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Biomedical subjects

P Magnus

Publications and source records attributed to P Magnus.

At least 91 records · Page 5Linked to original sources
PubMed1997

The prevalence of respiratory symptoms and asthma among school children in three different areas of Norway.

The role of exposure to ambient air pollution has been a topic of interest as a potential risk factor for respiratory symptoms and asthma. We expected that the prevalence rates would vary in Norway between the capital, Oslo, the mountainous area Hallingdal and the industrial area Odda. Surveys were conducted in school children, aged 6-16 years, in; Oslo (n = 2577), Hallingdal (n = 1177) and Odda (n = 831). The parent-reported prevalence of wheeze in past year was almost similar in Oslo (13.1 (95% CI 11.7-14.5)) and Upper Hallingdal (14.2 (13.1-15.3)), but lower in Odda (9.0 (7.0-11.0)). The findings for severe respiratory symptoms were almost equal. The age patterns within each area differed. The risk of wheeze ever (p < 0.001) and wheeze in past year (p = 0.04) decreased with increasing age in Odda, while there was an increase in the risk of exercise induced wheeze in Oslo (p = 0.02) and Hallingdal (p < 0.001). The lifetime prevalence of asthma was lowest in Odda (5.4 (3.8-7.0)) compared to Oslo (9.4 (8.2-10.6)) and Hallingdal (8.5 (6.8-10.2)). There was a positive association between physical activity and wheeze in past year. The results do not support the hypothesis that respiratory morbidity is more common in urban than rural areas, age and physical activity can influence the prevalence rates of respiratory symptoms in school children.

Adolescent↗
PubMed1997

Seropositivity against HPV 16 capsids: a better marker of past sexual behaviour than presence of HPV DNA.

OBJECTIVES: To assess if seropositivity to human papillomavirus type 16 capsids is a better marker of sexual history than the presence of HPV DNA. STUDY DESIGN: A population based age stratified random sample of 234 Norwegian women (mean age 32.8 years, range 20-44) was examined for HPV serum antibodies, cervical HPV DNA, cytology and age in relation to sexual behaviour. RESULTS: Neither age nor age at first sexual intercourse was associated with HPV 16 antibodies. Adjusted ORs for 4-5; 6-10 and > 10 versus 0-1 lifetime sexual partners, were 13.1 (95% CI 1.5-110.8), 8.2 (1.0-69.6) and 10.5 (1.2-94.0) for HPV 16 seropositivity, respectively; and 2.6 (0.2-27.8), 3.4 (0.4-31.7) and 4.1 (0.4-42.8) for HPV 16 DNA positivity, respectively. CONCLUSION: Seropositivity to HPV 16 capsids is positively associated with the number of sexual partners, suggesting that HPV 16 is predominantly sexually transmitted. The fact that serology had a stronger association with number of sexual partners than viral DNA suggests that seroreactivity is a better measure of lifetime history of HPV infection.

Adult↗
PubMed1997

No evidence for effects of family environment on asthma. A retrospective study of Norwegian twins.

The risk of developing asthma contingent upon the co-twins' history of asthma was analyzed in a population-based study of 5,864 Norwegian twins. A primary aim was to assess the significance of shared environment for the development of asthma from infancy through age 25. Retrospective reports were collected when the twins were 18 to 25 yr of age. The risk of developing asthma, contingent upon the co-twin's history of asthma, was estimated using survival analyses, and genetic and environmental sources of variation in liability for asthma were analyzed with structural equation models. The cumulative incidence of asthma was 6% for males and 5.4% for females. The relative risk of developing asthma among twins whose co-twin had a positive history of asthma compared with those whose co-twin had no history of asthma was 17.9 (95% CI, 10.3 to 31.0) for identical, and 2.3 (95% CI, 1.2 to 4.4) for fraternal twins. Although shared environment encompasses many of the exposures that are putative risk factors for asthma in this age range, there is no evidence of shared environmental influences for asthma. Rather, 75% of the variation in liability for asthma was explained by genetic effects and the remaining variation was due to nonshared environmental influences. These results suggest that the familial risk for asthma is primarily, genetic.

Actuarial Analysis↗
PubMed1997

Distribution and heritability of recurrent ear infections.

The distribution of recurrent ear infections was obtained from a population-based sample of 2,750 pairs of Norwegian twins born between 1967 and 1974. The lifetime prevalence of self-reported recurrent ear infections was 8.9%, with a significant predominance of female cases. The mean age of onset was 4.2 years, with a gradual decrease in occurrence from 2 to 7 years of age. Among monozygotic pairs, the rate of tetrachoric correlation between co-twins was almost identical in males (0.73, SE 0.08) and females (0.74, SE 0.06), but among the dizygotic pairs the correlation was clearly higher in males (0.53, SE 0.12) than in females (0.20, SE 0.12). The value in the unlike-sexed dizygotic twins (0.25, SE 0.05) was intermediate to that of the like-sexed male and female dizygotic pairs. The relative contribution of genes and environment to variability in the predisposition to develop otitis media was estimated by means of structural equation modeling. Variation in liability to ear infections was mainly explained by additive genetic and dominance factors in females, for whom heritability was estimated at 74%. The remaining 26% of the variation in liability was explained by individual environmental factors. In males, 45% of the variation could be accounted for by genetic factors, 29% by common familial environment, and the remaining 26% by individual environmental effects.

Acute Disease↗
PubMed1997

Changing prevalence of asthma in school children: evidence for diagnostic changes in asthma in two surveys 13 yrs apart.

It is still unclear whether the reported increase in the prevalence of asthma is real or due to changes in diagnostic criteria. The objectives of this study were to compare the prevalence of diagnosed asthma with the prevalence of respiratory symptoms, and to compare the association between asthma and other atopic diseases in 1981 and 1994. The study populations comprised randomly selected school classes in Oslo in 1981 (n=1,772) and 1994 (n=2,577). The main outcomes in these comparable cross-sectional studies of children, 6-16 yrs of age, were parent-reported prevalence of diagnosed asthma, respiratory symptoms, eczema and hay fever. The questionnaire was identical in 1981 and 1994. The response rates were 94% (1,674 out of 1,772) in 1981 and 85% (2,188 out of 2,577) in 1994. The lifetime prevalence of asthma increased from 3.4% in 1981 to 9.3% in 1994; odds ratio (OR) 2.9 (95% confidence interval (95% CI) 2.1-4.0) comparing 1994 to 1981. The prevalence of occasional wheezing increased from 9.0 to 10.8%; OR 1.2 (95% CI 1.0-1.5), and attacks of wheezing from 3.7 to 6.8%; OR 1.8 (95% CI 1.3-2.5). Survival analyses for 3 year birth cohorts showed that asthma was more readily diagnosed in the latest birth cohort (1985-1988). The association between asthma and other atopic diseases decreased during the period under study. The increase in diagnosed asthma and respiratory symptoms supports a true increase in asthma. However, the larger increase in diagnosed asthma than wheezing and a reduced association between asthma and other atopic diseases suggest that the increase in asthma may be explained, in part, by changes in diagnostic criteria.

Adolescent↗
PubMed1997

The impact of exposure group on the progression rate to acquired immunodeficiency syndrome. A comparison between intravenous drug users, homosexual men and heterosexually infected subjects.

The objective was to study the impact of exposure group on the progression rate to the acquired immunodeficiency syndrome (AIDS). 289 subjects in Oslo, Norway, infected with the human immunodeficiency syndrome (HIV) and without major clinical signs of HIV infection (102 intravenous drug users, 151 homosexual men and 36 heterosexually infected subjects) were recruited to the Oslo HIV Cohort Study from 1989 and followed until 1 January 1995. 15 (14.7%) of the intravenous drug users, 56 (37.1%) of the homosexual men and 5 (12.5%) of the heterosexually infected subjects developed AIDS during a mean time of 47 months (p < 0.001, log rank test). When controlling for possible confounding variables (age, number of CD4+ lymphocytes, antiviral therapy at study entry, gender and year of HIV diagnosis), the relative risk of AIDS progression was 2.2 [1.1-4.5, 95% confidence interval (CI)] for homosexual men and 0.5 (0.2-1.3, 95% CI) for heterosexually infected subjects as compared to intravenous drug users. In a subgroup with known time of seroconversion (n = 60), 47% (18/38) of the homosexual men, 20% (3/15) of the intravenous users and none (0/7) of the heterosexually infected subjects developed AIDS (p = 0.04, log rank test). The results suggest that homosexual men have more rapid progression to AIDS than intravenous drug users and heterosexually infected subjects.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Chronic bronchitis in farmers.

OBJECTIVES: Chronic bronchitis was studied in relation to work time and years of exposure in farming, as well as to production type, dusty occupation outside farming, and the combination of work exposure and smoking, in a population of farmers. METHODS: In 1989 a representative cohort of 10,792 farmers and spouses was selected from a government register and invited to participate in a cross-sectional study in 1991. The total response rate was 80%. There were 33% part-time farmers, and among the men 32% of the full-time and 42% of the part-time farmers had worked in dusty occupations outside farming. Bronchitis symptoms were recorded on a self-administered questionnaire, spirometric data were obtained, and internal reference equations were calculated for forced expiratory volume in 1 s (FEV1.0). RESULTS: The exposure factors of importance for chronic bronchitis were full-time farming versus part-time farming, livestock production types (poultry, dairy, swine, horse and combinations), and occupational dust exposure outside agriculture. The combinations of the work exposure factors were significant and showed a 2- to 3-fold increase in risk for chronic bronchitis. Combinations with smoking showed up to a 6-fold increase in risk. Over the age of 50 years, chronic bronchitis was a risk factor for airway obstruction defined as the standardized residuals for FEV1.0 less than -2 for both nonsmokers (OR 2.8, 95% CI 1.1-6.8) and smokers (OR 8.5, 95% CI 5.1-14.3). CONCLUSIONS: Work exposure factors in farming and other dusty occupations enhance the risk for chronic bronchitis from 2- to 3-fold for farmers. In combination with smoking the risk increases to up to 6-fold.

Adult↗
PubMed1997

Prevalence and trends in homosexual behaviour in Norway.

The three main objectives of this study were to estimate the proportion of the Norwegian population with experience of homosexual behaviour, to study the degree of change in sexual practices among homosexual men during a 5-year period and to study the degree of change in sexual practices reported by HIV positive homosexual men from before to after awareness of HIV-positivity. The data comes from two questionnaire surveys (in 1987 and 1992) of sexual behaviour in the general population of Norway and a questionnaire study of sexual behaviour before and after awareness of HIV-positivity among HIV-positive homosexual men taking part in a cohort study starting in 1988 (the Oslo HIV cohort study). Estimation of the proportion of subjects with homosexual experience was made as well as a trend analysis of the number of male sexual partners per year, number of intercourses per month, condom use and anal sex. Among men aged 18 to 60 from the general population, 3.8% reported homosexual practice during lifetime and 1.2% during the past 3 years. Among women, the same percentages were 3.1 and 1.0. In the surveys, the number of male partners per year decreased significantly for men with current homosexual experience from a yearly median of 1.0 in 1987 to 0.3 in 1992 (p = 0.02). Among HIV-positives, the number of male partners decreased from a yearly median of 4.3 before to 1.6 after awareness of HIV-seropositivity (p < 0.01). Among HIV-positives, a significant increase in the use of condoms, a decrease in the number of intercourses and a decrease in the frequency of anal sex was found. The results show that some changes in sexual practice may have occurred among homosexual men in general in the period from 1987 to 1992, and that more significant changes may have occurred for HIV-positive men. The present data do not support other findings of a relapse to more unsafe sex, but suggest that there is still a need to keep modifying behaviour in order to stop the spread of HIV among men who have sex with other men.

Adult↗
PubMed1997

Birth weight of relatives by maternal tendency to repeat small-for-gestational-age (SGA) births in successive pregnancies.

BACKGROUND AND METHOD: Small-for-gestational-age (SGA) infants represent a heterogeneous group of normal and growth-retarded children. To assess the familial aggregation of reduced fetal growth, birth weights in both maternal and paternal relatives of 1246 index children in the Scandinavian SGA Study were compared across groups defined by the SGA outcome of the index child as well as that of earlier siblings. RESULTS: Mean maternal birth weight +/- SEM was 3127 +/- 54 g for mothers who had experienced two SGA births as opposed to 3424 +/- 22 for mothers with no SGA births. Mean paternal birth weight was 3497 +/- 88 g and 3665 +/- 24 in the same two groups. The odds ratio (with 95% confidence interval) for having a mother with birth weight below the 10th percentile was 1.74 (0.85-3.58) for the group where two SGA births had occurred compared to no SGA births and it was 2.49 (1.22-5.07) for having a father with birth weight below the 10th percentile. There was no correlation between maternal and paternal birth weights. CONCLUSIONS: The association also to paternal birth weight suggests the presence of genetic or common environmental factors in explaining the tendency to have SGA children. Although taking parental birth weights into consideration will aid in diagnosing growth-retardation in a SGA child, SGA remains a heterogeneous group where familial and non-familial cases will be difficult to separate.

Birth Weight↗
PubMed1996

A population-based case-control study of human papillomavirus-type-16 seropositivity and incident high-grade dysplasia of the uterine cervix.

In order to study the association between seropositivity against human papillomavirus-type-16 capsids and CIN II-III in the general population in ages at which high-grade cervical dysplasia arises, 90 cases and 216 controls participating in a population-based case-control study of incident CIN II-III, were analyzed for the presence of HPV antibodies, HPV DNA and for the influence of behavioral factors. A significantly higher proportion of cases than controls were seropositive. Of HPV-16-DNA-positive cases and controls, 42 and 14% respectively were seropositive. A similar proportion of seropositivity was found among the 172 cytologically normal, HPV-DNA-negative controls. However, seropositivity was closely linked to the sexual history of the women. Logistic-regression analyses, adjusting for sexual behavior, smoking history and educational level, revealed that CIN II-III was associated with HPV-16 seropositivity and with HPV DNA. Controlling for the presence of HPV DNA indicated that antibodies were not independently associated with CIN. The low correlation between the presence of HPV antibodies and DNA, the finding that the association between seropositivity and CIN depended on the presence of HPV DNA, and the association of seropositivity with sexual history, may be explained by serology detecting both past and present persistent infections and presence of HPV DNA, reflecting mostly transient infections in controls and persistent infections in cases.

Adult↗
PubMed1996

[Quality adjusted life years in assessment of preventive measures. Should blood donors be tested for HTLV-I/II infections?].

In planning preventive health measures, quality adjusted life-years (QALYs) are useful as a measure of benefit. As an example, the question of whether blood donors should be routinely tested for antibodies to the Human T-lymphotropic viruses I and II (HTLV I/II) is analysed. A mathematical model was set up to describe the consequences, in terms of lost life-years and years with disease due to transfusion-mediated infection (if testing is not performed) or years with reduced quality of life (in the case of testing). These future outcomes were discounted and converted to QALYs. The cost per QALY is about NOK 2.33 million when the prevalence is 1 per 50,000 blood donors, and is reduced to 190,000 per QALY when the prevalence is 10 per 50,000. Using QALYs in evaluation of preventive medicine can be complicated, and calls for cooperation between epidemiologists and health economists.

Blood Donors↗
PubMed1996

[The AIDS epidemic in Norway--where did it go?].

The 1986 prognosis for the AIDS-epidemic in Norway has not been fulfilled. The epidemic has been far less extensive than anticipated. In 1986, little knowledge existed about the parameters that influence the spread of the human immunodeficiency virus (HIV): the prevalence of HIV, the HIV transmission rate, the duration of the infectious period and the extent of risk behaviour. The prognosis was therefore not reliable. The causes of the variability in HIV transmission and in the duration of the infectious period are still poorly understood and thus cannot be easily influenced. A reduction of risk behaviour among homosexual men has been observed. In the general population there has been a slight increase in use of condoms. The behavioural changes may express HIV-preventive measures. However, the large discrepancy between the early HIV/AIDS prognosis and the observed epidemic in Norway cannot be explained by behavioural change alone.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Otitis media: relationship to tonsillitis, sinusitis and atopic diseases.

In order to estimate the co-morbidity between ear infections and related childhood diseases, data about the occurrence of recurrent ear infections, tonsillitis, sinusitis and atopic diseases from a population based sample of 7992 Norwegian twins were analysed. Correlational results revealed two general clusters, one consisting of upper respiratory tract infections (URI), the other defined by the atopic diseases. Overall, associations between the diseases were greater in males. The sizes of the correlations within each subgroup of infections were moderate, but significant, ranging from 0.191 to 0.363. Similar results were found for the relationship within the subgroup of atopies, with correlations ranging from 0.134 to 0.466. The correlations between the infectious and atopic diseases were weak. Both ear infections and tonsillitis seemed to be predisposing factors for sinusitis. The relative risk of sinusitis among individuals with a history of ear infections was 3.4 (1.9-6.2) and 1.9 (1.2-3.0) for males and females, respectively. Ear infections conferred an increase in tonsillitis, estimated at 2.3 (1.6-3.0) and 2.0 (1.2-3.6) for males and females, respectively. In conclusion, the present study finds evidence for a common predisposition of upper respiratory infections as well as for atopic diseases, but only moderate correlation between the subgroups. Specifically, between ear infections and hay fever there was no covariation.

Adolescent↗
PubMed1996

The relationship between otitis media and intrauterine growth: a co-twin control study.

The association between intrauterine growth, as measured by weight and gestational age, and the occurrence of recurrent ear infections was studied using data from a population-based sample of 7992 Norwegian twins. Perinatal measures were collected from the Medical Birth Registry, and reports of recurrent ear infections were based on questionnaires completed when the twins were aged 18-25 years. First, the individual effects of birth weight and gestational age on the occurrence of otitis media (OM) were estimated Birth weight among individuals who reported OM was significantly lower than for controls, with a mean weight difference of 86 g. The average difference in gestational age was 3 days shorter among individuals with a positive history of OM. Next, the effect of birth weight was estimated using the co-twin control method. Among MZ twins, within-pair differences in birth weight reflect environmental differences experienced in utero. Among DZ pairs, birth weight differences may be due to genetic and environmental differences. Among OM-discordant pairs, the co-twin without a history of OM is a matched control for comparisons of intra-pair differences in birth weight. When within-pair birth weight differences were compared, the co-twin without a history of OM was used as the matched control. Results indicated that lower birth weight may be a risk factor for OM. The average birth weight difference among OM-discordant pairs was 48 g, with the control twin weighing significantly more than the twin with a history of OM.

Adolescent↗
PubMed1996

The association between maternal education and postneonatal mortality. Trends in Norway, 1968-1991.

BACKGROUND: This study examines whether the association between maternal educational level and postneonatal death has changed over time. METHODS: All single survivors of the neonatal period in Norway in three periods, 1968-1971, 1978-1981 and 1989-1991 were studied. There were 582 046 births and 1717 postneonatal deaths. Logistic regression analyses were applied. RESULTS: There has been an increasing inverse relationship between maternal educational level and postneonatal mortality in recent years. There was no statistically significant association between educational level and postneonatal mortality in the late 1960s. In the second period (1978-1981) the association is statistically significant for first-born children. In the third period (1989-1991) postneonatal mortality for first-born and later-born children was associated with maternal educational level, with adjusted odds ratios of 2.5 and 2.1 respectively. The overall level of education has increased tremendously, and the proportion of women with the lowest level of education has decreased from 56.3 to 10.7% in the period under study. CONCLUSIONS: The underlying causes of changes in the impact of educational level are hard to determine and are indicative of the complexity of using maternal educational level as an indicator of social status over time. Possible mechanisms by which certain variables may covary with educational level, and thus have an adverse effect on postneonatal mortality, are discussed. The fact that the inverse association between educational level and postneonatal mortality has increased over time should be a matter for concern. It may indicate that the growth of the welfare state has not reached all segments of the population.

Adult↗
PubMed1996

Prevalence and risk factors for asymmetric posture in preschool children aged 6-7 years.

BACKGROUND: Adult scoliosis can be a severe disease. Not much is known about its determinants and the predictive value of early trunk asymmetries. In Vilnius, Lithuania, a cohort study has been started among 6-7 year old children in 1994. The purpose of the present report was to estimate the prevalence of trunk asymmetry in 6-7 year old children, and the association between previous rachitis, frequent illness during childhood and reduced physical activity and trunk asymmetry. METHODS: The degree of asymmetry was established in 791 children in kindergartens by measuring with a ruler the distance from the seventh cervical vertebra to the lower angles of the left and the right scapulas. Rachitis and the number of illnesses were extracted from each child's medical card, whereas data on physical activity were based on questionnaires filled in by parents and kindergarten teachers. RESULTS: In all, 46.9% of children were found to have trunk asymmetry. The odds ratio of asymmetric posture was 2.76 (95% confidence interval [CI]: 1.62-4.72) for children with rachitis degree II compared to non-rachitic children, 3.97 (95% CI: 2.48-6.36) for those who were ill 16-28 times (over the years) compared to those who reported fewer than nine illnesses and 2.44 (95% CI: 1.21-4.91) for children with low physical activity level (13-22 points) as compared to children with a high level (> 33 points). CONCLUSION: These findings indicate the need for prophylactic measures to decrease the incidence of infantile rachitis, acute morbidity and to increase physical activity. The significance of the high frequency of asymmetric posture can only be assessed by a follow-up of this cohort.

Child↗