The importance of unresolved fatigue in depression: costs and comorbidities.

OBJECTIVE

To assess the cost outcomes of patients with a history of depression and clinically significant fatigue.

METHODS

Adults with ≥ 2 claims with depression diagnosis codes identified from the HealthCore Integrated Research Database were invited to participate in this study linking survey data with retrospective claims data (12-mo presurvey and postsurvey periods). Patient surveys included measures for depression (Quick Inventory of Depressive Symptomatology), fatigue (Fatigue Associated with Depression Questionnaire), anxiety (7-item Generalized Anxiety Disorder scale), sleep difficulty (Athens Insomnia Scale), and pain (Brief Pain Inventory). After adjusting for demographic and clinical characteristics using propensity scores, postsurvey costs were compared between patients with and without fatigue using nonparametric bootstrapping methods.

RESULTS

Of the 1982 patients who had completed the survey and had complete claims data, 653 patients had significant levels of fatigue. Patients with fatigue reported significantly higher scores, indicating greater severity, on measures of depression, pain, sleep difficulty, and anxiety (all p < 0.05). These patients also had higher levels of overall medication use and were more likely to have lower measures of socioeconomic status than patients without significant levels of fatigue (all p < 0.05). Mean annual total costs were greater for patients with fatigue than those without fatigue ($14,462 vs $9971, respectively, p < 0.001). These cost differences remained statistically significant after adjusting for clinical and demographic differences.

CONCLUSIONS

Clinically significant fatigue appears to add to the economic burden of depression. This reinforces the need for aggressive treatment of all symptoms and further examination of the variability of this relationship as patients approach remission.