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 life-chart 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.