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Lithium may have lower risk for self-harm than other bipolar disorder treatments

Individuals with bipolar disorder prescribed lithium had lower rates of self-harm and unintentional injury, compared with their peers prescribed valproate, olanzapine and quetiapine.

“Bipolar disorder is associated with an annual risk of suicidal acts that is 10 times that of the general population and a lifetime risk of suicide that is almost 15 times greater. Randomized clinical trials of maintenance medication show that drugs like lithium, valproate sodium, olanzapine and quetiapine fumarate can stabilize mood,” Joseph F. Hayes, MSc, MBChB, of University College London, and colleagues wrote. “However, balancing the relative benefits and potential risks of these medications is not straightforward, and potential drug effects on self-harm have been underexamined in this regard.”

To assess rates of self-harm, unintentional injury and suicide in individuals with bipolar disorder prescribed different medications, researchers analyzed electronic health records data from January 1995 through December 2013. The cohort included 6,671 individuals with bipolar disorder, of which 2,148 were prescribed lithium; 1,670 prescribed valproate; 1,477 prescribed olanzapine and 1,376 prescribed quetiapine as maintenance mood stabilizer treatment.

Individuals prescribed lithium had lower self-harm rates (205 per 10,000 person-years at risk; 95% CI, 175-241) compared with those prescribed valproate (392 per 10,000 person-years at risk; 95% CI, 334-460), olanzapine (409 per 10,000 person-years at risk; 95% CI, 345-483), or quetiapine (582 per 10,000 person-years at risk, 95% CI, 489-692).

This association remained after adjusting for propensity scores, with a hazard ratio of 1.4 (95% CI, 1.12-1.74) for individuals prescribed valproate, olanzapine and quetiapine, compared with those prescribed lithium.

After adjusting for propensity scores, unintentional injury rates were lower among individuals prescribed lithium, compared with those prescribed valproate (HR = 1.32; 95% CI, 1.1-1.58) and quetiapine (HR = 1.34; 95% CI, 1.07-1.69) but not olanzapine.

Overall, the suicide rate was 14 per 10,000 person-years at risk (95% CI, 9-21).

“In this representative [United Kingdom] study, individuals with [bipolar disorder] who were prescribed lithium had lower rates of self-harm and unintentional injury than those with [bipolar disorder] receiving other commonly prescribed maintenance treatments,” Hayes and colleagues wrote. “Contrary to the warning from the FDA, we did not find higher self-harm rates in those prescribed valproate than those receiving other (nonlithium) maintenance drug treatments. These findings are important because they support and augment the existing evidence from randomized clinical trials and smaller cohort studies. Self-harm, unintentional injury, and suicide are important morbidity and mortality outcomes in [bipolar disorder] that appear to be amenable to modification through appropriate drug treatment.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.