Follow-up The total cohort was followed for mortality until 30 April 2006. By means of the Dutch SAHA clinical trial Municipal Population Registries, information was collected on the vital status of each study subject. For deceased workers, the underlying cause of death
was obtained from the Central Bureau of Statistics. Ascertainment of vital status and causes of death The procedures that were applied to obtain the vital status and the causes of death were similar to the previous study. The municipal population registries (about 460 in The Netherlands in 2006) were requested to provide information on the whereabouts of the workers that were included in this study. For workers who had moved from one municipality to another, the new municipality was requested to provide vital status information on that particular worker. This process was repeated after each notification find more that a person had moved. In this way, all of the 570 ex-workers were traced. Selleckchem Savolitinib Another route for identification of vital status was by consulting a special registry for persons
who had left The Netherlands by means of emigration. It was noted that quite a lot of people who had emigrated during some time in their lives returned to The Netherlands after retirement. Checking the data provided by this registry revealed additional information on former workers. As a result, these persons were no longer considered lost to follow-up and their person years were calculated and added to the total person years of follow-up. (More detailed information on vital status is shown in Table 1.) Table 1 Vital status ascertainment on 1 May 2006 for 570 workers exposed the dieldrin and aldrin between 1 January 1954 and 1 January 1970 Vital status at end date of follow-up Follow-up until 1 January 1993 Follow-up until 1 January 2001 Follow-up until 1 May 2006 N (%) N (%) N (%) Alive 402 70.5 335 58.8 297 52.1 Emigrated 35 6.2 47 8.2 38 6.7 Lost to follow-up 15 2.6 17 3.0 9 1.6
Deceased 118 20.7 171 30.0 226 39.6 Number of person-years at risk 16,297.28 19,704.56 21,702.0 Total group 570 100 570 100 570 100 In the last step in identifying the individual causes of death for all the deceased former employers death certificate data was Avelestat (AZD9668) retrieved from the Central Bureau of Statistics (CBS). The CBS receives a copy of all Dutch death certificates after a person’s death. After the receipt of the death certificates, the causes of death are coded by trained nosologists and computerized to accumulate the annual vital statistics, which are presented by causes of death. For all deceased workers, the cause of death was identified in this database. Statistics The observed cause-specific mortality of the cohort was compared with the expected number based on age and time interval cause-specific mortality rates of the total male Dutch population.