Seasonal and geographic variations in the incidence of asthma exacerbations in the United States.

BACKGROUND: Exacerbations drive the burden of asthma and lead to significant morbidity and consumption of health care resources. Many prior studies of the epidemiology of asthma exacerbations have relied upon data from hospital care. OBJECTIVE: The objective of this study was to determine US patterns of geographic and seasonal variations of asthma exacerbations being defined as asthma episodes requiring hospital care and/or a prescription for oral steroid. METHODS: The study was a retrospective observational cohort study using administrative claims data for insured individuals from the HealthCore Integrated Research Database, including around 43 million members in the United States. Analyses examined 3 age groups, 6-17, 18-64, and ≥65 years and four US regions, Northeast, Southeast, Central, and Western. RESULTS: Monthly rates of asthma exacerbations showed the greatest variation over the year in children, less so in adults and in the elderly. Clinically important differences in rates of asthma exacerbation were observed between regions with the Western Region having the lowest in all three age groups followed by the Northeast, Central, and Southeast regions. Peaks in children occurred in the early fall following troughs in the summer months, and peaks at year-end occurred in adults, particularly in those over 65 years. CONCLUSIONS: There is a striking seasonal variation in asthma exacerbations in the United States. Substantial differences between regions of the United States in asthma exacerbation rates cannot readily be explained and invite further investigation.

Socioeconomic inequalities in knee pain, knee osteoarthritis, and health-related quality of life: a population-based cohort study in southern Sweden.

OBJECTIVES: To determine socioeconomic inequalities in frequent knee pain (FKP), knee osteoarthritis (OA), and associated health-related quality of life (HRQoL) in Sweden. METHOD: In 2007 a postal questionnaire about knee pain was sent to a random sample of 10 000 residents of Malmö, Sweden (7402 individuals responded). Subjects reporting pain with duration ≥ 4 weeks in one or both knees in the past 12 months were classified as having FKP. A random sample of 1527 subjects with and without FKP attended a clinical and radiographic knee examination and responded to generic and disease-specific HRQoL questionnaires. We used the individuals' level of education and occupation as socioeconomic status (SES) measures, and we calculated the relative index of inequality (RII) using Poisson regression with robust standard errors adjusted for age and gender. We applied weighting to account for a possible selection bias that might arise from non-responses in the study. RESULTS: With education, the RIIs for FKP and knee OA were 0.71 [95% confidence interval (CI) 0.61-0.84] and 0.56 (95% CI 0.34-0.93), respectively. With occupation, the corresponding figures were 0.70 (95% CI 0.60-0.82) and 0.59 (95% CI 0.37-0.94), respectively. There were socioeconomic gradients in HRQoL in favour of people with better SES. RIIs for FKP and HRQoL but not knee OA were essentially similar after additional adjustment for mediators. CONCLUSIONS: In Sweden there are socioeconomic gradients related to both FKP and knee OA as well as HRQoL in favour of people with better SES. SES should be taken into account in health resource allocation pertaining to knee-related disorders.

C-reactive protein, metabolic syndrome and incidence of severe hip and knee osteoarthritis. A population-based cohort study.

OBJECTIVE: To explore the relationships between C-reactive protein (CRP), metabolic syndrome (MetS) and incidence of severe knee or hip osteoarthritis (OA) in a prospective study. METHODS: A population-based cohort (n=5171, mean age 57.5+/-5.9 years) was examined between 1991 and 1994. Data was collected on lifestyle habits, measures of overweight, blood pressure as well as high-density lipoprotein (HDL) cholesterol, triglycerides, glucose and CRP measured with high-sensitive methods. Incidence of severe OA, defined as arthroplasty due to knee or hip OA, was monitored over 12 years of follow-up, in relation to CRP levels and presence of the MetS according to the adult treatment panel III-national cholesterol education program (ATPIII-NCEP) definition. RESULTS: A total of 120 participants had severe hip OA and 89 had knee OA during the follow-up. After adjustment for age, sex, smoking, physical activity and CRP, presence of MetS was associated with significantly increased risk of knee OA (relative risk [RR]: 2.1, 95% confidence interval [CI]: 1.3-3.3). However, this relationship was attenuated and non-significant after adjustment for body mass index (BMI) (RR: 1.1, 95% CI: 0.7-1.8). MetS was not significantly associated with incidence of hip OA. In women, CRP was associated with knee OA in the age-adjusted analysis. However, there was no significant relationship between CRP and incidence of knee or hip OA after risk factor adjustments. CONCLUSION: The increased incidence of knee OA in participants with the MetS was largely explained by increased BMI. CRP was not associated with incidence of knee or hip OA when possible confounding factors were taken into account.

Incidence of severe knee and hip osteoarthritis in relation to different measures of body mass: a population-based prospective cohort study.

OBJECTIVE: To determine in a prospective population-based cohort study relationships between different measures of body mass and the incidence of severe knee and hip osteoarthritis defined as arthroplasty of knee or hip due to osteoarthritis. MATERIALS AND METHODS: Body mass index (BMI), waist circumference, waist-hip ratio (WHR), weight and percentage of body fat (BF%) were measured at baseline in 11,026 men and 16,934 women from the general population. The incidence of osteoarthritis over 11 years was monitored by linkage with the Swedish hospital discharge register. RESULTS: 471 individuals had knee osteoarthritis and 551 had hip osteoarthritis. After adjustment for age, sex, smoking and physical activity, the relative risks (RR) of knee osteoarthritis (fourth vs first quartile) were 8.1 (95% CI 5.3 to 12.4) for BMI, 6.7 (4.5 to 9.9) for waist circumference, 6.5 (4.6 to 9.43) for weight, 3.6 (2.6 to 5.0) for BF% and 2.2 (1.7 to 3.0) for WHR. Corresponding RR for hip osteoarthritis were 2.6 (2.0 to 3.4) for BMI, 3.0 (2.3 to 4.0) for weight, 2.5 (1.9 to 3.3) for waist, 1.3 (0.99 to 1.6) for WHR and 1.5 (1.2 to 2.0) for BF%. CONCLUSION: All measures of overweight were associated with the incidence of knee osteoarthritis, with the strongest relative risk gradient observed for BMI. The incidence of hip osteoarthritis showed smaller but significant differences between normal weight and obesity. Our results support a major link between overweight and biomechanics in increasing the risk of knee and hip osteoarthritis in men and women.

Adult height in women with childhood asthma--a population-based study.

PURPOSE: To study adult height in children that grew up with asthma before inhaled steroids became first-line therapy. METHODS: Data from the Swedish Medical Birth Register (self-reported asthma) and the Hospital Discharge Register (first hospitalization for asthma) were used, to compare adult height for asthmatic and non-asthmatic pregnant women. The analysis was restricted to women in their first full-term pregnancy, born in Sweden between 1960-1974 and of Swedish citizenship. RESULTS: The mean height of all the women in the study population was 166.7 cm (SD = 8.8, n = 287,750) and of the women who reported asthma 166.5 cm (SD = 6.1, n = 13,059, p < 0.01). The mean height of women first hospitalized because of asthma at age 0-8 years was 165.5 cm (SD = 5.9 cm, n = 555, p < 0.01). Among the asthmatic women, there was no skew distribution of heights. CONCLUSIONS: Girls with moderate to severe childhood asthma who grew up before inhaled glucocorticosteroids became first-line therapy attained 0.7-1.2 cm lower adult height. The differences in height. while of statistical relevance, are not clinically relevant.

Reduced height in swedish men with asthma at the age of conscription for military service.

OBJECTIVE: To investigate the influence of asthma on growth in Swedish children during a period when inhaled corticosteroids (ICS) have been first-line therapy for persistent asthma. STUDY DESIGN: We analyzed the height of conscripts with and without asthma in the year they turned 18 years old, using Swedish military conscription records from 1983, 1986, 1993, and 1996, and assessed exposure to ICS using prescription records over the same period. RESULT: The mean height for conscripts without asthma was 179.3 cm (SD = 6.6 cm, n = 164,503) and for conscripts with asthma 178.6 cm (SD = 6.6 cm, n = 8,531, P <.001). The severity of asthma had a negative correlation with height in all study populations (P <.001 in each year tested). Since 1985, increasing numbers of children with asthma have been treated with ICS in Sweden. Sales of ICS for males from birth to age 19 years increased from 68,000 daily doses in 1983 to more than 3, 000,000 in 1995-1996. During this period, there was no statistically significant change in the height difference between conscripts with and without asthma. CONCLUSION: The introduction of inhaled steroids in Sweden, where budesonide is the predominant medication, has not changed the mean difference in heights between Swedish conscripts with and without asthma.

[Physical inactivity and cancer--is this a causal relationship?]. / Fysisk inaktivitet och cancer--är sambanden kausala?

Strong epidemiological evidence suggests relationship to exist between physical inactivity and the risk of large bowel cancer (especially colon cancer). Moreover, there are indications that inactivity is also associated with an increased risk of endogenous hormone-related cancer (especially breast cancer). However, further research is needed to determine whether such relationships are casual, and if so to identify the underlying mechanisms. Since a large proportion of the populations of industrial countries are characterized by a sedentary lifestyle, even a small risk may be associated with high attributable fraction. Moreover, not only are the types of cancer concerned common, but inactivity is also associated with a number of other chronic diseases. Accordingly, the health benefit to be derived from a general increase in physical activity might be substantial.

Avoidable cancers in the Nordic countries. Diet, obesity and low physical activity.

In the early 1980s, Doll and Peto estimated that about 35% of all deaths from cancer in the United States were attributable to dietary factors, with a margin of uncertainty ranging from 10 to 70%. Since then, several dietary factors, e.g. fat and meat, have been suggested to increase the risk for cancer, while other factors, e.g. fibre, fruit and vegetables, have been suggested to decrease the risk. The case-control and cohort studies have, however, given ambiguous results, and the overall evidence is far from conclusive. The major findings on dietary factors that increase risk have been reported from case-control studies, but have not been confirmed in large population-based cohort studies. Although the research in this area indicates that diet is important in cancer prevention, current knowledge does not allow reliable estimates of the numbers and proportions of cancers that could be avoided through well-described modifications of dietary habits. During the last 10 years, low physical activity has been pinpointed as a risk factor for cancers at various sites, especially the colon; however, the causal mechanism is still unknown. Obesity, defined as a body mass index of 30 or more, is consistently associated with endometrial and gall-bladder cancers in women and renal-cell cancer in both men and women. As the prevalence of obesity was between 5 and almost 20% in the Nordic populations in 1995, 625 cancer cases (310 endometrial cancers, 270 renal-cell cancers in men and women and 45 gall-bladder and bile-duct cancers among women) can be predicted in the Nordic countries around the year 2000 to be caused by obesity. This implies that about 1% of all cancers in Nordic women and less than 1% of those in Nordic men could be avoided around the year 2000 if a healthy body weight could be maintained by all inhabitants.

Summary of avoidable cancers in the Nordic countries.

An overview is given of the most important known causes of cancer in the five Nordic countries and the resulting number of cancers that are potentially avoidable. The main causes include active and passive smoking, alcohol consumption, exposure to asbestos and other occupational carcinogens, solar and ionizing radiation, obesity, human papillomavirus infection in the female genital tract and infection with Helicobacter pylori. The organs most commonly affected are those of the respiratory system, the upper digestive tract and stomach, skin, the lower urinary tract and the uterine cervix. Annually, more than 18,000 cancers in men and 11,000 in women in the Nordic populations could be avoided by eliminating exposure to known carcinogens which is equivalent to 33% and 20% of all cancers arising in men and women, respectively, around the year 2000. Smoking habits account for a little more than half of these avoidable cases. Estimates of avoidable cancers are given for each Nordic country, separately.

Dietary calcium, vitamin D, and the risk of colorectal cancer in Stockholm, Sweden.

The epidemiology of large bowel cancer suggests an etiological role for dietary factors. Although the evidence is inconsistent, several studies have suggested an inverse association between dietary vitamin D or calcium and colorectal cancer risk. We conducted a population-based case-control study to examine the relationship between dietary vitamin D and calcium and colorectal cancer among residents of Stockholm, Sweden. Between January 1986 and March 1988, 352 cases of colon cancer and 217 cases of rectal cancer diagnosed among living persons residing in Stockholm County were identified via a cancer surveillance network established among all the hospitals in Sweden and the Stockholm Regional Cancer Registry. Controls (512) were randomly selected from a computerized population registry. Dietary intake was assessed using a quantitative food frequency questionnaire focusing on average consumption during the preceding 5 years. Supplemental intake of vitamin D and calcium was not ascertained. Logistic regression was used to calculate odds ratios (ORs) as the measure of association between the exposure of interest (vitamin D or calcium) and cancer risk. Increasing levels of dietary vitamin D were inversely associated with the risk of colorectal cancer. The association was somewhat more pronounced for cancers of the rectum [OR, 0.5; 95% confidence interval (CI), 0.3-0.9 between the highest and lowest quartiles] than for cancers of the colon (OR, 0.6; 95% CI, 0.4-1.0) after adjustment for age, sex, and total caloric and protein intake. Dietary calcium was not associated with the adjusted risk of colon (OR, 1.2; 95% CI, 0.7-2.1) or rectal cancer (OR, 1.0; 95% CI, 0.5-1.9). Further adjustments for fat and dietary fiber intake, body mass index, and physical activity had little or no effect on the results. These results suggest that dietary vitamin D may reduce the risk of large bowel cancer, particularly rectal cancer. In addition, although some of the previous data suggested a protective effect for calcium against cancers of the large bowel, we could not document such an effect.

Alcohol consumption and stroke mortality. 20-year follow-up of 15,077 men and women.

BACKGROUND AND PURPOSE: Since stroke is a principal cause of death in elderly people, we analyzed the association between alcohol and stroke mortality in a cohort of 15,077 middle-aged and older men and women. METHODS: Data on alcohol habits were obtained from a questionnaire in 1967. The subsequent 20 years yielded 769 deaths from stroke, of which 574 were ischemic. Relative mortality risks (RR) were estimated from logistic regression analyses with lifelong alcohol abstainers as a reference group. Adjustments were made for age and smoking. RESULTS: No association was found between alcohol intake and hemorrhagic stroke. An elevated risk of ischemic stroke was found for men who drank infrequently, that is, a few times a year or less often (RR, 2.0; 95% confidence interval [CI], 1.3 to 3.2), for those who were intoxicated now and then (RR, 1.8; 95% CI, 1.1 to 2.8), and for those who reported "binge" drinking a few times in the year or less often (RR, 1.6; 95% CI, 1.1 to 2.5). Among women only ex-drinkers had an elevated risk of dying of ischemic stroke (RR, 3.3; 95% CI, 1.5 to 7.2). The risk was reduced for women who had an estimated average consumption of 0 to 5 g pure alcohol per day (RR, 0.6; 95% CI, 0.5 to 0.8); for those who did not drink every day (RR, 0.7; 95% CI, 0.5 to 0.9); and for those who never "went on a binge" (RR, 0.6; 95% CI, 0.5 to 0.8) or became intoxicated (RR, 0.7; 95% CI, 0.5 to 0.9). CONCLUSIONS: Drinking habits were associated only with deaths from ischemic stroke, and the risk patterns were different for men and women. In analyses, ex-drinkers should not be included with lifelong abstainers, since the former tend to run high health risk.

Mortality among HIV-infected intravenous drug addicts in Stockholm in relation to methadone treatment.

The aim of the study was to estimate the mortality rate and evaluate the causes of death in all diagnosed HIV-positive IDUs in the Stockholm area, 1986-90, and to compare the risk of death of those who received methadone treatment with that of those never admitted to or discharged from the programme. Data were collected from the Swedish National Bacteriological Laboratory, the Methadone Maintenance Programme (MMTP) and the Department of Forensic Medicine, as well as from hospitals in the Stockholm region. In Sweden 90% of all IDUs are HIV-tested. Most deceased IDUs are examined forensically. This examination always includes HIV-testing. During the observation period, 472 HIV-infected IDUs were reported from the Stockholm area. Of these addicts 135 participated in the methadone maintenance programme for a shorter or longer time during the study period. Most of them had received the HIV-diagnosis more than 1 year before first entering the programme. Sixty-nine subjects died during the observation period. A majority, 52 persons, died from violence or poisoning. Seventeen died from somatic complications of drug abuse. Nine of them were diagnosed as suffering from AIDS. Eight of the deceased had participated in the MMTP. The relative risk of death from external violence and poisoning was 0.25 (95% confidence interval 0.1-1.0) when participants in the MMTP were compared with HIV-infected IDUs never attending the programme. When all causes of death are compared the relative risk was 0.8. Those patients discharged from the programme have a higher mortality rate than those who never participated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen, some other drugs, some diseases and the risk of transitional cell carcinoma. A population-based case-control study.

The purpose of this study was to investigate the risk of transitional cell carcinoma among subjects with an intake of acetaminophen, aspirin, some other drugs and with some intercurrent diseases. The source person-time ('study base') included subjects living in Stockholm in 1985-1987. The study included 325 subjects with a transitional cell carcinoma of the urinary tract and 393 controls randomly selected from the source person-time. Data were obtained by a postal questionnaire supplemented by a telephone interview. A relative risk (with a 95% confidence interval) of 1.6 (1.1-2.3) was obtained after an intake of acetaminophen, adjusted for age, aspirin, gender and smoking. Conversely, a 30% decrease in risk was obtained after an intake of aspirin. No details in the exposure substantiated the finding for acetaminophen. The inherent validity problems of observational studies, and the weak evidence in this and previous studies of the association between acetaminophen and transitional cell carcinoma, makes available epidemiological evidence insufficient to regulate the use of this commonly ingested analgesic. Increased risks were, in addition, found for tetracyclines, nitrofurantoin and a history of allergic asthma and a decreased risk found for rheumatic symptoms. The findings stress the nonepidemiological data concerning the potential carcinogenicity of acetaminophen and may be a foundation for future research of some other drugs and diseases.

Epidemiologic studies on fried foods and cancer in Sweden.

Three population-based case-control studies in Sweden have found an association between fried foods and pancreatic cancer, urothelial cancer and colorectal cancer, respectively. Only one of these studies included questions about the preferred method of frying the meat surface. This study was performed in Stockholm in 1986-88 and included 347 cases of colon cancer, 212 cases of rectal cancer and 505 controls. Total meat intake, frequent consumption of brown gravy, and a preference for a heavily browned meat surface each independently increased the risk for colorectal cancer. The relative risks (RRs) were higher for frequent intake of boiled meat (RR colon = 1.7, RR rectum = 2.7) than for frequent intake of meat fried with a medium or lightly browned surface (RR colon = 0.8, RR rectum = 1.1), but the highest risks were for frequent intake of meat fried with a heavily browned surface (RR colon = 2.8, RR rectum = 6.0). The analyses were adjusted for year of birth, gender and fat intake. Further adjustments for total energy, dietary fiber intake, body mass and physical activity had little or no influence on the relative risks. These results indicate that the cooking method is a neglected risk factor for cancer, but also that the measurements of exposure, used so far, are inadequate. First, the agents (exposure) of interest have to be identified in laboratory studies; secondly, accurate methods to measure the exposure in epidemiologic studies have to be established; and thirdly, these methods have to be used in well-designed epidemiologic studies.

Coffee, tea, tobacco, and cancer of the large bowel.

The impact of tobacco use and coffee and tea intake on the risk of colorectal cancer is unclear. Previous research has suggested that coffee may be protective against these cancers, and investigation regarding tea or cigarette smoking has yielded inconsistent results. To clarify these issues, we evaluated coffee and tea intake and tobacco smoking as risk factors for cancer of the colon and rectum in a population-based case-control study from Stockholm, Sweden. Cases were ascertained from the regional cancer registry, and controls identified through population registers. Subjects completed a questionnaire requesting information regarding foods and beverages consumed, exercise, tobacco use, and personal characteristics. Logistic regression modelling was used to compute odds ratios. A total of 352 cases of colon cancer, 217 cases of rectal cancer, and 512 controls took part. High coffee intake was negatively associated with the risk of colon cancer: the odds ratio for those drinking 6 or more cups per day was 0.55 (95% confidence interval, 0.31-0.96) compared to those drinking one or fewer. There was no association with rectal cancer. For tea, the associations were the opposite: there was no association with colon cancer risk, but the odds ratio for rectal cancer was 0.56 (95% confidence interval, 0.34-0.90) for those drinking 2 or more cups per day compared with those drinking none. Smokers of 11 or more cigarettes per day had a 20 to 30% reduction in the risk of colon and rectal cancer, but these findings were consistent with chance. There was no association of long-term cigarette smoking with risk.

Alcohol and cancer of the colon and rectum.

The association between alcohol intake and colorectal cancer was examined in a population-based case-control study performed in Stockholm in 1986-88. The study included 352 cases of colon cancer, 217 cases of rectal cancer, and 512 controls. Relative risks, with 95% confidence intervals, were calculated for total alcohol intake and for different alcoholic beverages. Total alcohol intake (> or = 30 g 100% ethanol per day) was not associated with colon cancer (relative risk = 0.9, confidence intervals = 0.4-1.8) or rectal cancer (1.0, 0.4-2.1). There was no evidence supporting beverage specificity (for colorectal cancer and > or = 10 g 100% ethanol per day: beer 1.1, 0.6-2.0, wine 1.0, 0.4-2.7, spirits 1.0, 0.6-1.6). The associations did not vary according to gender or site within the large bowel. These analyses were adjusted for year of birth and gender (when appropriate). Further adjustments for diet, body mass or physical activity had little or no influence on the results. The present study does not support the hypothesis that alcohol plays an important role in the aetiology of cancer of the colon and rectum in a population with a relatively low alcohol intake.

Stressful life events and the risk of colorectal cancer.

We examined the relation of stressful life events to the risk of colorectal cancer in a population-based case-control study conducted in Stockholm from 1986 to 1988. Completed questionnaires were available for 569 incident cases ascertained through hospital records and the regional cancer registry. Controls were randomly selected from a population register and were frequency matched to the age and sex distribution of the cases; 510 controls completed the study questionnaire. A history of serious work-related problems in the prior 10 years was strongly associated with the occurrence of colorectal cancer. Compared with those with no such problems, the age- and sex-adjusted odds ratio (OR) was 5.5 [95% confidence interval (CI) = 2.3-23.5]. Change of residence was also associated with increased risk: relative to those who had not moved, the OR was 2.8 (95% CI = 1.1-7.1). Similar analyses revealed that increased odds of colorectal cancer were associated with death of a spouse: OR = 1.5 (95% CI = 1.0-2.3). After multivariate adjustment for dietary risk factors and physical activity, these ORs were not substantially altered. Because most of the events were relatively uncommon in this population, the estimates of effect were not precise.

The epidemiological evidence concerning intake of mutagenic activity from the fried surface and the risk of cancer cannot justify preventive measures.

In the fried meat surface layer (the meat crust) mutagenic heterocyclic amines are formed during cooking. A human cancer risk is conceivable after intake of such mutagenic activity. We investigated the current literature mentioning fried foods, and six studies of colorectal cancer, three of stomach cancer and one each of cancer of the breast, lower urinary tract and pancreas are included. None of the reports tried to assess directly the intake of mutagenic activity from the fried surface. One indirect measure of mutagenic activity is to look at the browning of the meat surface; two investigations are available for this variable. The content of mutagenic activity in the surface may vary with the 'doneness' of meat and two studies consider this variable. Another indirect measure is to compare results from meat irrespective of cooking methods (ie, comparing meat not fried with fried meat or fried foods). There are several validity problems in the reviewed studies. Major potential sources of bias include, quite apart from misclassification of mutagenic activity, possible confounding factors from meat per se and fat. The epidemiological evidence in the field is sparse and cannot justify preventive measures.