A respiratory survey in a black Johannesburg workforce

Factors associated with pulmonary impairment in HIV-infected South African adults

Background

HIV-infected individuals have increased risk of developing obstructive lung disease (OLD). Studies from developed countries report high viral load, low CD4 counts, and anti-retroviral therapy (ART) to be associated with OLD; but these findings may not be generalizable to populations in resource-limited settings.

Methods

We conducted a prospective cohort study of lung function in 730 HIV-infected black South African adults. Pre-bronchodilator spirometry was performed at enrollment and repeated annually for three years. Logistic regression models were used to identify factors associated with OLD, defined as FEV1/FVC<0.70, at enrollment. Excess annual declines in FEV1 and FVC were modelled as the product-term of follow-up time and exposures using random effects regression.

Results

Median (IQR) age at enrollment was 36 (32–41) years, 85% were female and 30% ever-smoked with a median (IQR) exposure of 3 (1–6) pack-years. Median (IQR) CD4 count and viral load at enrollment were 372 (261–518) cells/mm³ and 2655 (91–13,548) copies/mL respectively. Overall, 25% were receiving ART at enrollment, 16% of whom reported at least 6 months of ART receipt. OLD was found in 35 (5%) at enrollment. Increasing age (aOR = 2.08 per 10-years [95%CI 1.22–3.57], p = 0.007), current smoking (aOR = 3.55 [95%CI 1.20–10.53], p = 0.02), and CRP (aOR = 1.01 per unit-increase [95%CI 1.00–1.03], p = 0.04) were significantly associated with OLD at enrollment; while increasing CD4 count (aOR = 1.02 per-100 cells/mm³ [95%CI 0.85–1.22], p = 0.82), viral load (aOR = 0.67 per log-increase [95%CI 0.43–1.10], p = 0.12) and receipt of ART (aOR = 0.57 [95%CI 0.18–1.75], p = 0.32) were not. The median (IQR) follow-up time was 18 (12–24) months. Participants with a history of tuberculosis (TB) had a 35 mL (95%CI 2–68, p = 0.03) and 57 mL (95%CI 19–96, p = 0.003) per year excess loss of FEV1 and FVC respectively.

Conclusion

Prevalent OLD was associated with older age, current smoking and higher CRP levels, but not CD4 counts and ART, in HIV-infected South African adults. Better understanding of the long-term effects of TB, smoking and inflammation on lung function in HIV-infected populations is urgently needed.

South African and international reference values for lung function and its relationship with blood pressure in Africans

BACKGROUND

In South Africa respiratory diseases are highly prevalent, with cardiovascular disease being a manifestation. However, international reference values for lung function are commonly used, which may not be appropriate to correctly identify reduced lung function. An inverse relationship exists between lung function and blood pressure (BP) but is not investigated extensively in black South Africans.

METHODS

We included 2010 Africans from the PURE (Prospective Urban Rural Epidemiology) study (aged > 35 years) in the North West Province. Spirometry was performed and predicted values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were calculated from South African, European and United States prediction equations.

RESULTS

With the exception of the European predicted values, all other predicted mean FEV1 and FVC were above 80%. South African reference values displayed the highest percentages of the predicted values for FEV1 and FVC (87.9 and 99.7%, respectively.) BP increased from quintiles five to one for both FEV1 and FVC, (p for trend <0.001). After adjustment the differences remained (p<0.05).

CONCLUSIONS

South African reference values yielded higher percentages of predicted FEV1 and FVC values than European and US equations suggesting that South African prediction equations may be more useful when investigating lung function in black South Africans. Elevated BP is related to reduced lung function, highlighting the importance in managing both respiratory- and cardiovascular disease.

Respiratory symptoms and lung function impairment in underground gold miners in ghana

SUMMARY BACKGROUND

This is the first study in Ghana in the Obuasi gold mines where the silica content of the respirable dust is 10%, less than in previously studied gold mines, with only 23% of the miners having ever smoked.

OBJECTIVES

The study was to assess the prevalence of respiratory impairment in the Ghanaian gold miner and to quantify the effects of the respirable dust on pulmonary function

DESIGN

A cross sectional epidemiological study

METHOD

The study was carried out using MRC respiratory symptoms questionnaire, spirometry, and personal respirable dust measurements.

RESULTS

A total of 1236 miners were studied. The mean age was 39.7 +/-5.8 (SD) years with a mean of 12.6 +/- 6.7 (SD) years underground service and a mean total cumulative exposure to dust of 10.34 +/-5.61 (SD) mg.m(-3).years. The prevalence of chronic bronchitis was 21.2% and not clearly related to cumulative exposure. MRC breathlessness grade>/=2 was 31.3%, significantly related to cumulative respirable dust exposure after adjustment of age and smoking. There was however significant reduction in FEF(25-75%) with increasing dust exposure and an interaction with ever smoking. There was no correlation between cumulative exposure to respirable dust and FEV(1) % predicted in any group, suggesting that exposure to respirable silica at a mean level of 0.06 mg/m(3) had no deleterious effect on FEV(1) in a population with little tuberculosis, good housing and a low level of cigarette smoking.

CONCLUSION

The prevalence of chronic bronchitis in the Ghanaian gold mine is related more to smoking than any occupational factors.

Socioeconomic status and lung function

Poverty is a major social problem in the United States and throughout much of the world. Poverty and the broader term socioeconomic status (SES) are important determinants of overall health status and many pulmonary diseases. The purpose of this study was to review the medical literature from the past 20 years addressing the relationship between SES and lung function in both children and adults. There is a significant negative correlation between lung function (primarily FEV1 and FVC) and SES. This relationship exists even after adjusting for smoking status, occupational exposures, and race. The magnitude of the effect of low SES on lung function is variable, but FEV1 reductions of >300 mL in men and >200 mL in women have been reported. SES is an important determinant of lung function and an underrecognized contributor to pulmonary disease.

Prevalence of wheeze and self-reported asthma and asthma care in an urban and rural area of Tanzania and Cameroon

We investigated the prevalence of wheeze, self-reported asthma, and asthma care via four cross-sectional surveys among adults and children (5-15 years) in urban and rural populations from Tanzania and Cameroon. Age-standardized prevalence of current wheeze (in the previous year) was 2.2% to 5.0% in adults and 1.9% to 5.2% in children in Tanzania, and 1.3% to 2.5% (adults) and 0.8% to 5.4% (children) in Cameroon. There were no consistent patterns of urban:rural prevalence. Peak flow rates varied with age, peaking at 25-34 years, and were higher in urban areas (age adjusted difference 22-70 L/min) and in the Tanzania populations. Awareness (83%-86% versus 52%-58%) and treatment (43%-71% versus 30%-44%) of asthma was higher among those with current wheeze in rural areas. Use of inhaled drugs, particularly steroids, was rare. Diagnosis by traditional healers (15%) and use of traditional remedies (62% of those recalling any treatment) were common only among self-reported asthmatic patients in rural Cameroon. Asthma is an importantclinical condition in sub-Saharan Africa. There were major gaps in clinical care, particularly in urban areas. Sustainable methods for delivering accessible and effective asthma care in sub-Saharan Africa are required.

Absence of association between delayed type hypersensitivity to tuberculin and atopy in children in The Gambia

BACKGROUND

An inverse association between delayed type hypersensitivity to tuberculin and atopy has been observed in children, suggesting that exposure to mycobacteria may influence the immune response to allergens.

OBJECTIVE

To investigate the relationship between tuberculin responses and atopy in children living in three different environments in The Gambia.

METHODS

In this cross-sectional study a total of 507 school-aged children were recruited from rural, urban poor or urban affluent communities. They were assessed for skin responses to five common allergens and tuberculin, presence of bacille Calmette-Guérin (BCG) scar, presence of intestinal parasites, and total serum IgE. Atopy was defined as the presence of a skin prick test response > or = 3 x 3 mm to at least one allergen.

RESULTS

The overall prevalence of atopy was 33% but there was a significant variation among the three study groups. The prevalence of atopy was 22% in urban poor, 36% in urban affluent, and 43% in rural children. Controlling for potential confounding factors, children in the rural community had a significantly higher odds ratio, 3.3 (95% confidence interval 1.8-6.0) of being atopic than children from the urban poor community. No association between atopy and tuberculin response or BCG scar was observed in any of the three groups. Serum IgE levels were higher among children of the urban poor group but were not associated with tuberculin response or BCG scar in any of the groups.

CONCLUSION

Environmental factors have an important influence on the development of atopy in children in The Gambia but delayed type hypersensitivity to tuberculin is not a protective factor.

Respiratory symptoms and spirometric observations in relation to atmospheric pollutants in a sample of urban population

The prevalence of respiratory problems and the ventilatory functions in subjects belonging to three sample areas with different levels of pollution was studied to ascertain if there is any association between air pollutant levels and abnormal ventilatory functions. The predominant activity existing in that area served as the basis for stratification of the city into industrial (Group I), commercial (Group II) and residential (Group III) areas. Ambient air quality data of suspended particulate matter SPM, SO2 and NOx of the three sample areas were measured using standard methods. 216 men included in the study were administered the American Thoracic Society--Division of Lung Diseases ATS-DLD respiratory questionnaire, clinically examined and subjected to routine laboratory investigations. Spirometry and salbutamol reversibility tests were performed as per the ATS guidelines 1991. The mean and peak levels of SPM in the commercial area and the peak levels in the residential area were higher than the National Ambient Air Quality Standards (NAAQS). The mean and peak levels of NOx and SO2 in all the three areas were lower than the NAAQS. A high prevalence of approximately 30-50% of respiratory symptoms was reported in the present study. Respiratory and ventilatory abnormalities were higher in the commercial areas, which are associated with the higher mean and peak levels of SO2 and the peak levels of NOx. The pollution control measures should also aim at the peak levels of pollutants as they have been shown to exacerbate the respiratory symptoms in the present study.

Lung function prediction equations derived from healthy South African gold miners

OBJECTIVES

To estimate lung function prediction equations and to identify appropriate normal reference values for the population of about 250 000 of South African gold miners.

METHODS

Data from a lung function screening programme conducted at a large South African gold mine from 1994 to 1998 were used to estimate the lung function prediction equations. The most reliable period of lung function testing was identified in a previous study of a temporal pattern in reliability, and lung function tests from this period were used. Miners with a history of pulmonary tuberculosis or with radiological abnormalities were excluded from the study. The prediction equations were estimated cross sectionally on 15 772 black and 2752 white miners, and published reference equations that fitted most closely the observed data were identified.

RESULTS

The estimated prediction equations for forced vital capacity (FVC) are as follows: for black men, FVC (l)=- 2.901-0.025xage+4.655xheight; and for white men, FVC(l)=-4.407-0.036xage+ 5.940xheight. For forced expiratory volume in one second (FEV(1)) these equations are: for black men, FEV(1)(l)=-1.654- 0.30xage+3.665xheight; and for white men, FEV(1)(l)= -2.341- 0.038xage+4.314xheight. Units are years for age and metres for height. Knudson's and the European Community of Coal and Steel (ECCS) reference values provided the closest fit to the data on lung function of white miners, but the lower limits of normal from the ECCS equations were the closest to the observed one sided lower 95% confidence intervals (95% CIs). For black miners, reference equations that fitted best were derived by Louw et al on asymptomatic black South African men unexposed to occupational dust. There were significant differences between the two groups of miners in the estimated height adjusted mean lung function values for a 40 year old 1.7 m tall man (220 ml (5.2%) for FVC and 110 ml (3.2%) for FEV(1)); white men had higher FVC and FEV(1), but lower FEV(1)/FVC ratio. The ECCS reference values scaled by a conversion factor of 0. 93 for the FVC and 0.95 for the FEV(1) provided close fits to the data for black miners, but the rate of decline with age was higher than that in the observed data. None of the linear equations provided a good fit for the 20-29 and more than 55 years old age categories.

CONCLUSION

The ECCS and Knudson equations provided the best fit to the data for white miners, whereas the equations by Louw et al estimated on asymptomatic black South African bank workers provided the best fit to the data for black miners. The ECCS reference values scaled by a factor of 0.93 for FVC and by 0.95 for FEV(1) provided close fits, but the rate of decline with age was higher than that in the data for black miners.

Prevalence of wheeze and asthma and relation to atopy in urban and rural Ethiopia

BACKGROUND

Asthma and allergy in developing countries may be associated with adoption of an urbanised "western" lifestyle. We compared the rates of asthma symptoms and atopy in urban populations in Jimma, southwest Ethiopia, at an early stage of economic development with those among the population of remote, rural, subsistence areas, and assessed the potential role of environmental aetiological factors leading to the differences.

METHODS

Information on wheeze of 12 months' duration, diagnosed asthma, and cough for 3 months of the year was gathered by questionnaire in random household samples of 9844 people from urban Jimma and of 3032 from rural areas. Atopy was defined by allergen skin-test response to Dermatophagoides pteronyssinus and mixed threshings measured in a one-in-four subsample of those aged 5 years and older from both groups.

FINDINGS

All respiratory symptoms were rare in children and were significantly less common overall in the rural than in urban group (wheeze odds ratio 0.31 [95% CI 0.22-0.43], p < 0.0001). Asthma was reported by 351 (3.6%) of the urban group, with a median reported duration of 8.5 years (IQR 4-17 years) that was unrelated to age. Atopy was a strong risk factor for asthma in urban Jimma. In the rural areas, skin sensitivity to mixed threshings was only slightly less common than in urban Jimma (0.67 [0.40-1.12], p = 0.13), whereas sensitivity to D pteronyssinus was significantly more common (3.24 [2.40-4.38], p < 0.0001), and since none of the 119 atopic individuals in the rural area reported wheeze or asthma, atopy was possibly associated with a reduction in the risk of disease among this group. Wheeze or D pteronyssinus sensitivity were positively associated with housing style, bedding materials, and use of malathion insecticide, but no single factor accounted for the urban-rural differences.

INTERPRETATION

Wheeze and asthma are especially rare in rural subsistence areas, and atopy may be associated with a reduced prevalence of these symptoms in this environment. In urban Jimma, self-reported asthma seemed to emerge as a clinical problem about 10 years before our study began, which is consistent with an effect of new environmental exposures. The factor or factors leading to the increase in asthma and allergy have not been identified, although exposures related to general changes in the domestic environment are likely to be involved.

International union against tuberculosis and lung disease (IUATLD): initiatives in non-tuberculous lung disease

IUATLD initiatives in non-tuberculous lung disease developed in the late 1970s, coincident with improving tuberculosis control, and have targeted acute respiratory infections in children and chronic airways disease in adults and in children. The focus has been on methodology and the tools required to document the distribution and determinants of disease, and is illustrated in data gathered in African populations. Instruments developed include a simplified method of measuring bronchial hyper-reactivity and an asthma questionnaire Non-standard methods of questionnaire administration have also been validated, methods which are appropriate for use in the burgeoning urban communities and workforces of sub-Saharan Africa made up of rural migrants from different tribes and language groups. In addition, a review of reference values available for interpreting lung function in sub-Saharan African populations indicates a need to take into account a secular trend over the last two decades towards higher spirometric values. In the published data from Africa, not inconsiderable between-country differences are evident in the prevalence of chronic bronchitis in adults and of asthma in children. In addition, rates for childhood asthma were consistently higher in urban vs rural communities, with environmental factors playing an important role as well as being locally specific. Not only does the burden of morbidity attributable to both the chronic airway diseases reviewed justify past IUATLD initiatives in non-tuberculous lung disease, but it also argues that future initiatives should focus on investigating between- and within-country differences using a standardized methodology, with a view to identifying local environmental determinants susceptible to intervention and control. Curbing tobacco use is clearly important, not only to benefit the health of adult smokers for whom the ill-health consequences have long been recognized, but, and more important, to protect the health of children, born and unborn, with whom they share the environment.