Differential response in studies of "job stress"(job strain) and chronic disease may bias findings substantially toward null. Evidence shows high stress subjects are more likely to refuse recruitment, or be lost to follow-up. The more demanding the protocol (potentially increasing scientific validity) the more prominent the differential loss of high strain subjects, and the more potentially prominent the bias of a job strain hypothesis test.
In a complex study of cholesterol and diet that required four follow-up visits and blood samples, 428 subjects were recruited from a population base of 3,330 HMO members (13%). Substantially fewer individuals with high strain occupations than expected were found when compared to a U.S. working population (Karasek, 1988; Schwartz, 1988). This "low strain biased" population was the population base for a job strain study requiring 48-hour EKG monitoring, an activity diary, and Job Content Questionnaire (JCQ). Differential response favored low strain [15 of 35 (43%)] vs. high strain subjects [2 of 24 (8%)], a 5.2 differential ratio. High strain refusals were based upon study protocol demands too great given exhaustion from the normal workday, or scheduling conflicts.
Differential high strain loss-to-follow-up associated with reduced job strain/CHD associations (Karasek, 1981) was also found in a national random Swedish population (follow-up rate of 93%), where only high strain subjects displayed this high differential loss. The authors will report results of a second subject recruitment attempt of the 48-hour EKG study, with a modified protocol. Potential effects of differential response in other job stress studies will be discussed.
Learning Objectives: Participant will understand and recognize the potential for differential response rate bias when the health effects of job strain are investigated. Participant will understand the modifications in a research protocol which may be necessary to minimize this bias
Keywords: Occupational Disease, Epidemiology
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.