Smoking and tuberculosis in Hong Kong.

OBJECTIVE: To study the relationship between smoking and tuberculosis in Hong Kong. METHOD: Indirect sex and age adjustment was used to compare the prevalence of ever smokers between a sample of 851 patients from the 1996 tuberculosis notification registry and the general population. The clinical characteristics of smokers and non-smokers were compared by stratified univariate analysis and multiple logistic regression. RESULTS: Tuberculosis patients were more likely to have smoked than population controls. The respective odds ratios for ever smoking between tuberculosis patients and population controls were 2.44 and 2.08 for males and females aged 16-64 (Mantel-Haenszel weighted OR = 2.40, P < 0.001), and 2.09 and 2.83 for males and females aged > or = 65 (Mantel-Haenszel weighted odds ratio = 2.19, P < 0.001). Male sex, age > or = 65, working at onset of illness, regular alcohol use, drug abuse and absence of contact history were associated with ever smokers (all P < 0.05). Ever smokers were more likely to have cough (OR 1.69), dyspnoea (OR 1.84), upper zone involvement (OR 1.67), cavity (OR 1.76), miliary lung involvement (OR 2.77), positive sputum culture (OR 1.43), but less isolated extrathoracic involvement (OR 0.31), even after controlling for the confounding background variables (all P < 0.05). CONCLUSION: There was a consistent association between smoking and tuberculosis. More aggressive lung involvement was also found among ever smokers.     

Sex differences in tuberculosis in Hong Kong.

SETTING: The Hong Kong Tuberculosis and Chest Service, Department of Health, Hong Kong. OBJECTIVE: To examine sex differences in the rate and clinical manifestations of tuberculosis in Hong Kong. DESIGN: Notification rates of tuberculosis during the past five decades were obtained from the Hong Kong Tuberculosis and Chest Service, Department of Health, Hong Kong. In addition, all patients registered with the Chest Service for treatment of tuberculosis in 1996 were studied. RESULTS: The rate of tuberculosis during the past five decades was consistently higher in men than in women, irrespective of age group. The sex difference in rates was highest among those aged over 60 years. In 1996, a higher proportion of women had extra-pulmonary tuberculosis than men; the main site of involvement was the lymph nodes. More women completed treatment at 12 months and fewer women missed treatment appointments. A higher proportion of men had relapse pulmonary disease that was more extensive, a history of previous default from treatment and co-morbid illnesses. CONCLUSION: There are sex differences in the rates and clinical manifestations of tuberculosis in Hong Kong. Study of sex differences is essential for targeting prevention programmes at groups at higher risk.     

Extra-pulmonary and pulmonary tuberculosis in Hong Kong.

OBJECTIVE: To compare the characteristics of patients with pulmonary and extra-pulmonary tuberculosis and to describe the organ involvement, diagnosis and treatment of extra-pulmonary tuberculosis. MATERIALS AND METHODS: All patients with a diagnosis of tuberculosis treated by the Hong Kong Government Tuberculosis and Chest Service (Chest Service) in 1996 were studied. RESULTS: Of the 5757 patients treated, 13.7% had extra-pulmonary tuberculosis alone and 8.6% had both extra-pulmonary tuberculosis and pulmonary tuberculosis. Extra-pulmonary tuberculosis was more common in women under 30 and over 75 years of age. Only six patients had human immunodeficiency virus (HIV) infection, of whom two had extra-pulmonary tuberculosis. The most common site of extra-pulmonary involvement was the pleura, followed by the lymph nodes. Miliary tuberculosis occurred in only 2.9%. Lymph node involvement occurred significantly higher in women, while pleural disease was significantly higher in men. The duration of treatment varied according to the site of disease, being shorter (6 months) for those with pleural disease only and >9 months for those with miliary, meningeal, gastrointestinal and genitourinary disease; 80.3% completed treatment at 12 months and 85.5% at 24 months. Of those who completed treatment, 1.4% had a relapse of disease at 24 months follow-up; there was no significant difference between those with pulmonary or extra-pulmonary disease. CONCLUSION: In Hong Kong, extra-pulmonary tuberculosis is common, affecting 22.3% of TB patients, and is unrelated to HIV infection. There are sex differences in the organs most commonly affected. The rate of relapse of disease is low for those who completed treatment, irrespective of the site of involvement.     

Risk factors for multidrug-resistant tuberculosis in Hong Kong

SETTING: Previous anti-tuberculosis treatment is a widely reported risk factor for multidrug-resistant tuberculosis (MDR-TB), whereas other risk factors are less well described. In Hong Kong, the clinical characteristics of MDR-TB have not been systematically evaluated. OBJECTIVE: To explore the risk factors for MDR-TB in Hong Kong. DESIGN: MDR-TB patients treated between 1999 and 2003 were compared with non-MDR-TB patients by stratification of previous anti-tuberculosis treatment. RESULTS: One hundred and fifty-six MDR-TB patients, including 93 with and 63 without a previous history of anti-tuberculosis treatment, were identified. Among the 322 non-MDR-TB controls, respectively 192 and 130 patients did and did not have a previous history of anti-tuberculosis treatment. Using logistic regression analysis, non-permanent residents (OR 6.85, 95%CI 1.38-34.09), frequent travel (OR 2.48, 95%CI 1.07-5.74) and younger age were found to be independent predictors of MDR-TB in previously treated patients, whereas living on financial assistance just failed to reach statistical significance (OR 2.75, 95%CI 0.98-7.68, P=0.05). In the treatment-na?ve group, despite significant differences in baseline characteristics among MDR-TB and non-MDR-TB patients, no independent predictor variables could be identified. CONCLUSION: In Hong Kong, non-permanent residents, frequent travel and young age were independent predictors of MDR-TB among previously treated patients.     

Chest radiograph screening for tuberculosis in a Hong Kong prison.

SETTING: Long-stay prisoners are not regularly screened for TB in Hong Kong. OBJECTIVE: To evaluate tuberculosis (TB) screening in prison. METHOD: All prisoners in a maximum security prison as of 31 October 2001 were screened by chest radiograph (CXR), except for those being followed up for TB or examined by CXR in the last 6 months. RESULTS: A total of 814 male prisoners aged 34.6 +/- 9.6 (mean +/- SD) years were successfully screened. Of 53 cases (6.51%) with radiographic abnormalities, 10 active TB cases (8 culture-negative, 2 culture-positive) were diagnosed, giving an overall yield of 1.23% (95%CI 0.59-2.26). There was no statistical difference in age, ethnicity, place of birth or residency status between those with and those without TB (all P > 0.05). Incarceration > or = 2 years, being in current prison > or = 2 years and not having CXR in last 2 years were associated with TB in univariate analysis (all P < 0.05), but only the last remained an independent predictor in multiple logistic regression (OR 16.8, 95%CI 2.1-132.9, P = 0.008). In that group, the yield was 3.1% (95%CI 1.42-5.89). No further cases were detected in the subsequent 2 years. CONCLUSION: CXR screening of long-stay prisoners gave a high yield in this study.     

Directly observed treatment of tuberculosis in Hong Kong.

OBJECTIVE: To evaluate the local use of out-patient directly observed treatment (DOT) for tuberculosis (TB) control. SETTING: Seventeen government chest clinics managing around 80% of TB patients in Hong Kong. METHOD: A retrospective cohort. TB patients registered for treatment from 1 July to 31 August 2000 were followed up for 2 years. Baseline socio-demographic and clinical characteristics were correlated with adherence to DOT, mode of treatment and treatment outcomes. RESULTS: Of 988 patients, respectively 142, 140 and 21 switched to non-DOT within 2 months, 2-6 months and after 6 months. More Chinese patients than ethnic minorities switched to non-DOT within the first 2 months (15.2% vs. 0%, P = 0.001). Geographical inconvenience (31.7%) was the primary reason for switching initially, with increasing proportions giving no specific reason after the second month. Patients staying on DOT in the first 2 months had a significantly higher cure rate than those not on DOT, in both univariate (92.7% vs. 83.9%, P = 0.002) and multivariate analysis (OR = 2.5, P = 0.001). Subsequent switching, intermittent or daily regimen did not appear to affect the outcome. CONCLUSION: Significant numbers of patients failed to stay on DOT, and those staying initially had a better outcome.     

Early and late tuberculosis risks among close contacts in Hong Kong.

SETTING: Tuberculosis (TB) notification is a statutory requirement in Hong Kong, where contact investigations are performed by the Tuberculosis and Chest Service. OBJECTIVES: 1) To evaluate the risk of active TB in close contacts within 5 years, and 2) to identify risk factors associated with early and late development of active TB disease. DESIGN: The characteristics of consecutive TB cases notified from 18 January to 17 April 2000 were collected together with those of their contacts. Contacts were prospectively followed up through the territory-wide TB notification registry for 5 years for the development of disease. RESULTS: A total of 1537 index cases and 4661 close contacts were analysed. Screening found 31 (0.67%) active TB cases within a 3-month period, and another 58 (1.24%) cases presented subsequently. Index cases with cough or pulmonary cavities and diabetic contacts were independent risk factors of early cases (all P<0.05). Adjusted at risk index characteristics for late TB development included positive sputum smear (2.79, 95%CI 1.31-5.95) and family history of TB (4.26, 95%CI 2.01-9.03). Contact risk factors included diabetes mellitus (3.44, 95%CI 1.04-11.33) and institutionalisation (3.61, 95%CI 1.70-7.65). CONCLUSION: Considerable TB risk remains after initial contact screening. A number of possible risk factors were identified.     

Smoking and tuberculosis among the elderly in Hong Kong

A cohort of 42,655 clients that were first registered with the Elderly Health Service in 2000 were followed prospectively through the tuberculosis (TB) notification registry until the end of 2002. A total of 286 active TB cases (186 culture confirmed) were identified. The annual TB notification rates were 735, 427, and 174 per 100,000 among current smokers, ex-smokers, and never-smokers, respectively (p < 0.001). The trend in TB risk persisted after the control of background characteristics using Cox proportional hazards analysis (adjusted hazard ratios [HRs]: 2.63, 1.41, and 1, p < 0.001). In comparison with never-smokers, current smokers had an excess risk of pulmonary TB (adjusted HR, 2.87; 95% confidence interval [CI], 2.00-4.11; p < 0.001), but not extrapulmonary TB (adjusted HR, 1.04; 95% CI, 0.33-3.30; p = 0.95). Among the current smokers, those who developed TB smoked more cigarettes per day than those who did not (13.43, SD 8.76 vs. 10.96, SD 7.87, p = 0.01). A statistically significant dose-response relationship was observed with respect to active TB and culture-confirmed TB (both p < 0.05). Smoking accounted for 32.8% (95% CI, 14.9-48.0%), 8.6% (95% CI, 3.3-15.1%), and 18.7% (95% CI, 7.7-30.4%) of the TB risk among males, females, and the entire cohort, respectively. Approximately 44.9% (95% CI, 20.7-64.6%) of the sex difference was attributable to smoking.     

Socio-economic factors and tuberculosis: a district-based ecological analysis in Hong Kong.

BACKGROUND: Relatively little is known about the impact of socio-economic factors on tuberculosis in a metropolitan city with high disease incidence. METHOD: District-specific tuberculosis notification rates for 1995--1997 and 2000--2002 were indirectly sex- and age-adjusted and compared with the socio-economic characteristics in the 1996 by-census and 2001 census. RESULTS: The differences between the 18 districts persisted after 3-year averaging and indirect standardisation. Only the percentage of population born locally, the percentage of the population widowed or divorced and the percentage of households residing in rooms or bedsits were consistently associated with the standardised notification ratios (SNR) for both periods, the first being negatively so (all P < 0.05). In a combined analysis with a general linear model for both periods, birth in China, residence <7 years, speaking other Asian languages, being married and in a single household were also significantly associated with the SNR (all P < 0.05). Using a backward conditional approach, only local birth, being married, and residing in rooms or bedsits were independent predictors of SNR (all P < 0.05). There was no significant association between SNR and socio-economic indices on education, occupation, unemployment and income. CONCLUSION: Socio-economic factors other than simple poverty are affecting the district-specific tuberculosis rates in Hong Kong.     

A survey of deaths in Hong Kong attributed to tuberculosis

Records obtained for 578 (96 %) of the 602 patients certified as having died from tuberculosis in Hong Kong during a 1-year period were reviewed by an expert independent assessor in London. In his opinion 14 (2 % of the 578) had never had tuberculosis, and in 28 (5 %) it was not possible to decide whether or not the patient had ever had tuberculosis. Tuberculosis had been no more than a contributory factor in causing death in 44 (8 %), in 29 (5 %) it was irrelevant, and in 33 (6 %) it was not possible to determine what role it had played. The remaining 430 (74 %) patients were considered actually to have died from tuberculosis, 307 from active disease and 123 from the late effects of inactive disease.If all 578 patients had died from tuberculosis this would represent a death rate for the survey year of 13.1 per 100 000 of the population. The rate falls to 9.7 per 100 000 if based on the 430 patients considered by the assessor to have died from tuberculosis, a reduction of 26 %. Since the annual death rate from active disease (6.9 per 100 000 in this survey) is a better index of the current efficiency of an antituberculosis programme than the total death rate, it is suggested that efforts should be made to obtain and publish separate annual rates for deaths from active and from inactive tuberculosis.An analysis of potentially avoidable delays and failures in diagnosis showed that these were mainly due to the patient's delay in seeking or accepting advice, or inadequate investigation, particularly failure to examine the sputum, by the unofficial (non-governmental) medical services. The majority of failures in management were attributable in whole or in part to the patient.     

Intraoperative ultrasound examination is useful for monitoring transplanted islets

A 39-y-old man, who had an episode of pancreatic bleeding due to chronic pancreatitis, received total pancreatectomy with islet autotransplantation (TP with IAT). Intraoperative ultrasound (US) examination was done to detect transplanted islets and evaluate the quality of US imaging.

Islet isolation from the resected total pancreas was performed and approximately 230,000 islet equivalents (IEQ) (the tissue volume was 600 µL and the purity was 30%) were acquired. A double lumen catheter, used for transplantation and for monitoring the portal vein pressure, was inserted into the portal vein via the superior mesenteric vein, and the tip of the catheter was positioned at the bifurcation of the anterior and posterior branch of the portal vein to selectively infuse the islets into the right lobe of the liver in order to prevent total liver embolization. Intraoperative US examination (central frequency 7.5 MHz, Nemio? XG, Toshiba Medical System Co.) was started at the same time as the transplantation.

US examination revealed the transplanted islets as hyperechoic clusters that flowed from the tip of the catheter to the periphery of the portal vein. There were no findings of portal thrombosis or bleeding in the US image, and also no increase of the portal vein pressure during transplantation.

In conclusion, we succeeded in visualizing human islets using US, which enabled us to perform islet transplantation safely. The hyperechoic images were considered to be viable islets. Intraoperative US examination can be useful for detecting islets at transplantation in a clinical setting.     

Low yield of chest radiography in screening for active pulmonary tuberculosis in HIV-infected patients in Hong Kong.

This study assessed the usefulness of routine chest radiography for detecting active pulmonary tuberculosis in persons infected with human immunodeficiency virus (HIV) without suggestive symptoms in Hong Kong. Tuberculosis is common in this locality and tuberculosis/HIV co-infection has been a frequent and significant problem. Records of patients attending the largest HIV clinic were reviewed. Three hundred and eleven routine chest radiographs were performed among 191 HIV-infected patients with a total follow-up period of 792 person years. Of the 22 routine chest radiographs that had abnormalities in the lungs or hilar region, only one had led to the diagnosis of pulmonary tuberculosis. No patient with a normal chest radiograph was diagnosed to have tuberculosis within the following 2 months. The low yield (0.32%) suggests that routine chest radiography is not useful in screening for active pulmonary tuberculosis in asymptomatic HIV-infected patients even in a locality where the tuberculosis rate is high.     

Population-based prospective molecular and conventional epidemiological study of tuberculosis in Hong Kong

OBJECTIVE: To study the transmission of tuberculosis using conventional and molecular epidemiology in Hong Kong. METHODS: All patients with positive sputum culture for Mycobacterium tuberculosis residing on the Island of Hong Kong were recruited from May 1999 to April 2002. The restriction fragment length polymorphism technique was used to determine DNA patterns of isolates of M. tuberculosis using the IS6110 probe, supplemented by pTBN12 as a secondary probe. RESULTS: One thousand five hundred and fifty-three of 2337 (66%) of the patients with bacteriologically confirmed tuberculosis had restriction fragment length polymorphism analysis of their M. tuberculosis isolates. Four hundred and fifty-four (29.2%) patients belonging to 143 clusters were identified; the estimated rate of recent transmission was 20-24%. Significant predictors of clustering included young-age groups (<40 years) versus those >60 years of age (adjusted odds ratio (OR) 1.96, 95% confidence interval 1.47-2.62), permanent residency versus new or non-residents (adjusted OR 3.40, 95% 1.84-6.26) and previous default from treatment versus new cases (adjusted OR 6.12, 95% confidence interval 1.82-20.5). Alcohol and drug abuse, history of imprisonment and HIV infection were not significant risk factors for molecular clustering. Of patients belonging to clusters, 5.1% had definite, 5.5% had probable and 24.4% had possible epidemiological link, suggesting casual contact may be responsible for a high proportion of the clustered cases. CONCLUSION: One-fifth to one quarter of the new cases of active tuberculosis in Hong Kong are due to recent transmission. In addition to early diagnosis and successful treatment of all active disease, treatment of latent disease should receive more attention in the control of tuberculosis in Hong Kong.