Molecular and Conventional Epidemiology of Tuberculosis in Hong Kong: a Population-Based Prospective Study

Chan‐Yeung, Moira; Tam, Cheuk‐Ming; Wong, Hau Yan; Leung, Chi‐Chiu; Wang, Julie; Yew, Wing‐Wai; Lam, Chak-Wah; Kam, Kai‐Man

doi:10.1128/jcm.41.6.2706-2708.2003

Cited by 41 publications

(47 citation statements)

References 19 publications

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“…among males aged >50 years in Hong Kong) suggests that it may be far higher than for Western populations. The hypothesis that the high tuberculosis disease incidence observed in Hong Kong is attributable to reactivation, and not to ongoing transmission, is consistent with the low level of ' clustering' of isolates from tuberculosis cases found in a recent DNA fingerprinting study in Hong Kong [10].…”

Section: Introductionsupporting

confidence: 83%

“…1), none of the disease incidence is attributed to recent (primary) infection. studies in Hong Kong: these have found relatively few isolates from elderly cases to be in a ' cluster ' and have attributed <25% of cases to recent transmission [10]. The high risks of developing disease through reactivation have important implications for trends in disease incidence.…”

Section: Discussionmentioning

confidence: 99%

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Limited impact of tuberculosis control in Hong Kong: attributable to high risks of reactivation disease

Vynnycky¹,

Borgdorff

Leung³

et al. 2007

Epidemiol. Infect.

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SUMMARYOver 50% of the global burden of tuberculosis occurs in South East Asia and the Western Pacific. Since 1950, notification rates in high-income countries in these settings have declined slowly and have remained over ten-fold greater than those in Western populations. The reasons for the slow decline are poorly understood. Using an age-structured model describing the incidence of Mycobacterium tuberculosis infection and disease applied to notification data from Hong Kong, we illustrate that in Hong Kong, a high prevalence of M. tuberculosis infection among older individuals and a high risk of disease through reactivation (e.g. up to 17-fold greater than that estimated for infected males in the United Kingdom) may explain this slow decline. If this feature of the epidemiology of tuberculosis is widespread, the WHO directly observed treatment short-course (DOTS) strategy may have a smaller impact in Asia in the short term than has been implied by recent predictions, all of which have been based on disease risk estimates derived from Western Europe. As a result, it may be difficult to meet the targets for tuberculosis control, which have been prescribed by the UN Millennium Development Goals.

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Section: Introductionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Limited impact of tuberculosis control in Hong Kong: attributable to high risks of reactivation disease

Vynnycky¹,

Borgdorff

Leung³

et al. 2007

Epidemiol. Infect.

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“…The residual risk among those screened as negative was .2,500 out of 100,000 personyrs. New infection or reinfection after tuberculin testing cannot account for the high residual risk, as previous molecular analysis of culture isolates showed only a low percentage of clustering, suggesting a low proportion of disease (20-24%) due to recent transmission in Hong Kong [13,14].…”

Section: Discussionmentioning

confidence: 99%

“…In the presence of a low proportion (20-24%) of TB cases, due to recent transmission in the local population [13,14], it should indirectly reflect the relative risk of developing active TB for test-positive and test-negative subjects. Prospective data comparing the relative risk of active TB in test-positive with that in test-negative subjects are still pending for the new IFNrelease assays [8].…”

Section: Methodsmentioning

confidence: 99%

Comparison of T-Spot.TB and tuberculin skin test among silicotic patients

Leung

Yam²,

Yew³

et al. 2007

Eur Respir J

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In the present study, T-Spot.TB and the tuberculin skin test (TST) were compared in the screening of latent tuberculosis infection among silicotic patients.A conditional probability model was used to compare the potential clinical utilities of T-Spot.TB and TST performed on 134 silicotic subjects from December 1, 2004 to January 31, 2007. Data from a historical cohort were also reanalysed for further comparison.Agreement with T-Spot.TB was best using a TST cut-off of 10 mm. Age o65 yrs independently predicted a tuberculin reaction ,10 mm (odds ratio53), but not a negative T-Spot.TB response. Lower measures of agreement were observed among current smokers and those aged o65 yrs. Tuberculin reaction size was well correlated with both early secretary antigenic target 6 and culture filtrate protein 10 spot counts, except among current smokers. Within the current estimates of sensitivity (88-95%) and specificity (86-99%) for T-Spot.TB, the positive likelihood ratio for T-Spot.TB test would be substantially higher (6.29-95.0 versus 1.65-1.94) and negative likelihood ratio substantially lower (0.05-0.14 versus 0.32-0.41) than the corresponding ratios for the tuberculin test. A low tuberculosis risk differential was similarly observed between tuberculinnegative and untreated tuberculin-positive subjects in the historical cohort.T-Spot.TB is likely to perform better than tuberculin test in the screening of latent tuberculosis infection among silicotic subjects.

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“…The interaction of smoking with the huge latently infected pool in an ageing population is therefore a serious concern. As endogenous reactivation accounted for .70% of the tuberculosis risk in Hong Kong [29], the use of directly observed treatment, short course alone, is unlikely to be able to bring down the disease incidence rapidly. With the high male and rising female smoking prevalence in many parts of Asia, it would appear rational to include smoking cessation as one of the armaments for tuberculosis control.…”

Section: Discussionmentioning

confidence: 99%

Smoking and tuberculosis among silicotic patients

Leung¹,

Yew²,

Law³

et al. 2006

Eur Respir J

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The aim of the present study was to investigate the relationship between smoking and tuberculosis (TB) among high-risk silicotic patients in Hong Kong.A cohort of 435 silicotic patients tuberculin tested from 1995-2002 was prospectively followedup until the end of 2005. Baseline characteristics were analysed with respect to positive tuberculin reaction (o10 mm) at baseline and subsequent development of TB.Smoking, alcohol use and body mass index were independent predictors of positive tuberculin reaction at baseline in multiple logistic regression analysis. Total cigarette pack-yrs did not demonstrate any significant effect. The annual incidences of TB were 1,841, 2,294 and 4,181 per 100,000 for never-, ex-and current smokers, respectively. On Cox proportional hazard analysis, current smokers have a significantly higher risk of TB than other silicotic patients (adjusted hazard ratio (95% confidence interval (CI)): 1.96 (1.14-3.35)) after controlling for age, alcohol use, tuberculin status, treatment for latent TB infection and other relevant background/disease factors. A significant dose-response relationship was also observed with the daily number of cigarettes currently smoked. Smoking cessation may reduce 32.4% (95% CI: 6.5-54.0) of the risk.Smoking increases the risk of both tuberculosis infection and subsequent development of the disease among silicotic patients.

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Molecular and Conventional Epidemiology of Tuberculosis in Hong Kong: a Population-Based Prospective Study

Cited by 41 publications

References 19 publications

Limited impact of tuberculosis control in Hong Kong: attributable to high risks of reactivation disease

Limited impact of tuberculosis control in Hong Kong: attributable to high risks of reactivation disease

Comparison of T-Spot.TB and tuberculin skin test among silicotic patients

Smoking and tuberculosis among silicotic patients

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