Association between infections and functional somatic disorders: a cross-sectional population-based cohort study

Area of Science:

• Medical research
• Epidemiology
• Psychiatry

Background:

• Functional somatic disorders (FSD) are hypothesized to be triggered by infections.
• Existing evidence is limited by small studies, selected populations, and short follow-up periods.
• This study investigates the infection-FSD hypothesis using a large, nationwide cohort.

Purpose of the Study:

• To test the hypothesis that prior infections are associated with an increased risk of FSD.
• To examine the dose-response relationship between the number of infections and FSD risk.
• To differentiate the impact of bacterial versus viral infections on FSD development.

Main Methods:

• Utilized data from the Danish Study of Functional Disorders, a large population-based cohort.
• Retrospectively linked FSD cases to hospital contacts for infections via the Danish National Patient Registry.
• Employed logistic regression to analyze associations between FSD and infections over 17 years, adjusting for covariates.

Main Results:

• Former infections were associated with an elevated risk for all studied FSD delimitations, including bodily distress syndrome (BDS), irritable bowel (IB), chronic fatigue (CF), and chronic widespread pain (CWP).
• Associations were stronger for multisystemic FSD and showed a clear dose-response relationship with the number of prior infections (p<0.0001).
• Bacterial infections significantly increased the risk for BDS, IB, CWP, and CF, whereas viral infections did not show a significant association.

Conclusions:

• Hospital-diagnosed infections are linked to a higher risk of developing FSD.
• The risk increases with the number of infections and is more pronounced for bacterial infections.
• These findings support the role of severe infections, particularly bacterial, in the etiology of FSD.