Unemployment is a significant risk factor for acute myocardial infarction, results of a large cohort study suggested, although the risk fades with joblessness lasting more than a year.
Among more than 13,000 participants in the Health and Retirement Study, the hazard ratio for acute MI in those looking unsuccessfully for work was 1.35 (95% CI 1.10 to 1.66) relative to the continuously employed, after adjusting for sociodemographic factors, insurance status, smoking, alcohol consumption, certain comorbidities, and body mass index, reported Matthew Dupre, PhD, of Duke University, and colleagues.
The risk was especially great among participants with multiple job losses during the nearly 20-year follow-up period. For those with four or more periods of involuntary unemployment, the hazard ratio for an MI was 1.63 (95% CI 1.29 to 2.07) relative to those with no job losses.
“Results from our large prospective cohort study demonstrated the powerful effect of one’s lifetime employment history and cumulative job losses on risks for a major cardiovascular event,” Dupre and colleagues wrote online in Archives of Internal Medicine.
Unemployment is rarely a modifiable risk factor, but the researchers argued that the findings nevertheless have a clinical implication.
“Knowledge about employment status, number of job losses, and the amount of time unemployed may help to identify individuals at elevated risk for acute MI,” Dupre and colleagues suggested.
“Additional studies are needed to assess how such information can be used to target and aggressively treat vulnerable segments of the population.”
The Health and Retirement Study began in 1992, originally enrolling 9,824 individuals ages 51 to 61. Additional participants were recruited later on to replace those withdrawing or otherwise lost to follow-up. Participants were interviewed every 2 years.
For the current analysis, Dupre and colleagues had adequate data on 13,451 participants enrolled from 1992 to 2004, including 1,061 who reported suffering acute MIs during follow-up. (Data on MI was supplied by participants, not medical records.)
The participants reporting MIs were significantly more likely to have also reported being unretired but without work prior to the MI, Dupre and colleagues found.
Adjusting only for age, race, sex, marital status, and geographic region, the risk for MI among those reporting unemployment was increased by 74% (HR 1.74, 95% CI 1.42 to 2.14). But adjusting for additional variables including lifestyle factors, BMI, and other health conditions such hypertension, diabetes, and depression weakened the relationship.
Nevertheless, the fully adjusted hazard ratio of 1.35 remained significant.
Participants reporting they were retired showed a trend toward modestly increased risk as well (HR 1.20, 95% CI 0.97 to 1.48, relative to employed participants).
But chronic unemployment did not appear to be a risk factor — only joblessness lasting a year or less. The hazard ratio for MI among those with cumulative unemployment up to 1 year was 1.27 (95% CI 1.01 to 1.60), whereas for cumulative unemployment of 2 years or more it was just under 1.0.
In an accompanying commentary, William T. Gallo, PhD, of City University of New York in New York City, said that the study cemented the association between unemployment and serious health risk.
“The report by Dupre et al. should mark the end of an era in which outcomes studies of unemployment have been pursued,” Gallo wrote. “Plenty of compelling evidence exists to move on.”
He suggested that future studies should focus on topics in which research has been “egregiously absent,” such as how economic factors negatively affect patients’ health.
One goal of such research should be to identify “groups whose health is particularly vulnerable to the experience of job loss,” Gallo wrote, but he also noted that such studies must be very sophisticated because of the maze of factors that likely contribute.
The study was limited because of the lack of data on pre-MI medication usage for cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia, Dupre and colleagues noted.
They also could not identify the nature of work or the reasons for job loss.