Correlation between depression/anxiety symptom severity and quality of life in patients with major depressive disorder or bipolar disorder

Abstract

Objective: To study the correlation between depression/anxiety severity and the quality of life (QOL) in patients with major depressive disorder (MDD) or bipolar disorder (BP).

Methods: Two hundred forty-three outpatients diagnosed with MDD or BP were used to study the relationship between depression/anxiety severity and QOL. Depression and anxiety symptom-severity were measured with the QIDS-16-SR (the 16 Item Quick Inventory of Depressive Symptomatology - Self Report), and Zung-SAS (Zung Self-Rating Anxiety Scale). The QOL was measured with the Q-LES-Q short-form (the Quality of Life, Enjoyment and Satisfaction Questionnaire). Correlation was assessed with regression analysis.

Results: The percentage of maximum possible scores (MPS) of Q-LES-Q was 72.1%, 70.5%, and 67.6% for euthymic MDD, BPI, and BPII, respectively. Increases in QIDS-16-SR total scores significantly correlated to decreases in Q-LES-Q total scores, with an R² = 0.61, R² = 0.52, and R² = 0.45 for MDD, BPI, and BPII, respectively. Increases in Zung-SAS scores also significantly correlated to decreases in Q-LES-Q total scores with an R² = 0.20, R² = 0.21, and R² = 0.12 for MDD, BPI, and BPII. However, after controlling for depression severity, significant differences between Q-LES-Q and Zung-SAS scores disappeared in MDD and BP. After controlling for anxiety and other clinical variables, the negative correlation between QIDS-16-SR and Q-LES-Q scores remained significant in MDD and BP.

Conclusions: In this outpatient sample, the MPS of Q-LES-Q in euthymic MDD and BP patients was at the lower end of non-psychiatric or medical community norm spectrum. Depression severity was the only independent variable negatively correlated to the QOL in both disorders.

Keywords: Anxiety severity; Bipolar disorder; Correlation; Depression severity; Mood disorder; Quality of life.