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Biomedical subjects

N W White

Publications and source records attributed to N W White.

At least 19 recordsLinked to original sources
PubMed2006

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.

Adult↗
PubMed2006

An evaluation of symptom and chest radiographic screening in tuberculosis prevalence surveys.

SETTING: A tuberculosis (TB) prevalence survey was performed in 2002 in two urban communities in Cape Town, South Africa. The population was 36,334 in 2001, and the TB notification rate was 341 per 100,000 population for new smear-positive TB in 2002. OBJECTIVE: To evaluate the relative contributions of symptom and chest radiographic (CXR) screening in the detection of subjects with smear- and/or culture-positive TB in prevalence surveys. DESIGN: Information on symptoms, CXR abnormalities, sputum smear and culture was gathered from a random cluster sample of 1170 adults (aged > or = 15 years). Smear and/or culture-positive TB was used as the gold standard. RESULTS: Of 1170 adults, 29 had bacteriologically positive TB (smear- and/or culture-positive). The presence of any abnormalities on CXR had the highest sensitivity for detecting subjects with bacteriologically positive TB (0.97, 95%CI 0.90-1.00). Specificity for any abnormalities on CXR was 0.67 (95%CI 0.64-0.70). The specificity of any of five TB-related symptoms was 0.68 (95%CI 0.65-0.71). Individual symptoms had low sensitivities, ranging from 0.10 for fever to 0.54 for cough of > or = 2 weeks. CONCLUSION: In this TB prevalence survey, CXR screening, but not symptom screening, was a sensitive alternative to sputum examination of all participants.

Adolescent↗
PubMed2005

Development and evaluation of a new chest radiograph reading and recording system for epidemiological surveys of tuberculosis and lung disease.

OBJECTIVE: The development and evaluation of a new chest radiograph reading and recording system (CRRS) for community surveys of tuberculosis (TB) and lung disease. DESIGN: An experienced pulmonologist read 2608 chest X-rays (CXRs) performed as part of a TB prevalence survey using the newly developed CRRS. The kappa (kappa) for inter-reader agreement was calculated after a second reader reported on a stratified random sample of 810 (31%) of the 2608 CXRs. The kappa for intra-reader agreement was calculated from the repeated reporting of a stratified random sample of 104 CXRs. RESULTS: The kappa agreement between the two readers was 0.69 (95%CI 0.64-0.74) for abnormalities consistent with TB and 0.47 (95%CI 0.42-0.53) for any abnormalities. The kappa for intra-reader agreement was 0.90 (95%CI 0.81-0.99) for abnormalities consistent with TB and 0.85 (95%CI 0.74-0.95) for any abnormalities. CONCLUSION: This standardised method for CXR reading and recording provides satisfactory inter- and intra-reader agreement, making it suitable for surveys of TB and other forms of lung disease in the community. Its use will permit comparisons of results obtained in different surveys.

Epidemiologic Methods↗
PubMed2004

Capacity building for research: report on a UNION Strategic Planning Workshop. Report of a workshop held during the International Union Against Tuberculosis and Lung Disease World Conference on Lung Health, Montreal, Canada, 7 October 2002.

The International Union Against Tuberculosis and Lung Disease (UNION) has a decade of experience in conducting short courses on research methods for the promotion of lung health. In a parallel initiative, the UNION has collaborated with the American Thoracic Society (ATS) to develop courses on international respiratory epidemiology that have been expanded by the ATS throughout Latin America. The two initiatives have similar aims, and the courses offered by the two organisations have intentionally been similar in terms of focus and complementary in regions targeted. The target regions of the UNION, drawing on several decades of experience in offering short courses on tuberculosis, have been Africa, the Black Sea Rim, the Middle East and Asia, while the target regions of the ATS have been Central and South America. This workshop aimed first to provide an opportunity for those who have taught on the courses and those who have participated to share their experiences and learn from them, and second to provide a basis on which to develop a strategic plan for future courses. This report summarises the contributions of the workshop participants and the conclusions reached.

Education, Medical, Continuing↗
PubMed2004

Guideline for office spirometry in adults, 2004.

OBJECTIVE: To provide clinical guidelines for office spirometry in South Africa. OPTIONS: More stringent guidelines are required for diagnostic laboratories and research. OUTCOMES: To minimise variations in standard practice and improve the quality and usefulness of spirometry in the clinical setting. EVIDENCE: Recommendations are based on key international publications as well as research publications regarding reference values for South Africans. BENEFITS, HARM AND COSTS: The medical, social and economic benefits and costs of standardisation of office spirometry in South Africa were considered in the recommendations. VALIDATION: The document has been reviewed and endorsed by the South African Thoracic Society. CONCLUSIONS: The indications for spirometry must be specific and clear. Spirometry equipment must meet internationally accepted performance standards and carry proof of validation. Equipment must be regularly calibrated and maintained. Individuals performing spirometry must be adequately trained and demonstrate a high level of competence. Subject preparation, testing and quality control of results must be carried out according to published guidelines. Finally, test results must be interpreted according to current diagnostic guidelines, taking into account the purpose of the test, appropriateness of reference values and the clinical evaluation.

Adult↗
PubMed2004

Lung cancer epidemiology and risk factors in Asia and Africa.

In industrialised countries, lung cancer is the most common form of cancer among males and it is growing among females. For both sexes, rates reflect smoking behaviours. The pattern appears to be different in Asia, particularly in China, where lung cancer rates in men reflect high smoking rates but high rates among non-smoking women appear to be related to other factors. The incidence of lung cancer is low in most African countries, but it is increasing. In addition to tobacco smoking, a number of etiological factors have been identified for lung cancer: indoor exposure to environmental tobacco smoke, cooking oil vapour, coal burning, or radon, outdoor air pollution and occupational exposure to asbestos and other carcinogens. Recent studies have shown that dietary factors may be important, with high consumption of vegetables and fruits being protective while preserved food and fatty food are harmful, and certain infections such as Mycobacterium tuberculosis, human papilloma virus and Microsporum canis are associated with a high risk of lung cancer. Among non-smokers, the probable role of genetic predisposition in lung cancer by increasing the individual's susceptibility to environmental carcinogens is currently being studied actively. As the single most important cause for lung cancer is tobacco smoke and, with increased sales, a major epidemic is predicted for both Asia and Africa, all health care professionals, government health authorities and national and international health organisations must join in a concerted effort against tobacco.

Africa↗
PubMed2001

Occupational lung diseases among former goldminers in two labour sending areas.

OBJECTIVES: To compare and contrast the prevalence of pneumoconiosis in two groups of former migrant mineworkers in southern Africa, and to examine the effectiveness of the South African compensation system for occupational lung diseases. DESIGN: Comparison of two cross-sectional studies and follow-up data on compensation results. SETTING: The village of Thamaga, Botswana and the rural area of Libode, Eastern Cape, South Africa. SUBJECTS: Two hundred and thirty-four former underground mineworkers in Thamaga, and 238 in Libode. MAIN OUTCOME MEASURES: Prevalence and severity of pneumoconiosis, prevalence of radiological signs of tuberculosis (TB), Medical Bureau for Occupational Diseases (MBOD) certification committee decisions, and compensation results. RESULTS: Prevalence of pneumoconiosis > or = 2/1 was 15.4% in Libode and 13.6% in Thamaga. Significantly more Libode than Thamaga subjects (51.1% versus 29.0%) reported past TB treatment. Radiological signs of pulmonary TB were also more prevalent in Libode (33.3% v. 23.9%). Twenty-six per cent of Libode men and 16.1% of Thamaga men were certified with compensable disease. Libode payments were finalized within 30 months, whereas Thamaga cases only began receiving payments 52 months after medical examination, with 11 cases still pending 66 months after medical examination. CONCLUSION: There was a high prevalence of pneumoconiosis in both study groups. Many men were eligible for compensation but were previously uncompensated. The higher rate of compensable disease in the Libode group may relate to the higher prevalence of TB, as well as more active follow-up by the study group, including a large number of appeals. Socio-political changes in South Africa between 1994 and 1996 may also have influenced compensation results.

Cross-Sectional Studies↗
PubMed1998

Prevalence of occupational lung disease in a random sample of former mineworkers, Libode District, Eastern Cape Province, South Africa.

BACKGROUND: Gold mineworkers in South Africa are exposed to high levels of silica dust as a result of which they are at risk of developing silicosis, which is a compensable disease. The incidence of tuberculosis is also high. METHODS: To determine the prevalence of occupational lung disease and the previous compensation history in former migrant mineworkers, a study was undertaken in a random sample of men living in Libode, a rural district of Eastern Cape Province, South Africa. Two hundred thirty-eight ex-mineworkers were examined according to a protocol that included chest radiography and spirometry. Chest radiographs were read into the International Labour Organisation (ILO) classification for pneumoconioses by two readers. RESULTS: The mean age was 52.8 years, and the mean length of service was 12.15 years. The prevalence of pneumoconiosis (> or = ILO 1/0) was 22% and 36% (variation by reader). For both readers, a significant association between length of service and pneumoconiosis and between pneumoconiosis and reduction in FVC and FEV was found. Twenty-four percent of study subjects were eligible for compensation. CONCLUSION: There is a high prevalence of previously undiagnosed, uncompensated pneumoconiosis in the study group. As a result of the failure to diagnose and compensate occupational lung disease, the social and economic burden of such disease is being borne by individuals, households, and the migrant labor-sending communities as a whole.

Adult↗
PubMed1997

Prevalence of occupational lung disease among Botswana men formerly employed in the South African mining industry.

OBJECTIVE: To determine whether previous health experiences affect the prevalence of occupational lung disease in a semirural Botswanan community where there is a long history of labour recruitment to South African mines. METHOD: A cross sectional prevalence study of 304 former miners examined according to a protocol including a questionnaire, chest radiograph, spirometry, and medical examination. RESULTS: Overall mean age was 56.7 (range 28-93) years, mean duration of service 15.5 (range 2-42) years. 26.6% had a history of tuberculosis. 23.3% had experienced a disabling occupational injury. Overall prevalence of pnemoconiosis (> 1/0 profusion, by the International Labour Organisation classification) was 26.6%-31.0%, and 6.8% had progressive massive fibrosis (PMF). Many were entitled to compensation under South African law. Both radiograph readers detected time response relations between pneumoconiosis and PMF among the 234 underground gold miners. PMF could result from < 5 years of exposure, but was not found < 15 years after first exposure. Both pulmonary tuberculosis (PTB) and pneumoconiosis were found to be associated with airflow limitation. CONCLUSIONS: Former miners in Botswana have a high prevalence of previously unrecognised pneumoconiosis, indicative of high previous exposures to fibrogenic respirable dust. Their pneumoconiosis went unrecognised because they had no access to surveillance after employment. Inadequate radiographic surveillance or failure to act on results when employed or when leaving employment at the mines could have contributed to under recognition. Community based studies of former miners are essential to fully evaluate the effects of mining exposures. Our findings indicate a failure of established measures to prevent or identify pneumoconiosis while these miners were in employment and show that few of the social costs of occupational lung diseases are borne by mining companies through the compensation system.

Accidents, Occupational↗
PubMed1997

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.

Adult↗
PubMed1996

Acute-phase response and the hypercoagulable state in pulmonary tuberculosis.

In our experience, severe pulmonary tuberculosis (PTB) is often complicated by deep venous thrombosis (DVT). Because of the association between inflammation and haemostatic changes that can result in a hypercoagulable state, we have prospectively examined such predisposing factors in representative patients. Sequential analyses in a control group with active PTB showed anaemia, thrombocytosis, elevations in plasma fibrinogen, fibrin(ogen) degradation products (FDP), tissue plasminogen activator (t-PA) and inhibitor (PAI-1) with depressed antithrombin III levels. Age, sex and disease matched individuals with venographically proven DVT had higher FDP (15.8 +/- 14.3 v 3.2 +/- 1.7 micrograms/ml:P < 0.01), t-PA (19.4 +/- 14.9 v 11.3 +/- 0.8 ng/ml:P < 0.01), and functional PAI-1 activity (11.6 +/- 6.3 v 4.2 +/- 4.1:P < 0.01) with lower platelet counts (347 +/- 110 v 563 +/- 230 x 10(9)/1:P < 0.01). Fibrinogen levels in all patients rose during the first 2 weeks of therapy and, together with related disturbances, corrected within 12 weeks. In conclusion, elevated plasma fibrinogen with impaired fibrinolysis coupled with a decrease in antithrombin III and reactive thrombocytosis would appear to favour the development of DVT in PTB.

Acute-Phase Reaction↗
PubMed1994

Review and analysis of variation between spirometric values reported in 29 studies of healthy African adults.

Within- and between-population variation in spirometric measurements has been addressed in a systematic review of spirometric measurements from 29 studies published between 1965 and 1990 involving 9,690 men and 2,638 women of sub-Saharan African ancestry; FVC and FEV1 were age- and height-standardized at BTPS. Between- population differences were related to geographic region and sample source (workforce versus community). The effects of altitude, variation in sample mean height, and year of study publication were also significant variables in multivariate models explaining between-population differences. Altitude was the most important variable with an effect of 263 ml/1,000 m (95% confidence interval [CI] 120-410) on FVC in men. In women, variation in sample mean height was also important, with taller populations having larger values for FVC (64 ml/cm). In men, secular trends were evident, with date of study associated with negative trends among men in the U.S.A. (-35.3 ml/year), and positive trends (14.7 ml/year) in other regions. These differences in trend could not be explained. Population selection factors, altitude, date of study, and other biological sources of variation need to be taken into account in evaluating between- and within-population comparisons of spirometric measurements.

Adult↗
PubMed1992

Workmens' compensation and byssinosis in South Africa: a review of 32 cases.

Byssinosis has been compensable in the Republic of South Africa (RSA) since 1973. The legal and administrative provisions for byssinosis compensation are reviewed. A series of 32 cases of presumed byssinosis was submitted to the compensation authorities by the authors. Identical reports were submitted to an independent medical panel. The findings and outcomes in these cases are presented and compared. Seventeen of the 32 claims initially received compensation and four were subsequently accepted following appeals. Analysis of the medical basis of decision making indicated that seven claims were refused and at least four had their awards reduced as a consequence of inconsistent decisions. Arguable decisions resulted in five claims being refused and one award being reduced. Our experience illustrates problems inherent in the compensation system in South Africa. Initiation of a claim is expensive relative to wages in the industry, and awards are low since they are linked to wages (mean $60.47 per week). Processing of a claim took a mean of 13.8 months, while appeals for refusal to compensate took a further 29.8 months. It is argued that consensus medical definitions of compensable occupational disease should be used routinely and that provision must be made to facilitate entry of claimants into the compensation system.

Adult↗
PubMed1991

Silicosis among gemstone workers in South Africa: tiger's-eye pneumoconiosis.

Six cases of silicosis in workers involved in the processing of semiprecious gem stones have been seen in our clinic since 1976. They had been employed as stone sculptors in lapidaries where they processed tiger's-eye, rose quartz, amethyst, quartz crystal, and a variety of other locally occurring semiprecious stones. In five of the cases, exposure was in small and poorly regulated lapidaries without specific dust control measures. The sixth was detected during the course of a health and hygiene survey (including dust sampling) that was conducted in one of two lapidaries still operating in our area. Progressive massive fibrosis (PMF) or accelerated silicosis was noted in four of the six cases, three of whom had progression of their disease after cessation of exposure. With the development of PMF, the initial restrictive pulmonary function abnormalities were followed by steadily worsening airflow obstruction. Lung biopsies confirmed silicosis in three cases. Tuberculosis was confirmed in two cases and suspected and treated in a third. Workmen's Compensation was awarded in five cases. The survey confirmed that in semiprecious gem stone processing, the risk of silicosis appears to be confined to stone sculptors. Tried and proven techniques of general and local exhaust ventilation combined with water or oil to control dust at source were capable of effectively reducing dust emission to acceptable levels.

Adult↗
PubMed1990

Asthma and hyperthyroidism. A report of 4 cases.

For many years it has been known that thyrotoxicosis can worsen asthma, increasing both the frequency and severity of asthma attacks and increasing requirements for medication. Clinical recognition of this association may be difficult. Thyrotoxic asthmatics frequently experience side-effects from medications, particularly beta-receptor agonists and theophyllines. Four case reports of asthmatics in whom thyrotoxicosis was diagnosed are presented. All 4 patients improved on returning to euthyroid status. The mechanism responsible for the harmful interaction is not known.

Adult↗
PubMed1990

Comparison of dissection rates and angiographic results following directional coronary atherectomy and coronary angioplasty.

Directional coronary atherectomy is a new percutaneous transluminal technique for treating occlusive coronary artery disease. In this study, angiographic results (i.e., residual stenosis and angiographic evidence of postprocedure dissection) after directional coronary atherectomy and balloon angioplasty were compared. The atherectomy group consisted of 91 lesions in 83 consecutive patients who underwent either left anterior descending artery or right coronary artery atherectomy. The angioplasty group consisted of 91 lesions in 84 patients that were matched with the atherectomy lesions with respect to vessel and whether the lesion was a restenosis lesion. The mean preprocedure diameter stenosis was 76% in both groups as measured quantitatively with electronic calipers. After the procedure, the mean residual diameter stenosis of the atherectomy lesions was 13 +/- 17%, whereas for the angioplasty lesions it was 31 +/- 18% (p less than 0.001). Success rates in both groups were similar (94.5 and 93.4%, respectively). The incidence of postprocedure dissection was 11% in the atherectomy group and 37% in the angioplasty group (p less than 0.0001). Directional coronary atherectomy results in significantly improved postprocedure angiographic appearances due to significantly less severe residual stenosis and lower incidence of dissection.

Angioplasty, Balloon, Coronary↗