Research has shown that hip fracture risk increases with latitude; hypothetically due to reduced sunlight exposure and its effect on bone quality. Sweden, with large differences in latitude and UV radiation, is ideal to study in order to analyse the association between latitude and UV radiation on age- and sex-specific hip fracture rates among elderly.
Aggregated (2006-2008) age- and sex-specific hip fracture data was obtained for each Swedish municipality as well as the municipality's latitudinal coordinates and aggregated (2006-2008) UV radiation levels. Pearson correlations were calculated between hip fracture incidence rates, latitude and UV radiation. Independent t tests were calculated on tertile-categorized latitudinal data in order to investigate the difference in hip fracture risk between these categories.
Statistically significant correlations were seen in all groups between hip fracture incidence rates and latitude as well as UV radiation. The independent t tests showed that this correlation was mainly due to high incidence rates in high latitude municipalities.
Statistically significant correlations are seen between hip fracture incidence rates and latitude as well as UV radiation in Sweden and the northern parts of Sweden have an increased risk of hip fractures compared to the middle and southern parts. To our knowledge this is the first study using a national discharge register that shows this relationship and provides a starting point for further research to investigate why populations in northern Sweden have a higher risk of hip fractures compared to other Swedish regions.
The prevention of suicidal behavior is one of the most important tasks for mental health clinicians. Although a few studies have indicated an increased risk of suicidal behavior among individuals with attention-deficit/hyperactivity disorder, the development of more effective ways of identifying and modifying the risk is hampered by our limited understanding of the underlying mechanisms for this association.
To explore whether attention-deficit/hyperactivity disorder and suicidal behavior share genetic and environmental risk factors.
Matched cohort design across different levels of family relatedness recorded from January 1, 1987, to December 31, 2009. We identified 51?707 patients with attention-deficit/hyperactivity disorder (through patient and prescribed drug registers) in Sweden and their relatives by linking longitudinal population-based registers. Control participants were matched 1:5 on sex and birth year.
Any record of suicide attempt or completed suicide defined by discharge diagnoses of the International Classification of Diseases.
Individuals with attention-deficit/hyperactivity disorder (probands) had increased risks of attempted and completed suicide, even after adjusting for comorbid psychiatric disorders (odds ratio [OR]?=?3.62 [95% CI, 3.29-3.98] and 5.91 [95% CI, 2.45-14.27], respectively). The highest familial risk was observed among first-degree relatives (attempted suicide: OR?=?2.42 [95% CI, 2.36-2.49] among parents of probands with ADHD and OR?=?2.28 [95% CI, 2.17-2.40] among full siblings of probands with ADHD; completed suicide: OR?=?2.24 [95% CI, 2.06-2.43] and OR?=?2.23 [1.83-2.73], respectively), whereas the risk was considerably lower among more genetically distant relatives (attempted suicide: OR?=?1.59 [95% CI, 1.47-1.73] among maternal half siblings, OR?=?1.57 [95% CI, 1.45-1.70] among paternal half siblings, and OR?=?1.39 [95% CI, 1.35-1.43] among cousins; completed suicide: OR?=?1.51 [95% CI, 1.08-2.10], OR?=?2.02 [95% CI, 1.47-2.79], and OR?=?1.51 [95% CI, 1.36-1.67], respectively). These familial aggregation patterns remained similar across sex, after excluding relatives with attention-deficit/hyperactivity disorder and probands with suicidal behavior, and after excluding probands and relatives with severe comorbid disorders.
Attention-deficit/hyperactivity disorder is associated with an increased risk of both attempted and completed suicide. The pattern of familial risks across different levels of relatedness suggests that shared genetic factors are important for this association. This is an important first step toward identifying the underlying mechanisms for the risk of suicidal behavior in patients with attention-deficit/hyperactivity disorder and suggests that individuals with attention-deficit/hyperactivity disorder and their family members are important targets for suicide prevention and treatment.
Celiac disease (CD) is a major public health problem with estimated 1-3% prevalence in the general population. In recent years an increase in CD prevalence has been reported both in Sweden and worldwide. This study aimed at examining the annual incidence rate of biopsy-proven celiac disease among children in Sweden over a 36-year period, to assess variations by age, sex and birth cohort, and to assess the clinical impact of these changes.
The National Swedish Childhood CD Register was used to identify 9107 children aged 0-14.9 years who were diagnosed with CD during the period 1973 to 2009. From 1973 to 1990 the register covered 15% of the nation, this increased to 40% during 1991-1997; a full national coverage was obtained from 1998 onwards. Estimations for the annual incidence rate, cumulative incidence and clinical impact by age groups, calendar month and birth cohorts were made.
CD incidence is continuing to increase in the child population aged 2-14.9 years. A continued variation in CD incidence was observed in children aged 0-1.9 years, characterized by a marked decrease in most recent years. The median age at diagnosis has increased from 1.0 year in the 1970s to 6.8 years in 2009. The average number of new cases has risen from ~200 during 1973-1983 to ~600 during 2004-2009. In the birth cohorts of 2000-2002 the cumulative incidence even exceeded that of the epidemic cohorts at comparable ages. The highest cumulative incidence was observed in the birth cohorts of 1985-1995 and 2000-2002.
CD risk varies between birth cohorts, suggesting cyclic environmental and/or lifestyle risk factors in CD etiology. More research on underlying risk factors is required in order to move forward with preventive strategies.
Cites: Gut. 2013 Jan;62(1):43-5222345659
Cites: N Engl J Med. 2002 Sep 19;347(12):911-2012239261
In November 2010, ˜27,000 (˜45%) inhabitants of Östersund, Sweden, were affected by a waterborne outbreak of cryptosporidiosis. The outbreak was characterized by a rapid onset and high attack rate, especially among young and middle-aged persons. Young age, number of infected family members, amount of water consumed daily, and gluten intolerance were identified as risk factors for acquiring cryptosporidiosis. Also, chronic intestinal disease and young age were significantly associated with prolonged diarrhea. Identification of Cryptosporidium hominis subtype IbA10G2 in human and environmental samples and consistently low numbers of oocysts in drinking water confirmed insufficient reduction of parasites by the municipal water treatment plant. The current outbreak shows that use of inadequate microbial barriers at water treatment plants can have serious consequences for public health. This risk can be minimized by optimizing control of raw water quality and employing multiple barriers that remove or inactivate all groups of pathogens.
A 10-year follow-up of a population-based study of people with multiple sclerosis in Stockholm, Sweden: changes in health-related quality of life and the value of different factors in predicting health-related quality of life.
Health-related quality of life (HRQL) in people with multiple sclerosis (PwMS) is negatively affected compared to that of the general population. Cognitive impairment and depressive symptoms have been shown to predict worse HRQL in a short-term perspective. Considering the progressive nature of MS, it is essential to include the long-term (10 years) perspective of HRQL in PwMS.
The aim of this 10-year follow-up of a population-based sample of PwMS was to explore changes in and the predictive value of personal factors, degree of MS disability, depressive symptoms and cognitive impairment on HRQL.
Data on personal and disease-specific factors, mood, and cognitive function was collected. Data on HRQL was collected, seen as a health profile with the Sickness Impact Profile, as a health index with the EuroQol 5D and as a single global question with the EQ Visual Analog Scale.
HRQL worsened over 10 years according to the health profile (Sickness Impact Profile Total and its physical dimension) and according to the health index. The effect sizes were small. HRQL assessed with the single global question remained unchanged. Depressive symptoms and cognitive impairment predicted worse HRQL.
In a 10-year perspective the HRQL with regard to its physical domain or when seen as a total health profile tends to get worse in PwMS. Yet, HRQL with regard to its psychosocial domain and with regard to PwMS' self-rated health, remains stable. There is a potential for health-care professionals to decrease the impact of modifiable factors on HRQL in PwMS by identifying those with depressive symptoms and/or cognitive impairment and initiating evidence-based treatment as well as meeting the need for environmental facilitators aiming at reducing disability.
Methicillin-resistant Staphylococcus aureus (MRSA) was found in a dog for the first time in Sweden in 2006. Between October 2006 and May 2007, MRSA was diagnosed in 7 more dogs that had been treated in 3 different small animal hospitals, located 150-200 km apart, in different counties of Sweden. Screening of the animal hospital staff and environment in these small animal hospitals showed 20 of 152 staff to be positive for MRSA, with rates between 2% and 18% in the different hospitals, while all 128 environmental samples were negative. All MRSA isolates from dogs and staff belonged to spa type t032, were Panton-Valentine leukocidin (PVL)-negative, and had indistinguishable pulsed-field gel electrophoresis patterns, except for 2 isolates with closely related patterns. To our knowledge, this is the first report of multiple outbreaks of MRSA in dogs caused by the same strain within a short time frame, and appearing in a country with low prevalence of MRSA in both humans and dogs. This highlights the importance of infection control programs in animal hospitals and in animal health care. Awareness of MRSA as an occupational risk for veterinary personnel is essential.
Data on familial recurrence rates of complex diseases such as multiple sclerosis give important hints to aetiological factors such as the importance of genes and environment. By linking national registries, we sought to avoid common limitations of clinic-based studies such as low numbers, poor representation of the population and selection bias. Through the Swedish Multiple Sclerosis Registry and a nationwide hospital registry, a total of 28 396 patients with multiple sclerosis were identified. We used the national Multi-Generation Registry to identify first and second degree relatives as well as cousins, and the Swedish Twin Registry to identify twins of patients with multiple sclerosis. Crude and age corrected familial risks were estimated for cases and found to be in the same range as previously published figures. Matched population-based controls were used to calculate relative risks, revealing lower estimates of familial multiple sclerosis risks than previously reported, with a sibling recurrence risk (?s = 7.1; 95% confidence interval: 6.42-7.86). Surprisingly, despite a well-established lower prevalence of multiple sclerosis amongst males, the relative risks were equal among maternal and paternal relations. A previously reported increased risk in maternal relations could thus not be replicated. An observed higher transmission rate from fathers to sons compared with mothers to sons suggested a higher transmission to offspring from the less prevalent sex; therefore, presence of the so-called 'Carter effect' could not be excluded. We estimated the heritability of multiple sclerosis using 74 757 twin pairs with known zygosity, of which 315 were affected with multiple sclerosis, and added information from 2.5 million sibling pairs to increase power. The heritability was estimated to be 0.64 (0.36-0.76), whereas the shared environmental component was estimated to be 0.01 (0.00-0.18). In summary, whereas multiple sclerosis is to a great extent an inherited trait, the familial relative risks may be lower than usually reported.
Department of Ophthalmology, Örebro University Hospital, Örebro, Sweden2School of Health and Medical Sciences, Örebro University, Örebro, Sweden3Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Smoking is a risk factor for cataract development, but the effect of smoking cessation on the risk of cataract is uncertain.
To examine the association between smoking cessation and the risk of cataract extraction.
A total of 44,371 men, participating in the Cohort of Swedish Men, aged 45 to 79 years, who in 1997 completed a self-administered questionnaire on smoking habits and lifestyle factors. The men were followed up from January 1, 1998, through December 31, 2009. The cohort was matched with the Swedish National Day-Surgery Register and local registers of cataract extraction in the study area.
Incident cases of age-related cataract extraction.
During 12 years of follow-up, we identified 5713 incident cases of age-related cataract extraction. Smoking intensity and cumulative dose of smoking were associated with an increased risk of cataract extraction (P for trend
To our knowledge, no previous epidemiologic study has investigated the association between all antioxidants in the diet and age-related cataract. The total antioxidant capacity (TAC) concept aims to measure the capacity from all antioxidants in the diet by also taking synergistic effects into account.
To investigate the association between the TAC of the diet and the incidence of age-related cataract in a population-based prospective cohort of middle-aged and elderly women.
Questionnaire-based nutrition survey within the prospective Swedish Mammography Cohort study, which included 30,607 women (aged 49-83 years) who were observed for age-related cataract incidence for a mean of 7.7 years.
The TAC of the diet was estimated using a database of foods analyzed with the oxygen radical absorbance capacity assay.
Information on incident age-related cataract diagnosis and extraction was collected through linkage to registers in the study area.
There were 4309 incident cases of age-related cataracts during the mean 7.7 years of follow-up (234,371 person-years). The multivariable rate ratio in the highest quintile of the TAC of the diet compared with the lowest was 0.87 (95% CI, 0.79-0.96; P for trend =?.03). The main contributors to dietary TAC in the study population were fruit and vegetables (44.3%), whole grains (17.0%), and coffee (15.1%).
Dietary TAC was inversely associated with the risk of age-related cataract. Future studies examining all antioxidants in the diet in relation to age-related cataract are needed to confirm or refute our findings.
Cigarette smoking is an important cause of preventable death globally, but associations between smoking and mortality vary substantially across country and calendar time. Although methodological biases have been discussed, it is biologically plausible that persistent organic pollutants (POPs) like polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides can affect this association. This study was performed to evaluate if associations of cigarette smoking with mortality were modified by serum concentrations of PCBs and OC pesticides. We evaluated cigarette smoking in 111 total deaths among 986 men and women aged 70 years in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) with mean follow-up for 7.7 years. The association between cigarette smoking and total mortality depended on serum concentration of PCBs and OC pesticides (P value for interaction = 0.02). Among participants in the highest tertile of the serum POPs summary score, former and current smokers had 3.7 (95% CI, 1.5-9.3) and 6.4 (95% CI, 2.3-17.7) times higher mortality hazard, respectively, than never smokers. In contrast, the association between cigarette smoking and total mortality among participants in the lowest tertile of the serum POPs summary score was much weaker and statistically non-significant. The strong smoking-mortality association observed among elderly people with high POPs was mainly driven by low risk of mortality among never smokers with high POPs. As smoking is increasing in many low-income and middle-income countries and POPs contamination is a continuing problem in these areas, the interactions between these two important health-related issues should be considered in future research.
Cites: J Korean Med Sci. 2013 Aug;28(8):1122-823960436
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Factors favoring sensitization to house dust mites (HDM) were studied in a cold, temperate climate in northern Sweden. Sixty-five children previously found to react positively to a skin prick test (SPT) to HDM were included. The SPT to HDM was repeated, and serum IgE antibodies to D. pteronyssinus and D. farinae were determined. HDM, Euroglyphus maynei, Tarsonemus, or storage mites occurred in mattress dust samples from 23 of the 65 homes, and in 10 homes more than 100 HDM/g of mattress dust were found. Mites were more prevalent in mattress dust from the basement and ground levels than from the upper floors. Sensitization to HDM was strongly with the presence of domestic mites in mattress and floor dust. Previous longer stays in southern Sweden or Europe were also associated with present sensitization to HDM, and this was independent of occurrence of mites in the residence. The results indicate that HDM growth and potential for sensitization in cold, temperate regions is highly dependent on the microhabitat, and that sensitization to HDM should be possible to prevent in such climatic regions.
An analysis of a military database of about 36,000 tone audiograms from male Swedish conscripts aged 18 to 19 and recorded from 1969 to 1977 demonstrates a successively decreasing prevalence of hearing loss during this period. This might reflect improved therapy during the 1950s and 1960s of ear disorders causing hearing loss in small children. If observations in other studies on a reverse trend during the 1980s are confirmed, they indicate, together with the present study, that around 1980 young people began to be harmfully exposed to an environmental factor causing hearing loss. If this is the case, the causative factor would probably be non-occupational exposure to electronically amplified sounds from loudspeakers and headphones.
Environmental barriers are associated with disability-related outcomes in older people but little is known of the effect of environmental barriers on mortality. The aim of this study was to examine whether objectively measured barriers in the outdoor, entrance and indoor environments are associated with mortality among community-dwelling 80- to 89-year-old single-living people.
This longitudinal study is based on a sample of 397 people who were single-living in ordinary housing in Sweden. Participants were interviewed during 2002-2003, and 393 were followed up for mortality until May 15, 2012.Environmental barriers and functional limitations were assessed with the Housing Enabler instrument, which is intended for objective assessments of Person-Environment (P-E) fit problems in housing and the immediate outdoor environment. Mortality data were gathered from the public national register. Cox regression models were used for the analyses.
A total of 264 (67%) participants died during follow-up. Functional limitations increased mortality risk. Among the specific environmental barriers that generate the most P-E fit problems, lack of handrails in stairs at entrances was associated with the highest mortality risk (adjusted RR 1.55, 95% CI 1.14-2.10), whereas the total number of environmental barriers at entrances and outdoors was not associated with mortality. A higher number of environmental barriers indoors showed a slight protective effect against mortality even after adjustment for functional limitations (RR 0.98, 95% CI 0.96-1.00).
Specific environmental problems may increase mortality risk among very-old single-living people. However, the association may be confounded by individuals' health status which is difficult to fully control for. Further studies are called for.
Cardiovascular disease (CVD) is the number one cause of death globally and evidence is steadily increasing on the role of non-traditional risk factors such as meteorology and air pollution. Nevertheless, many research gaps remain, such as the association between these non-traditional risk factors and subtypes of CVD, such as acute myocardial infarction (AMI). The objective of this study was to investigate the association between daily ambient temperature and AMI hospitalisations using a case-crossover design in Gothenburg, Sweden (1985-2010). A secondary analysis was also performed for out-of-hospital ischemic heart disease (IHD) deaths. Susceptible groups by age and sex were explored. The entire year as well as the warm (April-September) and cold periods (October-March) were considered. In total 28,215 AMI hospitalisations (of 22,475 people) and 21,082 out-of-hospital IHD deaths occurred during the 26-year study period. A linear exposure-response corresponding to a 3% and 7% decrease in AMI hospitalisations was observed for an inter-quartile range (IQR) increase in the 2-day cumulative average of temperature during the entire year (11°C) and the warm period (6°C), respectively, with and without adjustment for PM10, NO2, NOx or O3. No heat waves occurred during the warm period. No evidence of an association in the cold period nor any association between temperature and IHD deaths in the entire year, warm or cold periods--with and without adjusting for PM10, NO2, NOx or O3 was found. No susceptible groups, based on age or sex, were identified either. The inverse association between temperature and AMI hospitalisations (entire year and warm period) in Gothenburg is in accordance with the majority of the few other studies that investigated this subtype of CVD.
A major challenge in cancer epidemiologic studies, especially those of rare cancers, is observing enough cases. To address this, researchers often join forces by bringing multiple studies together to achieve large sample sizes, allowing for increased power in hypothesis testing, and improved efficiency in effect estimation. Combining studies, however, renders the analysis difficult owing to the presence of heterogeneity in the pooled data. In this article, motivated by a collaborative nested case-control (NCC) study of ovarian cancer in three cohorts from United States, Sweden, and Italy, we investigate the use of penalty regularized partial likelihood estimation in the context of pooled NCC studies to achieve two goals. First, we propose an adaptive group lasso (gLASSO) penalized approach to simultaneously identify important variables and estimate their effects. Second, we propose a composite agLASSO penalized approach to identify variables with heterogeneous effects. Both methods are readily implemented with the group coordinate gradient decent algorithm and shown to enjoy the oracle property. We conduct simulation studies to evaluate the performance of our proposed approaches in finite samples under various heterogeneity settings, and apply them to the pooled ovarian cancer study.
Cites: Stat Med. 2002 Jun 15;21(11):1539-5812111919
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Cites: Am J Epidemiol. 2002 Aug 1;156(3):204-1012142254
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Rheumatoid arthritis (RA) is a complex disease that is associated with genetic and environmental factors. We have investigated geospatial variation in the risk of developing RA within Stockholm County, Sweden, with respect to established environmental risk factors for RA, as well as serologically defined subgroups of RA.
Information regarding geographical location for 1432 cases and 2529 controls from the Epidemiological Investigation of Rheumatoid Arthritis (EIRA) study, living in Stockholm County at RA symptom onset, or matched date for controls, was used to estimate geospatial variation in risk. We used generalized additive models (GAMs) to create a risk surface, calculate odds ratios (ORs), and adjust for potential confounding by smoking, education level, and RA within family. We performed a stratified analysis based on the presence/absence of anti-citrullinated peptide antibodies (ACPA).
We found significant spatial variation in the odds of developing RA in Stockholm County. After adjustment for smoking, education level, and family history of RA, this geospatial variation remained. The stratified analysis showed areas with higher ORs for ACPA-positive RA and ACPA-negative RA, after adjusting for smoking, education level, and having a family history of RA. Living in the city of Stockholm was associated with decreased risk of RA.
The risk of developing RA in Stockholm County is not distributed evenly and there are areas of increased risk that could not be explained by known factors. Further investigations of local exposures or social factors are warranted.
Cites: Autoimmun Rev. 2010 Jan;9(3):140-319427413
Cites: Eur J Public Health. 2011 Jun;21(3):347-5420570962
We investigated the relation of subjective cognitive impairment (SCI) and cognitive impairment no dementia (CIND) to common chronic diseases of the elderly and multimorbidity, and assessed the contribution of genetic background and shared familial environment to these associations. Subjects were 11,379 dementia-free twin individuals aged = 65 from the Swedish Twin Registry. SCI was defined as subjective complaint of cognitive change without objective cognitive impairment and CIND was defined according to current criteria. In unmatched, fully-adjusted regression models, mental, musculoskeletal, respiratory, and urological diseases were all significantly associated with increased odds ratios (ORs) of SCI and CIND. Circulatory and gastrointestinal diseases were related to SCI only, while endocrine diseases were associated with CIND. The adjusted ORs of multimorbidity were 2.1 [95% confidence intervals (95% CI): 1.8-2.3] for SCI and 1.5 for CIND (95% CI: 1.3-1.8). A dose-dependent relationship was observed between number of chronic diseases and ORs for SCI but not for CIND. In co-twin control analyses, the chronic diseases-SCI association was largely unchanged. On the other hand, the chronic diseases-CIND association was no longer statistically significant, except for cancer, where an increased OR was observed. In conclusion, chronic morbidity is associated with both SCI and CIND but disease profiles do not always overlap between the two cognitive syndromes. The association is stronger when diseases co-occur, especially for SCI. Genetic and early-life environmental factors may partially explain the association of CIND but not that of SCI with chronic diseases.
Cites: Arch Neurol. 1995 Jun;52(6):612-97763211
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There are many small villages where environmental contamination is substantial due to historical industrial activities. The aim of the present study was to investigate if long-term or current consumption of local foods, as reported in food frequency questionnaires, co-vary with measured concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), lead (Pb), cadmium (Cd) and mercury (Hg) in blood, urine and hair from a population living in a historically contaminated village. Blood, urine and hair were provided by men (n=38) and women (n=57), who had participated in a previous case-control study in the contaminated area, and were analyzed for PCB, OCPs, Pb, Cd and Hg. A detailed food frequency questionnaire, used in the previous epidemiological study, was repeated, and up-dated information of life-style, exposure factors and other covariates was collected. Associations between reported consumption of local foods and exposure biomarkers were explored in relation to age, gender, life-style factors and other covariates. A large part of the population in the area reported consumption of local food, and thus, was potentially exposed to the contaminants. Despite the limited number of participants and other weaknesses described, it was possible to link reported consumption of different foods to biomarker concentrations. Reported consumption of local vegetables, forest berries and mushrooms co-varied with urinary Cd, indicating an influence from the contaminated area on the Cd exposure. We found no associations between PCB plasma concentrations with reported consumption of local fish, but with consumption of herring (non-local sea fish) which is typically high in PCB. Pesticide (HCB, p,p'-DDE, trans-nonachlor) exposure was mainly associated with agricultural work and having a private well the first five years of life, but we found no associations between pesticide concentrations in plasma and consumption of local vegetables or fish. Exposure to Hg was associated with consumption of fish, both local and non-local, and Pb exposure was associated with the consumption of game. Overall, the contaminant concentrations measured in blood, urine and hair varied substantially among study participants, but on average, the concentrations were similar to concentrations measured in other groups of the general Swedish population in the same age range. Larger studies are needed to evaluate health risks (and causality) associated with historical environmental contamination.
Viral diagnosis of respiratory tract infections has so far required sampling by health professionals,hampering large-scale epidemiological studies of virus-specific disease outcomes. As part of a population-based, prospective study of work-related risk factors for transmission of viral infections (SWEDE-I), we developed a scheme for self-sampling with nasal swabs. Random selection from the gainfully employed population of a medium-sized town in central Sweden resulted in a study cohort of 2,237 men and women aged 25 to 63 years. From September 2011 through May 2012, the cohort reported all instances of respiratory tract infection or gastroenteritis and participants concomitantly sent self-sampled nasal swabs for analysis using regular mail. Diagnosis of 14 viruses was performed. A total of 1,843 samples were received. The week-wise average delay between disease on set and arrival of the specimens at the laboratory varied between four and six days, and the corresponding median delay was between 3.5 and six days. In line with previous community-based studies, picorna- and coronaviruses dominated in specimens obtained from the self-sampling scheme. The results of self-sampling were contrasted to those from contemporaneous routine clinical sampling, on the same age group, in the adjacent Stockholm county. Although higher proportions of positive samples for respiratory syncytial virus and influenza were observed in the clinical sampling scheme, estimations of seasonality for influenza A and picornaviruses derived from both schemes were similar. Our findings show that nasal self-sampling is feasible in large-scale surveillance of respiratory infections and opens new prospects for population based,virologically verified research on virus spread,burden of disease, and effects of environmental factors or interventions.
The purpose of the present study was to examine whether male painters reporting multiple chemical sensitivity (MCS) differ from their matched controls (male painters without such sensitivity) during controlled chamber challenges to singular and mixtures of odorous chemicals with respect to: (1) Subjective rating of symptoms (i.e., symptoms related to central nervous system (CNS) and symptoms related to irritation) and sensations of smell elicited by low-level chemical exposures. (2) Changes in serum prolactin and cortisol levels, changes in nasal cavity and eye redness as a result of the various exposures. Moreover, background assessments were made regarding mental well-being, sense of coherence (SOC) as well as state of anxiety and depression in both groups. The MCS and control group consisted of 14 and 15 male painters respectively. Regarding background assessments of mental well-being, anxiety, depression and SOC, statistically significant differences were obtained between painters with MCS and their controls. During the controlled chamber challenges, neither difference regarding sensations of smell nor development of CNS related symptoms were seen between MCS and control group. In contrast, subjective rating of symptoms related to irritation (i.e., eyes, nose, throat, skin, and breathing difficulties) was significant higher in subjects with MCS. No differences between the groups as a result of the different exposures were seen concerning nasal cavity, eye redness and serum cortisol levels. However, a trend (P = 0.056) between the groups was measured regarding a decline of serum prolactin levels in the MCS group. This is a relatively small study with a limited number of volunteers; and no definitive conclusions can be drawn concerning the above findings. But it is the first controlled challenge study that incorporates similarly exposed groups (painters) recruited from a community rather than from a clinical population.