The hypothesis that exposure to traffic-related air pollution increases the risk of developing cancer during childhood was investigated. The authors enrolled 1,989 children reported to the Danish Cancer Registry with a diagnosis of leukemia, tumor of the central nervous system, or malignant lymphoma during 1968-1991 and 5,506 control children selected at random from the entire childhood population. The residential histories of the children were traced from 9 months before birth until the time of diagnosis of the cases and a similar period for the controls. For each of the 18,440 identified addresses, information on traffic and the configuration of streets and buildings was collected. Average concentrations of benzene and nitrogen dioxide (indicators of traffic-related air pollution) were calculated for the relevant period, and exposures to air pollution during pregnancy and during childhood were calculated separately. The risks of leukemia, central nervous system tumors, and all selected cancers combined were not linked to exposure to benzene or nitrogen dioxide during either period. The risk of lymphomas increased by 25% (p for trend = 0.06) and 51% (p for trend = 0.05) for a doubling of the concentration of benzene and nitrogen dioxide, respectively, during the pregnancy. The association was restricted to Hodgkin's disease.
The aims of the study were to evaluate if the front-door concentrations of benzene, toluene, and xylenes can be used to classify the personal exposures of Danish children and to identify factors that affect their personal exposure. Average concentrations were measured over 1 week with diffusive samplers, and the personal exposures of 98 children and the concentrations outside the front doors of their homes were measured simultaneously. Time and activity patterns were noted in diaries. The front-door concentrations were significantly higher in Copenhagen than in rural areas (all P
Analysis of the treatment effect on recurrent bleeding and death in patients with cirrhosis and esophageal varices: multistage competing-risks model compared to conventional methods. The Copenhagen Esophageal Varices Sclerotherapy Project.
Multiple recurrences of bleeding with high mortality in cirrhosis with esophageal varices have been inadequately analyzed in previous trials. We propose analysis by the multistage competing-risks model, specifying the effect on overall mortality as an effect on mortality during bleeding, rate of cessation of bleeding, mortality rate without bleeding, and rate of rebleeding.
The Copenhagen Esophageal Varices Project enrolled patients after first bleeding and randomized 94 to usual treatment and 93 to sclerotherapy as supplement. During 9-52 months of follow-up, rebleeding occurred in 49 and 42, and death in 68 and 60 patients, respectively. The proportional hazards regression model (Cox model) was used for reanalysis both by the multistage competing-risks model and by conventional analysis for overall mortality and rate of first rebleeding. In the multistage model, time zero was at entry to any new disease stage, of which the first four were analyzed - two bleeding stages and two bleeding-free stages.
The conventional analysis showed a reduction of overall mortality rate in the sclerotherapy group of borderline significance, but no effect on rate of rebleeding. The multistage model indicated that sclerotherapy reduced the rate of rebleeding late in the disease course, and particularly after the first rebleeding. Rate of cessation of bleeding and mortality rates during bleeding and without bleeding were not affected by sclerotherapy.
Conventional analysis may give misleading conclusions, which might be avoided by applying the multistage model. The effect of sclerotherapy on overall mortality may be ascribed entirely to the reduced rate of rebleeding.
OBJECTIVE: To increase the knowledge of the long-term effects of artificial hip and knee joint implants. METHODS: The study groups consisted of 24,636 patients with osteoarthritis who underwent hip implant surgery and 5,221 who received knee implants during 1977-89. The post-implant rate of hospitalization for connective tissue disease (CTD) was compared with the rate in the general population of Denmark and with that among osteoarthritis patients without implant surgery. RESULTS: The rates of hospitalization for CTD were higher than the background level among both hip and knee implant patients with osteoarthritis, whereas the comparison with non-implanted osteoarthritis patients revealed that the hospitalization rate for CTD was reduced after hip implant surgery, but increased after knee implant surgery. CONCLUSION: Since the materials used in hip and knee implants in Denmark are not substantially different, these results are unlikely to reflect an implant effect but rather the selection criteria of referral for implant surgery.
In 91 healthy term infants breast-milk intake was measured at 2, 4, and 9 mo by test weighing and human milk macronutrient content by infrared analysis every 2-4 wk. In infants exclusively breast-fed, mean milk intake was 781 and 855 mL/24 h at 2 and 4 mo, respectively, and correlated positively with the current weight of the infant and negatively with the amount of formula supplement given at the maternity ward. Median daily energy intake was considerably below current recommendations (423 and 381 kJ/kg body wt at 2 and 4 mo, respectively). Protein concentration in the milk was approximately 8% higher in primipara. Median daily protein intake was 1.3 and 1.0 g/kg body wt at 2 and 4 mo, respectively. Median fat concentration was 39.2 g/L and was positively associated with pregnancy weight gain. This supports the hypothesis that maternal fat stores laid down during pregnancy are easier to mobilize during lactation than are other fat stores and, if low, may limit milk fat when exhausted.
Duration of breast feeding was studied in 249 randomly chosen, healthy, term infants of Danish origin of which 80.7% participated. Breast feeding was initiated by 99.5% of the mothers. At 3, 6 and 9 months, 71%, 52% and 33%, respectively, were still breast feeding. Only 1 infant (0.5%) was exclusively breast fed beyond 7 months of age. In a Cox multiple regression analysis of factors influencing duration of breast feeding, we found a positive association with maternal education (p or = 12 years) were still breast feeding, compared to 29% with a low school education (
The entire population of cystic fibrosis (CF) patients in Denmark diagnosed in the period January 1, 1945, to June 30, 1985, comprised 514 persons of whom 62 were diagnosed at autopsy. Of the remaining 452 patients, 372 were probands and 80 were secondary cases. The effect of a centralized treatment on the prognosis was evaluated using a Cox's regression model. Furthermore an incidence analysis was performed using probands including autopsies. Centralized treatment had a significantly beneficial effect on the prognosis (p = 0.02), the death intensity (hazard rate) being decreased by a factor of 0.60. It was calculated that at present 1 out of 4,760 newborn Danes may be diagnosed as suffering from CF before the age of 15 years, and 3% of the Danish population are heterozygotes for CF.
OBJECTIVE: A global epidemic of obesity is developing, but its causes are still unclear. In Denmark, two periods of steep increases in prevalence of obesity have occurred among young men born in the 1940s and 1960-70s. This study investigated the preceding changes in prevalence of obesity and in the entire body mass index (BMI = weight/height2) distribution by birth cohort, calendar time and age among Danish school boys. METHODS: Children attending Copenhagen schools 1937-1983 had annual health examinations, from which we computerized 1,037,468 measurements of height (m) and weight (kg) of 161,314 boys aged 7-13 y. Obesity was defined as age-specific BMI exceeding the 95.0, the 99.0 and the 99.9 percentile among those born 1930-1934, the latter corresponding to the prevalence of obesity among the young men in these cohorts. The median, standard deviation, skewness, and the 5th, 25th, 75th and 95th percentiles of the age-specific BMI were estimated for each birth cohort. RESULTS: The prevalence of obesity, defined by the 99.9 percentile, increased at all ages during the same birth years as among the young men, and, accordingly, at earlier calendar years. The prevalence of obesity, defined by the 95.0 percentile, showed a distinctly different pattern: a sharp increase, irrespective of age, during the calendar years 1947-1949, and thereafter a stable level until the 1970s, where a further modest increase began. The prevalence defined by the 99.0 percentile showed a mixture of the trends in those defined by the 99.9 and 95.0 percentiles. The median BMI showed small fluctuations, parallel at all ages. The standard deviation and right-sided skewness increased until birth year 1950, but were almost stable thereafter. The pattern of changes in the quartiles mostly reflected those in the median. CONCLUSIONS: The prevalence of obesity defined by the 99.9 or 99.0 percentile has increased in Danish boys born in the 1940s and since the mid 1960s, without corresponding changes in the central part of the BMI distribution. When defining obesity by the 95.0 percentile, there was a sharp distinct age-independent increase in the late 1940s. The development of the obesity epidemic is a heterogeneous phenomenon that has involved changes in environmental influences starting at preschool ages and affecting different subsets of the population, either because of selective exposure or particular susceptibility.
OBJECTIVE: Smoking serves different functions for men and women. Thus, we wanted to investigate the association between smoking behaviour and intakes of selected healthy foods in men and women with special focus on differences and similarities between the two genders. DESIGN: In 1993-1997, a random sample of 80 996 men and 79 729 women aged 50-64 y was invited to participate in the study 'Diet, Cancer and Health'. In all, 27 179 men and 29 876 women attended a health examination and completed a 192-item food-frequency questionnaire (FFQ). The association between smoking status and low, median and high intakes of selected foods was examined among 25 821 men and 28 596 women. SETTING: The greater Copenhagen and Aarhus area, Denmark. RESULTS: For both men and women, smoking status group was associated with diet, such that increasing level of smoking status ranging from never smokers over ex-smokers to currently heavy smokers was associated with a lower intake of the healthy foods: fresh fruit, cooked vegetables, raw vegetables/salad, and olive oil. For wine, increasing level of smoking status category was associated with a higher fraction of abstainers and heavy drinkers. The difference between the extreme smoking status categories was larger than the difference between men and women within smoking status categories such that never smoking men in general had a higher intake of healthy foods than heavy smoking women. Correction for age, educational level, and body mass index (BMI) did not affect the results. CONCLUSION: In this middle-aged population, intake of healthy foods were associated with smoking behaviour with a dose-response type of relationship. The overall pattern was similar for men and women.