摘要：Objectives. We examined whether the distinctive components of job control—decision authority, skill discretion, and predictability—were related to subsequent acute myocardial infarction (MI) events in a large population of initially heart disease–free industrial employees. Methods. We prospectively examined the relation between the components of job control and acute MI among private-sector industrial employees. During an 18-year follow-up, 56 fatal and 316 nonfatal events of acute MI were documented among 7663 employees with no recorded history of cardiovascular disease at baseline (i.e., 1986). Results. After adjustment for demographics, psychological distress, prevalent medical conditions, lifestyle risk factors, and socioeconomic characteristics, low decision autonomy ( P < .53) and skill discretion ( P < .10) were not significantly related to subsequent acute MI. By contrast, low predictability at work was associated with elevated risk of acute MI ( P = .02). This association was driven by the strong effect of predictability on acute MI among employees aged 45 to 54 years. Conclusions. Prospective evidence suggests that low predictability at work is an important component of job control, increasing long-term risk of acute MI among middle-aged employees. Cardiovascular diseases account for approximately 40% of deaths in developed countries. 1 Acute myocardial infarctions (MIs) account for nearly half of all the cardiovascular mortality. 2 According to current knowledge, acute MI is predicted by not only well-known risk factors, such as smoking and lack of physical activity, but also psychosocial factors. 3 Most working-age adults in industrialized countries spend about one third of their waking hours at work during an average period of more than 30 years. 4 Work environments often entail various stressful characteristics. 5 Correspondingly, recent reviews proposed that adverse work-related psychosocial risk factors may contribute to poor cardiac health. 6 , 7 In occupational epidemiology, the job strain model 8 has dominated research on cardiovascular risk factors. This model postulates that a combination of high work demands and low control at work (i.e., job strain), if prolonged, increases the risk of heart disease. Although some follow-up studies have supported this model, 9 , 10 many large-scale prospective studies with null findings also have been reported. 11 – 14 Poor job control may be more detrimental to heart health than high job demands, 15 but evidence on the independent predictive role of job control in coronary heart disease is scarce and mixed. 13 , 16 , 17 Several factors may explain the conflicting findings. First, dimensions of job control, such as decision authority (i.e., decision latitude concerning one's work pace and phases, and independence from other workers while carrying out tasks) and skill discretion (i.e., the level of cognitive challenges and variety of tasks at work) , could contribute differently to health outcomes. 18 Predictability on the job (i.e., the clarity of work goals and opportunity to foresee changes and problems at one's work) has been suggested to represent a further component of job control, but empirical research on this component is largely lacking. 19 – 21 Predictability involves relatively high stability of work and a lack of unexpected changes, which characterized the earlier industrial era which had stable production systems. 22 Predictable outcomes are less common in today's turbulent work life; thus, lack of predictability may represent a salient health hazard 23 , 24 and may contribute to myocardial risk. 25 Second, research indicates that physiological stress, especially exposure to long-term environmental stressors, can cause detrimental prolonged neurohormonal reactions as well as pathological physiological changes by adversely affecting the process of atherosclerosis, 16 , 26 , 27 thereby increasing the risk of acute MI. 28 , 29 However, most prospective studies on stressful work environment and subsequent cardiovascular disease have used follow-up periods of less than 10 years 6 , 7 or have studied all-cause cardiovascular outcomes rather than mortality and morbidity resulting from acute MI. 9 Thus, potential long-term effects of work-related psychosocial factors on acute MI events have not been examined. Third, age may play a role in the association between job strain and acute MI risk. Weaker effects have been found among older workers; plausible reasons for this are healthy worker survivor bias; retirement during follow-up may remove job strain and cause exposure misclassification (i.e., healthier older employees survive, retire, and are no longer exposed to work-related characteristics); and an increasing number of other age-related causes of acute MI. 30 Among younger employees, job strain may be associated with shorter exposures to harmful job characteristics than among middle-aged employees. Long-term prospective age-specific studies are therefore needed to determine whether current psychosocial risks of work environment predict acute MI events and whether the influence of work characteristics is stronger among middle-aged employees. The objective of our 18-year follow-up study was to examine whether the distinctive components of job control—decision authority, skill discretion, and predictability—were related to subsequent acute MI events in a large population of initially heart disease–free industrial employees after the effects of established risk factors were taken into account. We further tested age-specific vulnerability among these employees.
