Suicide mortality in patients on lithium maintenance therapy

Mood disorders are frequently recurrent and it has been shown that maintenance treatment can reduce long-term morbidity in this condition. It has also been shown that mood disorders carry an increased risk of suicide and that a significant proportion of individuals who commit suicide suffer from a mood disorder. This paper reports the results of a long term follow-up of a cohort of patients attending a specialist mood disorder clinic over a period of 18 years. Sixty-seven suffered from unipolar depression and 36 had bipolar or schizo-affective disorders In order to qualify for entry to the cohort the unipolar patients had to have had at least three episodes of depression and those with bipolar disorders had to have had at least three episodes – with at least one manic episode and one depressive episode. All patients were treated with lithium. The initial treatment refusal rate and drop our rates were low. The mortality from suicide in this group was compared with that reported in five recent studies – all of which involved patients who had not been given maintenance therapy. The standardised mortality ratio (SMR) for all causes for the whole group was 0.93. There were two suicides. In one case the patient had continued treatment with lithium until death and in the other the patient had discontinued treatment 12 months before death. The overall suicide rate was 1.3 per 1000 patient years. Amongst similar groups of patients who had not been given maintenance therapy suicide rates of about 5.5 per 1000 patient years have been reported. It is concluded that maintenance treatment of mood disorders reduces the suicide rate in this vulnerable group of patients.