In order to assess the acceptability of voluntary population screening for antibodies against human immunodeficiency virus (HIV), a random sample of 300 Danish men, aged 20-49 years, were sent a self-administered questionnaire. Among nonrespondents, recruitment attempts were repeated three times with intervals of 8-10 days. In total, 76.7% responded. Two hundred men (87.0% of the respondents) would accept an offer to be tested in an anti-HIV screening programme. Among respondents, 72.9% agreed to identify themselves to the researchers, 22.1% preferred to be tested under a code number known only by the participant himself, and 5% wanted the test information to be completely anonymous. Among the 30 men refusing HIV testing, 40% reported they were not concerned about AIDS, 16.7% expressed concern with confidentiality problems, and another 16.7% had been tested already and for this reason declined to participate. Previous reports have indicated high seroprevalences among nonrespondents and raised prevalences of behavior at high risk for HIV infection among persons who do themselves take the initiative to be tested or who decline to be tested because they worry about confidentiality. Low respondency and the associated disproportional loss of subjects at high risk of HIV infection may bias HIV seroprevalence estimates based on population probability sampling, especially in areas with low HIV infection prevalence. Because of these biases, voluntary population screening is likely to give only lower bound estimates of HIV seroprevalence. So, this technique should only be used in combination with other surveillance approaches.
CONTEXT: Hospital-based studies have found that increased susceptibility to certain infections is associated with low serum levels of mannose-binding lectin (MBL) due to MBL variant alleles. However, the contribution of MBL insufficiency to incidence of common childhood infections at a population level is unknown. OBJECTIVE: To investigate the effect of MBL insufficiency on risk for acute respiratory tract infection (ARI) in unselected children younger than 2 years. DESIGN AND SETTING: Population-based, prospective, cohort study conducted in Sisimiut, Greenland. PARTICIPANTS: Two hundred fifty-two children younger than 2 years who were followed up weekly between August 1996 and August 1998 for morbidity surveillance. MAIN OUTCOME MEASURE: Risk of ARI, based on medical history and clinical examination, compared by MBL genotype, determined from blood samples based on presence of structural and promoter alleles. RESULTS: A 2.08-fold (95% confidence interval [CI], 1.41-3.06) increased relative risk (RR) of ARI was found in MBL-insufficient children (n = 13) compared with MBL-sufficient children (n = 239; P
Comment In: JAMA. 2001 Mar 14;285(10):1348-911255392
It has been postulated that an infectious agent and/or specific sexual behaviour is involved in the aetiology of anal cancer, in analogy with the aetiology established for cancer of the cervix. A case-control study of 29,648 women with cancers registered in the Danish Cancer Registry during 1968-87 tested the hypothesis that anal cancer patients were more likely than patients with colon, stomach, or vulva cancer to have had a previous diagnosis of cervical intraepithelial neoplasia (CIN) or invasive cervical cancer. The odds ratio of CIN, adjusted for age and year of diagnosis, for anal vs colon cancer was 5.2 (95% confidence interval [CI] 3.3-8.3), that for anal vs stomach cancer 3.6 (2.1-6.0), and that for anal vs vulva cancer 1.6 (0.9-2.9). The median time from diagnosis of CIN to diagnosis of the registered cancer was 151 months for anal, 112 months for vulva, 114 months for colon, and 126 months for stomach cancer. The association with previous invasive cervical cancer was also investigated; no patient with cervical cancer in this second analysis had been included in the CIN analysis. The odds ratios were similar. In addition, anal cancer patients were significantly more likely to have had cervical cancer than were patients with vulva cancer (odds ratio 1.8 [1.0-3.9]). The strong association between anal cancer and CIN/invasive cervical cancer suggests that these cancers share common risk factors. The association is at least as strong as that between cervical and vulva cancer.
The period before the first birth is traditionally viewed as particularly critical for a woman's breast cancer risk. Nonetheless, the importance of early timing of a woman's first compared with subsequent births is not well understood. In the present study we examine this question using a population-based cohort of 1.5 million Danish women born between 1935 and 1978. Between 1968 and 1994, 13,049 incident cases of breast cancer were identified in the Danish Cancer Registry. According to our results, a woman's breast cancer risk is related to her age at any of her births. The risk increase per 5 year's increase in maternal age at first, second, third, and fourth birth was 9%, 7%, 5%, and 14%, respectively. For fifth and sixth births it was 5%. We observed a risk reduction after any birth occurring before 30 years of age (in uniparous women before 25 years of age). These effects were strongest more than 10 years after birth. Thus, our study shows that early timing of any additional birth induces an additional long-term reduction in maternal risk of breast cancer; that is, early reproductive years, rather than just the nulliparous years, constitute the critical period.
BACKGROUND: It has been proposed that early age at exposure to common childhood infections is associated with a decreased risk of allergy. Previous studies on the possible association between allergy and infection with measles, mumps, rubella, and varicella have not been conclusive as most did not include information on exact age at exposure. The objective of our study was to investigate whether early age at exposure to these infections was associated with a decreased risk of atopy using information on exact age at infection. METHODS: The study population consisted of 889 pregnant women who participated in a national birth cohort study in Denmark and for whom detailed information on history of measles, rubella, varicella, and mumps before school entry (age 7 years) was available from school health records from Copenhagen. Atopic status was assessed serologically by a specific response to 11 common inhalant allergens using serum samples obtained from the women during pregnancy. RESULTS: Measles in the first year of life was associated with a higher risk of atopy than no measles before age 7 years (OR 3.36, 95% CI 1.47 to 7.68). There was no association between atopy and mumps, rubella, or varicella in the first 7 years of life or with measles acquired after the first year of life. The risk of atopy increased significantly with increasing number of childhood infections in the first 2 years of life (p(trend)=0.01). CONCLUSIONS: These findings do not support the suggestion that childhood exposure to measles, rubella, varicella, or mumps protects against atopy, even if acquired very early in life.
BACKGROUND: A full-term pregnancy is associated with a reduced risk of breast cancer, but the underlying biologic mechanism has not been elucidated. During pregnancy, maternal serum levels of alpha-fetoprotein, an estradiol-binding protein, rise sharply. In culture, alpha-fetoprotein inhibits the growth of estrogen-sensitive cells, including estrogen-sensitive breast cancer cells. Thus, we investigated whether a high level of alpha-fetoprotein in maternal serum during pregnancy is associated with a reduced risk of breast cancer. METHODS: From a population-based cohort of 42057 pregnant women in Denmark, enrolled in an alpha-fetoprotein-screening program from 1978 through 1996, we obtained a complete reproductive history, vital status, and a possible diagnosis of breast cancer (in 117 women) to the end of follow-up on September 1, 1998. RESULTS: During pregnancy, women with an alpha-fetoprotein level greater than or equal to the median value had a 41% lower risk of breast cancer than women with an alpha-fetoprotein level below the median value (relative risk [RR] = 0.59; 95% confidence interval [CI] = 0.41-0. 85). RRs for breast cancer by mother's age at childbirth were as follows: 29 years or younger, RR = 0.21 (95% CI = 0.08-0.56); 30-34 years, RR = 0.61 (95% CI = 0.32-1.14); 35-37 years, RR = 0.96 (95% CI = 0.49-1.89); and 38 years or older, RR = 0.71 (95% CI = 0.29-1. 75) (P for trend =.02). Further analyses suggested that high levels of alpha-fetoprotein were associated with a reduced incidence of aggressive disease. The most striking finding was that women with high levels of serum alpha-fetoprotein, compared with women with low levels of serum alpha-fetoprotein, showed a particularly reduced incidence of large tumors (>2 cm; RR = 0.24 [95% CI = 0.11-0.50]). CONCLUSION: A high level of alpha-fetoprotein in maternal serum during any pregnancy is associated with a low overall incidence of breast cancer and, in particular, with a low incidence of advanced breast cancer at diagnosis. This association appears particularly strong for a pregnancy occurring at a young age.
Clinical case reports have suggested that specific bacterial infections are associated with certain non-Hodgkin lymphoma (NHL) subtypes. Epidemiological case-control studies have been conducted using antibiotics as a proxy for bacterial infections, but with inconclusive results. The aim of this study was, in a cohort design, based on the unique nationwide Danish registers, to investigate the association between use of antibiotics and the risk of NHL subtypes. On the basis of the Civil Registration System, we established a cohort of the entire adult (= 15 years) Danish population. Information on use of antibiotics came from the Danish Drug Prescription Registry and lymphoma diagnosis from the Danish Cancer Registry. Associations were assessed by adjusted rate ratios (RRs). In total, 13,602 patients were diagnosed with one of the NHL subtypes during 51.6 million person-years of follow-up (1995-2008). We observed positive associations between use of antibiotics and plasma cell myeloma [RR = 1.11, 95% confidence intervals (CIs) = 1.00-1.24], chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) (RR = 1.32, 95% CI = 1.20-1.45), mantle cell lymphoma (MCL) (RR = 1.40, 95% CI = 1.04-1.88) and anaplastic large T-cell lymphoma (ALCL) (RR = 1.83, 95% CI = 1.00-3.36). Among these, the increased risk of CLL/SLL, MCL and ALCL, respectively, did not vary by years since use, and only the risk of CLL/SLL risk differed by number of prescriptions. While causality could not be established in our study, an intriguing positive long-term association between antibiotic use and CLL/SLL risk was observed. To what extent these findings indicate a role for bacteria in lymphoma pathogenesis requires further investigation.
The aim of this study was to investigate the seroprevalence of antibody to human papilloma virus (HPV) among Danish dentists in order to determine whether this virus constitutes an occupational hazard for dentists. Serum samples from 452 Danish dentists were tested for antibody against a common capsid antigen to HPV by a complement fixation reaction. Nine (2.0%) were seropositive. Dentists' odds ratio for seropositivity was after adjustment for age 0.6 (90% confidence interval: 0.3-1.4) compared to that of voluntary blood donors. In conclusion, Danish dentists do not seem to be at an increased risk of becoming infected with HPV.
Greenland is a considered high risk area for a self-sustained heterosexual HIV-epidemic due to rather relaxed sexual norms in larger segments of the population and a high incidence of sexual transmitted diseases. However, the prevalence of HIV-positives is still low. As part of a monitoring programme longitudinal studies of young peoples' knowledge and sexual behaviour has been established. This paper presents results from the second survey among all students in vocational training and all 10th grade students in the public schools. Previous studies were performed in 1988 and 1989. The present study which took place in April 1991 involved a total of 1201 students, or about 85% of all students in the target groups (95% among students present on the day of surveying). Data collection was based upon standardized self-administered questionnaires. The study showed better knowledge than previously but no marked change in sexual habits. The age of sexual début even appeared to be decreasing. More than half reported a sexual début before the age of 15. More than 20% reported 10 sexual partners or more within the last year. HIV has still not reached the young population in Greenland but when it happens the present sexual behaviour carries a high risk of a self-sustained epidemic.