Starting lithium prophylaxis early v. late in bipolar disorder

Background No study has investigated when preventive treatment with lithium should be initiated in bipolar disorder. Aims To compare response rates among patients with bipolar disorder starting treatment with lithium early v. late. Method Nationwide registers were used to identify all patients with a diagnosis of bipolar disorder in psychiatric hospital settings who were prescribed lithium during the period 1995-2012 in Denmark (n=4714). Lithium responders were defined as patients who, following a stabilisation lithium start-up period of 6 months, continued lithium monotherapy without being admitted to hospital. Early v. late intervention was defined in two ways: (a) start of lithium following first contact; and (b) start of lithium following a diagnosis of a single manic/mixed episode. Results Regardless of the definition used, patients who started lithium early had significantly decreased rates of non-response to lithium compared with the rate for patients starting lithium later (adjusted analyses: first v. later contact: P < 0.0001; hazard ratio (HR) = 0.87, 95% CI 0.76-0.91; single manic/mixed episode v. bipolar disorder: P < 0.0001; HR = 0.75, 95% CI 0.67-0.84). Conclusions Starting lithium treatment early following first psychiatric contact or a single manic/mixed episode is associated with increased probability of lithium response.