Song H, et al. - Population- and sibling-matched retrospective cohort study was conducted in Sweden from January 1, 1981 to December 31, 2013 to discover if there was a relationship between stress-related disorders and subsequent autoimmune disease. Compared with matched unexposed individuals and with full siblings, exposure to a stress-related disorder was significantly correlated with increased risk of subsequent autoimmune disease.

Methods

• In this cohort, 106,464 exposed subjects with stress-related disorders, with 1,064,640 matched unexposed persons and 126,652 full siblings of these patients were included.
• Diagnosis of stress-related disorders, ie, posttraumatic stress disorder, acute stress reaction, adjustment disorder, and other stress reactions were the main exposures in this analysis.
• Through the National Patient Register, stress-related disorder and autoimmune diseases were identified.
• They used the Cox model to estimate hazard ratios (HRs) with 95% CIs of 41 autoimmune diseases beyond 1 year after the diagnosis of stress-related disorders, controlling for multiple risk factors.

Results

• According to the findings obtained, the median age at diagnosis of stress-related disorders was 41 years (interquartile range, 33-50 years) and 40% of the exposed subjects were male.
• Findings revealed that the incidence rate of autoimmune diseases was 9.1, 6.0, and 6.5 per 1000 person-years among the exposed, matched unexposed, and sibling cohorts, respectively (absolute rate difference, 3.12 [95% CI, 2.99-3.25] and 2.49 [95% CI, 2.23-2.76] per 1000 person-years compared with the population- and sibling-based reference groups, respectively) during a mean follow-up of 10 years.
• Patients with stress-related disorders were at increased risk of autoimmune disease (HR, 1.36 [95% CI, 1.33-1.40]) compared with the unexposed population.
• It was noted that the HRs for patients with posttraumatic stress disorder were 1.46 (95% CI, 1.32-1.61) for any and 2.29 (95% CI, 1.72-3.04) for multiple (≥3) autoimmune diseases and these associations were consistent in the sibling-based comparison.
• The findings demonstrated that relative risk elevations were more pronounced among younger patients (HR, 1.48 [95% CI, 1.42-1.55]; 1.41 [95% CI, 1.33-1.48]; 1.31 [95% CI, 1.24-1.37]; and 1.23 [95% CI, 1.17-1.30] for age at ≤33, 34-41, 42-50, and ≥51 years, respectively; P for interaction < .001).
• Results revealed that persistent use of selective serotonin reuptake inhibitors during the first year of posttraumatic stress disorder diagnosis was correlated with attenuated relative risk of autoimmune disease (HR, 3.64 [95% CI, 2.00-6.62]; 2.65 [95% CI, 1.57-4.45]; and 1.82 [95% CI, 1.09-3.02] for duration ≤179, 180-319, and ≥320 days, respectively; P for trend = .03).