Immigrants and tuberculosis in Hong Kong.

OBJECTIVE: To examine the impact of immigrant populations on the epidemiology of tuberculosis in Hong Kong. DESIGN: Longitudinal cohort study. SETTING: Hong Kong. PARTICIPANTS: Socio-demographic and disease characteristics of all tuberculosis notifications in 2006 were captured from the statutory tuberculosis registry and central tuberculosis reference laboratory. Using 2006 By-census population data, indirect sex- and age-standardised incidence ratios by place of birth were calculated. Treatment outcome at 12 months was ascertained from government tuberculosis programme record forms, and tuberculosis relapse was tracked through the notification registry and death registry up to 30 June 2013. RESULTS: Moderately higher sex- and age-standardised incidence ratios were observed among various immigrant groups: 1.06 (Mainland China), 2.02 (India, Pakistan, Bangladesh), 1.59 (Philippines, Thailand, Indonesia, Nepal), and 3.11 (Vietnam). Recent Mainland migrants had a lower sex- and age-standardised incidence ratio (0.51 vs 1.09) than those who immigrated 7 years ago or earlier. Age younger than 65 years, birth in the Mainland or the above Asian countries, and previous treatment were independently associated with resistance to isoniazid and/or rifampicin. Older age, birth in the above Asian countries, non-permanent residents, previous history of treatment, and resistance to isoniazid and/or rifampicin were independently associated with poor treatment outcome (other than cure/treatment completion) at 1 year. Birth outside Hong Kong was an independent predictor of relapse following successful completion of treatment (adjusted hazard ratio=1.76; 95% confidence interval, 1.07-2.89; P=0.025). CONCLUSION: Immigrants carry with them a higher tuberculosis incidence and/or drug resistance rate from their place of origin. The higher drug resistance rate, poorer treatment outcome, and excess relapse risk raise concern over secondary transmission of drug-resistant tuberculosis within the local community.

Smoking adversely affects treatment response, outcome and relapse in tuberculosis.

The impact of smoking on tuberculosis outcome was evaluated in a territory-wide treatment programme. 16,345 consecutive patients undergoing chemotherapy for active tuberculosis in government chest clinics in Hong Kong from 2001 to 2003 were followed up prospectively for 2 years for treatment outcome and subsequently tracked through the territory-wide tuberculosis notification registry for relapse until the end of 2012. Smoking was associated with more extensive lung disease, lung cavitation and positive sputum smear and culture at the baseline. In both current smokers and ex-smokers, sputum smears and cultures were significantly more likely to remain positive after 2 months of treatment. Both categories of smokers were significantly less likely to achieve cure or treatment completion within 2 years. Overall, 16.7% of unsuccessful treatment outcomes were attributable to smoking, with the key contributor being default in current smokers and death in ex-smokers. Among successful treatment completers, there was a clear gradient (hazard ratios of 1.00, 1.33 and 1.63) of relapse risk from never-smokers to ex-smokers and current smokers, with an overall population attributable risk of 19.4% (current smokers: 12.2%; ex-smokers: 7.2%). Smoking adversely affects baseline disease severity, bacteriological response, treatment outcome and relapse in tuberculosis. Smoking cessation likely reduces relapse and secondary transmission.

Delayed presentation and treatment of newly diagnosed pulmonary tuberculosis patients in Hong Kong.

OBJECTIVE: To measure patients' and providers' delays in the presentation and treatment of newly diagnosed pulmonary tuberculosis. DESIGN: Retrospective study using structured questionnaires. SETTING: Tuberculosis and Chest Service, Centre of Health Protection, Department of Health. PARTICIPANTS: Tuberculosis patients notified to the Department of Health, selected by systematic sampling of all notifications in the first 2 weeks of every even month in the year 2004. MAIN OUTCOME MEASURES: Health-seeking behaviour of pulmonary tuberculosis patients, including respective demographic, clinical, and disease factors. RESULTS: Of a total of 6262 notified tuberculosis patients in 2004, 1662 (26.5%) were recruited into the study; of these, 42.6% first presented to private doctors, and 57.4% to the public sector. The diagnosis of tuberculosis was made in 13.7% of these patients by the former and 86.3% by the latter. The median patient delay (elapsed time from symptoms to medical consultation) and provider delay (elapsed time from medical consultation to treatment) were both 20 days; 25th to 75th percentiles being 7-37 and 6-55 days, respectively. Longer patient delay was associated with positive sputum smear and culture, and more extensive radiological disease. On multiple regression analysis, unemployment independently predicted longer patient delay, while haemoptysis predicted shorter patient and total delay. Patients older than 60 years, with no initial sputum and chest X-ray examination predicted longer provider and total delays. CONCLUSIONS: Our patient and provider delays compared favourably with those of other countries, and very likely reflect easy service access. Adverse social factors and non-specific presentations prolong patient delay, whilst older age and unavailable bacteriological/radiological evidence delay diagnosis and treatment.