Age-period-cohort analysis with a constant-relative-variation constraint for an apportionment of period and cohort slopes

Reduced burden of Arsenic-Related cancers after water mitigation in Taiwan

BACKGROUND

Epidemiological evidence has demonstrated an association between arsenic in drinking water and increased cancer incidence. This population-based study investigates the impact of a tap water supply system installation in Blackfoot disease-endemic regions of Taiwan on cancer incidence.

METHODS

By using the Taiwan Cancer Registry dataset, we enrolled patients aged 40-84 diagnosed with arsenic-related cancers, including hepatocellular carcinoma, small and squamous cell lung cancer, Bowen's disease, basal and squamous cell skin cancer, urothelial bladder cancer, and upper tract urothelial carcinoma between 1995 and 2019. Random-effects age-period-cohort models were used to estimate the cancer incidence data, and a stabilized kriging method was employed to interpolate incidence rates to more precise spatiotemporal units.

RESULTS

The results showed that the age-standardized incidence rates of all six types of studied cancers were consistently higher in Blackfoot disease-endemic areas than those in other areas from 1995 to 2019. However, the gap in incidence rates between Blackfoot disease-endemic areas and the remaining regions began to narrow approximately after the 1960 birth cohort when the tap water supply system installation commenced. For small and squamous cell lung cancer, Bowen's disease, and urothelial bladder cancer, the excess incidence rates sharply declined to null for those born after the year of arsenic mitigation. For upper tract urothelial carcinoma, the excess incidence rates decreased more gradually for those born after the year of arsenic mitigation. For hepatocellular carcinoma and basal and squamous cell skin cancer, the excess incidence rates remained constant. Spatiotemporal clusters of high incidence rates were identified in the core townships of Blackfoot disease-endemic areas. These clusters began to dissipate mainly after the 1960 birth cohort.

CONCLUSION

Arsenic mitigation from drinking water in Taiwan is associated with a reduced burden of small and squamous cell lung cancers, Bowen's disease, urothelial bladder cancer, and upper tract urothelial carcinoma.

Epidemiology of Chronic Hepatitis B Infection in the Cohort of College Students with Vaccination in Taiwan

After the mass vaccination project in Taiwan, the prevalence of the hepatitis B virus (HBV) infection for the college-aged population of 18 to 21 years is uncertain. We aimed to investigate the prevalence of hepatitis B markers in different birth cohorts. A total of 38,075 students in universities in Kaohsiung area undergoing entrance examinations between July 2006 to September 2020 were included. Seroprevalence of the hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) status and laboratory data were collected. The seropositive rate of HBsAg was less than 1% for students born after 1991. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were significantly higher, and body mass index (BMI) was significantly lower in HBV carriers compared to those who were not carriers (all p < 0.001). Multivariate logistic regression showed that age, male, higher BMI, and positive HBsAg were risk factors of abnormal ALT value. A decrease in the positive rate of anti-HBs which was significantly higher in the cohort of plasma-derived vaccines than recombinant vaccines was found. We concluded that there were decreasing trends in seropositive rates of HBsAg and anti-HBs for students of the college-aged population in the Kaohsiung area. The status of HBsAg was a predictive factor of abnormal ALT levels. The period effect on anti-HBs seropositivity for DNA recombinant vaccine somehow existed.

Incidence trends and spatial distributions of lung adenocarcinoma and squamous cell carcinoma in Taiwan

Lung cancer is the second most common cancer in Taiwan. After Taiwan implemented the Tobacco Hazards Prevention Act in 1997, smoking rates declined. However, the incidence rates of lung cancer for both sexes are still increasing, possibly due to risk factors other than smoking. We used age-period-cohort analysis to examine the secular trends of lung cancer incidence rates by histological type in Taiwan. A stabilized kriging method was employed to map these lung cancer incidence rates. Lung adenocarcinoma incidence rates increased, but lung squamous cell carcinoma incidence rates decreased, for both the sexes in recent birth cohorts, particularly in women. In Taiwan, the hotspots of lung adenocarcinoma incidence rates were in the northern, northeastern, and western coastal areas; the incidence rates increased rapidly in the western and southern coastal regions and southern mountainous regions. The high incidence rates of lung squamous cell carcinoma in men were in the southwestern and northeastern coastal areas. The incidence rates rapidly increased in the central and southern coastal and mountainous regions. For both sexes in Taiwan, lung squamous cell carcinoma incidence rates declined from 1997 to 2017, but lung adenocarcinoma increased. The increased incidence rates of lung adenocarcinoma may be related to indoor and outdoor air pollution. Some areas in Taiwan have increasing lung cancer incidence rates, including the northwestern and southern coasts and mountains, and warrant particular attention.

Association of Nationwide Hepatitis B Vaccination and Antiviral Therapy Programs With End-Stage Liver Disease Burden in Taiwan

IMPORTANCE

Chronic infections of hepatitis B and C viruses are the main causes of end-stage liver disease (ESLD) worldwide. The successful control of viral hepatitis is critical to reducing the burden of ESLD.

OBJECTIVE

To examine the association of 2 world-first nationwide neonatal hepatitis B vaccinations and national antiviral therapy programs implemented in Taiwan (in 1984 and 2003, respectively) with the burden of ESLD.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included children and adults aged 5 to 39 years from the National Cancer Registry Database and the National Death Registry Database between 1979 and 2018 in Taiwan. Individuals who died from chronic liver disease (CLD) and cirrhosis and hepatocellular carcinoma (HCC) or were diagnosed with HCC were included for analysis. Analyses were performed in January 2021.

MAIN OUTCOMES AND MEASURES

The main outcomes were measures of age, period, and cohort associations with CLD mortality and HCC incidence and mortality using an age-period-cohort analysis.

RESULTS

Among the 43 604 individuals (mean [SD] age, 33.3 [6.0] years; 37 755 men [86.6%]) with ESLD in the cohort, there were 17 904 CLD deaths, 11 504 HCC deaths, and 14 196 HCC incident events. There was a significant increase in all 3 disease burdens after age 20 years. From 2004 to 2018, CLD mortality decreased by 26% (adjusted rate ratio [aRR], 0.74; 95% CI, 0.70-0.82), HCC mortality decreased by 50% (aRR, 0.50; 95% CI, 0.45-0.58), and HCC incidence decreased by 53% (aRR, 0.47; 95% CI, 0.44-0.52). A sharply declining association by cohort was observed from the 1982 to 1986 birth cohort to the 2007 to 2011 birth cohort, during which CLD mortality decreased by 82% (aRR, 0.18; 95% CI, 0.00-1.13), HCC mortality decreased by 63% (aRR, 0.37; 95% CI, 0.09-0.68), and HCC incidence decreased by 80% (aRR, 0.20; 95% CI, 0.00-0.48). The associations of age, period, and cohort were similar between male and female individuals and between urban and rural areas. The percentage of chronic hepatitis B infections in patients with HCC decreased from 83.3% (95% CI, 79.7%-86.5%) for those born from 1980 to 1984 to 55.6% (95% CI, 21.2%-86.3%) (from 2000 to 2004).

CONCLUSIONS AND RELEVANCE

These findings suggest that the national hepatitis B vaccination program and the antiviral therapy program jointly were associated with substantial reductions in the burden of ESLD in Taiwan.

A Survivorship-Period-Cohort Model for Cancer Survival: Application to Liver Cancer in Taiwan, 1997-2016

Monitoring survival in cancer is a common concern for patients, physicians, and public health researchers. The traditional cohort approach for monitoring cancer prognosis has a timeliness problem. In this paper, we propose a survivorship-period-cohort (SPC) model for examining the effects of survivorship, period, and year-of-diagnosis cohort on cancer prognosis and for predicting future trends in cancer survival. We used the developed SPC model to evaluate the relative survival (RS) of patients with liver cancer in Taiwan (diagnosed from 1997 to 2016) and to predict future trends in RS by imputing incomplete follow-up data for recently diagnosed patient cohorts. We used cross-validation to select the extrapolation method and bootstrapping to estimate the 95% confidence interval for RS. We found that 5-year cumulative RS increased for both men and women with liver cancer diagnosed after 2003. For patients diagnosed before 2010, the 5-year cumulative RS rate for men was lower than that for women; thereafter, the rates were better for men than for women. The SPC model can help elucidate the effects of survivorship, period, and year-of-diagnosis cohort effects on cancer prognosis. Moreover, the SPC model can be used to monitor cancer prognosis in real time and predict future trends; thus, we recommend its use.

A simplified approach for establishing estimable functions in fixed effect age-period-cohort multiple classification models

Estimable functions play an important role in learning about certain aspects of the impact of ages, periods, and cohorts in age-period-cohort multiple classification (APCMC) models. The advantage of these estimates is that they are unbiased estimates of, for example, the deviations of age, period, and cohort effects from their linear trends, or changes in the linear trends of cohort effects within cohorts, or the residuals of fixed effect APCMC models. If the fixed effect APCMC model contains the relevant variables (is well specified), these estimable functions are unbiased estimates of functions of the parameters that generated the dependent variable data, even though the parameters that generated that data are not identified. I provide a simplified approach to establishing which functions are estimable in fixed effect APCMC models that provides an intuitive understanding of estimable functions by showing clearly and simply why they are estimable. This approach involves the partitioning of the age, period, and cohort effects into linear components and deviations from the linear components; the use of the "line of solutions"; and of the "extended null vector."

Oral cancer incidence rates from 1997 to 2016 among men in Taiwan: Association between birth cohort trends and betel nut consumption

OBJECTIVES

Oral cancer is the fourth most common cancer among men in Taiwan. Betel nut consumption is a major risk factor for oral cancer, but the association between betel nut chewing and the long-term secular trend of oral cancer incidence is unclear.

MATERIALS AND METHODS

We conducted an age-period-cohort analysis to examine the incidence rates of oral cancer among men in Taiwan from 1997 to 2016.

RESULTS

The oral cancer incidence rate among men doubled between 1997 and 2009, but the trend leveled off thereafter. Oral cancer incidence rates in the oldest age group (80-84y) were approximately 85 times those of the youngest group (25-29y). The period effect was weak, and the cohort effect exhibited a drastically increasing trend from 1917 (midyear for 1913-1921) to 1972 (1968-1976) birth cohorts and then a decreasing trend afterward. The Spearman rank correlation coefficient between the cohort effects on oral cancer incidence among men and the average consumption of betel nut with a lag time of 30 years had a significant and extremely high value of 0.993.

CONCLUSIONS

Our findings suggest that betel nut chewing is the main driver of the cohort effect for oral cancer incidence rates among men in Taiwan. In addition to reduced betel nut consumption, a decrease in smoking prevalence may also have contributed to the reduction in oral cancer incidence after the 1972 birth cohort; moreover, the increasing prevalence of alcohol consumption in Taiwan is unlikely to be the reason for the cohort effect for oral cancer.