3D dissimilar-siamese-u-net for hyperdense Middle cerebral artery sign segmentation.

The hyperdense middle cerebral artery sign (HMCAS) representing a thromboembolus has been declared as a vital CT finding for intravascular thrombus in the diagnosis of acute ischemia stroke. Early recognition of HMCAS can assist in patient triage and subsequent thrombolysis or thrombectomy treatment. A total of 624 annotated head non-contrast-enhanced CT (NCCT) image scans were retrospectively collected from multiple public hospitals in Hong Kong. In this study, we present a deep Dissimilar-Siamese-U-Net (DSU-Net) that is able to precisely segment the lesions by integrating Siamese and U-Net architectures. The proposed framework consists of twin sub-networks that allow inputs of left and right hemispheres in head NCCT images separately. The proposed Dissimilar block fully explores the feature representation of the differences between the bilateral hemispheres. Ablation studies were carried out to validate the performance of various components of the proposed DSU-Net. Our findings reveal that the proposed DSU-Net provides a novel approach for HMCAS automatic segmentation and it outperforms the baseline U-Net and many state-of-the-art models for clinical practice.

Development of a data-driven COVID-19 prognostication tool to inform triage and step-down care for hospitalised patients in Hong Kong: a population-based cohort study.

BACKGROUND: This is the first study on prognostication in an entire cohort of laboratory-confirmed COVID-19 patients in the city of Hong Kong. Prognostic tool is essential in the contingency response for the next wave of outbreak. This study aims to develop prognostic models to predict COVID-19 patients' clinical outcome on day 1 and day 5 of hospital admission. METHODS: We did a retrospective analysis of a complete cohort of 1037 COVID-19 laboratory-confirmed patients in Hong Kong as of 30 April 2020, who were admitted to 16 public hospitals with their data sourced from an integrated electronic health records system. It covered demographic information, chronic disease(s) history, presenting symptoms as well as the worst clinical condition status, biomarkers' readings and Ct value of PCR tests on Day-1 and Day-5 of admission. The study subjects were randomly split into training and testing datasets in a 8:2 ratio. Extreme Gradient Boosting (XGBoost) model was used to classify the training data into three disease severity groups on Day-1 and Day-5. RESULTS: The 1037 patients had a mean age of 37.8 (SD ± 17.8), 53.8% of them were male. They were grouped under three disease outcome: 4.8% critical/serious, 46.8% stable and 48.4% satisfactory. Under the full models, 30 indicators on Day-1 and Day-5 were used to predict the patients' disease outcome and achieved an accuracy rate of 92.3% and 99.5%. With a trade-off between practical application and predictive accuracy, the full models were reduced into simpler models with seven common specific predictors, including the worst clinical condition status (4-level), age group, and five biomarkers, namely, CRP, LDH, platelet, neutrophil/lymphocyte ratio and albumin/globulin ratio. Day-1 model's accuracy rate, macro-/micro-averaged sensitivity and specificity were 91.3%, 84.9%/91.3% and 96.0%/95.7% respectively, as compared to 94.2%, 95.9%/94.2% and 97.8%/97.1% under Day-5 model. CONCLUSIONS: Both Day-1 and Day-5 models can accurately predict the disease severity. Relevant clinical management could be planned according to the predicted patients' outcome. The model is transformed into a simple online calculator to provide convenient clinical reference tools at the point of care, with an aim to inform clinical decision on triage and step-down care.

Automated Hierarchy Evaluation System of Large Vessel Occlusion in Acute Ischemia Stroke.

BACKGROUND: The detection of large vessel occlusion (LVO) plays a critical role in the diagnosis and treatment of acute ischemic stroke (AIS). Identifying LVO in the pre-hospital setting or early stage of hospitalization would increase the patients' chance of receiving appropriate reperfusion therapy and thereby improve neurological recovery. METHODS: To enable rapid identification of LVO, we established an automated evaluation system based on all recorded AIS patients in Hong Kong Hospital Authority's hospitals in 2016. The 300 study samples were randomly selected based on a disproportionate sampling plan within the integrated electronic health record system, and then separated into a group of 200 patients for model training, and another group of 100 patients for model performance evaluation. The evaluation system contained three hierarchical models based on patients' demographic data, clinical data and non-contrast CT (NCCT) scans. The first two levels of modeling utilized structured demographic and clinical data, while the third level involved additional NCCT imaging features obtained from deep learning model. All three levels' modeling adopted multiple machine learning techniques, including logistic regression, random forest, support vector machine (SVM), and eXtreme Gradient Boosting (XGboost). The optimal cut-off for the likelihood of LVO was determined by the maximal Youden index based on 10-fold cross-validation. Comparisons of performance on the testing group were made between these techniques. RESULTS: Among the 300 patients, there were 160 women and 140 men aged from 27 to 104 years (mean 76.0 with standard deviation 13.4). LVO was present in 130 (43.3%) patients. Together with clinical and imaging features, the XGBoost model at the third level of evaluation achieved the best model performance on testing group. The Youden index, accuracy, sensitivity, specificity, F1 score, and area under the curve (AUC) were 0.638, 0.800, 0.953, 0.684, 0.804, and 0.847, respectively. CONCLUSION: To the best of our knowledge, this is the first study combining both structured clinical data with non-structured NCCT imaging data for the diagnosis of LVO in the acute setting, with superior performance compared to previously reported approaches. Our system is capable of automatically providing preliminary evaluations at different pre-hospital stages for potential AIS patients.

Burden of large vessel occlusion stroke and the service gap of thrombectomy: A population-based study using a territory-wide public hospital system registry.

BACKGROUND: Ischemic stroke due to large vessel occlusion can be effectively treated with thrombectomy but access to this treatment is limited in many parts of the world. Local incidence of large vessel occlusion is critical in determining the development of thrombectomy service, but reliable data from Asian countries are lacking. AIMS: We performed a population-based study to estimate the burden of large vessel occlusion and the service gap for thrombectomy in Hong Kong. METHODS: All acute ischemic stroke patients admitted in 2016 to the public healthcare system, which provided 90% of the emergency healthcare in the city, was identified from the Hong Kong Hospital Authority's central electronic database. The diagnosis of large vessel occlusion was retrospectively verified by two independent cerebrovascular specialists in a randomly sampled cohort based on clinical and neuroimaging data. The incidence of large vessel occlusion in the population was estimated through weighting the sample results and compared with the thrombectomy data in the same period. RESULTS: There were 6859 acute ischemic stroke patients treated in the public health system in 2016. Amongst the 300 patients randomly sampled according to diagnosis coding, 130 suffered from anterior circulation large vessel occlusion. This translated to 918 patients (95% CI 653-1180) and 13.3% of all ischemic stroke patients. The estimated incidence of anterior circulation large vessel occlusion was 12.5 per 100,000 persons per year (95% CI 11.7-13.4). Large vessel occlusion stroke patients were more commonly female than male (67.4% vs. 31.6%, p = 0.003), and were older than non-large vessel occlusion stroke patients (mean of 80.5 years vs. 71.4 years, p = < 0.001). They also had higher 30-day mortality rate (31.1% vs. 4.6%, p = < 0.001), and longer hospital stay (mean 38.6 vs. 21.1 days, p = 0.003) than non-large vessel occlusion stroke. In the same period, 83 thrombectomies for large vessel occlusion were performed, representing 9.1% of the estimated large vessel occlusion incidence. CONCLUSION: The estimated incidence of anterior circulation large vessel occlusion in the Hong Kong Chinese population is lower than that in the West. There is however a substantial service gap for endovascular thrombectomy with less than 10% of large vessel occlusion patients receiving thrombectomy.

Acceptability and uptake of female adolescent HPV vaccination in Hong Kong: a survey of mothers and adolescents.

BACKGROUND: Organized population-based HPV vaccination programs can be effective in reducing the burden of cervical cancer, especially in the absence of a comprehensive cervical screening program (e.g. Hong Kong). Assessment of vaccine acceptability is important when evaluating the feasibility and cost-effectiveness of such vaccination programs. METHODS: To provide a more representative and updated assessment on the acceptability of female adolescent HPV vaccination in Hong Kong, we conducted surveys in 2008 among 1022 mothers with daughters aged ≤ 18 years through random digit-dialing telephone interviewing and 2167 schoolgirls aged 11-18 years using two-stage stratified cluster sampling. We conducted the maternal survey again in 2012 with an independent group of 1005 mothers. RESULTS: In 2008, 2.4% (95% confidence interval [CI]=1.8-3.2%) of the recruited schoolgirls reported having received HPV vaccination. In 2012, the mothers reported that 9.1% (7.0-11.6%) of their daughters who were in the same age range (11-18 years) as the schoolgirls had been vaccinated (p<0.01). Regarding acceptability, 27.5% (24.8-30.4%) and 37.6% (34.5-40.8%) of the mothers were willing to have their daughters vaccinated at market price in 2008 and 2012 (p<0.01), respectively. 27.1% (25.2-29.1%) of the schoolgirls were willing to receive HPV vaccination at market price in 2008. The willingness to pay for full-course vaccination among mothers had a median of US$128/HK$1000 (50% central range=US$64-192/HK$500-1500), i.e. substantially lower than the current market price. CONCLUSIONS: The gap between acceptability and actual uptake of HPV vaccination among adolescent girls suggested that coverage is likely to be low without an organized HPV vaccination program, although the difference might be partially attributed to the possibility that at the time of the interview female adolescents who were willing to be vaccinated had not yet taken action. Policymakers should devise tailored, targeted and efficient vaccination strategies to achieve universal coverage for an effectively organized HPV vaccination program.

Who receives, benefits from and is harmed by cervical and breast cancer screening among Hong Kong Chinese?

BACKGROUND: To estimate the proportion of and characterize women who had received cervical and breast screening and to quantify the associated preventable burden of disease and potential iatrogenic harm. METHODS: A total of 3484 Hong Kong Chinese women were interviewed in person. Screening prevalence and associated predictors, disability-adjusted life-years (DALYs), the numbers of false-positive tests and the resultant confirmatory procedures and related complications were estimated. RESULTS: A total of 6.2% of women (>or=18) reported regular pap but no mammography or clinical breast examination (CBE) as per local evidence-based guidelines, whereas among women aged >or=40 years, 5.2% reported regular screening by all three modalities and 55.3% had never been screened for either cancer. Women who underwent regular health checkups were consistently the most likely to have been screened, as were younger, married and socially advantaged respondents. Triennial pap screening would save 708 DALYs annually, or 528 more DALYs compared with the status quo. However, this would generate 28,600 repeat smears and 390 colposcopies from false-positive screens. Opportunistic mammographic screening averted 100 DALYs currently, but could have potentially reduced a further 546 with biennial screening. Mass screening mammography (CBE) would lead to 33,700 (20,200) false-positives per year requiring 29,900 (8300) repeat mammograms or ultrasonograms, 6800 (3000) biopsies and 620 (270) biopsy-related complications. CONCLUSIONS: Screening uptake patterns are suboptimal. By making explicit the possible risks and benefits based on this template, policy makers in developing Asia with a similar female cancer burden may be able to use the information to make evidence-based decisions that are consistent with local circumstances, values and preferences.

Effectiveness of an elderly smoking cessation counseling training program for social workers: a longitudinal study.

BACKGROUND: To achieve greater coverage of the elderly smoking population, the provider/client interface could be broadened to include other professional groups who work with the elderly. We evaluated the effectiveness of a 9-h smoking cessation counseling training program for social workers. METHODS: We recruited 177 social workers and used a preintervention/postintervention longitudinal design, analyzed by multilevel, multivariable modeling to adjust for between-subjects covariables and within-subjects correlation in repeated measurements at baseline, 3 months, 6 months, and 12 months after training. RESULTS: Overall, knowledge improved from a mean score of 6.70 +/- 1.03 (+/- SD) at baseline to 7.35 +/- 0.75 at 12 months (range, 0 to 8 correct responses), attitude from 2.84 +/- 0.41 to 3.10 +/- 0.48, and self-perceived competence from 2.49 +/- 0.38 to 2.85 +/- 0.36 (range, 1 to 4, where 4 is best). On multilevel modeling, three of the four "A"s (ask, advice, assist, arrange as per the Agency for Healthcare Research and Quality framework) registered significant gains from baseline to 12 months overall, whereas "advice" did not show any appreciable change. CONCLUSION: These findings demonstrate that our smoking cessation training program achieved sustained effectiveness in the first year after training in enhancing knowledge, positively shifting attitudes, boosting self-perceived competence, and increasing the self-reported frequency of practicing three of the four As in their routine interaction with elderly clients.

What is the most cost-effective population-based cancer screening program for Chinese women?

PURPOSE: To develop a policy-relevant generalized cost-effectiveness (CE) model of population-based cancer screening for Chinese women. METHODS: Disability-adjusted life-years (DALYs) averted and associated screening and treatment costs under population-based screening using cervical cytology (cervical cancer), mammography (breast cancer), and fecal occult blood testing (FOBT), sigmoidoscopy, FOBT plus sigmoidoscopy, or colonoscopy (colorectal cancer) were estimated, from which average and incremental CE ratios were generated. Probabilistic sensitivity analysis was undertaken to assess stochasticity, parameter uncertainty, and model assumptions. RESULTS: Cervical, breast, and colorectal cancers were together responsible for 13,556 DALYs (in a 1:4:3 ratio, respectively) in Hong Kong's 3.4 million female population annually. All status quo strategies were dominated, thus confirming the suboptimal efficiency of opportunistic screening. Current patterns of screening averted 471 DALYs every year, which could potentially be more than doubled to 1,161 DALYs under the same screening and treatment budgetary threshold of US $50 million with 100% Pap coverage every 4 years and 30% coverage of colonoscopy every 10 years. With higher budgetary caps, biennial mammographic screening starting at age 50 years can be introduced. CONCLUSION: Our findings have informed how best to achieve allocative efficiency in deploying scarce cancer care dollars but must be coupled with better integrated care planning, improved intersectoral coordination, increased resources, and stronger political will to realize the potential health and economic gains as demonstrated.

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.

Under-reporting of inpatient services utilisation in household surveys -- a population-based study in Hong Kong.

BACKGROUND: Recognising that household interviews may produce biased estimates of health services utilisation, we examined for under- and over-reporting of hospitalisation episodes in three recent, consecutive population-based household surveys in Hong Kong. METHODS: Territory-wide inpatient service utilisation volumes as estimated from the 1999, 2001 and 2002 Thematic Household Surveys (THS) were benchmarked against corresponding statistics derived from routine administrative databases. Between-year differences on net under-reporting were quantified by Cohen's d effect size. To assess the potential for systematic biases in under-reporting, age- and sex-specific net under-reporting rates within each survey year were computed and the F-test was performed to evaluate differences between demographic subgroups. We modelled the effects of age and sex on the likelihood of ever hospitalisation through logistic regression to compare the odds ratios respectively derived from survey and administrative data. RESULTS: The extent of net under-reporting was moderately large in all three years amounting to about one-third of all inpatient episodes. However, there did not appear to be significant systematic biases in the degree of under-reporting by age or sex on stratified analyses and logistic regression modelling. CONCLUSION: Under-reporting was substantial in Hong Kong's THS. Recall bias was likely most responsible for such reporting inaccuracies. A proper full-design record-check study should be carried out to confirm the present findings.

Cost-effectiveness of organized versus opportunistic cervical cytology screening in Hong Kong.

BACKGROUND: To assess the cost-effectiveness of alternative cervical cancer screening strategies to inform the design and implementation of a government-sponsored population-based screening programme in Hong Kong. METHODS: Cost-effectiveness analysis using a computer-based model of cervical carcinogenesis was performed. Strategies included no screening, opportunistic screening (status quo), organized screening using either conventional or liquid-based cytology conducted at different frequencies. The main outcome measures were cancer incidence reduction, years of life saved (YLS), lifetime costs and incremental cost-effectiveness ratios. Data were from local hospitals and laboratories, clinical trials, prospective studies and other published literature. RESULTS: Compared with no screening, a simulation of the current situation of opportunistic screening using cervical cytology produced a nearly 40 per cent reduction in the lifetime risk of cervical cancer. However, with organized screening every 3, 4 and 5 years, corresponding reductions with conventional (and liquid-based) cytology were 90.4 (92.9), 86.8 (90.2) and 83.2 per cent (87.3 per cent) compared with no screening. For all cytology-based screening strategies, opportunistic screening was more costly and less effective than an organized programme of screening every 3, 4 and 5 years. Every 3-, 4- and 5-year screening cost $12,300, $7100 and $800 per YLS, each compared with the next best alternative. CONCLUSIONS: Compared with the status quo of opportunistic screening, adopting a policy of organized, mass cervical screening in Hong Kong can substantially increase benefits and reduce costs.

Physicians' perceptions towards the impact of and willingness to pay for clinical computerization in Hong Kong.

BACKGROUND AND OBJECTIVES: We evaluated factors associated with physicians' perceptions towards the effects of computers on health care and on current levels of computerization in their practice. We also performed a contingent valuation to quantify physicians' perceived benefits from computerization in a hypothetical ambulatory, solo clinic. METHODS: We surveyed 949 representative physicians in Hong Kong by post. Factor analysis was performed to summarize similar items into categories. Multivariable log-linear regression models were employed to assess the relationships between different factor scores and the number of functions computerized. We elicited their willingness-to-pay (WTP) for three defined computer systems using contingent valuation techniques. WTP values were estimated using econometric modeling by both, parametric and geometric methods. Sociodemographic, attitudinal, and practice-related predictors of WTP were estimated through regression analyses. RESULTS: Factor analysis revealed a three-factor solution which explained 53% of total variance. The overall mean score (mean = 3.51 +/- 0.45) showed a generally positive attitude towards the effects of computers on health care. Respondents with a higher level of computer knowledge had significantly higher mean overall (P = 0.002) and factor scores for all three factors (P < 0.01). Higher factor scores on the effects of computers on patient care and clinicians (P = 0.006) and on the health system (P = 0.032) were associated with a higher number of functions computerized. The parametric median WTP values for computerizing administrative, clinical, and both sets of functions were HK dollars 21205 (US dollars 2719), HK dollars 34231 (US dollars 4389), and HK dollars 45720 (US dollars 5862), respectively, which were lower than the estimates obtained from demand curves using the geometric method [HK dollars 43286 (US dollars 5549), HK dollars 59570 (US dollars 7637), and HK dollars 84623 (US dollars 10849), respectively]. Doctors with higher incomes were willing to pay more to computerize the clinic, with strong dose-response gradients demonstrated. Those who worked in corporate settings were also more likely to accept higher WTP values. CONCLUSIONS: Our findings confirm that better knowledge about computers is contributory to a more positive attitude towards the effects of computers on health care, which is in turn significantly associated with higher levels of actual computerization in clinical practice. WTP values represent the likelihood, in monetary terms, of translating doctors' perceived benefits from computerization into investment action.