| Sun Quanfu,Zou Jianming,Liu Yusheng.Databases and statistical methods of cohort studies (1979-1995) in Yangjiang, China[J].Chinese Journal of Radiological Medicine and Protection,1997,17(6):381-385 |
| Databases and statistical methods of cohort studies (1979-1995) in Yangjiang, China |
| Received:June 23, 1997 Revised:August 29, 1997 |
| DOI： |
| KeyWords:Cohort study Database Dose reconstruction Risk estimates |
| FundProject: |
| Author Name | Affiliation | | Sun Quanfu | Labortary of Industrial Hygiene, Ministry of Health Beijing 100088, China | | Zou Jianming | 广东省职业病防治所 | | Liu Yusheng | Labortary of Industrial Hygiene, Ministry of Health Beijing 100088, China | | 袁镛龄 | 湖南省劳动卫生研究所 | | 李嘉 | Labortary of Industrial Hygiene, Ministry of Health Beijing 100088, China | | 陶祖范 | Labortary of Industrial Hygiene, Ministry of Health Beijing 100088, China | | 查永如 | 广东省职业病防治所 | | 秋叶澄伯 | 日本鹿儿岛大学医学部 | | 加藤宽夫 | 日本放射线影响研究所 | | 魏履新 | Labortary of Industrial Hygiene, Ministry of Health Beijing 100088, China |
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| Abstract:: |
| Objective Database management system and advanced statistical analysis were brought into practice around 1986 for data maintenance, lifetime dose estimation, and risk analysis in epidemiological studies in high background radiation areas of Yangjiang, Guangdong, China, which began in the early 1970s and covered more than 100,000 subjects. Methods We chose Foxbase series, a popular database management system for PC, to set up databases for our survey. Records can be linked through ID code for each subject in the cohort. General analysis including dose calculation was conducted using SAS package. Person years tabulation was calculated by Datab in Epicure. Standard Poisson model was used to compare relative risks among different dose rate groups. Excess relative risks based on cumulative dose were estimated using AMFIT in Epicure with stratification by sex, attained age and calendar years. Results There are epidemiological databases of some 40 MB available to risk analysis, mainly including databases of cohort follow up and deaths of 12000 subjects for the periods 1979—1986 and 1987—1995, and dosimetric database for 6783 households in 526 hamlets. Because of no strict projeetion relationship between database of the two periods of 1979—1986 and 1987—1995, we developed methods to combine the data of the two periods into one for risk analysis. The first one is to set up a theoretical cohort of 1979—1995 based on record linkage between the two periods. The other method is simply to sum up stratified person year tables of different periods. It is suggested through extensive analysis of dosimetric data that indoor exposures should be divided further into two parts (exposure received on bed and those received during other indoor activites), outdoor exposure is homogeneous within a hamlet, and occupancy factors are sex-and-age dependent. Cumulative dose estimates based upon hamlet specific average of dose rates in bedroom, living room, and outdoor and sex age specific occupancy factors are derived for each cohort member. Person years and number of deaths are tabulated with stratification by sex, attained age, calender years, and dose. Cancer risks are analyzed for the period of 1979—1990. Conclusion The epidemiological studies in high background radiation areas of Yangjiang, have been greatly improved by extensively using database management system and advanced statistical analysis with more attention paid to standardization and systemization of survey data management. |
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