Higher Doses of Antidepressants & Suicidal Behavior
They were twice as likely to try to hurt themselves if they were prescribed more than recommended dose
Nearly 18 percent of patients in the study were started on doses that were higher than those, in conflict with current medical guidelines.
Then researchers checked patients' medical records to see how many had committed acts of deliberate self-harm within a year of starting their medications.
Among those younger than 24, patients on higher doses harmed themselves at roughly twice the rate of those on lower doses. During the study period, there were 32 incidents of self-harm for every 1,000 young patients taking high doses while there were only 15 such incidents per 1,000 patients taking recommended doses.
The researchers further estimated that doctors would see one additional case of self-injury for every 136 younger patients treated with higher-than-recommended doses of antidepressants. And the risk of suicide attempts seemed to be highest in the first 90 days on the medications.
The investigators found no significant increase in the risk of self-harm by drug dosage for people over the age of 25, however, suggesting the effect was age-dependent.
And there was no increase in suicide risk in kids and teens treated with recommended drug dosages.
The study was observational, which means that researchers can't say for sure that drug dosage was the only thing that made young patients more likely to hurt themselves.
Dr. David Brent, who holds an endowed chair in suicide studies at the University of Pittsburgh, said he thinks there might also be something about the patients themselves that prompted doctors to start them on a higher dose in the first place.
"I am guessing that, assuming it was not just medical error, that there was something that the physicians were responding to -- either greater severity or that the patient had had a history of needing higher doses to respond in the past," said Brent, who wrote a commentary on the study, but was not involved in the research.
But the Harvard researchers don't think that's the case.
Miller said the team looked closely at the data to try to find differences that might explain why some patients were prescribed higher doses of the drugs.
Among the factors they considered were how recently patients were diagnosed with depression, where they were diagnosed as inpatients or outpatients, and whether they also had anxiety or a history of suicide attempts.
There were almost no differences between the patient groups, other than the dose of antidepressants they were initially prescribed, the study authors indicated.
The researchers even performed a statistical test to calculate the likelihood that there was some ghost factor they missed that might account for the differences. The test showed that was unlikely.
Brent agreed, adding that the research should encourage doctors to go low and slow with antidepressants in young patients, as clinical guidelines recommend, increasing the dose only as needed.