Predictors of lithium treatment responsiveness in bipolar patients. A two-year prospective study.

Twenty-nine bipolar patients were assessed before the start of lithium therapy to study the prognostic criteria of long-term response to therapy. Assessment included clinical and demographic data and laboratory tests administered before and 2-5 days after initiation of therapy. The tests included calcium and magnesium serum levels, and thyroid hormonal status. Patients were followed up for 2 years. None of the single variables predicted the response to lithium therapy, but a combination of clinical and demographic variables, used in a discriminant function analysis, correctly identified 78.9% of responders. Multiple regression analysis predicted 46.2% of the outcome. The strongest univariate predictors were mood quality, illness duration, and substance abuse.