findings were adjusted for parity, age and social factors, it is highly unlikely that these large differences are entirely related to microchimerism. The study shows that caution is needed when studying health effects of procreation with multiple partners.

Adult↗
PubMed2003

Does smoking during pregnancy affect sons' sperm counts?

BACKGROUND: There has been an apparent decline in sperm density during the last 5 decades in Denmark, a country in which women have among the highest rates of smoking in Europe. We examined semen quality and sex hormones in men in relation to their mothers' tobacco smoking during pregnancy. METHODS: Male participants were selected from the population-based Danish Twin Registry and the Danish Civil Registration System as part of a study on hereditary and environmental determinants of semen quality. From November 1999 to May 2000 we collected one fresh semen and blood sample from each of 316 men. Data on prenatal tobacco exposure were obtained for 265 of these men from a questionnaire filled in by their mothers. RESULTS: Adjusting for age, current smoking status and other factors, sperm density was 48% lower(95% confidence interval = -69% to -11) among sons of mothers who smoked more than 10 cigarettes per day during pregnancy. Total sperm counts and levels of inhibin-B were also reduced among this group, whereas follicular stimulating hormone levels were somewhat higher (16% increase; 95% confidence interval = -13% to 54%). These effects were not seen in the lower smoking category (1-10 cigarettes per day). CONCLUSIONS: High levels of smoking (> 10 cigarettes per day) during pregnancy may be a partial explanation for the apparent secular decline and the geographic differences in sperm counts.

Adult↗
PubMed2002

Conduct problems, gender and adult psychiatric outcome of children with attention-deficit hyperactivity disorder.

BACKGROUND: Attention-deficit hyperactivity disorder (ADHD) is a common childhood condition, and is more prevalent in boys. The adult outcome of girls with ADHD has never been studied. AIMS: To identify predictors for adult psychiatric outcome of children with ADHD, including gender and comorbidity. METHOD: Children aged 4-15 years, referred for hyperactivity/inattention and treated with stimulants were included (n=208). The Psychiatric Case Register provided follow-up data on psychiatric admissions in adulthood until a mean age of 31 years. RESULTS: A total of 47 cases (22.6%) had a psychiatric admission in adulthood. Conduct problems in childhood were predictive (hazard ratio HR=2.3; 95% CI 1.22-4.33). Girls had a higher risk compared with boys (HR=2.4; 95% CI 1.1-5.6). CONCLUSIONS: Girls with ADHD had a higher risk of adult psychiatric admission than boys. Conduct problems were also associated with a higher risk. Girls with ADHD with conduct problems had a very high risk of a psychiatric admission in adulthood.

Adolescent↗
PubMedDate not supplied

Mental illness and health care use: a study among new neurological patients.

We investigated 198 new neurological patients to learn if mental illness had an impact on nonpsychiatric health care use. Mental illness was assessed in a two-phase design, including the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), providing ICD-10 diagnoses and two brief rating scales: the Symptom Check List (SCL-8) for anxiety and depression and the Whiteley-7 for somatization. The patients' use of health care was studied 5-10 years before and 18 months after the psychiatric assessment, using data from national patient registers. Mental illness was linked to data on health care use through weighted logistic regression. ICD-10 psychiatric disorders increased the risk of subsequent high use of nonpsychiatric hospital admissions - somatoform disorders with more than five times (OR=5.6; 95% CI=1.6-20.1) and anxiety/depression with almost four times (OR=3.7; 95% CI=1.1-12.0). There was also a trend, though less marked, linking mental illness to previous hospital use. Use of primary care was also markedly increased by mental disorders, however, only in patients entering the study as inpatients. In conclusion, neurological patients are at risk of being high users of health care if they have a mental illness, somatoform disorders being the most powerful risk factor. The results are consistent with the findings among internal medical patients.

Adolescent↗
PubMedDate not supplied

Use of health services, mental illness, and self-rated disability and health in medical inpatients.

OBJECTIVE: The primary objective of this study was to investigate if among medical inpatients their health service use was associated with 1) presence and type of mental disorders, 2) emotional distress and somatization, 3) self-rated physical disability and health. METHOD: Health service use (number of admissions to nonpsychiatric departments and reimbursement of primary care services) as well as psychological distress (SCL-8D) and somatization (Whiteley-7) was assessed for 294 consecutive medical inpatients. Patients rated their own health and physical functioning, and medical consultants assessed them for chronic and life-threatening diseases. A subsample of 157 patients was assessed for ICD-10 psychiatric diagnoses by means of an extensive semistructured interview (SCAN). RESULTS: High use (above 80th percentile) of inpatient admissions was statistically significantly associated to mental disorders (adjusted OR = 3.6 [95%CI, 1.3-9.7]), to anxiety and/or depression, somatoform disorders, chronic and life-threatening physical disease, severe (self-rated) physical disability, and SCL-8 and Whiteley-7 scores. High use of primary care was statistically significantly associated to mental disorders (OR = 3.4 [95%CI, 1.5-8.0]), to anxiety and/or depression, somatoform disorders, moderate or severe (self-rated) physical disability, fair, poor or very poor (self-rated) health, and the Whiteley-7 score. The SCL-8D score was significant in men only. CONCLUSION: Mentally disordered medical inpatients use health care more heavily than patients without, also after adjustment for medical disease severity. Use is closely associated to the Whiteley-7 and the SCL-8D.

Adolescent↗
PubMedDate not supplied

Influence of number of surfaces and observers on statistical power in a multiobserver ROC radiographic caries detection study.

The aim of the study was to evaluate the influence of the number of surfaces (N(SURF)) and the number of observers (N(OBS)) on the statistical power of a study comparing the diagnostic accuracies of radiographic systems used for approximal caries lesion detection. A data set consisting of 338 surfaces examined by 10 independent observers using four radiographic systems was available. The presence of a caries lesion was assessed from a 5-point confidence scale. The true lesion diagnosis was established by histological validation. ROC curve areas (A(z)s) were used to express the diagnostic accuracy of the observers with the radiographic systems. Assuming that the A(z)s were tested by a two-way analysis of variance, we performed a simulation study in order to evaluate how the power of this statistical analysis depended on N(SURF) and N(OBS). As a measure of the statistical power we used the standard error of the difference between the expected A(z)s of two systems. The simulations were made with N(SURF) in the range from 25 to 338 and N(OBS) from 2 to 10. The simulations showed that the power increased as a function of the total number of evaluations per system (N(SURF) x N(OBS)), but how this number was attained in relation to the number of surfaces and observers had only marginal influence on the power. Thus, from a statistical point of view it may be concluded, provided that data are analyzed by a two-way analysis of variance, that study designs for comparing the accuracy of several systems can be composed freely in relation to the number of surfaces and observers as long as the total number of evaluations per system are identical.

Analysis of Variance↗
PubMedDate not supplied

Follow-up on mental illness in medical inpatients: health care use and self-rated health and physical fitness.

Consecutively admitted internal medical inpatients (N=294) who were psychiatrically assessed with the Schedules for Clinical Assessment in Neuropsychiatry in a two-phase design were followed up in a review of public files on their use of medical care over 18 months. Self-rated outcome was assessed from health and fitness ratings at admission and after 1 year. ICD-10 mental disorders had a statistically significant impact on the risk (odds ratio) of high use (above the 80th percentile) of primary care, as did ICD-10 anxiety/depression, and worry about illness (as assessed by the Whiteley-7 Scale). The authors found a less-than-significant tendency for mental illness to influence the use of inpatient admissions and self-rated outcome.

Adolescent↗