Early-Onset Insomnia among Patients with Hemifacial Spasm in South Korea: A Nationwide Cohort Study

This study aimed to investigate mental illnesses among patients with hemifacial spasms (HFS) based on nationwide claims data from the South Korea Health Insurance Review and Assessment Service. In this retrospective study, we defined the HFS group as subjects aged between 20 and 79 years with newly diagnosed HFS between January 2011 and December 2019 and set the date of diagnosis of HFS as the index date. Mental illnesses were defined through the International Classification of Diseases, the tenth revision from 90 days before to after the index date. Of these patients, we enrolled the participants who had visited a psychiatric outpatient clinic more than twice or had been admitted to a psychiatric department more than once diagnosed with psychiatric diseases. To select the control group, which was four times larger than the HFS group, propensity scores were used among those not diagnosed with HFS. The patients with HFS were more likely to have a mental illness than the control group (8.5% and 6.5%, respectively, p < 0.001) within 90 days before and after diagnosis. Among mental illnesses, insomnia (46.2% vs. 13.0%, p < 0.001) was significantly more prevalent in the HFS group. Other mental illnesses were significantly more prevalent in the control group or were not statistically significant. The results of this study suggest that patients diagnosed with HFS were significantly more likely to develop insomnia within a relatively short period than the controls.