The quest for a faster-acting and more effective treatment for depression has lead to a variety of medications. Some of the new medications are a different type or class of drug addressing distinct neurochemical mechanisms.
A new study compared the newer serotonin and norepinephrine reuptake inhibitors (SNRIs) to established medications called selective serotonin reuptake inhibitors (SSRIs).
Researchers wanted to know if SNRIs like venlafaxine (Effexor) provide a greater overall benefit than the older selective serotonin reuptake inhibitors (SSRIs), like fluoxetine (Prozac) and citalopram (Celexa).
To perform the study, researchers used a technique know as meta-analysis that involves combining the results of similar studies to enhance interpretation of true effects. In this review, scientists pooled the results of 34 double-blind randomized controlled trials that compared a single SNRI, venlafaxine, to other SSRIs.
The study is published in the journal Biological Psychiatry.
Dr. Charles Nemeroff, senior author on the paper, reports their findings: “Venlafaxine was superior to SSRIs in efficacy overall, and moreover, statistically superior to fluoxetine but not to paroxetine (Paxil), sertraline (Zoloft) or citalopram. Venlafaxine had a higher dropout rate due to adverse events.”
These findings indicated a 5.9 percent advantage in remission rates for venlafaxine. The authors also report that the typical doctor would need to treat 17 patients to have a single patient benefit from being treated with venlafaxine rather than an SSRI.
Acknowledging the seemingly small advantage, John H. Krystal, M.D., Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, comments that this article “highlights an advance that may have more importance for public health than for individual doctors and patients.”
He explains this reasoning:
If the average doctor was actively treating 200 symptomatic depressed patients and switched all of them to venlafaxine from SSRI, only 12 patients would be predicted to benefit from the switch. This signal of benefit might be very hard for that doctor to detect.
But imagine that the entire population of depressed patients in the United States, estimated to be 7.1 percent of the population or over 21 million people, received a treatment that was 5.9 percent more effective, then it is conceivable that more than 1 million people would respond to venlafaxine who would not have responded to an SSRI.
This may be an example of where optimal use of existing medications may improve public health even when it might not make much difference for individual doctors and patients.
Thus, in the typical clinical practice this difference constitutes a barely detectable benefit, but this difference could be meaningful across the large population of depressed patients in the United States.