Troy Brown, RN
April 10, 2019
Stress-related disorders may increase the risk for cardiovascular disease (CVD), especially during the first year after diagnosis, a large study shows.
"This population based, sibling controlled analysis showed a clear association between clinically confirmed stress related disorders and a higher subsequent risk of cardiovascular disease, particularly during the months after diagnosis of a stress related disorder, in the Swedish population," the researchers write.
The risk was almost twice as high for those with stress-related disorders compared with their unaffected full siblings. The association was seen equally among men and women and was independent of familial characteristics, history of somatic or psychiatric disorders, and psychiatric comorbidities.
Huan Song, from the Center of Public Health Sciences, Faculty of Medicine, University of Iceland, Reykjavík, and the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden, and colleagues report their findings online April 10 in The BMJ.
"One of the great strengths of this study is the sibling controlled design, which allows us to make reasonable assumptions about the similarity of the environment, lifestyles, and health behaviours between people with a disorder and their paired siblings without one," Simon L. Bacon, PhD, professor and Canadian Institutes of Health Research-Strategy for Patient-Oriented Research chair, writes in an accompanying editorial.
"Such assumptions allow inferences about alternative potential pathways linking these disorders to cardiovascular disease."
The study included 136,637 patients from the Swedish National Patient Register with diagnosed stress-related disorders, a full-sibling cohort of 171,314 unaffected individuals, and a matched group of 1,366,370 unexposed individuals from the general population. Patients were followed for as many as 27 years.
Stress-related disorders included post-traumatic stress disorder, acute stress reaction, adjustment disorder, and other stress reactions.
Among the exposed patients, their unaffected full siblings, and the matched unexposed participants, the crude incidence rate of any cardiovascular disease was 10.5, 8.4, and 6.9 per 1000 person-years, respectively, during the 27 years of follow-up.
Compared with their unaffected siblings, exposed patients had almost twice the risk for any cardiovascular disease during the first year of follow-up (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.45 - 1.84). The largest subtype-specific hazard ratio was seen for heart failure (HR, 6.95; 95% CI, 1.88 - 25.68).
Hazard ratios dropped after 1 year overall (HR, 1.29; 95% CI, 1.24 - 1.34) and subtype-specific HRs ranged from 1.12 (95% CI, 1.04 - 1.21) for arrhythmia to 2.02 (95% CI, 1.45 - 2.82) for artery thrombosis/embolus.
Associations were stronger among those who were younger at index date: (sibling analysis: HR, 1.52 for those aged 28 years or younger; HR, 1.26 for those aged 29 - 41 years; and HR, 1.30 for those aged 42 years and older; P for interaction = .010).
There was also a stronger association between stress-related disorders and early-onset CVD compared with later-onset CVD (sibling analysis: HR, 1.40 for attained age < 50 years vs 1.24 for attained age ≥ 50 years; P for difference =.002).
The presence of psychiatric comorbidity did not alter these associations, with the exception of fatal cardiovascular diseases.
Results were similar when compared with the population matched cohort (HR, 1.71; 95% CI, 1.59 - 1.83 for any cardiovascular disease during the first year of follow-up and HR, 1.36; 95% CI, 1.33 - 1.39 thereafter).
Noting the largest effect size was observed with heart failure during the year after diagnosis, Bacon explains, "Heart failure is often a slowly evolving chronic disease, so reverse causation cannot be ruled out entirely and further studies exploring the potential bidirectional nature of this relation are needed."
"[T]he ultimate test of an underlying unidirectional relation between acute stress induced psychiatric disorders and cardiovascular disease will be through intervention studies to treat these disorders. If the association is causal then effective treatment of the psychiatric disorder should reduce the risk of future cardiovascular disease events," he adds.
The often catastrophic nature of cardiovascular disease events emphasizes the importance of being alert for CVD in patients with stress-related disorders, the authors say. "These findings call for enhanced clinical awareness and, if verified, monitoring or early intervention among patients with recently diagnosed stress related disorders," Song and colleagues conclude.
The study authors have disclosed no relevant financial relationships. Bacon reports receiving investigator initiated research grants from GSK and Abbvie; consulting fees from Schering-Plough, Merck, Astra-Zeneca, Sygesa, and Bayer; and speaker fees from Novartis and Janssen, none of which are related to this topic.