Biomedical subjects

Sven Ove Samuelsen

Publications and source records attributed to Sven Ove Samuelsen.

8 recordsLinked to original sources

PubMed2006

[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.

Abortion, Legal↗

PubMed2006

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.

Bacterial Infections↗

PubMed2006

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.

Adolescent↗

PubMed2004

[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.

Educational Status↗

PubMed2004

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.

Adult↗

PubMed2003

[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.

Adolescent↗

PubMed2003

Exact inference in the proportional hazard model: possibilities and limitations.

It is suggested that inference under the proportional hazard model can be carried out by programs for exact inference under the logistic regression model. Advantages of such inference is that software is available and that multivariate models can be addressed. The method has been evaluated by means of coverage and power calculations in certain situations. In all situations coverage was above the nominal level, but on the other hand rather conservative. A different type of exact inference is developed under Type II censoring. Inference was then less conservative, however there are limitations with respect to censoring mechanism, multivariate generalizations and software is not available. This method also requires extensive computational power. Performance of large sample Wald, score and likelihood inference was also considered. Large sample methods works remarkably well with small data sets, but inference by score statistics seems to be the best choice. There seems to be some problems with likelihood ratio inference that may originate from how this method works with infinite estimates of the regression parameter. Inference by Wald statistics can be quite conservative with very small data sets.

Adolescent↗

PubMed2003

Intercourse debut age: poor resources, problem behavior, or romantic appeal? a population-based longitudinal study.

The most important predictors of early intercourse debut are reported to be poor social resources and early developing problem behaviors. In this study we have a new, additional emphasis on variables related to self-concept and social acceptance. In a population-based longitudinal study, 1399 Norwegians were followed over a 7-year span. We analyzed data using multivariate Cox-regression techniques. Early intercourse debut was part of a broader spectrum of problem behaviors, including early alcohol intoxication and early-developing conduct problems. A new finding was that a positive self-concept in the domain of romantic appeal was also a strong predictor, but only for boys. We suggest that the findings may have important implications for prevention and more research should be conducted along this line.

Adolescent↗