Occurrence and Long-Term Prognosis of Insomnia Disorder among Survivors of Acute Respiratory Distress Syndrome in South Korea

Rationale: As the most common type of sleep disorder, insomnia disorder can develop as a sequela among acute respiratory distress syndrome (ARDS) survivors. However, insomnia prevalence, its associated factors, and its impact on long-term survival remain controversial. Objectives: This study aimed to investigate insomnia prevalence and its associated factors among ARDS survivors. We also examined the association between insomnia and 2-year all-cause mortality. Methods: The National Health Insurance Database of South Korea was used for this nationwide cohort study. We included adult patients (>= 18 years of age) admitted to intensive care units for ARDS treatment from January 1, 2010, to December 31, 2018, and who survived for >= 1 year after diagnosis, defined as ARDS survivors. ARDS survivors who received a diagnosis of insomnia disorder before ARDS diagnosis were defined as the pre-ARDS insomnia disorder group, whereas those who had no history of insomnia disorder but received a new diagnosis of insomnia disorder within 1 year of diagnosis of ARDS were defined as the post-ARDS insomnia disorder group. Results: A total of 4,452 ARDS survivors were included in this study, with 895 patients (20.1%) in the pre-ARDS insomnia disorder group and 536 (12.6%) patients in the post-ARDS insomnia disorder group. In the multivariable logistic regression analysis, delirium occurrence (odds ratio [OR],1.61; 95% confidence interval [CI], 1.24-2.10; P< 0.001), underlying anxiety disorder (OR, 1.34; 95% CI, 1.08-1.66; P =0.007), depression (OR, 1.48; 95% CI, 1.17-1.86; P=0.001), and substance abuse (OR, 1.51; 95% CI, 1.01-2.26; P.0.042) were associated with a higher prevalence of post-ARDS insomnia disorder. In multivariable Cox regression analysis, the pre-ARDS insomnia disorder and post-ARDS insomnia disorder groups were associated with 1.33-fold (hazard ratio, 1.33; 95% CI, 1.08-1.64; P= 0.007) and 1.36-fold (hazard ratio, 1.36; 95% CI, 1.06-1.74; P= 0.016) increased prevalence of 2-year all-cause mortality among ARDS survivors, respectively. Conclusions: At 1 year after diagnosis of ARDS, 12.6% of ARDS survivors received a new diagnosis of insomnia disorder in South Korea. Delirium and underlying psychiatric illness (anxiety disorder, depression, and substance abuse) were potential risk factors for the diagnosis of post-ARDS insomnia disorder. Moreover, both pre- and post-ARDS insomnia disorders were associated with 2-year all-cause mortality among ARDS survivors.