Association of Depression and Anxiety Disorders With Autoimmune Thyroiditis: A Systematic Review and Meta-analysis.

Importance: With a prevalence of 4% to 13% in the United States, autoimmune thyroiditis (AIT) is a major health problem. Besides somatic complications, patients with AIT can also experience psychiatric disorders. The extent of these organic psychiatric diseases in patients with AIT, however, is so far not commonly known.

Objective: To provide meta-analytic data on the association of depression and anxiety with AIT.

Data Sources: Google Scholar, the EBSCO Host databases, the Web of Knowledge, and PubMed were searched from inception through December 5, 2017. Articles identified were reviewed and reference lists were searched manually.

Study Selection: Case-control studies that reported the association between AIT and either depression or anxiety disorders or both were included.

Data Extraction and Synthesis: Data extraction was performed by multiple observers following the PRISMA guidelines. Two univariate random-effects meta-analyses were performed, and moderators were tested with Bonferroni-corrected meta-regression analysis. Heterogeneity was assessed with the I2 statistic. Sensitivity analyses tested the robustness of the results. Small study effects were assessed with funnel plots and the Egger test.

Main Outcomes and Measures: The odds ratio of patients with AIT and depression compared with a healthy control group, as well as the odds ratio of patients with AIT and anxiety disorders compared with a healthy control group.

Results: Nineteen studies comprising 21 independent samples were included, with a total of 36 174 participants (35 168 for depression and 34 094 for anxiety). Patients with AIT, Hashimoto thyroiditis, or subclinical or overt hypothyroidism had significantly higher scores on standardized depression instruments, with an odds ratio of 3.56 (95% CI, 2.14-5.94; I2 = 92.1%). For anxiety disorders, patients with AIT, Hashimoto thyroiditis, or subclinical or overt hypothyroidism had an odds ratio of 2.32 (95% CI, 1.40-3.85; I2 = 89.8%). Funnel plot asymmetry was detected for studies of depression. Study quality assessed with the Newcastle-Ottawa Scale for case-control studies (mean [SD] score: anxiety, 5.77 [1.17]; depression, 5.65 [1.14]; of a possible maximum score of 9) and proportion of females did not modulate the meta-analytic estimate, whereas mean age did.

Conclusions and Relevance: This meta-analysis establishes the association between AIT and depression and anxiety disorders. Patients with AIT exhibit an increased chance of developing symptoms of depression and anxiety or of receiving a diagnosis of depression and anxiety disorders. This finding has important implications for patients and could lead to the choice of early treatment-and not only psychotherapeutic treatment-of the organic disorder.