Evaluation of the completeness of cancer case ascertainment in the Seoul male cohort study: application of the capture-recapture method

Completeness of cancer case ascertainment in Korea radiation effect and epidemiology cohort study

The aim of this study was to evaluate whether the completeness of case ascertainment during the follow-up of a cohort differed between the exposed and the nonexposed groups in Korea Radiation Effect and Epidemiology Cohort (KREEC). The completeness was defined as the proportion of the number of detected cases to the number of estimated cases, in which the estimation was performed by capture-recapture method. Data were obtained from the cancer registries, death certificates, and medical records during years 2004-2007. Among 11,367 subjects in the exposed group and 24,809 subjects in the unexposed group, the completeness of cancer case ascertainment were 88.2% vs 87.2% in cancer registry, 38.2% vs 41.1% in death certificate and 57.9% vs 62.0% in medical records data, 96.9% vs 97.1% for all combined sources and were not statistically different between the two groups. In conclusion, the method of ascertaining the cases in the KREEC was not biased depending on the exposure status, and thus adds credibility to the outcomes of the KREEC study as well as confirming the incident cases in the two groups.

Problems in using birth certificate files in the capture-recapture model to estimate the completeness of case ascertainment in a population-based birth defects registry in New York State

BACKGROUND

The limitations and underlying assumptions of the capture-recapture methods have hindered their application in epidemiological settings, especially in evaluating the completeness of birth defects registries. This study explored the possibility of using birth certificates as the secondary data source in a simple two-source capture-recapture model to estimate the completeness of case ascertainment of the Congenital Malformations Registry (CMR) for selected major birth defects.

METHODS

The CMR and the birth certificates were used as the primary and secondary sources, respectively. Children who were born in 1996-2001 and had selected major birth defects were identified from the two sources. The accuracy of the diagnoses was examined by comparing the individual birth defect categories of the children from the two sources.

RESULTS

Discrepancies in birth defect categories in the two data sources and false positives in the birth certificates were the major problems encountered in estimating the completeness of the CMR using the simple two-source capture-recapture method. The estimated completeness for selected major birth defects was only about 71%. Stratified analyses resulted in relatively high estimated completeness for oral clefts (90%) and Down syndrome (88%). CONCLUSIONS Although the birth certificate data was not a good source for estimating the completeness of case ascertainment of the CMR using capture-recapture methods, the analyses provided reasonable estimates for some conditions that were relatively easy to identify and diagnose at birth, such as oral clefts and Down syndrome.