Evaluating Linkage Quality of Population-Based Administrative Data for Health Service Research.

BACKGROUND: To overcome the limitations of relying on data from a single institution, many researchers have studied data linkage methodologies. Data linkage includes errors owing to legal issues surrounding personal information and technical issues related to data processing. Linkage errors affect selection bias, and external and internal validity. Therefore, quality verification for each connection method with adherence to personal information protection is an important issue. This study evaluated the linkage quality of linked data and analyzed the potential bias resulting from linkage errors. METHODS: This study analyzed claims data submitted to the Health Insurance Review and Assessment Service (HIRA DATA). The linkage errors of the two deterministic linkage methods were evaluated based on the use of the match key. The first deterministic linkage uses a unique identification number, and the second deterministic linkage uses the name, gender, and date of birth as a set of partial identifiers. The linkage error included in this deterministic linkage method was compared with the absolute standardized difference (ASD) of Cohen's according to the baseline characteristics, and the linkage quality was evaluated through the following indicators: linked rate, false match rate, missed match rate, positive predictive value, sensitivity, specificity, and F1-score. RESULTS: For the deterministic linkage method that used the name, gender, and date of birth as a set of partial identifiers, the true match rate was 83.5 and the missed match rate was 16.5. Although there was bias in some characteristics of the data, most of the ASD values were less than 0.1, with no case greater than 0.5. Therefore, it is difficult to determine whether linked data constructed with deterministic linkages have substantial differences. CONCLUSION: This study confirms the possibility of building health and medical data at the national level as the first data linkage quality verification study using big data from the HIRA. Analyzing the quality of linkages is crucial for comprehending linkage errors and generating reliable analytical outcomes. Linkers should increase the reliability of linked data by providing linkage error-related information to researchers. The results of this study will serve as reference data to increase the reliability of multicenter data linkage studies.

A case of carcinoma of the thyroid and cervical esophagus following irradiation.

It is well recognized that radiation can be carcinogenic for a wide variety of tumors, especially, in breast, thyroid, and bone marrow which appear to be radiosensitive. The criteria for establishing the dignosis of radiation- induced malignancy are the knowledge of prior irradiation and the appearance of a malignancy in the irradiated area. We report a case of carcinoma of the thyroid and esophagus following prior neck irradiation for thyroid mass.

[The clinical meaning of the emergence of viral breakthrough during lamivudine treatment in patients with hepatitis B virus related chronic liver disease].

BACKGROUND/AIMS: Viral breakthrough has been considered a major limitation of lamivudine in the treatment of hepatitis B virus related chronic liver disease. Its clinical meaning has not been thoroughly assessed. METHODS: 64 patients who showed viral breakthrough during lamivudine treatment were retrospectively reviewed. We evaluated the rate of HBeAg seroconversion and hepatic decompensation after viral breakthrough. RESULTS: After viral breakthrough, serum alanine transaminase (ALT) elevation more than 1.2 x upper limit of normal (ULN) was noticed in 40 patients (62.5%). Acute flare (serum ALT elevation > x 5 ULN, or serum bilirubin >3 mg/dL) occurred in 15 patients (23.4%). During the period of follow up (15.0 +/- 9.7 months; range, 0-31 months) since viral breakthrough, decreased serum HBV-DNA level to below the detection limit and serum ALT normalization was seen in 15 patients (23.4%). HBeAg seroconversion was noticed in 7 (13.7%) of a total of 51 HBeAg positive patients at base line; in 4 (15.4%) of 26 patients with non-hepatic failure (chronic hepatitis or Child-Pugh class A liver cirrhosis) at base line; and in 2 (40.0%) of 5 patients with non-hepatic failure at base line and acute flare after viral breakthrough. During this period, terminal hepatic decompensation (Child-Pugh class C) or death was noticed in 9 (90.0%) of 10 patients who had hepatic decompensation (Child-Pugh class B or C) at baseline and acute flare after viral breakthrough. CONCLUSIONS: Acute flare after viral breakthrough seemed to continue during HBeAg seroconversion and rarely developed into terminal hepatic decompensation or death in patients with non-hepatic decompensation at baseline. Its incidence is not only high but lethal to most patients with hepatic decompensation at baseline.