A multi-level spatio-temporal analysis on prostate cancer outcomes.

BACKGROUND: Geographic and temporal variation in positive surgical margins (PSM) for prostate cancer after radical prostatectomy (RP) has been observed. However, it is unclear how much of this variation could be attributed to patient, surgeon, institution, or socioeconomic-related factors and the impact of PSM on death among localized prostate cancer patients. METHODS: This study aimed to assess the independent and relative contribution of the patient, surgeon, institution and area-level risk factors on geographic and temporal variation of PSM and evaluate the impact of PSM on five-year all-cause and prostate cancer-specific mortality among localized prostate cancer patients. Within the hierarchical-related regression approach, we utilised Bayesian spatial-temporal multi-level models to study individual and area-level predictors with the outcomes, while accounting for geographically structured and unstructured correlation and non-linear trends. RESULTS: Individual-level data included 10,075 localized prostate cancer cases with RP reported to the Prostate Cancer Outcomes Registry Victoria between 2009 and 2018. Area-level data comprised socio-economic disadvantage and remoteness data at the local government area level in Victoria, Australia. 26 % of patients had PSM, and the rates varied across areas by years. This variation was mainly associated with NCCN risk, followed by RP techniques, surgical institution type, surgeon volume and socio-economic disadvantage. Intermediate (Odds ratio/OR = 1.21,95 % credible interval/Crl = 1.05-1.41), high/very-high risk groups (OR = 2.24,95 % Crl = 1.91-2.64) and public surgical institution (OR = 1.64, 95 % Crl = 1.46-1.84) were independently associated with a higher likelihood of PSM. Robot-assisted (OR = 0.61, 95 % Crl = 0.55-0.68), laparoscopic RP (OR = 0.76, 95 % Crl = 0.62-0.93), high-volume surgeon (OR = 0.84, 95 % Crl = 0.76-0.93) and socio-economically least disadvantaged status (OR = 0.78, 95 % Crl = 0.64-0.94) showed a lower likelihood of PSM. PSM was also independently associated with a higher five-year all-cause and prostate cancer-specific mortality. CONCLUSION: Aggressive tumour characteristics and RP techniques were the main contributors to the likelihood of PSM following RP. Reducing the prevalence of PSM will generally improve prostate cancer-specific and all-cause mortality.

Geospatial and temporal variation of prostate cancer incidence.

OBJECTIVES: The objective of this study was to evaluate geographical and temporal variations in prostate cancer incidence in Victoria, Australia. STUDY DESIGN & METHODS: This study analysed 105,349 cases of incident prostate cancer between 1982 and 2016 from the population-based Victorian Cancer Registry. We performed Poisson regression analyses to identify an association between an annual number of prostate cancer counts, prostate-specific antigen (PSA) tests and the elderly male population (≥65) after adjusting for population at risk and years. We also applied Bayesian spatial-temporal models to determine any association with prostate cancer incidence and area-level factors. RESULTS: The overall trend of the age-standardized prostate cancer incidence was increasing. The highest age-specific incidence was observed among people aged 65-74 years in the pre- and post-PSA periods. Every increase in 1000 PSA tests per 100,000 population, prostate cancer incidence increased by 17% (relative risk [RR] = 1.17, 95% confidence interval [CI] = 1.13-1.22). A 1% increase in the proportion of the male population (≥65) correlated with a 7% increase in prostate cancer cases (RR = 1.07, 95% CI = 1.06-1.10). Compared with early PSA periods, decreasing trends of low-grade cases and growing trends of high- and intermediate-grade cases were observed after a decline in PSA test usage in late PSA periods. Men living in the most socioeconomically advantaged postal areas had a decreased risk of prostate cancer (RR = 0.914, 95% CI = 0.858-0.976). CONCLUSIONS: Age-specific risk of developing biological prostate cancer, temporal changes in PSA testing and an increasingly elderly population contributed to an increasing trend of prostate cancer incidence. When incidence trends were investigated at a more granular geographic level, socioeconomically advantaged status was associated with decreased prostate cancer risk.

Ethnic Differences and Trends in ST-Segment Elevation Myocardial Infarction Incidence and Mortality in a Multi-Ethnic Population.

INTRODUCTION: This study aimed to compare the incidence and mortality of ST-segment elevation myocardial infarction (STEMI) across the 3 main ethnic groups in Singapore, determine if there is any improvement in trends over the years and postulate the reasons underlying the ethnic disparity. MATERIALS AND METHODS: This study consisted of 16,983 consecutive STEMI patients who sought treatment from all public hospitals in Singapore from 2007 to 2014. RESULTS: Compared to the Chinese (58 per 100,000 population in 2014), higher STEMI incidence rate was consistently observed in the Malays (114 per 100,000 population) and Indians (126 per 100,000 population). While the incidence rate for the Chinese and Indians remained relatively stable over the years, the incidence rate for the Malays rose slightly. Relative to the Indians (30-day and 1-year all-cause mortality at 9% and 13%, respectively, in 2014), higher 30-day and 1-year all-cause mortality rates were observed in the Chinese (15% and 21%) and Malays (13% and 18%). Besides the Malays having higher adjusted 1-year all-cause mortality, all other ethnic disparities in 30-day and 1-year mortality risk were attenuated after adjusting for demographics, comorbidities and primary percutaneous coronary intervention. CONCLUSION: It is important to continuously evaluate the effectiveness of existing programmes and practices as the aetiology of STEMI evolves with time, and to strike a balance between prevention and management efforts as well as between improving the outcome of "poorer" and "better" STEMI survivors with finite resources.

Composite Measures of Individual and Area-Level Socio-Economic Status Are Associated with Visual Impairment in Singapore.

PURPOSE: To investigate the independent relationship of individual- and area-level socio-economic status (SES) with the presence and severity of visual impairment (VI) in an Asian population. METHODS: Cross-sectional data from 9993 Chinese, Malay and Indian adults aged 40-80 years who participated in the Singapore Epidemiology of eye Diseases (2004-2011) in Singapore. Based on the presenting visual acuity (PVA) in the better-seeing eye, VI was categorized into normal vision (logMAR≤0.30), low vision (logMAR>0.30<1.00), and blindness (logMAR≥1.00). Any VI was defined as low vision/blindness in the PVA of better-seeing eye. Individual-level low-SES was defined as a composite of primary-level education, monthly income<2000 SGD and residing in 1 or 2-room public apartment. An area-level SES was assessed using a socio-economic disadvantage index (SEDI), created using 12 variables from the 2010 Singapore census. A high SEDI score indicates a relatively poor SES. Associations between SES measures and presence and severity of VI were examined using multi-level, mixed-effects logistic and multinomial regression models. RESULTS: The age-adjusted prevalence of any VI was 19.62% (low vision = 19%, blindness = 0.62%). Both individual- and area-level SES were positively associated with any VI and low vision after adjusting for confounders. The odds ratio (95% confidence interval) of any VI was 2.11(1.88-2.37) for low-SES and 1.07(1.02-1.13) per 1 standard deviation increase in SEDI. When stratified by unilateral/bilateral categories, while low SES showed significant associations with all categories, SEDI showed a significant association with bilateral low vision only. The association between low SES and any VI remained significant among all age, gender and ethnic sub-groups. Although a consistent positive association was observed between area-level SEDI and any VI, the associations were significant among participants aged 40-65 years and male. CONCLUSION: In this community-based sample of Asian adults, both individual- and area-level SES were independently associated with the presence and severity of VI.

Reducing ambulance response times using discrete event simulation.

OBJECTIVES: The objectives of this study are to develop a discrete-event simulation (DES) model for the Singapore Emergency Medical Services (EMS), and to demonstrate the utility of this DES model for the evaluation of different policy alternatives to improve ambulance response times. METHODS: A DES model was developed based on retrospective emergency call data over a continuous 6-month period in Singapore. The main outcome measure is the distribution of response times. The secondary outcome measure is ambulance utilization levels based on unit hour utilization (UHU) ratios. The DES model was used to evaluate different policy options in order to improve the response times, while maintaining reasonable fleet utilization. RESULTS: Three policy alternatives looking at the reallocation of ambulances, the addition of new ambulances, and alternative dispatch policies were evaluated. Modifications of dispatch policy combined with the reallocation of existing ambulances were able to achieve response time performance equivalent to that of adding 10 ambulances. The median (90th percentile) response time was 7.08 minutes (12.69 minutes). Overall, this combined strategy managed to narrow the gap between the ideal and existing response time distribution by 11-13%. Furthermore, the median UHU under this combined strategy was 0.324 with an interquartile range (IQR) of 0.047 versus a median utilization of 0.285 (IQR of 0.051) resulting from the introduction of additional ambulances. CONCLUSIONS: Response times were shown to be improved via a more effective reallocation of ambulances and dispatch policy. More importantly, the response time improvements were achieved without a reduction in the utilization levels and additional costs associated with the addition of ambulances. We demonstrated the effective use of DES as a versatile platform to model the dynamic system complexities of Singapore's national EMS systems for the evaluation of operational strategies to improve ambulance response times.