Factors associated with poor asthma control in children aged five to 13 years.

BACKGROUND: Most children with asthma should be able to achieve acceptable control. However, are there differences between those with acceptable and poor control, and if so, how can health care approaches be modified accordingly? OBJECTIVE: To examine the characteristics of elementary school children aged five to 13 years with acceptable and poor levels of asthma control. METHODS: The present cross-sectional study of children with asthma used five indicators of control, as outlined by the Canadian Asthma Consensus Report, to categorize acceptable and poor asthma control. RESULTS: Of 153 children, 115 (75%) were rated as having poorly controlled asthma. Of those with poor control, 65 (64%) children were currently using inhaled corticosteroids, and 65% of those reported using inhaled corticosteroids daily versus as needed. Fifty-one per cent of the children with poorly controlled asthma had exposure to tobacco smoke, whereas 79% of the children with asthma under acceptable control were from households with no smokers (P=0.002). The poor control group also had significantly worse parental perceptions of the psychosocial impact of asthma on their child. No significant difference was found in the percentage of those who had written action plans in the poor control group (28%) compared with the acceptable control group (26%), and similar percentages in each group stated that they used the plans. CONCLUSIONS: Despite the high use of inhaled corticosteroids, the majority of children had poorly controlled asthma. The poor control group had more exposure to tobacco smoke and a worse psychosocial impact due to asthma. Few children had past asthma education and action plans, suggesting that there is a need to improve access to and tools for education.

Lung health in sawmill workers exposed to pine and spruce.

Workers exposed to a variety of wood dusts have been shown to exhibit occupational asthma, lung function deficits, and elevated levels of respiratory symptoms. Despite the popularity of pine and spruce, the health effects of exposures to these woods have not been extensively investigated. A study was undertaken to investigate the respiratory health of a group of sawmill workers processing pine and spruce (n = 94). Data collection included a respiratory symptom questionnaire, spirometry, and allergy skin testing. The sawmill workers were compared with a group of oil field workers from the same geographic area who underwent the same study protocol (n = 165). The results showed that the sawmill workers had significantly lower average values for FEV1 and FEV1/FVC (%), adjusted for age, height, and smoking. The largest differences were for current smokers. Significantly elevated age and smoking-adjusted odds ratios (OR) were detected for shortness of breath (2.83; 95% confidence interval [CI], 1.47 to 5.46) and wheeze with chest tightness (2.58; 95% CI, 1.18 to 5.62). Nonsignificant elevations were also seen for usual cough (1.47; 95% CI, 0.68 to 3.16), usual phlegm (1.94; 95% CI, 0.98 to 3.87), shortness of breath with exercise (1.45; 95% CI, 0.66 to 3.20), chest tightness (1.43; 95% CI, 0.80 to 2.57), and attacks of wheeze (1.70; 95% CI, 0.79 to 3.68). Sawmill workers were 2.5 times as likely as oil field workers to report current asthma (95% CI, 0.76 to 8.32). Workers employed more than 3 years showed significantly more asthma (OR = 3.67; 95% CI, 1.00 to 13.5) and bronchitis (OR = 2.14; 95% CI, 1.02 to 4.52). Sawmill workers were only 43% as likely to report a history of hay fever (95% CI, 0.20 to 0.94). These health effects were noted despite an average concentration of respirable dust of 1.35 mg/m3 (range, 0.1 to 2.2 mg/m3). These levels are below the present occupational standard.

Terminal digit preference in blood pressure measurements: effects on epidemiological associations.

A study was conducted to determine the extent of terminal digit preference in recording blood pressures in an industrial screening programme and its effect on the estimates of the associations between blood pressure and both age and body mass index (BMI). The results showed that 78.5% of systolic and 74.2% of diastolic blood pressure readings were digit preferenced (p less than 0.0001) and that the examining doctors were least likely to preference their readings near the diagnostically important cut-off points of 150 mmHg systolic and 90 mmHg diastolic. Digit preferencing did not generally affect estimates of the slopes and intercepts of the relationships between blood pressure and age or BMI, however, the associations between blood pressure and both age and BMI showed greater error variance when digit preferenced readings were used compared to non-digit preferenced readings. Digit preferencing would have the effect of reducing the power of statistical tests thereby making it more difficult to assess associations between blood pressure and other potential risk factors.

Tuberculosis among institutionalized elderly in Alberta, Canada.

Previous studies in the US have suggested that the risk of tuberculosis is increased among elderly residents of nursing homes. This registry-based study determined and compared the tuberculosis incidence rate for the elderly in nursing homes and community dwellings in Alberta, Canada, over the 5-year period 1979-1983. Rate ratios (RR) using the community elderly rate as baseline, were estimated for all notified cases and for culture positive cases only. Adjustment was made for the variables age, sex, and ethnicity. The nursing home elderly in Alberta did not have an increased risk of tuberculosis: adjusted RR = 1.09, 95% CI : 0.38-1.80.

Respiratory questionnaires in occupational studies: their use in multilingual workforces on the Witwatersrand.

The mother tongue of the majority of black workers in the industrial workforces of the Witwatersrand is either Zulu or S Sotho/Tswana, and these are also the main languages spoken in the area. However a substantial minority cite one of several other languages as their mother tongue. In consequence, in occupational surveys using a respiratory questionnaire, the accepted practice has been to use multilingual interviewers who administer the questionnaire in whichever of the two main languages the interviewee requests, but work from an English language version. To test the reproducibility of the information so gathered, a standardized questionnaire was administered to 56 subjects on two occasions approximately three weeks apart by each of two interviewers, one of whose mother tongue was Zulu and the other S Sotho. Reproducibility was little affected by whether the interviewer used her mother tongue or not, pointing to the multilingual competence of both interviewers. Reproducibility was, however, less in subjects not interviewed in their mother tongue compared to those who were. In general, reproducibility was also less for symptom than for history questions, though the phlegm question performed comparably to that reported for more homogeneous language/ethnic groups. Thus, even if internally valid, respiratory symptom information obtained by this method may have limited generalizability. However respiratory history information appears more reliable and may prove of value in the investigation of the natural history of chronic lung disease in this and similar communities.

Lung health in Alberta farmers.

SETTING: A study conducted in the rural areas of two counties in east-central Alberta, Canada. OBJECTIVE: To investigate the relationship between lung health and dust exposure in farmers. DESIGN: A cross-sectional study of 781 farmers growing grain crops and raising livestock. Measurements included a questionnaire on respiratory symptoms, smoking habits and occupation, skin prick tests using common aeroallergens, and spirometry. RESULTS: Immediate skin reactivity to common aeroallergens was less prevalent in farmers with higher reported intensity of dust exposure. Respiratory symptoms suggestive of bronchitis had a significant dose-response relationship with the reported intensity of dust exposure. Respiratory symptoms consistent with bronchial responsiveness were significantly positively associated with cumulative dust exposure. There was a significant positive association between a physician's diagnosis of bronchitis and intensity of dust exposure. FEV1 and FEV1/FVC were significantly negatively associated with cumulative dust exposure. Ten years of exposure to a moderate dust level was associated with a deficit of 43 ml in the FEV1 and a deficit of 0.44% in the FEV1/FVC. CONCLUSIONS: Despite evidence of worker selection related to dust exposure, these farmers experienced respiratory symptoms, respiratory conditions, and reduced lung function associated with reported occupational dust exposure.

Hearing loss among construction workers in Edmonton, Alberta, Canada.

Hearing acuity among electricians, plumbers and pipefitters, and boilermakers with > or = 20 years of union membership was compared with that of telephone workers. Automated pure tone audiometry was performed and a questionnaire was administered. Most construction workers were exposed to occupational noise and wore hearing protection. Median thresholds for electricians and telephone workers were comparable. Thresholds of plumbers and pipefitters were higher but comparable to expected values. Boilermakers had high levels of hearing loss. Thresholds at 4000 Hz among older workers were similar for all groups and were above expected values, suggesting a cohort effect. Audiometric screening seems to be warranted for some construction workers.

Pulmonary effects of simultaneous exposures to MDI formaldehyde and wood dust on workers in an oriented strand board plant.

A study was undertaken in a plant producing oriented strand board (OSB) from aspen and balsam wood, bonded by methylene diisocyanate (MDI) and phenol formaldehyde. A group of 127 production workers in the plant was compared to 165 oil workers from the same geographic area. Measurements of MDI ranged from 6 to 33 micrograms/m3 (0.001-0.003 ppm), of respirable dust ranged from 0.05 to 0.5 mg/m3, and of formaldehyde were 0.05 ppm or less. The ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) was significantly lower among the OSB workers compared to the oil workers, and this was more pronounced for ex-smokers and current smokers. A number of respiratory symptoms suggestive of airway reactivity were significantly more common among the OSB workers. It was known that changes to reduce worker exposure had been made in the plant before the study, and it is unclear whether the health effects documented were the result of these low levels or if previous, probably higher levels were responsible.

Lung health among electricians in Edmonton, Alberta, Canada.

Respiratory symptoms, lung function, and radiographic changes among 100 actively employed electricians in Edmonton, Alberta, Canada, with 20 or more years of union membership were compared with those of 100 telephone workers. Posteroanterior chest radiographs were evaluated by two experienced chest physicians, with a third arbitrating films that were disagreed upon. Employment in a number of industrial sectors was compared for time and for time-weighted exposure to dust and fumes. Compared with telephone workers, electricians had more usual cough (odds ratio [OR] = 3.36; 95% confidence interval [CI], 1.36-8.31), usual phlegm (OR = 2.44; 95% CI, 1.01-5.86), chronic phlegm (OR = 2.74; 95% CI, 1.13-6.60), and shortness of breath (OR = 2.26; 95% CI, 1.10-4.67), but no differences in lung function. The prevalence of radiographic changes in both groups was low. The electricians had more radiographic changes, but only for the category "any change" was the difference statistically significant (OR = 5.2; 95% CI, 1.06-23.93). Only two electricians had small irregular opacities. Phlegm, chronic phlegm, and chest tightness were significantly associated with cumulative exposure to fumes in the gas and oil industry and to total industrial construction.

Silica, silicosis, and lung cancer: a response to a recent working group report.

The relationship between crystalline silica and lung cancer has been the subject of many recent publications, conferences, and regulatory considerations. An influential, international body has determined that there was sufficient evidence to conclude that quartz and cristobalite are carcinogenic in humans. The present authors believe that the results of these studies are inconsistent and, when positive, only weakly positive. Other, methodologically strong, negative studies have not been considered, and several studies viewed as providing evidence supporting the carcinogenicity of silica have significant methodological weaknesses. Silica is not directly genotoxic and is a pulmonary carcinogen only in the rat, a species that seems to be inappropriate for assessing particulate carcinogenesis in humans. Data on humans demonstrate a lack of association between lung cancer and exposure to crystalline silica. Exposure-response relationships have generally not been found. Studies in which silicotic patients were not identified from compensation registries and in which enumeration was complete did not support a causal association between silicosis and lung cancer, which further argues against the carcinogenicity of crystalline silica.

The Alberta Heart Health Survey: methods and results.

OBJECTIVE: The Alberta Heart Health Survey is a population-based investigation of cardiovascular disease (CVD) risk factor prevalence and awareness among Albertans 18 to 74 years of age. DESIGN: A stratified, two-stage, replicated probability sample design developed by Statistics Canada was used to select 3437 individuals (2740 were located) from the Alberta Health Care Insurance Plan enrollment list. Trained community health nurses (n = 36) from 13 public health units conducted home interviews (n = 2237, response rate 82%) and subsequent clinic visits (n = 1993) from February to June 1990, using a core protocol common to similar studies conducted in other provinces, as part of the Canadian Heart Health Initiative. SETTING: The home interview collected data on individual and household demographic characteristics, smoking, alcohol consumption, physical activity, treatment and control of high blood pressure and high blood cholesterol, and family history of CVD. Clinic visits included blood collection for analysis of total plasma cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides; weight, height, waist and hip circumference, and two blood pressure measurements. Standardized protocols were used. Lipid analyses were conducted by the Lipid Research Laboratory, University of Toronto. Data management and analysis were conducted at the University of Alberta. MAIN RESULTS: The overall risk factor prevalence estimates were: high blood pressure 14%; smoking 27%; total cholesterol of at least 5.2 mmol/L, 36%; HDL cholesterol less than 0.9 mmol/L, 10%; LDL cholesterol of at least 3.4 mmol/L, 29%; body mass index 25 or more, 51%; sedentary lifestyle 37%. One or more of the three major risk factors (smoking, high blood pressure, high blood cholesterol) occurred in 57% (70% in those with 12 years of education or less). CONCLUSIONS: While the prevalence rates for the major risk factors are among the lowest in Canada, they are unacceptably high.

The epidemiology of childhood asthma in Red Deer and Medicine Hat, Alberta.

OBJECTIVES: To document the prevalence of asthma among school-aged children in two Alberta communities, to understand host and indoor environmental factors associated with asthma, and to compare these factors between the two communities. DESIGN: A cross-sectional study with a nested, case-control follow-up. SETTING: Red Deer and Medicine Hat, Alberta. PATIENTS AND METHODS: Questionnaires were sent to families of children aged five to 19 years in Red Deer (n=5292) and Medicine Hat (n=5372) to identify children with current asthma. A random sample of 592 children with current asthma and 443 with no history of asthma constituted a case-control population; they were followed up by telephone to obtain responses to the European Respiratory Health Survey and, in children with current asthma, the Pediatric Quality of Life Questionnaire. RESULTS: Cross-sectional response rates were 84% and 73% for Red Deer and Medicine Hat, respectively. The prevalence of asthma was higher in Medicine Hat (17.0%) than in Red Deer (12.8%). In the follow-up study, factors associated with the presence of asthma were parental asthma or allergies, number of siblings, presence of cats, serious respiratory illnesses before five years of age, sex, age, presence of mould and/or mildew and use of a gas cooking stove. The presence of mould and/or mildew was a significant risk factor in Red Deer but not in Medicine Hat. CONCLUSIONS: Asthma prevalence among school children in Red Deer was consistent with recently published Canadian data; the prevalence in Medicine Hat was higher than expected, especially given the low relative humidity. Risk factor data are consistent with other studies in that parental asthma, especially maternal asthma, was a significant predictor of childhood asthma. Cats in the house (both communities) and environmental tobacco smoke (Medicine Hat only) were significantly less common among children with asthma, suggesting that preventive actions may have been taken in the homes of some children with asthma.

Factors that influence emergency department visits for asthma.

BACKGROUND: Asthma can usually be controlled through allergen avoidance and/or appropriate medication. An emergency department visit for an acute exacerbation of asthma often represents a breakdown in asthma management. Emergency department treatment results in significant health care expenditures and reflects a compromised quality of life. OBJECTIVES: To identify risk factors associated with an emergency department visit for asthma. METHODS: This case-control study compared 299 people (76% of 390 cases contacted) who attended one of two emergency departments in Alberta in 1992 and 1993 for an acute exacerbation of asthma (cases) with 212 unmatched community controls with asthma who were located by random digit dialing. Cases and controls were asked to complete a mailed questionnaire to obtain data regarding severity, visits to doctors and emergency departments, medication use, allergies and other triggers, and smoking history. Data analysis included bivariate analysis of risk factors and multivariate model development using logistic regression. RESULTS: The response rate was similar between cases and controls. Cases were younger than controls (odds ratio [OR] 2.16, 95% CI 1.34 to 3.48) and more often reported their asthma to be severe (OR 4.25, 95% CI 2.24 to 8.06), and had experienced nocturnal symptoms (stratified OR range 1.36 to 6.82). Cases used more health care services in the previous year, had been admitted to hospital at some time for asthma (OR 1.62, 95% CI 1.10 to 2.38) and used more medication than controls. CONCLUSIONS: Physicians and other health care workers should be sensitive to the risk factors and target interventions to high risk individuals.

Acute respiratory infections in the Canadian Native Indian population: a review.

Acute respiratory infections (ARI) are a major cause of morbidity and mortality among Natives in Canada. Studies examining the mortality experience of Canadian Natives have reported SMRs for ARI ranging from 2.92 to 21.23. Morbidity from ARI is also increased relative to other Canadians with rate ratios for pneumonia ranging from 3.28 to 17.6. Several risk factors have been associated with an increase in ARI including smoking, exposure to passive smoke, feeding practices, and socioeconomic factors such as housing, residential crowding and family size. The effects of other risk factors are less clear. There continues to be a need for epidemiological studies of ARI in Canadian Natives while at the same time, ARI control programs should be implemented to reduce the incidence and severity of acute respiratory infections in this population.

Health behaviours of pregnant women in Fort McMurray, Alberta.

Baby. Vision was a survey of lifestyle behaviours of pregnant women in the Fort McMurray area, conducted between April and June 1989. The survey goal was to establish baseline data for coordinated health promotion programs for expectant parents. Questionnaires were completed by 173 pregnant women. Overall the women were well educated and in high-income households. Approximately one third of the women (36.6%) reported smoking during pregnancy. Most (90%) were exposed to second-hand smoke. Almost half (48.8%) stated they had consumed alcoholic beverages since learning of their pregnancy. Thirty percent were unaware of their immunization status. Most (98%) reported doing something to improve their health during this pregnancy, improved eating habits being most often mentioned. The results indicate that health promotion activities might improve the birth outcomes in Fort McMurray and outlying areas. The data may be relevant to other relatively remote areas in Canada.

The hopes and hazards of health goals development.

As part of the Edmonton Board of Health's centennial celebrations, health goals and objectives were developed for the city. The intensely collaborative process used to develop the goals and objectives is reviewed and critical activities such as communication, media and community involvement, committee membership, and implementation are discussed. It is hoped that the information will be useful for others who are developing health goals and objectives at the municipal level.

Asthma and limitation of activities in Fort Saskatchewan, Alberta.

A study was undertaken to determine the prevalence and impact of asthma in elementary school children in Fort Saskatchewan, Alberta. Questionnaires were distributed at all seven elementary schools and were completed by the parents. Of the 1,457 eligible students in grades one to six, questionnaires were returned for 1,083 (74%). A history of physician-diagnosed asthma was reported for 12.9% of the children: 16.0% of boys and 9.7% of girls. Currently, 9.9% of children had asthma: 11.6% of boys and 8.2% of girls. Compared to children without, those with asthma were more than 10 times as likely to have to limit their activities for a health reason (70.5% versus 6.6%), missed school more often for health reasons (32.7% versus 14.8% missed two or more days in the previous month), reported more "colds" in the previous year and were three times as likely to have had pneumonia. The prevalence of asthma is approximately twice as high as that found in children across Canada and underscores the need to determine risk factors for asthma in this population. The finding that 1 in 10 children had asthma emphasized the need for programs aimed at children with asthma.

Validation of self-reported transfusion histories in renal dialysis patients.

The purpose of this analysis was to assess the validity of self-reported transfusion histories in dialysis patients. Using data from a cross-sectional study of a dialysis population being investigated for hepatitis C virus (HCV) infection, the correspondence between self-reported transfusion history and transfusion records was explored. Demographic data and dialysis histories were examined in relation to the accuracy of self-reports. Overall, the questionnaire data and the blood bank records agreed for 89% of participants. The Kappa statistic was 0.72 (95% CI: 0.61, 0.83) indicating an acceptable level of agreement. The effect of non-differential exposure misclassification on the risk estimates for transfusion history as a determinant of HCV infection is demonstrated. Exploring the discrepancies between self-reports and documented transfusion histories underlines the need to communicate clearly medical interventions in chronically ill patients. Additionally, it suggests that studies into transfusion-acquired blood-borne pathogens should use all available information sources to establish exposure.

Acute care hospital morbidity in the Blood Indian Band, 1984-87.

Acute care hospital morbidity of the Blood Indian Band was compared with that of all Albertans between April 1, 1984 and March 31, 1987. The Blood Indians had over 2.5 times as many hospital separations and 2.2 times as many patient days as the Albertans. The highest separation rare ratios by ICD-9-CM chapter for both Blood males and females were for endocrine, metabolic and nutritional disorders. Blood females had higher rate ratios for hospitalizations for all chapters except neoplasms and Blood males had higher rate ratios for all except congenital anomalies and neoplasms. For individual conditions, Blood males had the highest separation rate ratios for alcohol dependence syndrome, gastritis/duodenitis and diabetes mellitus. Bronchitis/emphysema and diabetes mellitus had the highest rate ratios for Blood females. The results are consistent with those reported in other studies of North American Indians. Their health status is more consistent with a developing country than that expected in Canada and does not appear to be improving.

Occupational noise exposure and blood pressure: longitudinal and cross-sectional observations in a group of underground miners.

The question of an association between occupational noise exposure and blood pressure has important public health implications. The harmful effects of hypertension are well known, and noise is considered the most pervasive of all occupational exposures. Most previous studies have looked cross-sectionally at blood pressure and noise exposures in workers. The present study examined historic medical and personnel records of 2,197 white male South African miners. At approximately 3-y intervals, the job title, diastolic and systolic blood pressures, height, weight, and use of medication for hypertension were recorded. Noise levels were estimated, based on noise measurements of individual jobs and work areas. In the cross-sectional analyses, multiple linear regression was used with blood pressure as the dependent variable; age, body mass index (BMI), and noise exposure were the independent variables. Longitudinal analyses were performed for those miners who had observations at four or more time periods, by calculating regression coefficients for individuals for blood pressure and noise, controlling for age and BMI. Additional longitudinal analyses compared blood pressure changes between two points in time for individual miners with changes in noise exposure, controlling for changes in age and BMI. The results of the cross-sectional and longitudinal analyses indicated no association between blood pressure and noise exposure. On the basis of these results, it does not appear that occupational noise exposure has an effect on blood pressure. Inconsistencies in the literature and shortcomings in the present study indicate that additional study is needed.