Bigert et al. (2004) also conducted a study examining trends in the incidence ofMIamong
professional drivers (1183 cases and 6072 controls) in Stockholm County, Sweden, during
1977–1996. They used registers of hospital discharges and deaths, and controls selected
randomly from the general population (20,364 cases and 136,342 controls) that were linked
to national occupational register job titles. Between 1977 and 1984, the risk among bus, taxi,
and truck drivers was increased compared to manual workers, but risks subsequently
declined among all three through 1996. Finkelstein et al. (2004) assessed mortality due
to ischemic heart disease (1416 cases, ICD9 codes 410–414) in seven Ontario construction
unions, and compared deaths among heavy equipment operators to deaths in other
occupations. The construction workers had an increased risk of ischemic heart disease
mortality (OR ¼ 1.32;95%CI ¼ 1.13–1.55). Although there was no information regarding
smoking or other risk factors in these studies, the comparison groups were other workers,
making it unlikely that cardiovascular risk factors substantially differed among case and
referent groups.