Accuracy of chest x-ray screening of silica-exposed miners for tuberculosis.

BACKGROUND: The World Health Organization recommends systematic chest X-ray (CXR) screening for tuberculosis (TB) in silica-exposed workers. However, evidence on the accuracy of CXR screening in such populations is lacking. AIMS: To measure the accuracy of CXR screening for active TB in silica-exposed miners, in a population with a high prevalence of silicosis, post-TB lung disease and HIV. METHODS: A secondary analysis of data from a miner screening programme in Lesotho was undertaken. We measured the performance of CXR (in participants with and without cough) for 'abnormalities suggestive of TB' against Xpert MTB/RIF (Xpert). The sample size was 2572 and positive Xpert prevalence was 3%. RESULTS: CXR alone had high sensitivity (0.93, 95% confidence interval [CI] 0.87-0.99), but low specificity (0.41, 95% CI 0.39-0.42). Requiring cough and a positive CXR increased specificity (0.79, 95% CI 0.77-0.81), resulting in reduced sensitivity (0.41, 95% CI 0.30-0.52). There was no difference in CXR accuracy by HIV status. However, specificity was markedly reduced in the presence of silicosis (from 0.70, 95% CI 0.68-0.72, to 0.03, 95% CI 0.02-0.04) or past TB history (from 0.59, 95% CI 0.56-0.62 to 0.27, 95% CI 0.25-0.29). Throughout, positive predictive value remained very low (5%) and negative predictive value very high (99%). CONCLUSIONS: CXR screening accurately identifies TB-negative CXRs in this population, but post-TB lung disease and silicosis would result in a high proportion of Xpert-negative referrals and an increased risk of unneeded empirical treatment. Adapted screening algorithms, practitioner training and digital access to previous mining CXRs are needed.

Disulfiram reaction in an artist exposed to solvents.

This case report describes an artist on treatment for alcoholism with disulfiram (Antabuse) who suffered chronic symptoms similar to those of a disulfiram alcohol reaction, which we attribute to his occupational exposure to products containing alcohol and other solvents. Symptoms abated with strict precautions to prevent exposure, although gradually returned over the course of months, causing him eventually to stop the medication. Medical practitioners should be aware of possible adverse interactions between occupational solvent exposures and disulfiram.

Lung function loss in relation to silica dust exposure in South African gold miners.

OBJECTIVE: To estimate exposure-response relationships between respirable dust, respirable quartz and lung function loss in black South African gold miners. METHODS: 520 mineworkers aged >37 years were enrolled in a cross-sectional study. Gravimetric dust measurements were used to calculate cumulative respirable dust and quartz exposures. Excess lung function loss was defined as predicted minus observed forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC). The association between excess loss and exposure was estimated, adjusting for smoking, tuberculosis and silicosis. RESULTS: Mean service length was 21.8 years, mean respirable dust 0.37 mg/m(3) and mean respirable quartz 0.053 mg/m(3). After adjustment, 1 mg-yr/m(3) increase in cumulative respirable dust exposure was associated with 18.7 ml mean excess loss in FVC [95% confidence interval (CI) 0.3, 37.1] and 16.2 ml in FEV1 (95% CI -0.3, 32.6). Mean excess loss with silicosis was 224.1 ml in FEV1 and 123.6 ml in FVC; with tuberculosis 347.4 ml in FEV1 and 264.3 ml in FVC. CONCLUSION: Despite a healthy worker effect, lung function loss was demonstrable whether due to silicosis, tuberculosis or an independent effect of dust. A miner working at a respirable dust intensity of 0.37 mg/m(3) for 30 years would lose on average an additional 208 ml in FVC (95% CI 3, 412) in the absence of other disease, an impact greater than that of silicosis and comparable to that of tuberculosis. Improved dust control on the South African gold mines would reduce the risk of silicosis, tuberculosis and lung function impairment.

Excess lung function decline in gold miners following pulmonary tuberculosis.

BACKGROUND: Few if any studies of the association between pulmonary tuberculosis (TB) and lung function loss have had access to premorbid lung function values. METHODS: Using a retrospective cohort design, the study recruited employed South African gold miners who had undergone a pulmonary function test (PFT) between January 1995 and August 1996. The 'exposed' group comprised 185 miners treated for pulmonary TB after the initial PFT and the 'unexposed' group comprised 185 age-matched miners without TB. All participants had a follow-up PFT between April and June 2000. The outcome of interest was decline in lung function during the follow-up period as measured by forced vital capacity (FVC) and forced expiratory volume in 1 s(FEV(1)). RESULTS: After controlling for age, height, baseline lung function, silicosis, years of employment, smoking and other respiratory diagnoses, pulmonary TB during the follow-up period was associated with a mean excess loss of 40.3 ml/year in FEV(1) (95% CI 25.4 to 55.1) and 42.7 ml/year in FVC (95% CI 27.0 to 58.5). Lung function loss was greater among those with more severe or later clinical presentation of TB. Breathlessness was twice as common among TB cases (OR 2.20, 95% CI 1.18 to 4.11). CONCLUSION: There is a need for greater clinical recognition of the long-term respiratory consequences of treated pulmonary TB. Early detection of TB would help to reduce these sequelae and remains a priority, particularly in a workforce already subject to silica dust disease. However, strategies such as dust control, worker education about TB and dust and TB preventive therapy are also needed to avert the disease itself.

Tuberculosis and silica exposure in South African gold miners.

AIMS: To examine the effect of silica exposure, in the absence of silicosis, on the prevalence of pulmonary tuberculosis (PTB), which is epidemic among South African gold miners. METHODS: Cross-sectional study of 520 gold miners over 37 years of age. Length of service, and cumulative and average dust and quartz exposure indices were derived for each miner. Chest radiographs were read for PTB by two NIOSH "B" readers. PTB was defined as a self-reported history of PTB or PTB on chest radiograph. Logistic regression was used to adjust for age, smoking, and silicosis. PTB effects of different exposure metrics for silica, scaled on their interquartile range (IQR), were compared. RESULTS: Means (ranges) were: age 46.7 (37.1-59.9) years; length of service 21.8 (6.3-34.5) years; average intensity of respirable quartz 0.053 (0-0.095) mg/m3. PTB prevalence was 19.4% (95% CI 16.0 to 22.8) on history alone, and 35.2% (95% CI 31.1 to 39.3) on history or on chest radiograph. Length of service was poorly predictive of PTB, while all exposure indices which included dust or quartz yielded prevalence odds ratios (PORs) of approximately 1.4 (95% CI approximately 1.1 to 1.8) for changes of one interquartile range in exposure. Controlling for silicosis--by adjustment or restriction--did not modify these results. Drillers and winch operators had the highest PTB prevalences and the highest dust and silica exposures. CONCLUSION: Older in-service gold miners in South Africa have a high prevalence of PTB, which is significantly associated with dust and silica exposure, even in the absence of silicosis. Limitations include a survivor workforce and the use of cumulative exposures based on current exposures. Dust control is an important component in control of the PTB epidemic in South African gold mines.

Prevalence and reliability of asthma symptoms in primary school children in Cape Town.

BACKGROUND: Childhood asthma is believed to be a serious problem in Cape Town, South Africa. This study aimed to measure the prevalence and reliability of asthma symptoms and reported asthma in Cape Town schoolchildren aged mainly 7 and 8 years, and to assess underdiagnosis. METHOD: A questionnaire was completed by parents of 1955 children, followed by 620 personal interviews repeating the questions. RESULTS: The prevalence of recent wheeze (previous 12 months) (26.8%) was high by international comparison, but not that of reported asthma (10.8%). Among children with more than 12 recent attacks of wheeze, only 60% were reported as asthmatic and 55% as receiving regular treatment. Symptom prevalences varied with the respondent's familial relationship to the child. On some questions the interview produced higher wheeze prevalences than the self-administered questionnaire. Repeatability of questions varied: asthma over (kappa = 0.69), recent wheeze (kappa = 0.59), and recent sleep disturbance by wheeze (kappa = 0.56) were the most reliable. CONCLUSIONS: Prevalence based on symptom reports may vary with the respondent and between self- and interviewer-administered questionnaires. Also, certain questions currently proposed for childhood asthma questionnaires may be unreliable. Nevertheless, it can be concluded that the prevalence of wheeze is high in this population, and that underdiagnosis and undertreatment of asthma are a problem.

Predictors of chronic bronchitis in South African adults.

SETTING: National household survey of adults in South Africa, a middle income country. OBJECTIVE: To determine the prevalence and predictors of chronic bronchitis. DESIGN: A stratified national probability sample of households was selected. All adults in the selected households were interviewed. Chronic bronchitis was defined as chronic productive cough. Socio-demographic predictors were wealth, education, race, age and urban residence. Personal and exposure variables included history of tuberculosis, domestic exposure to smoky fuels, occupational exposures, smoking and body mass index. RESULTS: The overall prevalence of chronic bronchitis was 2.3% in men and 2.8% in women. The strongest predictor of chronic bronchitis was a history of tuberculosis (men, odds ratio [OR] 4.9; 95% confidence interval [CI] 2.6-9.2; women, OR 6.6; 95%CI 3.7-11.9). Other risk factors were smoking, occupational exposure (in men), domestic exposure to smoky fuel (in women) and (in univariate analysis only) being underweight. Wealth and particularly education were protective. CONCLUSION: The pattern of chronic bronchitis in South Africa suggests a combination of risk factors that includes not only smoking but also tuberculosis, occupational exposures in men and domestic fuel exposure in women. Control of these risk factors requires public health action across a broad front. The protective role of education requires elucidation.

Asthma deaths among coloured and white South Africans: 1962 to 1988.

To determine whether death rates from asthma have been rising in South Africa, asthma mortality rates among coloured and white South Africans were calculated from official figures for the years 1962-1988. Sharp increases in the 1960s were noted in both groups. Since the early 1970s whites rates have generally shown a downward trend. In contrast, coloured rates have remained high, with a marked excess of male deaths. In the age stratum 5-34 years, there has been considerable fluctuation, with the long-term trend being slightly downward. Some increase in death rates occurred among the young in the early 1980s, but coloureds in this age group have shown falling rates in the most recent years. Coloured death rates in the younger age stratum have, however, continued to exceed whites rates, although by a decreasing margin, and have been high by international comparison. These group disparities are unlikely to be due to differences in certification or in coding. Variation in prevalence or severity of asthma may explain some of the disparity. However, these group differences, taken with well-known inequalities in medical care, suggest that preventable determinants of asthma deaths related to access to and quality of medical care may be important and accordingly a target for preventive strategies.

Body mass index and the risk of asthma in adults.

Asthma and obesity are both chronic conditions and their prevalences have risen in affluent societies. A positive association between asthma and being overweight or obese has been reported in children and women, but associations in men are less clearly described. The objective of this study was to explore the association between body mass index (BMI) and asthma in men and women of diverse ethnic and socioeconomic background living in New York State, USA. In this study, we analyzed cross-sectional data on 5524 subjects aged 18 years and older who were interviewed by telephone in the 1996 and 1997 New York State Behavioral Risk Factor Surveillance System. Asthma (doctor-diagnosed), and weight and height were self-reported. BMI (kg/m2) was used as a measure of adiposity. Weighted logistic regression analysis, with stratification by gender and age, was used to examine the relationship between asthma prevalence and BMI, adjusting for race/ethnicity, education, health insurance, time since last physical examination, physical activity and smoking status. The results showed that the prevalence of asthma was 4.6% (CI: 3.6-5.5%) among men and 8.1% (CI: 7.1-9.1%) among women. In women, the prevalence of asthma was significantly increased in those with a BMI 25 kg/m2 or higher (BMI 25-27.5: OR = 1.76, 95% CI: 1.06-2.94; BMI 27.5-29.9: OR = 2.45, 95% CI: 1.41-4.25; BMI > or = 30: OR = 2.67, 95% CI: 1.66-4.29) when compared to the reference category (BMI: 22-24.9 kg/m2). In men, the prevalence of asthma was increased in the lowest weight category, BMI < 22 kg/m2 (OR = 3.05, 95% CI: 1.37-6.78) and in the highest category, BMI > or = 30 kg/m2 (OR = 2.92, 95% CI: 1.39-6.14). This U-shaped association persisted when restricting the analysis to men who had never smoked and was more pronounced for those between 18 and 49 years of age. In conclusion, this cross-sectional study showed that men and women differ significantly in the association between BMI and asthma prevalence only with respect to the lowest weight category. While women had a monotonic association, men showed a U-shaped relationship, indicating that both extremes of weight are associated with a higher prevalence of asthma.

Environmental tobacco smoke exposure in children: household and community determinants.

To determine the most important sources of environmental tobacco smoke exposure to young children, the authors studied the associations among urinary cotinine, reported household smoking habits, and socioeconomic variables in 575 schoolchildren aged 6-11 y. The school children were among a population of prodigious smokers in Cape Town, South Africa. Eighty percent of the children were exposed to environmental tobacco smoke. Maternal smoking, which was adjusted for creatinine, accounted for 21.8% of the variation in urinary cotinine--more than all other sources combined. The male parent and other household smokers accounted for 12.7% of the variation, and socioeconomic indicators explained an additional 4.8%. By defining the ecological variable of smoking prevalence per school, the authors estimated a "community" contribution of 3.3%. The relative importance of different sources of smoke should be taken into account in the prevention of environmental tobacco smoke exposure in young children. Most importantly, of all the sources of environmental tobacco smoke, mothers' smoking habits had the greatest impact on exposure to children.

Chronic airflow obstruction and respiratory symptoms following tuberculosis: a review of South African studies.

BACKGROUND: There is renewed interest in the chronic respiratory sequelae of pulmonary tuberculosis (PTB), particularly chronic airflow limitation. A number of South African epidemiological studies have been published, which, although not specifically designed to examine this association, provide useful data on the nature of the relationship. OBJECTIVE: To review population-based and occupational studies conducted in South Africa that provide estimates of the association between PTB, chronic symptoms and lung function loss. RESULTS: Two general population and a number of occupational studies were included. Most were able to control for likely confounders. Chronic chest symptoms and lung function loss were consistently associated with PTB, whether measured by self-report or prospectively in cohort studies. Odds ratios (ORs) were higher for chronic bronchitis (range 1.5-7.2) than for asthma (range 0.7-2.2). For spirometrically defined chronic obstructive pulmonary disease, the OR range was 2.6-8.9, depending on definition. Combined obstructive/restrictive lung function loss was the most common functional outcome, with a net obstructive effect. The association of past TB with non-specific bronchial hyperresponsiveness was equivocal. CONCLUSION: These studies add to the evidence of a strong association between PTB, even if treated, and subsequent airflow obstruction as well as restrictive loss. Unanswered questions include extent of recovery over time, effect modification by smoking and other cofactors, and degree of reversibility by treatment.

Wheeze, asthma diagnosis and medication use: a national adult survey in a developing country.

BACKGROUND: As relatively little is known about adult wheeze and asthma in developing countries, this study aimed to determine the predictors of wheeze, asthma diagnosis, and current treatment in a national survey of South African adults. METHODS: A stratified national probability sample of households was drawn and all adults (>14 years) in the selected households were interviewed. Outcomes of interest were recent wheeze, asthma diagnosis, and current use of asthma medication. Predictors of interest were sex, age, household asset index, education, racial group, urban residence, medical insurance, domestic exposure to smoky fuels, occupational exposure, smoking, body mass index, and past tuberculosis. RESULTS: A total of 5671 men and 8155 women were studied. Although recent wheeze was reported by 14.4% of men and 17.6% of women and asthma diagnosis by 3.7% of men and 3.8% of women, women were less likely than men to be on current treatment (OR 0.6; 95% confidence interval (CI) 0.5 to 0.8). A history of tuberculosis was an independent predictor of both recent wheeze (OR 3.4; 95% CI 2.5 to 4.7) and asthma diagnosis (OR 2.2; 95% CI 1.5 to 3.2), as was occupational exposure (wheeze: OR 1.8; 95% CI 1.5 to 2.0; asthma diagnosis: OR 1.9; 95% CI 1.4 to 2.4). Smoking was associated with wheeze but not asthma diagnosis. Obesity showed an association with wheeze only in younger women. Both wheeze and asthma diagnosis were more prevalent in those with less education but had no association with the asset index. Independently, having medical insurance was associated with a higher prevalence of diagnosis. CONCLUSIONS: Some of the findings may be to due to reporting bias and heterogeneity of the categories wheeze and asthma diagnosis, which may overlap with post tuberculous airways obstruction and chronic obstructive pulmonary disease due to smoking and occupational exposures. The results underline the importance of controlling tuberculosis and occupational exposures as well as smoking in reducing chronic respiratory morbidity. Validation of the asthma questionnaire in this setting and research into the pathophysiology of post tuberculous airways obstruction are also needed.

Fate of Outstanding COIDA Occupational Disease Claims Following Closure of the Western Cape Provincial Medical Advisory Panel in 2008 : An audit

Background and objectives: The Western Cape Provincial Medical Advisory Panel (PMAP) was established in 2004 in terms of Section 70(1) of COIDA. A primary function was to improve the efficiency of medical assessment of occupational disease claims. The PMAP was closed by the Compensation Commissioner in 2008. This audit aimed to determine the fate of claims outstanding at the time of closure. Methods: A total of 68 claims outstanding in April 2008 were followed up by telephone; email and/or internet to determine what proportion had progressed or; if accepted; had resulted in a permanent disablement compensation payment. Results: Of the 68 claims; 31 (44) were confirmed as having progressed. Of these; payment of permanent disablement awards could be confirmed in only 15 claims (22). The remaining 56 either showed no progress or no longer had a record in the COIDA system. Those stages of the claims process that had previously been aided by PMAP functioning had deteriorated in efficiency. Conclusions: Overall; the low proportion of outstanding claims finalised and awarded is consistent with inefficiency in claims handling of occupational disease; a finding echoed by recent complaints about general Compensation Fund performance from both healthcare providers and parliamentary investigation

Fatal asthma in a baker: a case report.

A case of baker's asthma with a fatal outcome is described. Clinical features and the circumstances of death are recounted. While the case documents the potential severity of occupational asthma, it also illustrates the difficulties of managing occupational asthma in the absence of good social security.

The occupational medicine clinic of the National Centre for Occupational Health.

The clinic of the National Centre for Occupational Health is described as an example of a referral clinic for occupational disease. The activities and limitations of the clinic are described. Trends relevant to the development and running of such clinics in the RSA are considered. Features of clinical occupational medicine which distinguish it from other medical specialties are discussed, as is the problem of where to site such a clinic.

Increase in hospital admissions for acute childhood asthma in Cape Town, 1978-1990.

To determine whether hospital admissions for acute childhood asthma were rising in Cape Town in line with the experience of other countries, Red Cross War Memorial Children's Hospital's records for the period 1978-1990 were analysed. These were compared with total admissions for non-surgical causes and lower respiratory tract illness as well as those for bronchiolitis and pneumonia. Asthma admissions showed a sharp upward trend from 1978 to 1984, a slower rise through 1987 and a levelling off since. The profile of hospital admissions for respiratory illness was also analysed. Black children were under-represented among asthma admissions compared with those for pneumonia. Asthma admissions occurred throughout the year but showed seasonal peaks in May and November. Reasons for these trends and patterns are discussed, as well as hypotheses for further research into the epidemiology of asthma in South Africa.

Occupational history-taking in the RSA.

Medical practitioners need to elicit a comprehensive occupational history from their patients, since this may play an integral part in establishing the diagnosis, may indicate the most appropriate form of management, and will ensure that claims for Workmen's Compensation are initiated when appropriate. This history can also assist in identifying undetected workplace hazards and in formulating and testing hypotheses concerning the relationship of work to health. The particular problems encountered in taking an occupational history effectively in the RSA are discussed.

Regression of polyvinylchloride polymer pneumoconiosis.

A 35 year old man heavily exposed to polyvinylchloride (PVC) polymer dust developed dyspnoea and a mild restrictive lung disorder consistent with PVC pneumoconiosis. Clinical and radiological abnormalities cleared on removal from exposure, suggesting that in its early stages PVC pneumoconiosis is reversible.

Trends in photochemical smog in the Cape Peninsula and the implications for health.

There has been growing public concern over reports of increasing air pollution in the Cape Peninsula. Attention has been focused on the 'brown haze' and on photochemical smog. Because of deficiencies in the monitoring equipment, information on trends in photochemical smog levels over the past decade is limited. Trends in oxides of nitrogen, one of the main precursors of photochemical smog, and therefore an indicator of the potential for its formation, were examined for the period 1984-1993. Meaningful data for determining trends were available from only a single site. Increases in mean monthly levels, peak hourly levels and the number of times guidelines were exceeded were demonstrated. Given the dynamics of formation of photochemical smog and the particular role of motor vehicles, it is argued that the trends measured at this site are probably an underestimate of the trends in other parts of the Cape Town metropolitan area. Some of the precursors of photochemical smog, notably nitrogen dioxide, and some of its components, notably ozone, have been shown to be detrimental to respiratory health at levels close to, or below, current recommended guidelines. A continuing increase in these pollutants will therefore result in more respiratory illness, particularly among susceptible groups. This calls for an upgrading of monitoring of air pollution in Cape Town and for appropriate steps to prevent its further increase.