Browsing by Author "Kok, Victor C."

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Incidence of retinal vein occlusion with longterm exposure to ambient air pollution
(2019-09-24)
Zhang, Han-Wei
;
Lin, Chao-Wen
;
Kok, Victor C.
;
Tseng, Chun-Hung
;
Lin, Yuan-Pei
This study aimed to investigate whether long-term exposure to airborne hydrocarbons, including volatile organic compounds, increases the risk of developing retinal vein occlusion (RVO) among the population of Taiwan. A retrospective cohort study involving 855,297 people was conducted. Cox proportional hazards regression analysis fitted the multiple pollutant models for two targeted pollutants, including total hydrocarbons (THC), nonmethane hydrocarbons (NMHC) were used, and the risk of RVO was estimated. The chi-squared test and one-way analysis of variance were used to test differences in demographics and comorbidity distribution among tertiles of the targeted pollutants. Before controlling for multiple pollutants, hazard ratios for the overall population were 19.88 (95% CI: 17.56-22.50) at 0.51-ppm increases in THC and 4.33 (95% CI: 3.97-4.73) at 0.27-ppm increases in NMHC. The highest adjusted hazard ratios for different multiple pollutant models of each targeted pollutant were statistically significant (all p values were.0.05) for all patients at 29.67 (95% CI: 25.57-34.42) for THC and 16.24 (95% CI: 14.14-18.65) for NMHC. Our findings suggest that long-term exposure to THC and NMHC contribute to RVO development.
Long-term ambient hydrocarbons exposure and incidence of ischemic stroke
(2019-12-04)
Zhang, Han-Wei
;
Kok, Victor C.
;
Chuang, Shu-Chun
;
Tseng, Chun-Hung
;
Lin, Chin-Teng
Exposure to air pollutants is known to have adverse effects on human health; however, little is known about the association between hydrocarbons in air and an ischemic stroke (IS) event. We investigated whether long-term exposure to airborne hydrocarbons, including volatile organic compounds, increased IS risk. This retrospective cohort study included 283,666 people aged 40 years or older in Taiwan. Cox proportional hazards regression analysis was used to fit single- and multiple-pollutant models for two targeted pollutants, total hydrocarbons (THC) and nonmethane hydrocarbons (NMHC), and estimated the risk of IS. Before controlling for multiple pollutants, hazard ratios (HRs) of IS with 95% confidence intervals for the overall population were 2.69 (2.64-2.74) at 0.16-ppm increase in THC and 1.62 (1.59-1.66) at 0.11-ppm increase in NMHC. For the multiple-pollutant models controlling for PM2.5, the adjusted HR was 3.64 (3.56-3.72) for THC and 2.21 (2.16-2.26) for NMHC. Our findings suggest that long-term exposure to THC and NMHC may be a risk factor for IS development.
Long-Term Exposure to Ambient Hydrocarbons Increases Dementia Risk in People Aged 50 Years and above in Taiwan
(2019-01-01)
Zhang, Han-Wei
;
Kok, Victor C.
;
Chuang, Shu-Chun
;
Tseng, Chun-Hung
;
Lin, Chin-Teng
Background: Alzheimer's disease, the most common cause of dementia among the elderly, is a progressive and irreversible neurodegenerative disease. Exposure to air pollutants is known to have adverse effects on human health, however, little is known about hydrocarbons in the air that can trigger a dementia event. Objective: We aimed to investigate whether long-term exposure to airborne hydrocarbons increases the risk of developing dementia. Method: The present cohort study included 178,085 people aged 50 years and older in Taiwan. Cox proportional hazards regression analysis was used to fit the multiple pollutant models for two targeted pollutants, including total hydrocarbons and non-methane hydrocarbons, and estimated the risk of dementia. Results: Before controlling for multiple pollutants, hazard ratios with 95% confidence intervals for the overall population were 7.63 (7.28-7.99, p <0.001) at a 0.51 -ppm increases in total hydrocarbons, and 2.94 (2.82-3.05, p <0.001) at a 0.32-ppm increases in non-methane hydrocarbons. The highest adjusted hazard ratios for different multiple-pollutant models of each targeted pollutant were statistically significant (p <0.001) for all patients: 11.52 (10.86-12.24) for total hydrocarbons and 9.73 (9.18-10.32) for non-methane hydrocarbons. Conclusion: Our findings suggest that total hydrocarbons and non-methane hydrocarbons may be contributing to dementia development.
Positive association between hypertension and urinary bladder cancer: epidemiologic evidence involving 79,236 propensity score-matched individuals
(2018-01-01)
Kok, Victor C.
;
Zhang, Han-Wei
;
Lin, Chin-Teng
;
Huang, Shih-Chung
;
Wu, Ming-Feng
Introduction: We hypothesized that hypertensive patients harbor a higher risk of urinary bladder (UB) cancer. Material and methods: We performed a population-based cohort study on adults using a National Health Insurance Research Database (NHIRD) dataset. Hypertension and comparison non-hypertensive (COMP) groups comprising 39,618 patients each were propensity score-matched by age, sex, index date, and medical comorbidities. The outcome was incident UB cancer validated using procedure codes. We constructed multivariable Cox models to derive adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Cumulative incidence was compared using a log-rank test. Results: During a total follow-up duration of 380,525 and 372,020 person-years in the hypertension and COMP groups, 248 and 186 patients developed UB cancer, respectively, representing a 32% increase in the risk (aHR, 1.32; 95% CI, 1.09-1.60). Hypertensive women harbored a significantly increased risk of UB cancer (aHR, 1.55; 95% CI, 1.12-2.13) compared with non-hypertensive women, whereas men with hypertension had a statistically non-significant increased risk (aHR, 1.22; 95% CI, 0.96-1.55). The sensitivity analysis demonstrated that the increased risk was sustained throughout different follow-up durations for the entire cohort; a statistical increase in the risk was also noted among hypertensive men. Conclusion: This nationwide population-based propensity score-matched cohort study supports a positive association between hypertension and subsequent UB cancer development.