Death by unnatural causes, mainly suicide, is increased in patients with Hashimoto's thyroiditis. A nationwide Danish register study

Purpose Hashimoto's thyroiditis (HT) is associated with excess psychiatric in addition to reduced quality of life. However, little is known about risk of unnatural manners of death in HT. We investigated the risk of death by accidents, suicide, violence/homicide, and unknown causes in patients with HT, compared to a matched control population. Methods Register study covering all adult Danes diagnosed with HT during 1995-2012. In total, 111,565 HT cases were identified and matched for age and sex with four euthyroid controls. The hazard ratios (HR) for mortality were calculated using Cox regression analyses, adjusted for pre-existing morbidity. Median follow-up time was 5.9 years (range 0-17.5). Results Compared to controls, HT patients had an increased frequency of death by suicide (0.10% vs 0.07%, p < 0.001) and unknown manners (0.05% vs 0.02%, p < 0.001). There were no significant differences between controls and HT patients in risk of death by accidents (0.36% vs 0.37%, p = 0.384) or violence (0.004% vs 0.005%, p = 0.749). After adjustment for pre-existing somatic and psychiatric morbidity HT patients still had an increased risk of suicide and death by unknown causes, whereas risk of death caused by accidents was reduced. Conclusions Mortality due to suicide and unknown causes, but not accidents and violence, was increased in HT. This indicates that HT may have a significant role in the pathophysiological mechanisms of suicidal behavior. This suggests that physicians caring for HT patients should be vigilant when facing expressions of suicidal ideation or signs and symptoms of self-harm as a first step towards prevention.