Background/Purpose: Osteoarthritis (OA), the most common type of arthritis, is prevalent and costly. Pain is the principal reason patients with OA seek treatment. Older adults with OA often report co-existing insomnia and depression. OA pain, insomnia, and depression greatly increase health care use (HCU) in this population. The purpose of this study is to examine the independent and combined effects of OA pain, insomnia and depression on HCU.

Methods: 8,057 participants aged 60+ with an electronic medical record OA diagnosis were mailed a screening survey which asked about their pain, sleep disturbance, and depressive symptoms. Pain was assessed by the Graded Chronic Pain Scale (GCPS); Grades 2-4 were positive for chronic pain. Insomnia severity was measured by the Insomnia Severity Index (ISI); a score of 7 or greater indicates at least mild insomnia. Depression was measured by the Patient Health Questionnaire depression scale (PHQ-8), with a score greater than 9 representing current depression. All participants were members of Group Health Cooperative (GHC), a Seattle-based health maintenance organization. HCU variables were extracted from participant medical records and included total number of office visits, length of stay (LOS) (days), and outpatient costs related to OA, insomnia and depression. Patient demographics (age, sex, race, ethnicity, education, employment and martial status), days of enrollment in GHC a year before screening date, and Charlson Comorbidity Index scores were also recorded. Negative binominal model and generalized linear model were used for the data analysis.

Results: 3,056 participants completed the survey and gave permission to access their medical records. Average age was 72 years; participants were largely Caucasian (87.4%), female (66.3%), married (59.3%) and highly educated (86.4% community college or higher). Participants had a positive level of pain (46.6%), at least mild insomnia (55.1%), and current depression (17.3%). For independent effects on HCU controlling for patient characteristics, OA pain, insomnia, and depression were associated with office visits (p < 0.001). In addition, OA pain (p < 0.001), insomnia (p = 0.020), and depression (p < 0.001) were associated with outpatient costs, but none were associated with LOS. For joint effects of those symptoms controlling for patient characteristics, pain was significantly related to office visits and outpatient costs (p < 0.001) but not LOS. Insomnia given pain level contributed to office visits (p < 0.01) but not for outpatient costs. Depression given pain level contributed to both office visits and outpatient costs (p < 0.01). No significant interactions were found between pain and insomnia, or pain and depression.

Conclusion: OA pain and depression were associated with office visits and outpatient costs in this population after adjusting for covariates. However, insomnia was only associated with office visits prior to adjustment. OA pain, insomnia, and depression were not associated with LOS in this population. Joint contributions of pain, insomnia and depression to HCU were additive.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/influences-of-osteoarthritis-pain-comorbid-insomnia-and-depression-on-health-care-use-in-older-adults-with-osteoarthritis/