Accounting for Immigrant Status when Calculating Cancer Incidence Rates for Bangkok

Objective: Cancer-registry data are crucial for definingcancer incidence rates for use in setting service priorities and monitoringservice effects. This applies in Thailand where cancer is the leading cause of death and service needs are high. The Bangkok Cancer Registry (population-based) was established in 1990to determine cancer incidence rates for Bangkok. This proved difficult, however, because the Bangkokpopulation (>8million) fluctuates with numbers of temporary visitors, many of whom visit Bangkok temporarily for services. If these visitors are mis-categorized as usual residents, cancer incidence rateswould be inflated. During 2013-2015, residential addresses on the Registry were cross-checked against official addresses on the National Civil Registration records of the Ministry of Interior. The effectsof this cross-checking on incidence rates are discussed. Methods: Residential addresses recorded on the Registry for cancer diagnoses in 2013-2015 were corrected using official Ministry data. Effects on numbers of recorded cancers and crude and directly age-standardized rates (World Population) were determined. Results: Of 44,813 cancer casesdiagnosed and recorded on the Registryduring 2013-2015, 36,327 (81.1%) had an official Bangkok address. When limiting analyses to these cases, the crude incidencefor all cancer sites combined reduced by 18.9% (19.7% for males and 18.3% for females). Corresponding reductions in age-standardized incidence rates were 20.0% for males and 18.8% for females. These reductions varied for common cancer sites:in males,from 14.8% for lung to 25.9% for colorectal cancer; and in females, from 12.9% for lung to 24.0% for cervical cancer. Conclusions: These differences are considered sufficient in magnitude to justifyroutine use of official residential data when calculating cancer incidence rates for Bangkok. If these rates are to be compared with comparable rates for other Asian citiesthat serve broader populations, equivalent methodologies for determining residential status would be needed for all cities.

Data Reliability and Coding Completeness of Cancer Registry Information Using Reabstracting Method in the National Cancer Institute: Thailand, 2012 to 2014.

PURPOSE: Data quality is a core value of cancer registries, which bring about greater understanding of cancer distribution and determinants. Thailand established its cancer registry in 1986; however, studies focusing on data reliability have been limited. This study aimed to assess the coding completeness and reliability of the National Cancer Institute (NCI) hospital-based cancer registry, Thailand. METHODS: This study was conducted using the reabstracting method. We focused on seven cancer sites-the colon, rectum, liver, lung, breast, cervix, and prostate-registered between 2012 and 2014 in the NCI hospital-based cancer registry. Missing data were identified for coding completeness calculation among important variables. The agreement rate and κ coefficient were computed to represent data reliability. RESULTS: For reabstracting, we retrieved 957 medical records from a total of 5,462. These were selected using the probability proportional to size method, stratified by topology, sex, and registered year. The overall coding completeness of the registered and reabstracted data was 89.9% and 93.6%, respectively. In addition, the overall agreement rate among variables ranged from 84.7% to 99.6%, and κ coefficient ranged from 0.619 to 0.995. The misclassification among unilateral organs caused lower coding completeness and agreement rate of laterality coding. The completeness of current residency could be improved using the reabstracting method. The lowest agreement rate was found among various categories of diagnosis basis. Sex misclassification for male breast cancer was identified. CONCLUSION: The coding completeness and data reliability of the NCI hospital-based cancer registry met the standard in most critical variables. However, some challenges remain to improve the data quality. The reabstracting method could identify the critical points affecting the quality of cancer registry data.

Quality of case ascertainment in cancer registries: a proposal for a virtual three-source capture-recapture technique.

BACKGROUND: The ability and behaviour of the capture-recapture method using a virtual three-source model for evaluation of the level of completeness of case ascertainment requires exploration. METHODS: Cancer cases obtained from 9 population-based cancer registries in Thailand during 2003 to 2007 were applied for capture-recapture using a model based on clinical, pathological and mortality data. These three virtual sources were derived from three actual items common to all cancer registries: the basis of diagnosis, ICD-O morphology code, and last known patient status. Poisson regression models were fit to the data to estimate parameters which were then transformed into demographic values. A linear model was used to determine the predictors and estimated percentage of completeness (EPC) in case ascertainment among the cancer registries. RESULTS: The EPC was greater than 97% in 5 and less than 90% in 4 registries. The worst had an EPC of 70%. The percentage death certificate only (%DCO) and the interaction between %DCO and morphological verification (MV) were significantly associated with EPC. Other factors intrinsic to registries also exerted influence on the EPC. CONCLUSIONS: In addition to other standard indicators to monitor completeness of cancer registries, the present virtual three-source capture-recapture model can be routinely used to estimate the level of completeness of case ascertainment in cancer registries.