Diagnosis of multiple anxiety disorders predicts the concurrent comorbidity of major depressive disorder

It has been established that a single anxiety disorder (AD) is more likely to be comorbid with other ADs as well as major depressive disorder (MDD). However, little is known about the comorbidity risks of MDD in patients with double or multiple ADs in comparison with those with a single AD. In this study, we estimated the comorbidity risks of MDD in patients with multiple ADs.

The subjects were 217 consecutive outpatients with any ADs who were comprehensively diagnosed using the Mini International Neuropsychiatric Interview. The comorbidity rates of MDD in subjects with 2 or more ADs were compared with those in subjects with a single AD.

The comorbidity rates of MDD in subjects with a single AD (n = 119), 2 ADs (n = 75), and 3 or more ADs (n = 23) were 20.1%, 45.3%, and 87.0%, respectively. The relative risks of the comorbidity of MDD in subjects with 2 and with 3 or more ADs compared with those with a single AD were 3.3 (95% confidence interval, 1.7-6.3) and 26.4 (95% confidence interval, 8.2-118.7), respectively. Generalized anxiety disorder was associated with a higher comorbidity rate of MDD in subjects with a single AD but not in subjects with 2 or more ADs.

The results showed that the presence of multiple ADs strongly predicts comorbidity with MDD in an exponential manner, suggesting that we should pay attention to the fact that patients with multiple ADs are more likely to be comorbid with MDD.