Irene Wong

The impact of community psychological responses on outbreak control for severe acute respiratory syndrome in Hong Kong

Objective: To examine the public’s knowledge and perception of SARS and the extent to which various precautionary measures have been adopted. Design: Cross sectional survey. Setting: General population of Hong Kong at the height of the SARS outbreak (29 March to 6 April 2003). Participants: 1115 ethnic Chinese adults. Main results: Forty per cent did not recognise fomites as a possible mode of transmission whereas 55.1% believed that the infection could be transmitted airborne. A large proportion (30.1%) believed they were very or somewhat likely to contract SARS while only one quarter believed they were very likely to survive if they contracted the disease, benchmarked against an actual case fatality ratio of 2.8% at the time of the survey and 15%–20% according to current best estimates. Precautionary measures directed against person to person droplet spread were generally adopted by most while the prevention of transmission through fomites was not practised as frequently. Respondents with higher risk perceptions and a moderate level of anxiety were most likely to take comprehensive precautionary measures against the infection, as were older, female, more educated people as well as those with a positive contact history and SARS-like symptoms. Conclusions: The findings demonstrate that the promotion of protective personal health practices to interrupt the self sustaining transmission of the SARS virus in the community must take into account background perceptions of risk and anxiety levels of the public at large. Continuing public education about preventive measures should be targeted at the identified groups with low current uptake of precautions.

Age-period-cohort analysis of tuberculosis notifications in Hong Kong from 1961 to 2005

Background: Despite its wealth, excellent vital indices and robust health care infrastructure, Hong Kong has a relatively high incidence of tuberculosis (TB) (85.4 per 100 000). Hong Kong residents have also experienced a very rapid and recent epidemiological transition; the population largely originated from migration by southern Chinese in the mid 20th century. Given the potentially long latency period of TB infection, an investigation was undertaken to determine the extent to which TB incidence rates reflect the population history and the impact of public health interventions. Methods: An age-period-cohort model was used to break down the Hong Kong TB notification rates from 1961 to 2005 into the effects of age, calendar period and birth cohort. Results: Analysis by age showed a consistent pattern across all the cohorts by year of birth, with a peak in the relative risk of TB at 20–24 years of age. Analysis by year of birth showed an increase in the relative risk of TB from 1880 to 1900, stable risk until 1910, then a linear rate of decline from 1910 with an inflection point at 1990 for a steeper rate of decline. Period effects yielded only one inflection during the calendar years 1971–5. Conclusions: Economic development, social change and the World Health Organisation’s short-course directly observed therapy (DOTS) strategy have contributed to TB control in Hong Kong. The linear cohort effect until 1990 suggests that a relatively high, but slowly falling, incidence of TB in Hong Kong will continue into the next few decades.

P1-372 An age-period-cohort analysis of mortality associated with bacterial diseases in Hong kong

Introduction We aim to investigate longitudinal trends in bacterial disease related mortality in HK in order to describe how socio-economic transition affects mortality due to infections and to provide generalised aetiological insights. We use one of the major bacterial disease related death, septicaemia, as an exemplar. Methods We used local data on mortality due to septicaemia and mid-year population figures (1976–2005). We fitted Poisson age-period-cohort models on the age, period and cohort effects. We also looked for any possible difference in age, cohort or period effects by sex assessed from the model fit using the deviance information criterion (DIC). Results Septicaemia-related deaths increased exponentially with age in both sexes, while there was a down turn in the period effects in both sexes (peaked in the 1991–1995 for females, and in the 1986–1990 for males). The birth cohort curves mainly had downward inflections in both sexes, however there was a steeper deceleration in women after 1945s, which was confirmed by the model fit as shown by the DIC. Conclusion Sex difference in birth cohort effects might reflect changes which affect mortality risk due to septicaemia in a given birth cohort throughout their lifetime. The observed changes could be living conditions of the individual at different stages in life, and better immunity against bacteria in women born in HK but not in men. It is compatible with our hypothesis that the gonadotropic axis upregulation with better early living conditions enhance immunity in women but not men.

The Effect of Increasing Breast Cancer Incidence on the Cost-Effectiveness of Mammography Screening in Hong Kong

Rationale: Whereas the cost-effectiveness of screening mammography in most western developed population has been accepted, these results may not apply to Chinese women with a much lower breast cancer incidence. We estimate the cost-effectiveness of biennial mammography in Hong Kong Chinese women to inform evidence-based screening polices. We also evaluated how the rising breast cancer incidence changes the cost-effectiveness ratio of the mammography screening polices. Objectives: To use projections of future breast cancer rates to allow robust prediction of the cost-effectiveness of mammography screening in the short to medium term in Hong Kong and East Asia. Methodology: We derived model inputs from local clinical, epidemiological and economic data, and from a literature review. We developed a state-transition Markov model to simulate the costs and effects of mammography screening, breast cancer diagnosis and treatment in a hypothetical cohort of Chinese women. We modeled the benefit of mammography by assuming a stage shift, where cancers in screened women were more likely to be diagnosed at an earlier disease stage. We compared quality-adjusted life years (QALY) saved, costs and cost-effectiveness for five screening strategies: four biennial screening strategies, beginning at age 40 or 50 and ending at age 69 or 79 and no screening. We projected breast cancer incidence rates to 2018 using an age-period-cohort model, and incorporated these future rates into the cost-effectiveness model to predict the cost-effectiveness of the screening strategies in the next 15 years. RESULTS: Using breast cancer incidence rates in 2003, we estimated that biennial mammography screening resulted in a gain in life expectancy ranging from 4.3 to 9.4 days compared with no screening at an incremental cost of US

Cost-effectiveness analysis of mammography screening in Hong Kong Chinese using state-transition Markov modelling

1,170 to

Caesarean section rate in England and Wales

2,239 per woman. The least costly non-dominated screening option was screening women from 40 to 69 years of age, with an incremental cost-effectiveness ratio (ICER) of US

Caesarean section rate in England and Wales: Caesarean section rates in Hong Kong

52,600 per QALY saved compared with no screening. Using the age-period-cohort model we projected that age-standardised breast cancer incidence would continue to rise by an average of 1.1% per annum over the next 15 years, from 45.9 cases per 100,000 women in 2001 to 54.3 per 1000 in 2016. Incorporating the projections of age-specific breast cancer incidence rates into the cost-effectiveness model suggested that biennial screening from ages 40-69 will cost US

Disease burden of breast cancer in Hong Kong: an exploration of trends for screening policy and resource allocation.

50,200, US

Generalised cost-effectiveness analysis for breast cancer prevention and care in Hong Kong Chinese

47,400 and US

Cost effectiveness of mammography screening for chinese women (Cancer (2007) 110, (885-895))

46,100 per QALY saved in 2006, 2011, and 2016, compared to no screening. Conclusions: Routine mammography for Chinese women in Asia is currently an inefficient use of scarce public health dollars, but may become more attractive as the ICER decreases below the commonly accepted, albeit arbitrary threshold of