Self-harm is a major cause of illness and injury in patients with bipolar disorder. Randomized clinical trials show maintenance medications such as lithium, valproate sodium, olanzapine, and quetiapine fumarate can stabilize mood, but there has been little research on the link between these medications and self-harm.
Joseph F. Hayes, M.Sc., M.B.Ch.B., of the University College London and coauthors compared rates of self-harm, unintentional injury (for example, falls or car accidents), and suicide deaths in patients diagnosed with bipolar disorder who were prescribed lithium, valproate, olanzapine, or quetiapine as a maintenance mood stabilizer using a large database of primary care electronic health records (EHRs) in the United Kingdom.
The team of researchers analyzed EHR data from 6,671 patients with bipolar disorder (2,148 prescribed lithium, 1,670 prescribed valproate, 1,477 prescribed olanzapine, and 1,376 prescribed quetiapine), collected between 1995 and 2013. They found that self-harm rates were lower in patients prescribed lithium (175-241 per 10,000 person-years at risk [PYAR]) compared with those prescribed valproate (334-460 per 10,000 PYAR), olanzapine (345-483 per 10,000 PYAR), or quetiapine (489-692 per 10,000 PYAR). Rates of unintentional injury were also lower in people taking lithium compared with those taking valproate or quetiapine but not olanzapine. The number of suicides was too low to show differences by the individual medications, the report noted.
“The lower rates of self-harm in those prescribed lithium may be due either to improved mood stabilization compared with other treatments or specific effects on impulsive aggression and risk taking,” the authors wrote. “The similarity of the negative association between lithium use and unintentional injury and that between lithium use and self-harm supports the latter hypothesis because there is little reason to expect that lower rates of depressive symptoms would reduce unintentional injury.”
They concluded, “Self-harm, unintentional injury, and suicide are important morbidity and mortality outcomes in BPD [bipolar disorder] that appear to be amenable to modification through appropriate drug treatment.”
For related information, see the Psychiatric News article “Treating Bipolar Disorder in Primary Care” by Joseph Cerimele, M.D., M.P.H., of the University of Washington.