Abstract not available

Background. Obstructive Sleep Apnoea (OSA) is associated with an increase in nocturnal gastro-oesophageal reflux (nocturnalGOR) events and symptoms, however the mechanism for this remains undefined. Treatment of OSA with continuous positive airway pressure (CPAP) has been shown to reduce nocturnalGOR in individuals with OSA however the reasons for this reduction are not clear. The combination of OSA and nocturnalGOR could be particularly problematic for individuals who have had a lung transplant in whom Bronchiolitis Obliterans Syndrome (BOS) limits survival. It is thought that GOR plays a role in the development of BOS in these individuals. Methods and Results. Five interrelated studies were undertaken. The first two studies sought to determine and compare the prevalence and risk factors of nocturnalGOR in OSA patients with the general population. To do this, a GOR questionnaire was completed by 2,042 members of the general community as part of the Busselton Health Survey and by 1,116 patients with polysomnography-diagnosed OSA. Risk of OSA in the general population was determined using a standardised sleep questionnaire. 137 of the OSA patients completed the questionnaire before and after treatment with CPAP. The prevalence of nocturnalGOR symptoms reported more than once a week (frequent symptoms) was greater in OSA patients (10.1%) than the general population (5.8%) (p<0.001), in individuals from the general population at high (11.2%) than low risk of OSA (4.5%) (p<0.001) and in patients with severe (14.7%) than mild OSA (5.2%) (p<0.001). Treatment of OSA with CPAP decreased the prevalence of frequent nocturnalGOR from 9.0% to 3.8% (p=0.04). In the general population, high risk of OSA was independently associated with a 2.4-fold increased risk of frequent ABSTRACT vi nocturnalGOR symptoms than low risk. In the OSA group, disease severity was independently associated with nocturnalGOR symptoms, with an adjusted odds ratio of 1.7 for frequent nocturnalGOR symptoms.

Aim The aim of this study was to determine the contribution of occupational exposures to the burden of Chronic Obstructive Pulmonary Disease (COPD) among a sample of hospital based patients. Methods Cases (n=110) with specialist physician diagnosed COPD from the three public sector specialist respiratory clinics in KZN and controls (n=102) from other nonrespiratory chronic ailment specialist clinics at the same institutions were selected. An interviewer administered questionnaire and exposure history was obtained for each participant. In addition, a valid lung function test was obtained for each case. Data was analysed using STATA version 10. Multivariate regression models were developed to examine the relationship between COPD and occupational exposures while adjusting for age, sex, smoking and previous history of tuberculosis. The relationship of FEV1 and occupational exposures, adjusted for age, height, previous history of tuberculosis and smoking history, was investigated among cases. Results Cases and controls were similar with respect to age and sex distribution. Cigarette smoking differed significantly between cases and controls with a larger proportion of cases having ceased to smoke compared to controls (72% vs 46%, p<0.01). A higher proportion of controls reported employment in administrative, managerial and quality control positions (21.3% vs 12.0%, 7.7% vs 2.6% and 5.4% vs 0.3% respectively). Employment in the construction and shoe manufacturing industries was reported more frequently by cases (10.3% vs 3.2% and 10.0% vs 4.9% respectively). Cases were more likely than controls to have been exposed to dust (72% vs 28%, p<0.001) or to chemicals, gas or fumes (74% vs 25.5%, p<0.001) and reported exposure durations 3-4 fold higher than that of controls (p<0.001). Dust and chemical, gas or fume exposure was associated with an increased odds of developing COPD. Exposure to dusts (OR 7.9, 95% CI 3.9-15.7, p<0.001), chemicals, gas or fumes (OR 6.4, 95% CI 3.2-12.8, p<0.001) were significantly associated with odds of developing COPD. In addition, previous history of tuberculosis, as well as smoking were associated with an increased odds of COPD (OR 5.7, 95% CI 1.2-27.4 p<0.001 and OR 6.4, 95% CI 2.3-17.7, p<0.001). Discussion and Conclusion This is one of the first hospital based case-control studies looking at occupational contribution to COPD undertaken in South Africa. In this sample of participants, strong associations were observed between self-reported occupational exposures to dust, and chemicals, gas or fumes, and physician’s diagnosis of COPD. The study also demonstrated a strong association between smoking and previous history of tuberculosis, and risk of COPD. The findings suggest that persons with known occupational exposures to respiratory irritants should be monitored to detect the onset of respiratory ill-health and that preventive strategies should reduce exposure to these agents in the workplace. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2009.