A Comparison of Occupation, Education, and Cause of Death from National Death Certificates and Deaths Data Due to Workplace Injuries from WELCO in Korea

Son, Mia

Abstract

PURPOSE: The variables (occupation, education, cause of death, age, and sex) on death certificates can be used for health related studies, however, there has been little research on health related studies using death certificates in Korea. Also, the validity of the values of these variables on death certificates is questionable in Korea. Therefore, we compared occupation, data obtained from WELCO(Korea Labour Welfare Corporation) between 1995 and 1997.
METHODS
WELCO data on deaths due to workplace injury between 1995-1997 were merged with data from NSO on deaths occurring during the same period, using social security numbers. Out of a total of 7,698 deaths due to workplace injury reported to WELCO between 1995 and 1997, final study population are linked to 6,513 deaths among aged 20-64 between 1995 and 1997. On linking the data sets, two different sources of data are cross-tabulated to determine the percentage of agreement. Expected agreement and Kappa index are also calculated.
RESULTS
The results are as follows : Some manual workers are promoted into the non-manual group in the national death data from the National Statistics Office. Educational groups are promoted or demoted between NSO and WELCO death data. The Kappa index for occupational group is 0.49 when the occupational groups are categorised as manual and non-manual workers. The Kappa index is 0.50 in the two-category classification for education : beyond and below university levels; 0.32 in the three-category classification : university, high-school and less than middle-school; 0.25 in the four category classification : university, high-school, middle-school and less than elementary school. The Kappa index is 0.69 for the three-category disease classification : injury, poisoning and certain other consequences of external causes (S00-T98, ICD10), disease of the circulatory system(I00-I99, ICD10) and other disease categories except the two-category classification. The Kappa index for the 5-year age band is 0.99. There is no disagreement for the sex.
CONCLUSIONS
The comparison between national workplace injury data and national death data and tells us that occupational and educational variables are not in the range of 'excellent agreement' suggested by Koch(1997). Our comparison study suggests strong prediction of random errors as well as systemic errors. As for the cause of death, injury and cardiovascular disease from the NSO data are well-matched with those from the WELCO workplace injury death data. However, this comparison may have a limitation as the present study is confined to comparing only the categories of infury and cardiovascular disease. This study suggests that national death data as well as workplace injury data need to be improved for use as health indicators in studies relating socio-economic factors and working conditions to mortality in Korea.