Cobb & Rose (1973) Illness rates in air traffic controllers
The study sought to compare the experience of stress and illness rates in two groups of workers: air traffic controllers and second-class airmen at a US airbase. These groups were chosen because, although comparable in other respects, the air traffic controllers had responsibility for people’s safety, whereas the airmen did not.
This was a retrospective comparison based on a comparison of the medical records of 4,325 air traffic controllers with those of 8,435 other men involved in the aviation industry. The records were available because both groups of men were required to obtain yearly medical examinations from the same group of doctors physicians (Aeromedical Examiners) to maintain their licences in commercial or general aviation.
The study found thatcertain diseases were unduly frequent in air traffic controllers.The largest differences involved prevalence and incidence of CVD. The controllers were found tohave a 5.6 times greater incidence of newcases of high BP (hypertension) in 1969 to 1970 than the other group of aviation workers. The incidence of diagnosed hypertension inthe air traffic controllers was found to be 4 times higher than in the control group. Other stress related diseases (e.g. stomach ulcers and diabetes) were twice as common. All there diseases were more likely to be diagnosed at a younger age in the air traffic controllers.
These findings strongly suggested that the increased rate of illness from these three diseases among controllers could ahve resulted from the more stressfull demands of the conntrollers jobs.
In any study of this type (ie correlation) it is difficult to establish the precise cause of differences between the two groups. Other factors could account for the greater incidence of stress symptoms. For example, some of the difference in disease rates could be attributable to a preselection factor in the control group, from which 17% had been excluded earlier after diagnosis of hypertension, while only 3% had been excluded, after diagnosis of hypertension, from the air traffic controller group. However, difference in the incidence of hypertension was still very large even after accounting for this.
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