When looking for an effect, be it cancer drugs, cognitive therapy, etc, how much is enough? Cancer drugs usually enter the market on basis of incremental benefit - extending someone's life by a few months, for example. Is the extra two or three months' worth of life, when compared with extra hospital bills, potential additional side effects, and other burdens worth it?

These were some of the questions running through my mind after I read a study published in JAMA today on prevention of depression in at-risk adolescents. Studying prevention can be fraught with inherent difficulties, as in many cases you can't say for certain whether the prevented event would have happened. (Kind of like Cheney saying they "saved" hundreds of thousands of lives by torturing prisoners.) Yet I think that preventive measures could make a huge difference in certain conditions - if we all ate properly, exercised and didn't smoke, the skyrocketing rates of type 2 diabetes, obesity, CVD and associated co-morbidities would be drastically reduced.

The randomized controlled study was a step in the right direction, and especially important given the stressors in our lives today. The context for the research was that adolescent offspring of depressed parents are at "markedly increased risk of developing depressive disorders," and results from small studies suggesting depression risk can be reduced need to be replicated and extended to larger-scale, at-risk populations. "One of the most potent and clinically salient risk factors for the development of depression in youth is parental depression," the authors say. "Ofspring of depressed parents are at a 2- to 3-fold increased risk of developing depressive disorders. Additionally, youth history of a prior depressive episode or subsyndromal symptoms of depression also substantially increase risk of subsequent episodes."

The reseachers randomly assigned 316 adolescents (13-17 years old) of parents with current or prior depressive episodes to usual care or a group cognitive behavioral prevention program (consisting of 8 weekly, 90-minute group sessions followed by 6 monthly sessions), Adolescents had a past history of depression, current elevated but subdiagnostic depressive symptoms, or both. Assessments were conducted at baseline, after the 8-week intervention, and after the 6-month continuation phase.

How well did the CB group therapy work? Depressive episodes were lower for those in the CB prevention program than for those in usual care (21.4% versus 32.7%, HR 0.63). And among adolescents whose parents were not depressed at baseline, the CB prevention program was more effective in preventing onset of depression than usual care (11.7% vs 40.5%; HR, 0.24). But for adolescents with a currently depressed parent, there wasn't a significant difference between the two groups. Interestingly, adolescents' baseline self-reported depressive scores at baseline, or history of depressive episodes, did not have an impact on outcomes.

The authors do a nice job detailing the limitations of the study, including only a 25% minority population the disclosure by participants to evaluators of their assigned group (although the disclosure had no impact on outcomes). They also note that this study is more in line with the NIH's "translational progression" plan to move clinical trials toward more real-world settings, and offer advice for future design.

What caught my eye at the end was this paragraph:

In this study, [depressive] episodes were 11% lower in the CB prevention program condition. Borrowing a concept from the evidence-based medicine literature, this risk reduction could be translated into a number needed to prevent of 9; that is, for every 9 adolescents receiving the intervention, we would expect to prevent one from developing a depressive episode. For comparison purposes, the number needed to treat for antidepressants in adolescent depression is 10, suggesting that the preventive effect of the CB program was of a similar magnitude as treatment response to medication.
Really? Just one? Not to pan that one at all - one is better than none, especially if you are that one. But is that enough? And flipping the point on its head - if CB is of similar magnitude as treatment response to medication, doesn't that suggest there are a lot of kids out there on medication that would be served just as well with group therapy?