Risk of Insomnia Disorder in Japanese Cancer Patients: A Matched Cohort Study Using Employer-Based Health Insurance Claims Data.

BACKGROUND

Insomnia is a common clinical symptom that significantly impairs quality of life (QOL) and it frequently occurs in cancer patients. However, the risk of insomnia in Japanese cancer patients compared with cancer-free patients has not yet been studied.

AIMS: This study evaluated the association between cancer diagnosis and the risk of insomnia disorder in the Japanese health insurance claims database.

METHODS

A population-based matched cohort study was performed comparing cancer patients with cancer-free patients. The primary outcome was the time to onset of insomnia disorder in cancer and cancer-free patients. Multivariate analyses were performed to determine hazard ratio (HR) for all patients and for each cancer type.

RESULTS

A total of 36,230 cancer patients and 362,300 cancer-free patients were enrolled in this study. The median age was 53 years. Among cancer patients, the time to onset of insomnia disorder was significantly shorter than that of cancer-free patients (stratified log-rank testing; p < 0.001). In the multivariate analysis, the HR of cancer status (HR 3.39; 95% CI 3.28-3.49) was largest. In the subgroup analysis, the insomnia disorder risk was highest in patients with esophageal cancer, multiple cancers, gallbladder/biliary tract cancer, and bone and articular cartilage cancer.

CONCLUSIONS

This study shows that Japanese cancer patients have a higher risk of developing insomnia disorder compared with cancer-free patients. The risk was especially high in cancer types which have a poor prognosis or impair the QOL of patients. These findings highlight the importance of assessing insomnia disorder frequently in cancer patients and providing interventions when it is needed.