The prevalence and clinical correlates of suicide attempts in comorbid subclinical hypothyroidism in patients with never-treated major depressive disorder in China.

BACKGROUND

Previous studies have emphasized the possible association between subclinical hypothyroidism (SCH) and major depressive disorder (MDD). This study aimed to further investigate suicide attempts and their clinical correlates in MDD patients with comorbid SCH.

METHODS

This cross-sectional study recruited 1706 eligible MDD outpatients. The Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression of Severity Scale (CGI-S) were applied to evaluate mental status. Fasting blood samples were collected to examine thyroid function. SCH was defined as thyroid stimulating hormone (TSH) > 8 mIU/L with normal free thyroxine levels.

RESULTS

The prevalence of suicide attempts in the SCH group (51.7 %) was significantly higher than that in the non-SCH group (15.4 %; p < 0.001). Logistic regression showed that patients with comorbid SCH were 1.81 times more likely to have attempted suicide as compared with those without (p = 0.001). Among those with TSH > 8 mIU/L, patients with severe anxiety were 3.57 times more likely to attempt suicide compared with those without (p < 0.01). Logistic regression also showed that the CGI-S score (p < 0.001) was independently associated with suicide attempts, while TSH level was not.

CONCLUSIONS

SCH comorbidity may pose a specific hazard in MDD patients due to increased suicide attempts. Exhibiting severe anxiety, overall severity of depressive and psychotic symptoms, but not TSH levels, may be independently correlated with suicide attempts in MDD patients with TSH > 8 mIU/L.