Biomedical subjects

P Nafstad

Publications and source records attributed to P Nafstad.

At least 37 records · Page 2Linked to original sources

PubMed2000

Associations between outdoor air pollutants and hospitalization for respiratory diseases.

The concentration of particulate matter in outdoor air, as indicated by daily measures of particulate matter 10 microm in diameter (PM10) in many cities, has been found to be associated with the daily number of deaths and hospital admissions in these cities. To understand this association better, we studied the daily number of hospital admissions for respiratory diseases and the concentrations of eight pollutants in ambient air, during a period of 38 months, in an area with cold winters and air pollution that comes mainly from motor vehicles. We estimated the changes in risk of hospitalization by interquartile increases in pollutant concentrations by Poisson regression analyses. Controlling for periodic trends and weather, the relative risk of hospitalization associated with an interquartile increase of PM10 was 1.038 [95% confidence interval (CI) = 0.991-1.087]. In contrast, the relative risk associated with benzene was 1.105 (95% CI = 1.047-1.166). In a two-pollutant model, the relative risk estimates were 1.014 (95% CI = 0.966-1.063) for PM10 and 1.090 (95% CI = 1.031-1.153) for benzene. We evaluated other two- and three-pollutant models and concluded that pollutants other than PM10 are more strongly associated with hospital admissions for respiratory diseases.

Air Pollutants↗

PubMed2000

Early respiratory infections and childhood asthma.

OBJECTIVE: To assess the role of early respiratory infections in the development of bronchial obstruction in the first 2 years of life, and asthma by the age of 4 years in the Oslo Birth Cohort, established in 1992-1993. Having older siblings and attendance to a day care center were also considered as proxy measures of early infections. METHODS: A total of 2531 children were followed from birth to 4 years of age. Experiences of respiratory infections were recorded in the follow-up surveys at 6 and 12 months of age, and children with symptoms and signs of bronchial obstruction during the first 2 years of life were identified and examined. The presence of current asthma was recorded when the children were 4 years old. RESULTS: Children with respiratory infections during infancy had a higher risk of having bronchial obstruction during the first 2 years of life and of having asthma at 4 years of age. In logistic regression adjusting for confounders including other infections, the risk of asthma at 4 years of age was related to lower respiratory tract infection (odds ratio [OR]: 3.4; 95% confidence interval [CI]: 2.3-7.0), otitis media (OR: 1.8; 95% CI: 1.2-2.6), croup (OR: 2.1; 95% CI: 1.2-3.7) in the first year and related to the common cold (OR: 2.0; 95% CI: 1.3-3.1) in the first 6 months of life. The risk of current asthma was inversely related to older siblings after controlling for early respiratory infections. CONCLUSION: Early respiratory infections indicate increased, rather than decreased, risk of developing bronchial obstruction during the first 2 years of life and of having asthma at 4 years of age.

Asthma↗

PubMed1999

Perinatal risk factors for recurrent wheeze in early life.

The possible value of tidal flow volume (TFV) loops measured at birth in relation to the risk of developing recurrent or persistent bronchial obstruction within two years of life was assessed. TFV loops were measured at a mean age of 2.7 days in 802 neonates enrolled in the 'Environment and Childhood Asthma' (ECA) study in Oslo. Of these, 77 children developed recurrent or persistent bronchial obstruction (cases) and were included in a nested case-control study within the ECA study; 88 controls (the child born closest in time to the case), with no history of bronchial obstruction in the first two years of life, were also included. Information on socio-economic factors, parental atopic diseases and parental smoking habits during the pregnancy was collected from a questionnaire completed by the parents in the maternity ward, and cord blood IgE (CB-IgE) was determined as part of routine sampling in the delivery ward. Mean tPTEF/tE (time to reach peak flow to total expiratory time) was slightly lower in cases (0.31; 95% CI 0.28-0.34) than in controls (0.33; 0.31-0.35) (difference not significant), whereas geometric mean CB-IgE was significantly higher among cases (0.39; 0.30-0.52) than controls (0.27; 0.23-0.33). No significant differences between cases and controls were found for respiratory rate, peak tidal expiratory flow or expiratory volume. However, the odds ratio for developing recurrent or persistent bronchial obstruction was 3.5 (1.1-11.6) if tPTEF/tE was < 0.20 and 4.1 (1.1-14.5) with maternal daily smoking during the pregnancy, after adjusting for age, weight, sex, CB-IgE, parental atopy, maternal education and family income. The TFV parameter tpTEF/tE < 0.20 measured within the first week of life as well as maternal daily smoking during pregnancy are significant, independent risk factors for developing recurrent or persistent bronchial obstruction within the first two years of life.

Case-Control Studies↗

PubMed1999

Ventilation in homes and bronchial obstruction in young children.

We assessed the role of ventilation rate in homes in the development of bronchial obstruction during the first 2 years of life. We conducted a matched case-control study based on a cohort of 3,754 newborns in Oslo in 1992-93 that was followed for 2 years. The case series comprised 172 children with bronchial obstruction, and the control series was one-to-one matched for date of birth. Ventilation rate and other building characteristics were measured/collected in home visits, and questionnaires were used to obtain additional information. We found that the risk of bronchial obstruction was not directly associated with the ventilation rate in liters per second and per person (ventilation rate quartiles: 6.9, 11.5 and 17.6 l/s,p [liter/second and person]) in the homes (odds ratio; OR 0.98, 95% confidence interval (CI) 0.96-1.01). The odds ratios of bronchial obstruction were higher in the low air change group (air change rate < or =0.5 h(-1)) than in the high air change group owing to exposure to environmental tobacco smoke (low 1.8; 95% CI: 0.35-9.66; high 1.5; 95% CI: 0.74-3.20), dampness problems (low 9.6; 95% CI: 1.05-87.4; high 2.3; 95% CI: 0.83-6.39), and the presence of textile wall paper (low 3.7; 95% CI: 0.62-21.5; high 1.7; 95% CI 0.72-3.94) and plasticizer-containing surfaces (low 12.6; 95% CI: 1.00-159; high 2.6; 95% CI: 1.02-6.58). Our results are consistent with the hypothesis that low ventilation rates strengthen the effects of indoor air pollutants.

Air Pollution, Indoor↗

PubMed1999

Day care centers and respiratory health.

OBJECTIVE: To estimate the effects of the type of day care on respiratory health in preschool children. METHODS: A population-based cross-sectional study of Oslo children born in 1992 was conducted at the end of 1996. A self-administered questionnaire inquired about day care arrangements, children's health, environmental conditions, and family characteristics (n = 3853; response rate, 79%). RESULTS: In logistic regression controlling for confounding, children in day care centers had more often nightly cough (adjusted odds ratio, 1.89; 95% confidence interval, 1.34-2. 67), and blocked or runny nose without common cold (1.55; 1.07-1.61) during the past 12 months compared with children in home care. Poisson regression analysis showed an increased risk of the common cold (incidence rate ratio, 1.21; 1.12-1.30) and otitis media (1.48; 1.22-1.80), and the attributable proportion was 17.4% (95% confidence interval, 10.7-23.1) for the common cold and 32.4% (18. 0-44.4) for otitis media. Early starting age in the day care center increased the risk of developing recurrent otitis media. Also the lifetime risk of doctor-diagnosed asthma was higher in children who started day care center attendance during the first 2 years of life. CONCLUSIONS: Attendance to day care centers increases the risk of upper respiratory symptoms and infections in 3- to 5-year-old children. The starting age seems to be an important determinant of recurrent otitis media as well as asthma. The effect of day care center attendance on asthma is limited to age up to 2 years. This effect is most likely mediated via early respiratory tract infections that are substantially more common in children in day care centers compared with children in home care.

Age Factors↗

PubMed1999

Interior surface materials in the home and the development of bronchial obstruction in young children in Oslo, Norway.

OBJECTIVES: This study assessed the role of polyvinyl chloride (PVC) plastics and textile materials in the home in the development of bronchial obstruction during the first 2 years of life. METHODS: The study was a matched pair case-control study based on a cohort of 3754 newborns in Oslo in 1992 and 1993 who were followed up for 2 years. The case group consisted of 251 children with bronchial obstruction; the control group was matched one-to-one for date of birth. RESULTS: In conditional logistic regression analysis, the risk of bronchial obstruction was related to the presence of PVC flooring (adjusted odds ratio [OR] = 1.89; 95% confidence interval [CI] = 1.14, 3.14) and textile wall materials (adjusted OR = 1.58; 95% CI = 0.98, 2.54). The reference category was wood or parquet flooring and painted walls and ceiling. Further analysis revealed an exposure-response relationship between the assessed amount of PVC and other plasticizer-containing surface materials and the risk of bronchial obstruction. CONCLUSIONS: This study provides new evidence of the role of PVC and textile wall materials in the development of bronchial obstruction in young children.

Bronchial Diseases↗

PubMed1998

[Prevention of femoral neck fractures in the Stovner district of Oslo].

By collecting data on hip fractures among people over 66 years of age in the Stovner district of Oslo, we were able to evaluate a programme to prevent fall accidents in the elderly population. The programme has several approaches. It includes information for both the elderly and the personnel working with them on accident risk factors and identification and removal of risk factors at home. The incidence of hip fractures among those over 66 years of age in the Stovner district was reduced from 30/1,000 in 1990 to 16/1,000 in 1996. There was a significant downward trend during the whole period (p < 0.001). A similar reduction was not seen for the rest of Oslo. We believe that the programme has contributed to reducing the number of hip fractures. However, as several approaches were tried simultaneously, it is difficult to decide whether one particular approach was more efficient than the others.

Accidental Falls↗

PubMed1998

Exposure to nitrogen dioxide and the occurrence of bronchial obstruction in children below 2 years.

BACKGROUND: The objective of the investigation was to test the hypothesis that exposure to nitrogen dioxide (NO2) has a causal influence on the occurrence of bronchial obstruction in children below 2 years of age. METHODS: A nested case-control study with 153 one-to-one matched pairs was conducted within a cohort of 3754 children born in Oslo in 1992/93. Cases were children who developed > or = 2 episodes of bronchial obstruction or one episode lasting >4 weeks. Controls were matched for date of birth. Exposure measurements were performed in the same 14-day period within matched pairs. The NO2 exposure was measured with personal samplers carried close to each child and by stationary samplers outdoors and indoors. RESULTS: Few children (4.6%) were exposed to levels of NO2 > or = 30 microg/m3 (average concentration during a 14-day period). In the 153 matched pairs, the mean level of NO2 was 15.65 microg/m3 (+/-0.60, SE) among cases and 15.37 (+/-0.54) among controls (paired t = 0.38, P = 0.71). CONCLUSIONS: The results suggest that NO2 exposure at levels observed in this study has no detectable effect on the risk of developing bronchial obstruction in children below 2 years of age.

Air Pollution, Indoor↗

PubMed1998

Residential dampness problems and symptoms and signs of bronchial obstruction in young Norwegian children.

To assess the role of dampness problems and house dust mite exposure in the development of bronchial obstruction in early life, a cohort of 3,754 children born in Oslo during 1992 and 1993 was followed for 2 yr. Bronchial obstruction was defined as two or more episodes with symptoms and signs of obstruction or one lasting 1 mo or more. A matched case-control study was carried out in 251 cases of bronchial obstruction (response rate: 98%) and their 251 paired controls. Information on home dampness problem(s), house dust mite exposure, and potential confounders was collected during home visits and by questionnaires. Dampness problems were confirmed in the homes of 27% of the cases and 14% of the controls, while a concentration of Dermatophagoides pteronyssinus allergens > 2 microg/g dust was found in the beds of 11 (4.5%) cases and three (1.2%) controls. In conditional logistic regression analysis controlling for potential confounders, confirmed dampness problems increased the risk of bronchial obstruction (adjusted odds ratio: 3.8; 95% confidence interval: 2.0-7.2). Exposure to D. pteronyssinus allergens > 2 microg/g dust increased the risk of bronchial obstruction (adjusted odds ratio: 2.8; 95% confidence interval: 0.7-11.7). Residential dampness problems in Oslo dwellings seem to increase symptoms and signs of bronchial obstruction in young children, apparently without increasing their exposure to house dust mites.

Airway Obstruction↗

PubMed1998

Nicotine concentration in the hair of nonsmoking mothers and size of offspring.

OBJECTIVES: The purpose of this study was to estimate the risk of small-for-gestational-age birth by levels of nicotine in the hair of mothers and offspring. METHODS: In a sample of 58 case subjects and 105 control subjects, hair nicotine concentrations were measured by gas chromatography and mass spectrometry. RESULTS: With women whose hair nicotine concentrations were in the lowest quartile as the reference group, the odds ratio (OR) for small-for-gestational-age birth was increased among women with concentrations in the upper and two middle quartiles (OR=4.2, 95% confidence interval [CI]=1.5, 11.5, and OR = 3.2, 95% CI=1.3, 8.0). When smoking mothers were excluded from the analysis, the corresponding odds ratios were 2.1 (95% CI=0.4, 10.1) and 3.4 (95 % CI= 1.3, 8.6). CONCLUSIONS: The results suggest that passive maternal smoking increases the risk of small-for-gestational-age births.

Case-Control Studies↗

PubMed1997

The role of passive smoking in the development of bronchial obstruction during the first 2 years of life.

We assessed the effect of exposure to environmental tobacco smoke on the risk of developing bronchial obstruction in a 2-year cohort study of 3,754 children born in Oslo, Norway, during a period of 15 months in 1992-1993. We collected questionnaire information on the child's health and environmental exposures at birth and when the child was age 6 months (follow up rate = 95%), 12 months (92%), 18 months (92%), and 24 months (81%). The outcome of interest was defined as two or more episodes of bronchial obstruction or one obstruction lasting more than 1 month, and it was verified by a specialist group evaluating data from questionnaires, clinical examinations, and health records. The risk of bronchial obstruction was increased in children exposed to environmental tobacco smoke (cumulative incidence = 0.109) compared with unexposed children (0.071), with an adjusted odds ratio of 1.6 [95% confidence interval (CI) = 1.3-2.1]. The effect was seen for maternal smoking alone (odds ratio = 1.6; 95% CI = 1.0-2.6), paternal smoking alone (odds ratio = 1.5; 95% CI = 1.1-2.2), and both parents smoking (odds ratio = 1.5; 95% CI = 1.0-2.2). There was no clear exposure-response pattern. The findings indicate that exposure to environmental tobacco smoke such as is experienced in Norwegian housing increases the risk of developing bronchial obstruction during the first 2 years of life.

Asthma↗

PubMed1997

Weight gain during the first year of life in relation to maternal smoking and breast feeding in Norway.

OBJECTIVE: To assess the weight gain during the first year of life in relation to maternal smoking during pregnancy and the duration of breastfeeding. DESIGN: This was a one year cohort study. SETTING: The city of Oslo, Norway. PARTICIPANTS: Altogether 3020 children born in Oslo in 1992-93. Children were divided into three groups as follows: 2208 born to non-smoking mothers, 451 to mothers who were light smokers (< 10 cigarettes per day), and 261 to mothers who were heavy smokers (> or = 10 cigarettes per day). MAIN RESULTS: The mean birth weights were 3616 g, 3526 g, and 3382 g and 1 year body weights were 10,056 g (gain 6440 g per year), 10,141 g (6615 g), and 10,158 g (6776 g) in children of non-smoking and light and heavy smoking mothers respectively. Cox regression analysis showed that children of heavy smokers were 2.0 (95% confidence interval, 1.7, 2.3) times and children of light smokers 1.3 (1.2, 1.5) times more likely to have stopped breast feeding during their first year of life compared with children whose mothers were non-smokers. Linear regression analysis, adjusting for confounders, showed that weight gain was slower in breast fed children than in those who were not breast fed (-38 g (-50, -27) per month of breast feeding). Compared with children of non-smokers, the adjusted weight gain was 147 g (40, 255) per year greater in children of light smokers and 184 g (44, 324) per year in children of heavy smokers. CONCLUSION: Children catch up any losses in birth weight due to maternal smoking, but some of the catch up effect is caused by a shorter duration of breast feeding in children of smoking mothers.

Birth Weight↗

PubMed1997

In utero exposure to cigarette smoking influences lung function at birth.

To avoid the possible confounding effects of postnatal exposure to tobacco smoke, we investigated possible effects of uterine tobacco smoke (UTS) exposure upon infant lung function shortly after birth. Infants with no major disease, in one maternity ward in Oslo, Norway, participating in a cohort study established in 1992/1993, were included in the present study (n=803). Exposure information, assessed as maternal active and passive smoking during pregnancy and other personal and environmental factors, was obtained by questionnaire. Tidal flow-volume (TFV) loops (n=802) and compliance (Crs) and resistance (Rrs) of the respiratory system (n=663) were measured at a mean age of 2.7 days. In girls, the TFV ratio (time to reach peak expiratory flow to total expiratory time (tPEF/tE)), and Crs were significantly lower with active as well as passive maternal smoking compared to nonexposure to UTS. Respiratory rate and Rrs were not significantly influenced by UTS exposure. However, in linear regression analysis adjusted for confounding factors (including respiratory rate), tPEF/tE and Crs, but not Rrs, were related to maternal active but not passive daily smoking. One daily cigarette corresponded to a change in tPEF/tE of -0.0021 (95% confidence interval (95% CI) -0.0040 to -0.0002) and a change in Crs of -0.026 mL x cmH2O (95% CI -0.045 to -0.007 mL x cmH2O). The decrease was 0.023 and 0.29, respectively, in infants of an average smoker. Maternal smoking during pregnancy adversely affected tidal flow-volume ratios in healthy newborn babies, as well as the compliance of the respiratory system in girls, independently of the reduced body size also resulting from maternal smoking.

Airway Resistance↗

PubMed1997

Recurrent acute otitis media: the significance of age at onset.

In order to assess the relationship between recurrent acute otitis media (rAOM) and age at first acute otitis media (AOM) episode, a prospective cohort of 3754 Norwegian children born in 1992-1993 was followed from birth to 2 years. Recurrent acute otitis media was defined by the criterion of four or more episodes of AOM during a 12-month period. Approximately 5.4% of the children experienced rAOM before the age of 2. Furthermore, children whose first AOM episode occurred before the age of 9 months were at a significantly higher risk for developing rAOM compared to children whose first AOM episode was 10-12 months. In children who had the first ear infection during the first 9 months of life, one-quarter developed rAOM before the age of 2. Multiple logistic regression analysis adjusted for confounding showed that gender and a familial history of atopy were significantly associated with rAOM. In conclusion, the present study found an association between age at first AOM episode and the later subsequent AOM proneness. Additionally, both gender and a family history of atopy seemed to predispose towards otitis-proneness.

Age of Onset↗

PubMed1997

Early acute otitis media: determined by exposure to respiratory pathogens.

The purpose of the present study is to assess the relationship between early acute otitis media (AOM) and exposure to respiratory pathogens mediated by siblings and day-care. A prospective cohort of 3,754 Norwegian children born in 1992-93 was followed from birth through 12 months. One or more episodes of AOM had been experienced by 25% of the children before age one. Logistic regression analysis showed that siblings attending day-care is the most important risk factor for early AOM (ORadj = 1.9 (1.4-2.3)). The total number of children in the day-care setting is another determinant for early AOM (ORadj = 2.0 (1.4-2.6) in groups of 4 or more other children and ORadj = 1.3 (1.0-1.7) in groups of 1-3 other children as compared with those who are cared for alone). Siblings who attend day-care and the number of children in the child's own day-care setting are the most important determinants for AOM the first year of life.

Acute Disease↗

PubMed1996

[A local health center for adolescents].

A local centre for information to adolescents on sexual behaviour and use of contraceptives was opened in 1990 in the Stovner district of Oslo. At the end of 1993, the centre had recorded 975 visits. 248 of the 271 girls who had consulted the centre's doctor, had already had intercourse. No use or unsatisfactory use of contraceptives was reported by 40%. The two main reasons for contacting the centre were a need for contraceptives (58%) and fear of sexually transmitted diseases (21%). The findings indicate a need for this kind of centre for health information.

Adolescent↗

PubMed1996

Partner's smoking: a major determinant for changes in women's smoking behaviour during and after pregnancy.

To study determinants for changes in maternal smoking behaviour during and after pregnancy, questionnaire information on smoking habits was recorded in a cohort of 3710 Norwegian women during early pregnancy, at delivery, and one year later. Of 3039 cohabiting women with complete information on smoking at all three occasions 31% smoked in early pregnancy 23% in the late pregnancy and 28% one year after delivery. Among the cohabiting mothers who smoked in early pregnancy, 44% stopped during pregnancy. After adjusting for confounding factors, the odds ratio for smoking cessation among these women who had cohabitants who smoked as opposed to not smoking was 0.2 (95% CI: 0.1-0.2). Among cohabiting non-smoking women during late pregnancy the odds ratio for being a smoker one year after child birth was 3.0 (95% CI: 2.2-4.0), if their cohabitants smoked as opposed to not smoking. The women's smoking behaviour changes considerably during and after pregnancy and their cohabitants' smoking seems to be a major determinant for changes in their smoking behaviour.

Adult↗

PubMed1996

Early acute otitis media and siblings' attendance at nursery.

To assess the relation between early acute otitis media and exposure to respiratory pathogens mediated by siblings and other children, a prospective cohort of 3754 Norwegian children born in 1992-3 was followed up from birth to 12 months. Of these, 25% had one or more episodes of acute otitis media during the first year. Results from multiple logistic regression analysis adjusted for confounding showed that siblings' attendance at daycare is the most important risk factor for early acute otitis media (adjusted odds ratio, ORadj = 1.9). The total number of children in the daycare setting is another determinant for early acute otitis media (ORadj = 2.0 in groups of four or more other children and ORadj = 1.3 in groups of one to three other children, as compared to those who are cared for alone). Having siblings in daycare outside the home and the number of children in the daycare setting are the most important determinants for early acute otitis media.

Acute Disease↗