Depression severity and quality of life of qualified and unqualified patients with a mood disorder for a research study targeting anhedonia in a clinical sample.

Abstract

To investigate the depression severity and quality of life of qualified and unqualified patients with a mood disorder for a research study based on anhedonia severity. Diagnosis of major depressive disorder (MDD) or bipolar disorder (BPD) was ascertained with the MINI International Neuropsychiatric Interview. The severity of depression was measured with the 16-item Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-16-SR), and Item 5, "feeling sad (sadness)," QIDS-16-SR Item 13, "change in general interest," was used to measure the severity of anhedonia. The quality of life was measured with the Quality of Life, Enjoyment and Satisfaction Questionnaire (Q-LES-Q). Of 96 patients with MDD and 147 with bipolar I or II disorder, the severity rating on sadness and anhedonia was similar. The severities of anhedonia and sadness were highly correlated with R2 of ≥0.91. Without considering depressive severity, 55% of patients would be eligible for a study if≥mild anhedonia was used as a severity criterion, but only 26% of patients eligible for a study if≥moderate anhedonia was used without considering substance use and medical comorbidities. If patients with ≥ moderate overall depressive symptoms were considered, 88.1% of patients would be eligible if≥mild anhedonia was required for a study, and 45.2% of patients would be eligible for a study if≥moderate anhedonia was required. For those who were unqualified for the study based on≥moderate anhedonia, about 1/3 had≥moderate overall depressive symptoms and less than 40% of maximum possible scores of Q-LES-Q. If only patients in remission based on overall depressive symptom severity were considered for a study of anhedonia, no patient would be eligible for the study. Depressive mood and anhedonia are highly correlated. Screening patients with a mood disorder and an overall moderate depressive severity is a cost-effective approach for a study targeting anhedonia, especially for a study requiring≥moderate severity of anhedonia. However, 1/3 of the unqualified patients will have≥moderate overall depressive symptoms and poor quality of life.