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Thuan Q Thach

Publications and source records attributed to Thuan Q Thach.

7 recordsLinked to original sources
PubMed2006

Age-period-cohort analysis of cervical cancer incidence in Hong Kong from 1972 to 2001 using maximum likelihood and Bayesian methods.

OBJECTIVE: To examine the secular effects of opportunistic screening for cervical cancer in a rich, developed community where most other such populations have long adopted organised screening. DESIGN, SETTING, AND PARTICIPANTS: The analysis was based on 15 140 cases of invasive cervical cancer from 1972 to 2001. The effects of chronological age, time period, and birth cohort were decomposed using both maximum likelihood and Bayesian methods. RESULTS: The overall age adjusted incidence decreased from 24.9 in 1972-74 to 9.5 per 100,000 in 1999-2001, in a log-linear fashion, yielding an average annual reduction of 4.0% (p<0.001) during the 30 year period. There were two second order and thus identifiable changes: (1) around the mid-1920s cohort curve representing an age-period interaction masquerading as a cohort change that denotes the first availability of Pap testing during the 1960s concentrated among women in their 40s; (2) a hook around the calendar years 1982-83 when cervical cytology became a standard screening test for pregnant women. CONCLUSIONS: Hong Kong's cervical cancer rates have declined since Pap tests first became available in the 1960s, most probably because of increasing population coverage over time and in successive generations in a haphazard fashion and punctuated by the systematic introduction of routine cytology as part of antenatal care in the 1980s.

Adult↗
PubMed2005

Short-term, medium-term, long-term, and lifetime risks of developing and dying of breast carcinoma in a Westernized Chinese population: Evidence from Hong Kong between 1976 and 2000.

BACKGROUND: Estimates of lifetime and shorter-term risks of developing and dying of breast carcinoma are useful translational statistics for risk communication; however, these statistics are unknown for Chinese women, who account for one-fifth of the world's female population. In the current study, the authors examined age-specific 5-year, 10-year, 20-year, and lifetime risks of breast carcinoma incidence and disease-related mortality among Hong Kong women. METHODS: Multiple-decrement life tables were constructed by applying age-specific incidence and mortality rates obtained from cross-sectional data to a hypothetic birth cohort. Incidence, mortality, and population data from 1976 through 2000 were used. RESULTS: For Hong Kong women in the period 1996-2000, the overall lifetime risk of developing invasive breast carcinoma was 5.7% (1 in 17), compared with 10.6% (1 in 9) for U.S. Asian/Pacific Islander women and 14.5% (1 in 7) for U.S. white women. The lifetime breast carcinoma-related mortality risk for Hong Kong women in that same period was 1.7% (1 in 58). For women age 50 years, the 5-, 10-, and 20-year risks of developing breast carcinoma were 0.6% (1 in 172), 1.1% (1 in 87), and 2.1% (1 in 47), respectively. The absolute lifetime probability of developing breast carcinoma increased from 3.81% (1 in 26) during the period 1976-1980 to 5.73% (1 in 17) during the period 1996-2000; 44.5% of this change can be attributed to the increased longevity of women in the latter time period, and the remaining 55.5% can be ascribed to a secular rise in breast carcinoma incidence. CONCLUSIONS: As China becomes more Westernized, the authors expect that the risks of developing and dying of breast carcinoma for Chinese women will become more similar to the corresponding risks for Western women. The current data from Hong Kong, the most Westernized Chinese community, appear to support this conclusion.

Adult↗
PubMed2004

The epidemiology of severe acute respiratory syndrome in the 2003 Hong Kong epidemic: an analysis of all 1755 patients.

BACKGROUND: As yet, no one has written a comprehensive epidemiologic account of a severe acute respiratory syndrome (SARS) outbreak from an affected country. OBJECTIVE: To provide a comprehensive epidemiologic account of a SARS outbreak from an affected territory. DESIGN: Epidemiologic analysis. SETTING: The 2003 Hong Kong SARS outbreak. PARTICIPANTS: All 1755 cases and 302 deaths. MEASUREMENTS: Sociodemographic characteristics; infection clusters by time, occupation, setting, and workplace; and geospatial relationships were determined. The mean and variance in the time from infection to onset (incubation period) were estimated in a small group of patients with known exposure. The mean and variance in time from onset to admission, from admission to discharge, or from admission to death were calculated. Logistic regression was used to identify important predictors of case fatality. RESULTS: 49.3% of patients were infected in clinics, hospitals, or elderly or nursing homes, and the Amoy Gardens cluster accounted for 18.8% of cases. The ratio of women to men among infected individuals was 5:4. Health care workers accounted for 23.1% of all reported cases. The estimated mean incubation period was 4.6 days (95% CI, 3.8 to 5.8 days). Mean time from symptom onset to hospitalization varied between 2 and 8 days, decreasing over the course of the epidemic. Mean time from onset to death was 23.7 days (CI, 22.0 to 25.3 days), and mean time from onset to discharge was 26.5 days (CI, 25.8 to 27.2 days). Increasing age, male sex, atypical presenting symptoms, presence of comorbid conditions, and high lactate dehydrogenase level on admission were associated with a greater risk for death. LIMITATIONS: Estimates of the incubation period relied on statistical assumptions because few patients had known exposure times. Temporal changes in case management as the epidemic progressed, unavailable treatment information, and several potentially important factors that could not be thoroughly analyzed because of the limited sample size complicate interpretation of factors related to case fatality. CONCLUSIONS: This analysis of the complete data on the 2003 SARS epidemic in Hong Kong has revealed key epidemiologic features of the epidemic as it evolved.

Adult↗
PubMed2003

Transmission dynamics of the etiological agent of SARS in Hong Kong: impact of public health interventions.

We present an analysis of the first 10 weeks of the severe acute respiratory syndrome (SARS) epidemic in Hong Kong. The epidemic to date has been characterized by two large clusters-initiated by two separate "super-spread" events (SSEs)-and by ongoing community transmission. By fitting a stochastic model to data on 1512 cases, including these clusters, we show that the etiological agent of SARS is moderately transmissible. Excluding SSEs, we estimate that 2.7 secondary infections were generated per case on average at the start of the epidemic, with a substantial contribution from hospital transmission. Transmission rates fell during the epidemic, primarily as a result of reductions in population contact rates and improved hospital infection control, but also because of more rapid hospital attendance by symptomatic individuals. As a result, the epidemic is now in decline, although continued vigilance is necessary for this to be maintained. Restrictions on longer range population movement are shown to be a potentially useful additional control measure in some contexts. We estimate that most currently infected persons are now hospitalized, which highlights the importance of control of nosocomial transmission.

Cluster Analysis↗
PubMed2002

Cesarean trends.

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Cesarean Section↗
PubMed2002

Will screening mammography in the East do more harm than good?

OBJECTIVES: We sought to systematically review the evidence for population-based mammography as applied to a Chinese population. METHODS: Primary reports for meta-analysis were identified by a search of MEDLINE and the Cochrane Library. Outcome measures included breast cancer-related mortality, the number needed to be screened to prevent 1 death, and the positive predictive value of mammography. RESULTS: Pooled relative risk for breast cancer-related death in the screened group was 0.80 (95% confidence interval = 0.71, 0.90). Applied to Hong Kong, this figure translates into a number needed to screen of 1 302 healthy women screened annually for 10 years to prevent 1 death. CONCLUSIONS: Evidence is insufficient to justify population-based breast cancer screening by mammography for women in Hong Kong and other Asian populations with low breast cancer prevalence.

Aged↗