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Petter Kristensen

Publications and source records attributed to Petter Kristensen.

13 recordsLinked to original sources
PubMed2006

Early life determinants of musculoskeletal sickness absence in a cohort of Norwegians born in 1967-1976.

In order to investigate the extent to which musculoskeletal sickness absence was influenced by a range of circumstances concerning family background and health in early life, we established a register-based cohort of all live-born in Norway between 1967 and 1976. Personal data on parental factors and health early in life were recorded prospectively from birth onward in the Medical Birth Registry of Norway, the National Insurance Administration, Statistics Norway, and the Central Population Register. We collected data in the National Insurance Administration on the first spell of medically certified long-term (>16 days) musculoskeletal (International Classification of Primary Care group L) sickness absence in 2000-2003 among 378, 356 participants who were considered to be at risk of sickness absence on January 1st, 2000. The 4-year musculoskeletal absence risk was 0.264 for women and 0.156 for men. Parental education level was associated with musculoskeletal sickness absence, with increasing adjusted relative risks by decreasing educational level for both genders. Associations with other early determinants (birth weight, childhood disease, parental survival, parental disability, parental income, and parental marital status) were all close to unity. Parental education level attributed 36% (95% confidence interval 33-38) to the population risk for women and 67% (64-70) for men. The parental education association was partly mediated through own educational attainment, which was strongly associated with musculoskeletal sickness absence in itself. Our data suggest that mechanisms acting early in life could influence later risk of musculoskeletal sickness absence.

Adult↗
PubMed2006

[A follow up of persons who received basic and/or supplemental benefits in childhood].

BACKGROUND: Consequences of chronic diseases in childhood with respect to health, educational achievement and participation in the labour force in young adult age are evaluated. MATERIAL AND METHODS: A total of 14,364 children (2.3%) of the 626,928 born in Norway 1967-76 received basic and /or supplemental benefits for at least one year of the age span 0-16 years. The more common diagnoses included Endocrine diseases (diabetes), disease classified under Mental diagnoses, Neurological diseases and Congenital malformations. All the children were followed up to the age of 27 with respect to mortality and disability pensioning and to the age of 25 with regard to education, participation in the labour force and income, and in addition national service for the men. The study was made possible through the linking of data from several national registers, performed by Statistics Norway. Before the file was released for analyses, all personal identification was removed. RESULTS: Basic and supplementary benefits in childhood predict adverse outcomes in young adult age: mortality, disability, low education, lack of gainful employment and low pensionable income. The diagnosis registered with the benefit strongly influenced the outcomes. Conscripts who had received benefits were judged to have a mean score for general ability of 4.5 compared to 5.2. Adjusted for score for general ability the proportion of those having received benefits achieving higher education was 84% of that of those that had not received benefits. After adjustment for educational attainment, the percentage gainfully employed was 11-12% less among subjects having received benefits in childhood. This negative association between having received a benefit in childhood and gainful employment in adulthood was restricted to the low educational group. INTERPRETATION: Persons with health problems in childhood did not achieve the education, employment and income they should have been capable of judged by their general ability and the education they had actually achieved.

Adolescent↗
PubMed2006

Immunological exposures in Norwegian agriculture and pre-eclampsia.

Immune system perturbations are involved in pre-eclampsia pathophysiology. We hypothesised that immunomodulating substances, such as mycotoxins, endotoxins or pesticides, affect pre-eclampsia risk. Associations between indicators of immunomodulating exposures in agriculture and pre-eclampsia are reported. In a Norwegian family cohort based on participants in agricultural censuses conducted by Statistics Norway 1969-89, 183 313 pregnancies to farmers were identified in the Medical Birth Registry of Norway. Cases notified as pre-eclampsia as well as pregnancies indicated by hypertension in combination with proteinuria were included. Data on farm production and meteorologically based fungal forecasts 1973-90 (a marker of temperate and humid climatic conditions known to favour fungal growth and mycotoxin formation in grain) were obtained and allocated to each farm. Pre-eclampsia prevalence rates were studied in strata of exposure indicators using Poisson regression models. Adjusted rate ratios (RR) and 95% confidence intervals [CI] were computed. We identified 4912 cases, equivalent to 26.8 pre-eclampsia cases per 1000 pregnancies [95% CI 26.1, 27.6]. Pre-eclampsia showed moderate associations with animal farming, RR 1.14, [95% CI 1.07, 1.22] and moderate negative associations with grain production, RR 0.93, [95% CI 0.86, 1.01], and two or more fungal forecasts appearing in any year 1973-90, RR 0.90 [95% CI 0.84, 0.97], using no years with two or more forecasts as reference. Exposure to immunomodulating substances as indicated by grain farming, animal farming and fungal warnings could possibly have moderate effects on pre-eclampsia risk, thus supporting the study hypothesis. The use of exposure indicators as surrogates for real exposures may introduce a non-differential misclassification of the exposure that would attenuate any true exposure-outcome association. The use of exposure proxies warrants that inferences from the study should be made with caution.

Adolescent↗
PubMed2005

[Bias from dependent errors in observational studies].

Measurement errors in two variables are dependent when the degree of error in one of them correlates with the degree of error in the other. When dependent error affects measured exposure and measured outcome, the estimated association between the two is likely to be falsely inflated. Such information bias is probably not uncommon in cross-sectional studies providing data on both variables from questionnaires. This often occurs in published studies, but there seems to be limited awareness of the problem. The basic source of dependent error is usually normal variation in certain personality traits, but it may also be in more transitional moods in the study population or inadequate measurement tools. The major precaution that should be taken in order to eliminate bias from dependent error is to break the bond between information on exposure and outcome by gathering data from two separate sources. We should also recognise that not all study designs and not all data are suited for establishing etiology.

Bias↗
PubMed2005

Indicators of mancozeb exposure in relation to thyroid cancer and neural tube defects in farmers' families.

OBJECTIVES: The fungicide mancozeb has been suspected of causing thyroid cancer and neural tube defects. The aim of the study was to investigate associations of indicators of mancozeb exposure with thyroid cancer and neural tube defects in farmers' families. METHODS: National registers in Norway, identifying 105 403 female and 131 243 male farmers, born in 1925-1971, and their 300 805 children available for analyses, born in 1952-1991, were cross-linked with national agricultural censuses, 1969-1989, and the population register. Neural tube defects (ICD-8 740-742) at birth among the 102 703 children conceived between May 1973 and April 1991 were identified in the medical birth register. Likewise thyroid cancer (ICD-7 194) was identified in the cancer register through 2000. Data on farm production and fungal forecasts (humid and temperate weather conditions) in 1973-1990, obtained from agricultural censuses and meteorological measurement stations, respectively, served as the mancozeb exposure indicators. The adjusted rate ratio or prevalence ratio (PR) estimates with 95% confidence intervals (95% CI) were computed in a Poisson regression analysis. RESULTS: Neural tube defects (131 cases, prevalence 12.8/10 000 births) was moderately associated with potato cultivation (PR 1.6, 95% CI 1.1-2.3) and paternal work of > 500 hours/year (PR 1.6, 95% CI 1.1-2.5). Altogether 319 thyroid cancer cases were identified: 141 in female farmers (incidence 10.2/100 000 person-years), 79 in male farmers (incidence 3.2/100 000 person-years), and 99 in offspring (female and male incidence 3.4 and 0.6/100 000 person-years, respectively). Mancozeb exposure was not associated with thyroid cancer. CONCLUSIONS: A moderate association seems to exist between mancozeb exposure and neural tube defects, but not between mancozeb exposure and thyroid cancer.

Agriculture↗
PubMed2004

[Employment trends--the impact of chronic disease in childhood and low educational level].

BACKGROUND: Our aim was to analyse long-term employment trends among disadvantaged groups on the assumption that they may be more exposed to unemployment during recessions or be at increasingly higher risk of unemployment because of stricter requirements in the workplace. MATERIAL AND METHODS: We established a cohort through links between data on individuals in national registers for all 321,975 men born 1967 through 1976. Disadvantaged groups under study were those receiving supplementary benefits in childhood because of chronic disease, and those with few educational attainments. Using Poisson regression we estimated associations with unemployment or disability over the course of the 1991-2001 period. RESULTS: Disadvantaged groups had higher risk of unemployment or disability. Associations between chronic disease in childhood and subsequent unemployment followed the business cycle; they were highest during the 1993 recession and lowest during the boom years around 1999. Over the long term, the gap in unemployment widened between those with low educational attainment and the better-educated. We found similar but less clear trends for disability. INTERPRETATION: The observed negative effect of chronic childhood disease on employment status paralleled the business cycle: it was weakest in boom years and strongest in recession years. Low educational attainment was associated with a gradual decline in the level of employment.

Adolescent↗
PubMed2004

Birthweight and work participation in adulthood.

BACKGROUND: In a number of studies, birthweight has been associated with cognition and educational attainment into adult age. However, the association is not clear between birthweight and work participation in adulthood. We investigated this association assessing to which extent it was influenced by circumstances concerning family background or disease in early life. METHODS: Through linkage between several national registers containing personal information from birth into adult age we established a longitudinal, population-based cohort study. Study participants were all 308 829 singletons born in Norway in 1967-1971 as registered by the Medical Birth Registry of Norway who were national residents at age 29. The study outcome was unemployment defined as a lack of personal income among people who were not under education in the calendar year of their 29th birthday as registered by the National Insurance Administration and Statistics Norway. RESULTS: Birthweight below the standardized mean was associated with unemployment. The risk of unemployment increased by decreasing birthweight for both women and men and also after adjustment for potential confounding factors. The association was evident both in people with or without social disadvantage, as well as people with or without childhood disease. Still, birthweight below the standardized mean explained much less of the unemployment risk than did social disadvantage (attributable fractions 8.0% versus 28.3% for women and 10.0% versus 40.2% for men). CONCLUSION: Birthweight below the standardized mean was independently associated with unemployment at age 29, also in the normal birthweight range.

Adult↗
PubMed2004

Trichothecene mycotoxins and their determinants in settled dust related to grain production.

We hypothesise that inhalant exposure to mycotoxins causes developmental outcomes and certain hormone-related cancers that are associated with grain farming in an epidemiological study. The aim of the present study was to identify and validate determinants of measured trichothecene mycotoxins in grain dust as work environmental trichothecene exposure indicators. Settled grain dust was collected in 92 Norwegian farms during seasons of 1999 and 2000. Production characteristics and climatic data were studied as determinants of trichothecenes in settled dust samples obtained during the production of barley (N = 59), oats (N = 32), and spring wheat (N = 13). Median concentrations of trichothecenes in grain dust were <20, 54, and < 50 mg/kg (ranges < 20-340, < 30-2400, and < 50-1200) for deoxynivalenol (DON), HT-2 toxin (HT-2) and T-2 toxin (T-2) respectively. Late blight potato rot (fungal) forecasts have been broadcast in Norway to help prevent this potato disease. Fungal forecasts representing wet, temperate, and humid meteorological conditions were identified as strong determinants of trichothecene mycotoxins in settled grain dust in this study. Differences in cereal species, production properties and districts contributed less to explain mycotoxin concentrations. Fungal forecasts are validated as indicators of mycotoxin exposure of grain farmers and their use in epidemiological studies may be warranted.

Agricultural Workers' Diseases↗
PubMed2003

Impact of low birthweight on subsequent fertility: population-based register study.

Adverse birth outcomes may influence a family's wish for additional children. We investigated the influence of low birthweight in live births on subsequent fertility, and estimated secular trends of such an effect in a population-based cohort study of births arranged in consecutive sibship records in the Medical Birth Registry of Norway. We included births of order one to seven to all 587 785 mothers in Norway who had a first singleton birth in 1967-91. Associations between birthweight in 1 158 072 surviving index births of order one to six, 1967-91, and subsequent fertility (probability of another birth), 1967-97, were estimated as fertility ratios in Cox regression analysis. Giving birth to a live infant weighing < 3000 g had a negative effect on subsequent fertility, increasingly strong for decreasing birthweight. Low birthweight (<2500 g) was associated with a fertility ratio of 0.88 [95% confidence interval 0.87, 0.89]. This negative impact was stronger if the mother had also given birth to surviving children of low birthweight previously, particularly if combined with caesarean section in the most recent birth. The negative fertility effect of low birthweight grew slightly stronger between 1967 and approximately 1980, according to year of first birth. This trend paralleled reduced population fertility in the same period. The moderate negative impact of giving birth to a live infant of low birthweight on subsequent fertility could result from the combination of reduced wish for additional children and biological subfertility.

Female↗
PubMed2003

Respiratory symptoms and ventilatory function in workers exposed to portland cement dust.

The healthy worker effect and incomplete exposure information have been problems in former studies regarding the association between exposure to Portland cement dust and respiratory effects. We included former workers and made an individual estimation of particle exposure to reduce the selection bias in this controlled cross-sectional study on the effects of cement dust exposure on respiratory symptoms and ventilatory function in long-term exposed Norwegian cement plant workers. A total of 119 workers from the largest cement plant in Norway and 50 workers from a nearby control plant, born 1918 to 1938, performed spirometry and gave information on respiratory symptoms in 1998 and 1999. The prevalence of symptoms and mean pulmonary function indices were similar for exposed workers and controls. There was no dose-response-related increase in symptoms or decrease in lung function indices. The estimated power to detect a true difference between forced expiratory volume in one second (FEV1) in the two groups of 0.3l was 0.90, assuming 95% significance level. The prevalence of chronic obstructive pulmonary disease was 14.3% in the exposed group and 14.0% among the controls. These findings do not support the hypothesis that cement dust exposure has a negative impact on lung function or gives an increase in respiratory symptoms.

Adult↗