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

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.

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.

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.

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

ClinicalTrials.gov identifier: NCT00692445.