Can lithium salts prevent depressive episodes in the real world?
To critically examine the effectiveness of lithium in preventing depressive symptoms (mixed and depressive episodes) in real life settings, taking into account adherence to drug treatment and its implications for the clinical costs of the disease. Overall, 72 patients with bipolar disorder initially treated with lithium carbonate were included and followed-up for 10 years. Patients were assessed every 8 weeks for morbidity and alcohol/drug consumption. Patients with good adherence to lithium had fewer episodes with depressive features than poor adherers (B = 2.405, p = 0.046) and also fewer manic and hypomanic episodes (B = 2.572; p < 0.001), after controlling for confounders. Time to relapse into a depressive or mixed episode and into a manic or hypomanic episode was shorter in patients with poor adherence. The costs of the 1.95 ± 2.38 (mean ± standard deviation) admissions of adherent patients through the 10 years of follow-up were €10,349, while the costs of the 6.25 ± 4.92 admissions of non-adherent patients were €44,547. In clinical practice settings, long-term lithium salts seem to have a preventive effect on depressive symptoms.