PubMed Health⌕ Search

Biomedical subjects

Wing Wai Yew

Publications and source records attributed to Wing Wai Yew.

13 recordsLinked to original sources
PubMed2006

Risk of active tuberculosis among schoolchildren in Hong Kong.

OBJECTIVE: To estimate the risk of active tuberculosis (TB) and its implication on preventive treatment among BCG-vaccinated schoolchildren. DESIGN: Cohort and case-control designs. SETTING: Community settings in a high-prevalence area. PARTICIPANTS: Children in primary school. The main exposure was their tuberculin response. MAIN OUTCOME MEASURES: Of 94,928 primary schoolchildren tuberculin tested during a routine school revaccination program in 1999, 656 with a tuberculin response at 20 mm or more were followed up prospectively through the territory-wide TB registry up to December 31, 2003, for the development of TB. In a separate case-control analysis, the tuberculin responses of children who subsequently had active TB (at the age of 10-15 years) were compared with those of their sex- and age-matched classmates to ascertain the relative risks of TB for different tuberculin reaction categories. The absolute and relative risks were applied to the 1999 cohort for estimating the incidence of TB among different tuberculin reactors. RESULTS: The annual incidence (95% confidence interval) of active TB was estimated to be 13.4 (5.6-40.6) per 100,000 for the entire cohort and 7.5 (2.4-24.5), 7.5 (1.7-32.0), 16.0 (4.4-57.2), 92.6 (26.6-320.2), and 340.6 (163.3-626.4) per 100,000 for children with a tuberculin reaction at 0 to 4, 5 to 9, 10 to 14, 15 to 19, and 20 mm or more, respectively. By using 10 mm as the cutoff, 482 (95% confidence interval, 163-1391) children have to be treated to prevent a single case of active TB within 5 years. Treatment will cover 17.5% of the cohort, but prevent only 54.1% of all active TB cases. CONCLUSION: It is desirable to reexamine the existing screening method for BCG-vaccinated children from high-prevalence countries.

Adolescent↗
PubMed2006

Antituberculosis drugs and hepatotoxicity.

Isoniazid, pyrazinamide and rifampicin have hepatotoxic potential, and can lead to such reactions during antituberculosis chemotherapy. Most of the hepatotoxic reactions are dose-related; some are, however, caused by drug hypersensitivity. The immunogenetics of antituberculosis drug-induced hepatotoxicity, especially inclusive of acetylaor phenotype polymorphism, have been increasingly unravelled. Other principal clinical risk factors for hepatotoxicity are old age, malnutrition, alcoholism, HIV infection, as well as chronic hepatitis B and C infections. Drug-induced hepatic dysfunction usually occurs within the initial few weeks of the intensive phase of antituberculosis chemotherapy. Vigilant clinical (including patient education on symptoms of hepatitis) and biochemical monitoring are mandatory to improve the outcomes of patients with drug-induced hepatotoxicity during antituberculosis chemotherapy. Some fluoroquinolones like ofloxacin/levofloxacin may have a role in constituting non-hepatotoxic drug regimens for management of tuberculosis (TB) in the presence of hepatic dysfunction. Isoniazid administration is currently the standard therapy for latent TB infection. Rifamycins like rifampicin or rifapentine, alone or in combination with isoniazid, may also be considered as alternatives, pending accumulation of further clinical data. During treatment of latent TB infection, regular follow up is essential to ensure adherence to therapy and facilitate clinical monitoring for hepatic dysfunction. Monitoring of liver chemistry is also required for those patients at risk of drug-induced hepatotoxicity.

Antitubercular Agents↗
PubMed2005

Seasonal pattern of tuberculosis in Hong Kong.

BACKGROUND: Summer predominance of tuberculosis (TB) was reported previously in temperate regions. No consistent data were available for lower latitudes. METHOD: The monthly TB notification data in Hong Kong from 1991 to 2002 were examined for seasonal fluctuation. A seasonal model was then developed after standardization by period, sex, age, history of TB, form of disease, and bacteriological status. RESULTS: The raw monthly counts showed remarkably consistent seasonal fluctuation across different periods, sexes, and age groups. A sine model was fitted for 82 104 notifications (adjusted R(2) = 0.373, P < 0.001). A summer peak was observed with seasonal fluctuation of 18.4% (P < 0.001), which was substantially higher than that reported previously for temperate regions. The amplitudes of fluctuation were 35.0, 15.0, 19.0, and 20.2% for those aged < or =14, 15-34, 35-64, and >/=65 years, respectively (all P < 0.001). No gender difference was noted (18.2% vs 19.0%, P = 0.790). Seasonal pattern was detected among new cases (18.6%, P < 0.001), but not retreatment cases (5.2%, P = 0.333). Culture-positive cases showed greater fluctuation than culture-negative cases (29.4% vs 6.4%, P < 0.001). No significant difference was found between pulmonary and extrapulmonary cases (16.8% vs 21.6%, P = 0.356). TB cases notified in summer were more likely to be smear-positive [odds ratio (OR) 1.100, 95% confidence interval (CI) 1.045-1.158, P < 0.001] and culture-positive (OR 1.175, 95% CI 1.121-1.232, P < 0.001) than those notified in winter, even after stratification by other key variables. CONCLUSION: A consistent seasonal pattern was found, with variable amplitudes of fluctuation in different subgroups and differing disease characteristics in different seasons. These observations are suggestive of the presence of a seasonal disease-modifying factor.

Age Distribution↗
PubMed2004

Protease inhibitor phenotypes and serum alpha-1-antitrypsin levels in patients with COPD: a study from Hong Kong.

OBJECTIVE: Many studies have suggested that an imbalance of protease activation and inhibition might result in COPD with emphysema. Levels of alpha-1-antitrypsin (alpha1-AT), the key protease inhibitor, are genetically determined by alleles that present in many phenotypes/subtypes, some of which are associated with deficiency of the protein. We prospectively evaluated the prevalence of the protease inhibitor (Pi) alleles and phenotypes together with the serum alpha1-AT levels in Chinese patients with COPD. METHODOLOGY: The study population comprised 356 patients with COPD. The male-to-female ratio was 4 : 1 with a mean age of 72.4 years (range 44-93 years). Isoelectric focusing was used for Pi phenotyping/subtyping. The frequencies of Pi alleles and phenotypes were compared with the frequencies in 1085 healthy unrelated Chinese control subjects. The serum alpha1-AT levels were measured by the Cobas Fara assay. RESULTS: PiZ was not detected. No significant difference in distribution of PiM phenotypes/subtypes between patients with COPD and healthy controls was observed, except for M1M3 and M2M3. There was also a significant difference in the proportion of variant S and F alleles between the disease group and the control population. CONCLUSION: The low prevalence of deficiency Pi phenotypes/subtypes suggests a lack of contribution of alpha1-AT deficiency to the pathogenesis of COPD in Chinese patients. The strategy of launching an alpha1-AT deficiency detection program among COPD patients, based on the recommendation of the World Health Organization, may not be readily applicable in our local setting.

Adult↗
PubMed2003

Multidrug-resistant tuberculosis in a lung transplant recipient.

Tuberculosis infection has been a relatively rare complication after lung transplantation. However, as more countries in which Mycobacterium tuberculosis infection remains endemic embark on lung transplant programs, the occurrence of multidrug-resistant tuberculosis after transplantation is a genuine threat. We report the first case of multidrug-resistant tuberculosis in a double-lung transplant recipient who probably acquired the disease from the donor. We discuss the problems in clinical management of post-transplant tuberculosis infection and of drug-resistance.

Adult↗
PubMed2003

Comparative roles of levofloxacin and ofloxacin in the treatment of multidrug-resistant tuberculosis: preliminary results of a retrospective study from Hong Kong.

OBJECTIVE: To compare levofloxacin and ofloxacin in the treatment of multidrug-resistant tuberculosis (MDR-TB). PATIENTS AND METHODS: A retrospective analysis of 106 patients with MDR-TB (February 1990 through December 2000) receiving directly observed therapy with fluoroquinolone and accompanying drugs, which mainly included aminoglycosides, cycloserine, ethionamide/prothionamide, and pyrazinamide, was performed. Clinical data from 99 suitable patients were subjected to univariate analysis, stratification, and multiple logistic regression to compare the roles of levofloxacin and ofloxacin in multidrug regimens. RESULTS: Forty patients received 612.5 +/- 79.0 mg qd levofloxacin (mean +/- SD), and 59 patients received 628.8 +/- 101.8 mg qd ofloxacin together with similar active second-line drugs for similar durations. The times to sputum smear (both 1.8 months) and culture conversion (both 2.1 months) were equivalent. Adverse reactions occurred at similar rates (10.0% vs 11.9%). The combined treatment success rate was 83.8%, being higher among ofloxacin-susceptible than ofloxacin-resistant cases (90.5% vs 64.0%, p < 0.01). The success rates for the levofloxacin group were 90.0% (overall), 96.2% (ofloxacin-susceptible cases), and 78.6% (ofloxacin-resistant cases) in comparison with 79.7%, 87.5%, and 45.5%, respectively, for the ofloxacin group (Mantel-Haenszel common odds ratio estimate, 4.0; p < 0.05). Bacillary susceptibility to ofloxacin, good adherence, radiographic extent of one lung or less, and use of levofloxacin were independent predictors of favorable outcome (odds ratios, 7.6 to 21.3). One patient each from both groups relapsed. CONCLUSION: Levofloxacin was found to be more efficacious than ofloxacin when incorporated into multidrug regimens used for treatment of MDR-TB.

Anti-Infective Agents↗
PubMed2003

Initial experience on rifampin and pyrazinamide vs isoniazid in the treatment of latent tuberculosis infection among patients with silicosis in Hong Kong.

OBJECTIVE: To compare the adverse effects and treatment adherence between 2 months of rifampin plus pyrazinamide (2RZ) and 6 months of isoniazid (6H). BACKGROUND: Patients with silicosis in Hong Kong are at high risk of acquiring tuberculosis. A previous study showed that treatment with 6H reduced the risk of silico-tuberculosis by one half. METHOD: Patients with silicosis and a Mantoux skin test reaction > or =10 mm were randomized to receive either 2RZ or 6H daily. Liver function testing was done monthly during the initial 2 months. The adverse effects and treatment adherence were compared between the two regimens. RESULTS: Forty patients (mean age, 61.6 +/- 9.1 years) and 36 patients (mean age, 57.6 +/- 9.7 years) were randomized to the 2RZ and 6H arms, respectively (p > 0.05) [+/- SD]. Baseline characteristics were comparable. Nineteen patients in the 2RZ arm had peak alanine transaminase (ALT) levels > 1.5 times the upper limit of normal (ULN) in comparison with only five study subjects of the 6H arm (47.5% vs 13.9%, p < 0.01). Fourteen patients (35%) in the 2RZ arm and 1 patient (2.8%) in the 6H arm had peak ALT levels more than five times the ULN (p < 0.001). Only seven patients had symptoms suggestive of hepatitis; none of the patients had jaundice. All recovered after withholding treatment. In the 2RZ study arm, none of the baseline characteristics predicted hepatotoxicity. Other adverse effects were generally mild and comparable between both study arms. Treatment was stopped prematurely in 45% and 36.1% of patients in the 2RZ and 6H arms, respectively (p = 0.43). The main reasons were hepatotoxicity for the 2RZ arm and voluntary withdrawal after experiencing other minor adverse effects for the 6H arm. CONCLUSION: A higher incidence of hepatotoxicity was associated with rifampin plus pyrazinamide than isoniazid in the treatment of latent tuberculosis infection among patients with silicosis in Hong Kong.

Aged↗
PubMed2002

Delayed sternotomy wound infection due to Paecilomyces variotii in a lung transplant recipient.

We report a case of sternotomy wound infection caused by Paecilomyces variotii in a previously bronchiectatic patient, occurring 10 months after bilateral sequential lung transplantation. The use of prophylactic antifungal therapy, the persistent colonization with Paecilomyces, and sternal instability after clamshell incision may have contributed to the development of delayed deep sternal wound infection. Besides antifungal therapy, vigorous surgical debridement is vital for treatment success. With the more liberal use of early post-transplant fungal prophylaxis, potentially drug-resistant fungi, such as the Paecilomyces species, may be emerging as important opportunistic pathogens after lung transplantation.

Adult↗