[Use of lithium in the Norwegian counties Oslo and Sogn og Fjordane].

The Norwegian prescription database (NorPD) provides an opportunity to examine lithium consumption at an individual level. This article presents an assessment of lithium use (based on data from NorPD) in light of two population-based studies on prevalence of psychiatric illness in the counties Oslo and Sogn og Fjordane. All persons between 18 and 65 years who received at least one prescription for lithium between July 2005 and June 2006 were identified in NorPD. County and gender specific prevalence rates, incidence rates, and average dose were calculated. Some pharmacoepidemiological parameters were derived. The incidence of lithium users was 1.5 per 1000 inhabitants in Oslo and 5.5 in Sogn og Fjordane in the period assessed. The incidence was highest for men in Sogn og Fjordane. More lithium was prescribed to each patient in Oslo than in Sogn og Fjordane, and more was prescribed for men than women. Patients with bipolar disease are apparently much more likely to be treated with lithium in Sogn og Fjordane than in Oslo. Previous estimates of the prevalence of bipolar disorder in Sogn og Fjordane are probably too low. In addition, there might be a broader indication for the use of lithium in this county.