To facilitate assessment of fatigue-related symptoms, we developed a customized global assessment scale based upon the original CGI. The CGI is subject to scoring variability that can obscure the assessment of the intended symptoms. In this study, CGI-severity and Patient Global Impression of severity (PGI-S) for Fatigue instruments were developed to focus on “targeted” symptoms of fatigue. We have demonstrated that the CGI-S and PGI-S for fatigue are reliable and valid, as used in a psychiatric population.

56 subjects consented to participate. There were two clinic visits during which the CGI-S and PGI-S for fatigue rating instruments were administered. The MGH cognitive and physical functioning questionnaire (MGH-CPFQ), a validated self-rated scale was also used as a validation instrument. The patient-rated MGH-CPFQ and PGI-Severity for fatigue preceded the clinician-rated CGI-S at screen and the CGI-S and CGI-Improvement (CGI-I) at the second visit.

Most subjects revealed mild to moderate levels of fatigue associated with a range of Axis I psychiatric disorders. Clinical and Patient Impressions of fatigue were well correlated. Both CGI-S and PGI-S for fatigue were well correlated with the CPFQ. At the second visit the CGI-S for fatigue revealed temporal stability in the test-retest assessment. The correlation between CGI-S and PGI-S remained high (r = 0.61) as did convergent validity for the CPFQ (r = 0.74 for CGI-S and 0.61 for PGI-S).

In this study, we have demonstrated that the customized CGI-S and PGI-S for fatigue are reliable measures of fatigue in this population of psychiatric patients.