Abstract
BackgroundThe clinical global impression of severity (CGI-S) scale is a frequently used rating instrument for the assessment of global severity of illness in Central Nervous System (CNS) trials. Although scoring guidelines have been proposed to anchor these scores, the collection of sufficient documentation to support the derived score is not part of any standardized interview procedure. It is self evident that the absence of a standardized, documentary format can affect inter-rater reliability and may adversely affect the accuracy of the resulting data.MethodWe developed a structured interview guide for global impressions (SIGGI) and evaluated the instrument in a 2-visit study of ambulatory patients with Major Depressive Disorder (MDD) or schizophrenia. Blinded, site-independent raters listened to audio recorded SIGGI interviews administered by site-based CGI raters. We compared SIGGI-derived CGI-S scores between the two separate site-based raters and the site-independent raters.ResultsWe found significant intraclass correlations (p = 0.001) on all SIGGI-derived CGI-S scores between two separate site-based CGI raters with each other (r = 0.768) and with a blinded, site-independent rater (r = 0.748 and r = 0.706 respectively) and significant Pearson’s correlations between CGI-S scores with all MADRS validity comparisons for MDD and PANSS comparisons for schizophrenia (p- 0.001 in all cases). Compared to site-based raters, the site-independent raters gave identical “dual” CGI-S scores to 67.6% and 68.2% of subjects at visit 1 and 77.1% at visit 2.ConclusionWe suggest that the SIGGI may improve the inter-rater reliability and scoring precision of the CGI-S and have broad applicability in CNS clinical trials.
Highlights
The clinical global impression of severity (CGI-S) scale is a frequently used rating instrument for the assessment of global severity of illness in Central Nervous System (CNS) trials
We suggest that the structured interview guide for global impressions (SIGGI) may improve the inter-rater reliability and scoring precision of the CGI-S and have broad applicability in CNS clinical trials
We believe that the SIGGI may have broad applicability in CNS clinical trials
Summary
The clinical global impression of severity (CGI-S) scale is a frequently used rating instrument for the assessment of global severity of illness in Central Nervous System (CNS) trials. The Clinical Global Impressions of severity (CGI-S) scale is a well-known and relatively straightforward single-item instrument used to assess the overall (global) severity of illness as a graded measure of increasing psychopathology from 1 to 7 [1]. Specific queries are provided to identify the relevant, acute symptoms and assess the clinical relevance of these symptoms, the SIGGI stays true to the original intent of the CGI to provide a global impression of illness based primarily on the clinician’s sound judgment and experience with a particular patient population. We believe that the SIGGI is a reliable and valid instrument that standardizes the documentation of the global severity of illness assessment. We believe that the SIGGI may have broad applicability in CNS clinical trials
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