Preliminary evidence of the reliability and validity of the prospective life-chart methodology (LCM-p)

This article describes the use of the NIMH prospective life-charting methodology (NIMH LCM-p) in the context of a formal double-blind, clinical trial and provides preliminary evidence of its reliability and validity. Subjects included in this report were 30 outpatients with bipolar I and II disorder who completed the first 2 years of a long-term maintenance study: 1 year on carbamazepine or lithium and a crossover to the other in the second year. The LCM-p follows the same types of guidelines and principles utilized in the previously described retrospective lifechart process, allowing for continuity of illness assessment prior and subsequent to study entry. In the LCM-p, daily ratings of severity of mood symptoms based on the degree of associated functional incapacity, provide a more detailed topography of manic and depressive fluctuations. Inter-rater reliability was examined by comparing the severity of daily LCM-p ratings assigned by two raters. In order to assess the validity, we correlated the LCM-p ratings with well-standardized scales, including Hamilton and Beck Depression Ratings, Young Mania Ratings and the Global Assessment Scale (GAS). The Kappa scores for inter-rater reliability demonstrated significant and satisfactory strength of agreement with no fall off over 14 days prior to the rating interview. Strong correlations were found: (1) between the LCM-p average severity for depression rating and the mean Hamilton Depression Rating (r = 0.86,p < .001), and the Beck Depression Inventory (r = 0.73, p < .001); 2) between the LCM-p average severity for mania rating and the Young Mania Rating Scale (r = 0.61, p < .001); and (3) between the LCM-p average severity and the GAS (r = -0.81, p < .001). These preliminary data suggest the reliability and validity of the NIMH-LCM-p in assessing manic and depressive episode severity. It also provides a useful continuous daily measure of affective illness-related symptom fluctuations that allows for detailed prospective assessment of frequency and pattern of illness, treatment response, and continuity with retrospective life chart assessments.