Alcohol, psychoactive drugs and fatal road traffic accidents in Norway: a case-control study

A case-control study was conducted on 204 drivers fatally injured in road traffic accidents in south-eastern Norway during the period 2003-2008. Cases from single vehicle accidents (N = 68) were assessed separately. As controls, 10540 drivers selected in a roadside survey in the same geographical area during 2005-2006 were used. Blood samples were collected from the cases and oral fluid (saliva) samples from the controls. Samples were analysed for alcohol, amphetamines, cannabis, cocaine, opioid analgesics, hypnotics, sedatives and a muscle relaxant; altogether 22 psychoactive substances. Equivalent cutoff concentrations for blood and oral fluid were used. The risk for fatal injury in a road traffic accident was estimated using logistic regression adjusting for gender, age, season of the year, and time of the week. The odds for involvement in fatal road traffic accidents for different substances or combination of substances were in increasing order: single drug < multiple drugs < alcohol only < alcohol+drugs. For single substance use: medicinal drug or THC < amphetamine/methamphetamine < alcohol. For most substances, higher ORs were found when studying drivers involved in single vehicle accidents than for those involved in multiple vehicle accidents, but confidence intervals were wider.

Maternal human parvovirus B19 infection and the risk of fetal death and low birthweight: a case-control study within 35 940 pregnant women

OBJECTIVES

To assess the association between maternal parvovirus B19 infection and fetal death, birthweight and length of gestation.

DESIGN

Case-control study.

SETTING

Population based.

POPULATION

Cases were all 281 women with fetal death within a cohort of 35 940 pregnant woxmen in Norway. The control group consisted of a random sample of 957 women with a live born child.

METHOD

Information on pregnancy outcome was obtained from the Medical Birth Registry of Norway. First trimester serum samples were tested for antibodies against parvovirus B19 (IgM and IgG). In seronegative women, further serum was analysed to detect seroconversion during pregnancy.

MAIN OUTCOME MEASURES

Fetal death, length of gestation and birthweight.

RESULTS

Two of 281 (0.7%) of the women who experienced fetal death and nine of 957 (0.9%) of the controls had presence of IgM antibodies, crude odds ratio 0.8; 95% CI (0.2-3.5). In initially, seronegative women, 3.1% (2/65) with fetal death and 2.6% (8/307) with a live birth seroconverted, crude odds ratio 1.2; 95% CI (0.2-5.7). Presence of maternal parvovirus-specific IgG or IgM antibodies in the first trimester, or seroconversion during pregnancy were not associated with lower birthweight or reduced length of gestation in live born children, but was associated with low birthweight in stillborn offspring.

CONCLUSION

Maternal parvovirus B19 infection was not associated with fetal death in our study. Very few cases of fetal death may be attributed to maternal parvovirus B19 infection.

A review of cohort sampling designs for Cox's regression model: Potentials in epidemiology

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A dietary pattern characterized by high intake of vegetables, fruits, and vegetable oils is associated with reduced risk of preeclampsia in nulliparous pregnant Norwegian women

Several dietary substances have been hypothesized to influence the risk of preeclampsia. Our aim in this study was to estimate the association between dietary patterns during pregnancy and the risk of preeclampsia in 23,423 nulliparous pregnant women taking part in the Norwegian Mother and Child Cohort Study (MoBa). Women participating in MoBa answered questionnaires at gestational wk 15 (a general health questionnaire) and 17-22 (a FFQ). The pregnancy outcomes were obtained from the Medical Birth Registry of Norway. Exploratory factor analysis was used to assess the associations among food variables. Principal component factor analysis identified 4 primary dietary patterns that were labeled: vegetable, processed food, potato and fish, and cakes and sweets. Relative risks of preeclampsia were estimated as odds ratios (OR) and confounder control was performed with multiple logistic regression. Women with high scores on a pattern characterized by vegetables, plant foods, and vegetable oils were at decreased risk [relative risk (OR) for tertile 3 vs. tertile 1: 0.72; 95% CI: 0.62, 0.85]. Women with high scores on a pattern characterized by processed meat, salty snacks, and sweet drinks were at increased risk [OR for tertile 3 vs. tertile 1: 1.21; 95% CI: 1.03, 1.42]. These findings suggest that a dietary pattern characterized by high intake of vegetables, plant foods, and vegetable oils decreases the risk of preeclampsia, whereas a dietary pattern characterized by high consumption of processed meat, sweet drinks, and salty snacks increases the risk.

Reproduction rates after cancer treatment: experience from the Norwegian radium hospital

PURPOSE

Most studies on postcancer reproduction are limited in patient numbers and lack of control group. We have computed 10-year first postdiagnosis cumulative reproduction rates (10-PDRs) and hazard ratios (HRs) avoiding these limitations.

PATIENTS AND METHODS

Six thousand seventy-one patients with cancer age 15 to 45 years at diagnosis, treated from 1971 to 1997, and 30,355 controls from the general population, all born after 1950, were observed from the true (patients) or assigned (controls) date of diagnosis for a median of 10 years (range, 0 to 35). The primary focus of the study was the 10-PDR before and after 1988+ based on data from the Medical Birth Registry of Norway. Cox proportional hazards regression models were adjusted for age and calendar year at diagnosis, stratified by sex and prediagnosis parenthood.

RESULTS

Across all cancer types, HRs of females were approximately 50% lower than those of the controls, the comparable percentage for male patients being approximately 30%, with some improvement after 1988+ for selected diagnoses. The highest 10-PDRs were observed in childless patients, with more favorable HRs in male than in female patients. In survivors with at least one child at diagnosis, the post-1988+ HRs improved significantly in patients with testicular and localized cervical cancer compared to pre-1988+ reproduction, with borderline improvement in localized ovarian cancer.

CONCLUSION

Postcancer reproduction is lower than that of the general population and influenced by sex, age at diagnosis, prediagnosis parenthood, and diagnostic period with more favorable rates in males than in females. Post-1988+ fertility-saving strategies may have improved the reproduction rates for select genital cancers.

Birth order pattern in the inheritance of chronic lymphocytic leukaemia and related lymphoproliferative disease

Rank order of affected offspring in a sibship can inform on epigenetic factors in disease susceptibility. Here we report an analysis of birth order in 32 families segregating chronic lymphocytic leukaemia (CLL) and other B-cell lymphoproliferative disorders. A paternal-offspring, but not a maternal-offspring birth rank order was observed. Cox regression analysis provided relative risks (RR) for paternal and maternal transmission of 3.60 (CI 95%: 1.54 - 8.42; P = 0.0005) and 1.64 (CI 95%: 0.90 - 3.01; P = 0.096), respectively. The significance of paternal and maternal transmission of CLL-CLL pairs employing Haldane and Smith's test were 0.006 and 0.63, respectively. There was no evidence of a relationship between parental age and birth order. The genetic mechanism behind the birth order effect observed is discussed in the light of non-Mendelian imprinting and pregnancy related microchimerism.

Possible imprinting and microchimerism in chronic lymphocytic leukemia and related lymphoproliferative disorders

Based on the concept that the tumorogenesis in chronic lymphocytic leukaemia comprises both an initial, inherited mutation and subsequent somatic mutations, the pleiotypic diversity of familial chronic lymphocytic leukaemia and related malignant lymphoproliferative disorders is generally explained by a repertoire of monoallelic polygenes in the initial mutation. Epigenetic genomic imprinting is a likely mechanism behind of the asynchroneous replicating monoallelic polygenes which is discussed in the light of pleiotrophy and birth order effect. Furthermore, it is discussed that one possible mechanism available for the epigenetic transfer of these genes could be the physiological pregnancy-related microchimerism between mother and fetus.

Attributable fractions with survival data

Attributable fraction (AF) is an important concept in clinical and epidemiological studies. The concept has mainly been discussed in relation to case-control studies, cross-sectional studies, and follow-up studies of fixed length. Here, we propose and discuss several ways of defining and estimating AFs with right-censored survival data, and thus with varying lengths of follow-up. In particular, we define the attributable hazard fraction, the AF before time t, and the AF within study. These measures have different interpretations and may give different numerical values, as illustrated in an application to real data on time to the first receiving of cash benefits for hearing impairment in children. The results underline the need for careful selection of the type of measure and interpretation when reporting AFs for survival data.

A short matrix-version of the Edinburgh Depression Scale

OBJECTIVE

Given the importance of depression as a world health problem, depression assessment should be standard practice in large-scale health surveys. The aim of the study was to construct a short matrix-version of the Edinburgh Depression Scale (EDS) that can be used in questionnaire studies.

METHOD

On the basis of the complete EDS scale of ten items, answered by 2730 women, stepwise multiple regression analysis was used to find the combination of items that explains the maximum proportion of the variance of the full scale sum score. The selected EDS items were thereafter correlated with the Hopkins Symptom Check List (SCL-25) for external validation.

RESULTS

The sum of five selected items from the EDS correlated at r = 0.96 with the full version. The EDS-5 scores correlated strongly with the SCL-25 (r = 0.75).

CONCLUSION

The EDS-5 version shows good psychometric properties and may, for some scientific purposes, substitute the full EDS scale.

Urine flavonoids and plasma carotenoids in the validation of fruit, vegetable and tea intake during pregnancy in the Norwegian Mother and Child Cohort Study (MoBa)

OBJECTIVE

To validate a new food-frequency questionnaire (FFQ) for measuring the intake of fruit, vegetables and tea reported by women participating in the Norwegian Mother and Child Cohort Study (MoBa).

DESIGN

Intake of fruits, vegetables and tea estimated by the FFQ was compared with urinary flavonoid excretion, plasma carotenoid concentration and intake measured by a 4-day weighed food diary (FD). The triangular method was applied to calculate FFQ validity coefficients using two independent biomarkers.

SETTING AND SUBJECTS

One hundred and nineteen women participating in MoBa.

RESULTS

The FFQ estimate of fruit intake was significantly correlated with urine phloretin (r = 0.33), citrus fruit/juice with urine hesperetin (r = 0.44), cooked vegetables with plasma alpha-carotene (r = 0.37), and tea with urine kaempferol (r = 0.41) (P < 0.01 for all). On average, 60% of the participants fell into the same or adjacent quintiles when classified by FFQ and biomarkers. Significant correlations between the FFQ and FD were found for fruit (r = 0.39), vegetables (r = 0.34), juices (r = 0.50) and tea (r = 0.53). The FFQ validity coefficient was 0.65 for citrus fruit/juice and 0.59 for cooked vegetables as calculated by the triangular method.

CONCLUSIONS

The validation study shows that the MoBa FFQ can be used to estimate fruit, juice, vegetable and tea intake in pregnant Norwegian women, and to rank individuals within the distribution.

Association between level of physical activity and lung function among Norwegian men and women: the HUNT study

OBJECTIVE

To estimate the association between level of physical activity in 1984-1986 and 1995-1997 and lung function in 1995-1997 among Norwegian men and women aged 28-80 years.

DESIGN

In 1984-1986 and 1995-1997, all residents of Nord-Trøndelag County, Norway, aged > or =20 years were invited to participate in the Nord-Trøndelag Health Studies. These analyses included a sample that took part in both studies and underwent spirometry (n = 8047). We used linear regression models adjusting for potential confounders stratified by sex and age groups (28-49 years, 50-69 years and > or =70 years) to estimate the association between forced expiratory volume in 1 second (FEV1) and physical activity.

RESULTS

Men and women who were physically active in 1985 and 1995 had the highest lung function in both sexes and in all age groups. The reduction in FEV1 ranged from 20 ml to 170 ml, similar to 1-7% of predicted values dependent on physical activity level. Lung function was also associated with body mass index (BMI), height, smoking and subjective health.

CONCLUSIONS

The findings show that a high level of physical activity corresponds to about 3-5 years of normal decline in FEV1 (30 ml/year), and may therefore overcome the disadvantages of a decline in FEV1 from increasing age.

[Abortion among young women--the importance of family environment factors and social class]

BACKGROUND

The aim of the study was to investigate possible associations between social background, other aspects of childhood environment and induced abortion among young women.

MATERIAL AND METHODS

Norwegian girls (N = 2,198), comprising a representative sample, were followed up through three data collections from they were in their teens in 1992 till they were young adult women (20 - 27 years) seven years later. A questionnaire was used to collect the data and the analyses were conducted by Cox regression. The response rate for the first data collection was 97%. The cumulative response rate over all three data collections was 69 %.

RESULTS

In young adulthood we uncovered a steady reduction of induced abortion rates with increasing educational level. Women who had grown up in Northern Norway had higher rates than other women. There was a lower risk for induced abortion when parents were well educated and had fairly good jobs. Further, there were associations to parental divorce, weak parental monitoring and parental alcohol abuse.

INTERPRETATION

A host of socioeconomic factors are associated with abortion risk. We need more thorough knowledge about these factors. We can, however, conclude that preventive efforts in this area should be targeted towards groups with risk factors.

Post-neonatal mortality in Norway 1969-95: a cause-specific analysis

BACKGROUND

We recently reported increased social inequality for post-neonatal death. The aim of the present study was to investigate the association between socioeconomic status and cause-specific post-neonatal death.

METHODS

All 1,483,857 live births recorded in the Medical Birth Registry of Norway from 1969-95 with information on parents' education were included. During the post-neonatal period (from 28 to 364 days of life) 4,464 infants died. Differences between education groups were estimated as risk differences, relative risks, population attributable fractions, and relative index of inequality.

RESULTS

The major causes of death were congenital conditions, sudden infant death syndrome (SIDS), and infections. Post-neonatal mortality declined from 3.2/1,000 in the 1970s to 1.9/1,000 in the 1990s, mainly due to reduced mortality from congenital conditions. The absolute risk for SIDS increased by 0.51/1,000 in the same period among infants whose mothers had low education, while it decreased by 0.56/1,000 for those whose mothers had high education. The relative risk for SIDS among infants whose mothers had low education increased from 1.02 in the 1970s to 2.39 in the 1980s and 5.63 in the 1990s. Among infants whose fathers were not recorded in the Birth Registry, the absolute risk of SIDS increased by 0.79/1,000 from the 1970s to the 1990s.

CONCLUSIONS

Increased social inequality for post-neonatal death was primarily due to increases in the absolute and relative risks of SIDS among infants whose mothers have low education. Social inequality widened during the study period for SIDS and deaths caused by infections.

Head circumference at birth and risk of brain cancer in childhood: a population-based study

BACKGROUND

Studies have found only a weak or no association between birthweight and brain cancer in childhood. However, previous studies have not assessed the association between head circumference at birth and brain cancer. We aimed to assess the risk of brain cancer in childhood according to head circumference at birth.

METHODS

We investigated the association between incidence of brain cancer in childhood and factors recorded at birth such as head circumference, birthweight, and gestational age based on the Norwegian medical birth registry from 1978-98, linked to the Norwegian cancer registry from 1978-2002.

FINDINGS

We analysed 1,010,366 individuals with 12,378,172 person-years of follow-up, from which 453 individuals aged 0-15 years were diagnosed with brain cancer. The relative risk of brain cancer was 1.27 (95% CI 1.16-1.38) per 1-cm increase in head circumference after adjustment for birthweight, gestational age, and sex.

INTERPRETATION

Head circumference is positively associated with incidence of brain cancer in childhood, suggesting that brain pathology originates during fetal life.

A simple correction for ties when censoring times depend on covariates

We point out that the conventional methods for ties correction may be seriously biased when censoring times depend on covariates. A simple modification to the Efron correction method is suggested which works remarkably well in simulation studies. The method corresponds closely to breaking ties by random ordering. The modified correction method is easy to implement and computationally no more demanding than the Efron correction.

Cesarean delivery and cow milk allergy/intolerance

The present study provides support for a positive association between cesarean delivery and persistent cow milk allergy/cow's milk intolerance. Correspondingly, a negative association was seen between cesarean delivery and early outgrown cow milk allergy/intolerance. A possible explanation is that cesarean delivery, rather than increasing the overall risk of food allergy, increases the risk of persistency of disease among food allergic children.

[Parents' education and infant mortality 1967-1998]

BACKGROUND

We have examined the association between socioeconomic status and risk of infant death in Norway between 1967 and 1998.

METHODS

Information from the Medical Birth Registry of Norway on all live births and infant deaths was linked to information from Statistics Norway on parents' education. There were 1,777,364 eligible live births and 15,517 infant deaths. Differences between educational-attainment groups were estimated as risk difference, relative risk, population-attributable fraction, and index of inequality ratio.

RESULTS

The risk of infant death decreased in all educational-attainment groups and the level of education increased over time. For neonatal (0-27 days of life) death the risk difference between infants whose mothers had high or low education was reduced from 3.5/1000 in the 1970s to 0.9/1000 in the 1990s. The inequality ratio declined from 1.72 to 1.32 and the population-attributable fraction from 22.3 to 8.4. For risk of postneonatal (28-364 days of life) death, the difference between infants whose mothers were in high or low education brackets increased from 0.7/1000 in the 1970s to 2.0/1000 in the 1990s. The inequality ratio went up from 1.31 to 4.00 and the population-attributable fraction from 9.7 to 39.5.

INTERPRETATION

Since the late 1960s, infant mortality has decreased and parental educational levels have risen. There is a higher degree of social equality with regard to risk of neonatal death, while the opposite holds for postneonatal death.

Socioeconomic status and risk of infant death. A population-based study of trends in Norway, 1967-1998

BACKGROUND

The aim of this study was to examine the association between socioeconomic status and risk of infant death in Norway from 1967 to 1998.

METHODS

Information from the Medical Birth Registry of Norway on all live births and infant deaths was linked to information from Statistics Norway on parents' education. There were 1777364 eligible live births and 15517 infant deaths. Differences between education groups were estimated as risk differences, relative risks, population attributable fractions, and index of inequality ratios.

RESULTS

The risk of infant death decreased in all education groups, and the level of education increased over time. The trends differed for neonatal and postneonatal death. For neonatal death the risk difference between infants whose mothers had high and low education was reduced from 3.5/1000 in the 1970s to 0.9/1000 in the 1990s. The relative index of inequality (RII) for maternal education decreased from 1.72 to1.32. The proportion of neonatal deaths that could be attributed to <13 years of education decreased from 22.3 to 8.4. For postneonatal death the risk difference between infants whose mothers had high and low education increased from 0.7/1000 in the 1970s to 2.0/1000 in the 1990s. The RII for maternal education increased from 1.31 to 4.00. The population attributable fraction increased from 9.7 to 39.5.

CONCLUSIONS

An inverse association between socioeconomic status and risk of postneonatal death persists, albeit there was a considerable reduction in risk between 1967 and 1998.

[New patterns of sexual behaviour among adolescents]

BACKGROUND

We wanted to investigate erotic and sexual behaviour in adolescents, with emphasis on the trend over the last decade.

MATERIALS AND METHODS

Two large, survey-based representative studies of Norwegian adolescents (each with approx. 11 000 respondents) from 1992 and 2002 (response rates 97% and 92%).

FINDINGS

Median age at first intercourse has decreased by 12 months in females over this ten-year time span (to 16.7 years), while the decrease among males was more modest. Furthermore, oral sex now has the same prevalence as coitus from the mid-teen years on and seems to be introduced at the same point in time. Finally, females are as inclined as males to break the norm of being in love as the basis for a sexual relationship.

INTERPRETATION

More adolescents are now sexually active and more risky sexual behaviour might be a consequence. However, the findings also suggest increased gender equality and a new cohort of more sexually active and self-confident females.