Thursday, February 22, 2007

Working Paper of the Day

Mankiw alerts us to this important study; Anti-depressants and Suicide- some excerpts from the conclusion below.

“Our results are consistent with the hypothesis that the net effect of the introduction and subsequent sales of SSRIs is to reduce death by suicide. We find that increase in SSRI sales of 1 pill per capita per year (about a 12% increase over 2000 sales levels) is associated with a decline in suicide mortality of around 5%. This IV estimate is about twice as large in absolute value as OLS estimates, consistent with our general concern that both the timing of SSRI approval and the rate at which SSRI sales increase over time may be endogenous to what is happening with mental health and suicide within countries. We also demonstrate that that we estimate no relationship between SSRI sales and accident deaths, which should not be affected by SSRI use, and that there is little relationship between trends across countries in log suicide rates over the course of the 1980s and predicted SSRI sales growth in the 1990s….

Our estimates suggest that on balance SSRIs may be a very cost-effective means for saving lives, which is important in part because data from the National Comorbidity Survey from 2001-3 suggest that only around 40 percent of people with severe mental health disorders were receiving any treatment [Kessler, Demler et al., 2005]. Commonly used SSRIs can currently be obtained in the United States for around $0.10 per pill. Our estimates thus imply that each additional $20,000 spent on SSRIs will avert one suicide completion, far below the cost per life saved from most other public health, regulatory, or other forms of government intervention. But using this estimate in a more formal benefit-cost analysis raises difficult conceptual and normative questions about the appropriate way to value the life of someone who subjectively prefers death (at least at the time of the intervention). If SSRIs reduce the risk of suicide by reducing access to a method of self harm, then the suicidal person may or may not experience a switch to SSRIs as a net benefit, depending on the transience or permanence of their state of pain. On the other hand if SSRIs reduce the risk of suicide by improving the subjective utility of life, then persons at risk for suicide and their loved ones may have a considerable willingness to pay for such an intervention.29 Of course SSRIs also generate other benefits beyond their net effects on mortality that should be counted in this calculus, including improvements in mood, health status, functioning, and productivity.

One important limitation of our study is that we are estimating the average effect of expansions in SSRI use on overall suicide mortality rates. Previous medical studies have raised special concerns about drug impacts on certain patient sub-groups. We provide suggestive evidence that the effects of SSRI use on suicide mortality might have, if anything, even more beneficial impacts for younger people (15-24), the age group that has been a particular focus of recent government warnings in the U.S. and U.K. However this finding should be qualified by the observation that we can measure suicide mortality separately for specific age groups but we cannot disaggregate by age country-level sales of SSRIs. Moreover our data are not at all informative about sub-group effects on patients by pre-existing mental health status, which is important in light of the view by some researchers that any effect of SSRIs to worsen mood might be particularly pronounced among some patients – for example, those with undiagnosed bipolar disorder. Understanding more about heterogeneity in SSRI effects on different types of patients remains arguably the top priority for future research in this area."

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