Stress-related disorders up risk of life-threatening infections

Clinically diagnosed stress-related disorders appear to increase the risk of life-threatening infections, according to a study in a Swedish population.

“Despite a relatively low absolute risk, the high mortality from life-threatening infections calls for increased clinical awareness among health professionals caring for patients with stress-related disorders, especially those diagnosed at younger age,” the researchers said.

Mean age at diagnosis of a stress-related disorder was 37 years (n=55,541; 38.3 percent men). The incidence of life-threatening infections during a mean follow-up of 8 years was higher among individuals with a stress-related disorder (2.9 per 1,000 person-years) than siblings without a diagnosis (1.7 per 1,000 person-years) and matched individuals without a diagnosis (1.3 per 1,000 person-years).

Individuals with a stress-related disorder had an increased risk of life-threatening infections (any stress-related disorder: hazard ratio [HR], 1.47, 95 percent confidence interval [CI], 1.37–1.58; post-traumatic stress disorder [PTSD]: HR, 1.92, 95 percent CI, 1.46–2.52) compared with full siblings without such a diagnosis. [BMJ 2019;367:l5784]

The population-based analysis revealed similar estimates (any stress-related disorder: HR, 1.58, 95 percent CI, 1.51–1.65; p=0.09 for difference between sibling and population-based comparison; PTSD: HR, 1.95, 95 percent CI, 1.66–2.28; p-difference=0.92).

An association existed between stress-related disorders and all life-threatening infections analysed, with the highest relative risk (RR) seen for meningitis (sibling-based analysis: RR, 1.63, 95 percent CI, 1.23–2.16) and endocarditis (RR, 1.57, 95 percent CI, 1.08–2.30).

Higher HRs were associated with younger age at diagnosis of a stress-related disorder and the presence of psychiatric comorbidity, especially substance use disorders. On the other hand, reduced HRs correlated with the use of selective serotonin reuptake inhibitors in the first year after diagnosis of a stress-related disorder.

“Importantly, the observed excess risks remained after controlling for most of the known risk factors of the studied infections, such as socioeconomic factors, familial background, physical conditions at baseline (including baseline susceptibility to infection) and the occurrence of other severe somatic diseases during follow-up,” the researchers said. [Nat Rev Dis Primers 2016;2:16074; Neth J Med 2015;73:53-60; Br J Gen Pract 2017;67:185-186]

These results also support the relation between stress and infection reported in experimental studies. [N Engl J Med 1991;325:606-612; Psychosom Med 2003;65:652-657; Psychol Sci 2003;14:389-395; Psychosom Med 2010;72:823-832]

The current population and sibling-matched cohort study included 144,919 individuals with stress-related disorders (eg, PTSD, acute stress reaction, adjustment disorder and other stress reactions) diagnosed from 1987 to 2013 and compared with 184,612 full siblings of those with a stress-related disorder and 1,449,190 matched individuals without such a diagnosis from the general population.

“Further studies are needed to understand the potential mediating role of behaviour-related factors in the observed association as well as potential mitigating role of various treatments for stress-related disorders in reducing the excess risk of life-threatening infections,” the researchers said.