Test–retest Reliability of a New Questionnaire for the Retrospective Assessment of Long-Term Lithium Use in Bipolar Disorder

BACKGROUND:The identification of predictors of treatment response holds tremendous potential for the improvement of clinical outcomes in bipolar disorder (BP). The goal of this project is to evaluate the test-retest reliability of a new clinical tool, the Lithium Questionnaire (LQ), for the retrospective assessment of long-term lithium use in research participants with BP.METHODS:Twenty-nine individuals with BP-I (n=27), major depression (n=1), or schizoaffective disorder (n=1) were recruited for participation. The LQ was administered to all participants at two time-points, spaced 17 months apart on average, and used to determine each subject׳s score on the Retrospective Criteria of Long-Term Treatment Response in Research Subjects with Bipolar Disorder Scale, or the Alda Scale. Scores were confirmed through a best-estimate procedure, and test-retest reliability (intra-class correlation coefficient [ICC]) of the LQ was calculated.RESULTS:The correlation between the total Alda Scale scores at the two time-points was in the moderate range (ICC=0.60). Relevant clinical factors such as age or presence of Axis I psychiatric comorbidity did not influence the reliability.LIMITATIONS:The validity of the LQ was not examined. Inclusion of two participants with non-BP diagnoses may have affected the LQ׳s reliability, but re-analysis of our data after exclusion of these participants did not influence the reliability. The absence of measures of mood and cognition at time of LQ may be a limitation of this work.CONCLUSIONS:The LQ holds promise for the standardization of the retrospective assessment of long-term treatment in BP.