Irene O. L. Wong

Cost effectiveness of mammography screening for Chinese women

Although the cost effectiveness of screening mammography in most western developed populations has been accepted, it may not apply to Chinese women, who have a much lower breast cancer incidence. The authors estimated the cost effectiveness of biennial mammography in Hong Kong Chinese women to inform evidence‐based screening policies.

Age-period-cohort projections of breast cancer incidence in a rapidly transitioning Chinese population.

Breast cancer incidence should be assessed separately in different populations, as it differs substantially between Chinese and Caucasian women, and more generally in developing versus developed populations. Estimation of future trends is important for public health planning. On the basis of the recent breast cancer incidence trends, we projected future disease rates in the rapidly transitioning Chinese population of Hong Kong. We used local data on breast cancer incidence and mid‐year population figures for the years 1974–2003. We fitted Poisson age‐period‐cohort models with autoregressive priors on the age, period and cohort effects, and used projections of these effects to forecast future incidence to 2018. We found that age‐standardized breast cancer incidence would continue to rise by ∼1.1% per annum over the next 15 years, from 45.9 cases in 1999–2003 to 54.3 per 100,000 (95% credible interval: 50.9, 58.4) in 2014–2018. Recent secular incidence increases can be attributed to both ageing and intergenerational effects beginning with the postwar baby boomers, whereas there is no evidence for important changes by time period. There does not appear to be differential cohort‐related risk for pre‐ vs. postmenopausal disease. Unlike most other cancers, breast cancer risk in local women would continue to increase in the short to medium term, at a similar rate of increase compared with historical trends. This could most likely be attributed to Hong Kongs socioeconomic developmental history and continuing adoption of westernized lifestyle changes.

Waiting time, doctor shopping, and nonattendance at specialist outpatient clinics: case-control study of 6495 individuals in Hong Kong.

Objective. Nonattendance is a major health services research and management issue that has received little attention or systematic study in Asia. We examined the independent associations between waiting time, doctor shopping, and nonattendance in specialist outpatient clinics of 4 large public hospitals in Hong Kong. Research Design. Case-control study. Setting and Participants. A total of 6495 attenders and nonattenders enrolled from July 2000 through October 2001. Pain Outcome Measures. Odds ratios (ORs) and associated 95% confidence intervals (CI) for nonattendance. Results. Longer waiting times (adjusted OR2nd quartile, 1.67; 95% CI, 1.38–2.03; adjusted OR3rd quartile, 1.90; 95% CI, 1.56–2.30; adjusted OR4th quartile, 2.30; 95% CI, 1.91-2.78) and doctor-shopping behavior (adjusted OR, 2.91; 95% CI, 2.51–3.38) were independent risk factors for nonattendance. These effects were robust after multivariate adjustment and testing for effect modification. They also appeared to persist uniformly across hospitals and specialties. There was no demonstrable relationship between waiting time and doctor shopping. Conclusions. This is the largest study of nonattendance at outpatient clinics and the first such study carried out in Asia. Targeted strategies should be implemented and evaluated using these results to reduce waiting time, doctor shopping, and ultimately nonattendance.

Alternative methods of estimating an incubation distribution: examples from severe acute respiratory syndrome.

Background: Accurate and precise estimates of the incubation distribution of novel, emerging infectious diseases are vital to inform public health policy and to parameterize mathematical models. Methods: We discuss and compare different methods of estimating the incubation distribution allowing for interval censoring of exposures, using data from the severe acute respiratory syndrome (SARS) epidemic in 2003 as an example. Results: Combining data on unselected samples of 149 and 168 patients with defined exposure intervals from Toronto and Hong Kong, respectively, we estimated the mean and variance of the incubation period to be 5.1 day and 18.3 days and the 95th percentile to be 12.9 days. We conducted multiple linear regression on the log incubation times and found that incubation was significantly longer in Toronto than in Hong Kong and in older compared with younger patients, while it was significantly shorter in healthcare workers than in other patients. Conclusions: Our findings suggest subtle but important heterogeneities in the incubation period of SARS among different strata of patients. Robust estimation of the incubation period should be independently carried out in different settings and subgroups for novel human pathogens using valid statistical methods.

A multilevel analysis of the effects of neighbourhood income inequality on individual self-rated health in Hong Kong ☆

We examined the effect on self-rated health of neighbourhood-level income inequality in Hong Kong, which has a high and growing Gini coefficient. Data were derived from two population household surveys in 2002 and 2005 of 25,623 and 24,610 non-institutional residents aged 15 or over. We estimated neighbourhood-level Gini coefficients in each of 287 Government Planning Department Tertiary Planning Units. We used multilevel regression analysis to assess the association of neighbourhood income inequality with individual self-perceived health status. After adjustment for both individual- and household-level predictors, there was no association between neighbourhood income inequality, median household income or household-level income and self-rated health. We tested for but did not find any statistical interaction between these three income-related exposures. These findings suggest that neighbourhood income inequality is not an important predictor of individual health status in Hong Kong.

Breast cancer incidence and mortality in a transitioning Chinese population: current and future trends

Background:Projections of future trends in cancer incidence and mortality are important for public health planning.Methods:By using 1976–2010 data in Hong Kong, we fitted Poisson age-period-cohort models and made projections for future breast cancer incidence and mortality to 2025.Results:Age-standardised breast cancer incidence (/mortality) is projected to increase (/decline) from 56.7 (/9.3) in 2011–2015 to 62.5 (/8.6) per 100 000 women in 2021–2025.Conclusions:The incidence pattern may relate to Hong Kong’s socio-economic developmental history, while falling mortality trends are, most likely, due to improvements in survival from treatment advancement and improved health service delivery.

Optimizing resource allocation for breast cancer prevention and care among Hong Kong Chinese women

Recommendations about funding of interventions through the full spectrum of the disease often have been made in isolation. The authors of this report optimized budgetary allocations by comparing cost‐effectiveness data for different preventive and management strategies throughout the disease course for breast cancer in Hong Kong (HK) Chinese women.

Measuring moral hazard and adverse selection by propensity scoring in the mixed health care economy of Hong Kong

OBJECTIVES To evaluate the presence of moral hazard, adjusted for the propensity to have self-purchased insurance policies, employer-based medical benefits, and welfare-associated medical benefits in Hong Kong. METHODS Based on 2005 population survey, we used logistic regression and zero-truncated negative binomial/Poisson regressions to assess the presence of moral hazard by comparing inpatient and outpatient utilization between insured and uninsured individuals. We fitted each enabling factor specific to the type of service covered, and adjusted for predisposing socioeconomic and demographic factors. We used a propensity score approach to account for potential adverse selection. RESULTS Employment-based benefits coverage was associated with increased access and intensity of use for both inpatient and outpatient care, except for public hospital use. Similarly, welfare-based coverage had comparable effect sizes as employment-based schemes, except for the total number of public ambulatory episodes. Self-purchased insurance facilitated access but did not apparently induce greater demand of services among ever users. Nevertheless, there was no evidence of moral hazard in public hospital use. CONCLUSIONS Our findings suggest that employment-based benefits coverage lead to the greatest degree of moral hazard in Hong Kong. Future studies should focus on confirming these observational findings using a randomized design.

Vulnerability to diabetes in Chinese: an age–period–cohort analysis

PURPOSE Hong Kong, in common with other Asian settings, has high rates of diabetes mellitus (DM) despite a relatively nonobese population. Given the rapid economic development in the region, most Asians grew up in limited living conditions. We examined the longitudinal mortality trends of DM. We assessed whether the first generation (birth cohorts in the 1930s) with late adolescence in a more economically developed environment had a lower risk of DM. METHODS We used DM deaths and population figures in Hong Kong, 1976 to 2010. We fitted age-period-cohort models to decompose mortality rates into effects for age at mortality, calendar period of mortality, and birth cohort. RESULTS The risk of death from DM fell for the first generation (births in the early 1930s) with late adolescence in Hong Kong, but possibly the risk rose again for the first generation (birth 1960s) affected by the obesity epidemic. CONCLUSIONS Adiposity might contribute to diabetes in Hong Kong, and similar Asian settings, however current vulnerability of many older Asians to DM in plentiful environments may be the result of limited living conditions until adulthood. Furthermore, our findings are more consistent with limited adolescent conditions than fetal undernutrition playing a role in vulnerability to DM.

Helicobacter pylori associated gastric intestinal metaplasia: Treatment and surveillance.

Gastric cancer (GC) is one of the leading causes of cancer related death in the world, particularly in East Asia. According to the Correas cancer cascade, non-cardia GC is usually developed through a series of mucosal changes from non-atrophic gastritis to atrophic gastritis (AG), intestinal metaplasia (IM), dysplasia and adenocarcinoma. Atrophic gastritis and IM are therefore generally considered to be pre-neoplastic gastric lesions. Helicobacter pylori (H. pylori) infection is an important initiating and promoting step of this gastric carcinogenesis cascade. Emerging long-term data showed that eradication of H. pylori reduced the risk of subsequent cancer development. It however remains confusing whether eradication of the bacterium in individuals with pre-neoplastic gastric lesions could regress these changes as well as in preventing cancer. Whilst H. pylori eradication could likely regress AG, the presence of IM may be a point of no return in this cascade. Hence, surveillance by endoscopy may be indicated in those with extensive IM or those with incomplete IM, particularly in populations with high GC risk. The optimal interval and the best tool of surveillance endoscopy remains to be determined in future studies.