Assessing the Reliability and Validity of the Sheehan Irritability Scale in Patients With Major Depressive Disorder

Objective: Irritability is a significant component in the clinical manifestation of major depressive disorder (MDD). The Sheehan Irritability Scale (SIS) was developed to assess irritability-related symptoms in patients with psychiatric disorders. Data from a phase 2 clinical trial (June 2008-July 2009) was utilized to evaluate the psychometric properties of the SIS. The trial population included patients diagnosed with MDD, according to DSM-IV and confirmed via the MINI diagnostic scale, who had inadequate response to citalopram.

Method: The secondary analyses included 586 patients from the United States and India. Data from the SIS, depression severity measures (17-item Hamilton Depression Rating Scale [HDRS-17], Montgomery-Asberg Depression Rating Scale [MADRS], Quick Inventory of Depressive Symptomatology-Self-Report [QIDS-SR]), and other measures (Sheehan Disability Scale [SDS], Clinical Global Impressions-Severity of Illness scale [CGI-S]) were used in the psychometric evaluation. All statistical tests used a significance level of .05 unless otherwise noted.

Results: Internal consistency (0.92-0.99) and test-retest reliability (0.83 to 0.98) were excellent. Concurrent validity was demonstrated through strong correlations between the SIS total score and HDRS-17, QIDS-SR, SDS, CGI-S, and MADRS scores. SIS total scores were significantly different by clinical severity level (P < .001). Minimally important difference estimates suggest that a 7- to 8-point change in the SIS total score may be clinically meaningful.

Conclusions: The SIS has excellent reliability, acceptable validity, and good responsiveness, making the SIS appropriate for use in clinical research and practice.

Trial Registration: ClinicalTrials.gov identifier: NCT00692445