In the January edition of the AJGP, Erlangsen and Conwell look at the relationship of completed suicide and antidepressant redemption in a nationwide cohort in Denmark. The methodology of this study is not available in the United States. Denmark has several registers based on a unique personal identifier for all of its citizens. The authors looked at the Register of Medicinal Product Statistics and suicide as a cause of death in the Registry of Causes of Death for a cohort of people who were 50 years of age or older on January 1, 1996 through December 31, 2006. Data on antidepressant use was identified and classified into tricyclic antidepressants, selective serotonin reuptake inhibitors and other types of antidepressants. A treatment episode was considered to have occurred if a second prescription of antidepressants was filled and the patient appeared to be taking 0.75 tablets per day.
In terms of sheer number the study included 1,22,941 men and 1,346,973 women. In the follow up period deaths by suicide numbered 3,061 men and 1,456 women. As illustrated by Figure 1. below there is a decreasing number of those dying by suicide who redeemed antidepressant prescriptions. In the 80+ year olds it was less than one in four women and less than one in eight men. Trends were noted that percentage of men and women dying of suicide who took antidepressants decreased with increasing age. This data is consistent with previous data that show that most elderly patient die by suicide are not in treatment at the time and they have clinically significant symptoms of depression.
(graphic removed by copyright manager - please see the original article)
This study is a good example of what kind of data is available with large databases across entire populations. The limitations of the data are discussed by the authors including the fact that the pharmaceutical registry does not have any diagnoses and antidepressants have numerous indications. They discuss why antidepressant redemption may not be the optimal proxy for antidepressant use. In this case their study design considering only people who have redeemed the second antidepressant prescription to be in treatment. That contrasts with some data suggesting the highest risk for suicide may occur in the initial days or weeks of antidepressant treatment. They point out the usual qualification about association versus causality, but also conclude that "it is possible that antidepressants protect the oldest old from death by suicide" and point out the important public policy question of how to identify these patents.
There is a similar interesting study available that looks at a database that includes 3/4 of the population of the Netherlands (see reference 2). It looks at the correlation between antidepressant use and both suicide and violence and concludes that there are significant negative correlations with both. In other words increased antidepressant use led to decreased rates of suicide and violent behavior over the years 1994-2008.
When I read this study, I was also interested in what medical specialty is prescribing the bulk of the antidepressants. I e-mailed one of the authors and asked that question. The response was that the specific specialty of the prescriber was unknown but that bulk of antidepressants in Denmark were prescribed by primary care physicians and the likelihood of antidepressant prescription by primary care increases with patient age. Psychiatric consultation was more likely to occur at a younger patient age.
In the United States we need pharmaceutical registries similar to the Danish registry. We need a more factual basis to evaluate issues of pharmaceutical use over time, complications of prescription drugs, over prescription of drugs, and adequate drug utilization. For example, with the recent concerns about stroke risk factor reduction in the elderly and stroke risk reduction from atrial fibrillation graphs similar to Figure 1. looking at all of the relevant medications may prove very useful. Practically all pharmacy data in this country is proprietary and the largest database was developed to see if pharmaceutical representatives were having an impact on prescriptions written by individual physicians. The current development by individual states focused on the prescription of controlled substances is an opportunity to expand that data to identify important public health trends and reduce speculation.
George Dawson, MD, DFAPA
Figure 1. is reprinted from Am J Geriatr Psychiatry 2014 Jan; 22(1) Erlangsen A, Conwell Y. Age-related response to redeemed antidepressants measured by completed suicide in older adults: a nationwide cohort study, with permission from Elsevier.
1: Erlangsen A, Conwell Y. Age-related response to redeemed antidepressants measured by completed suicide in older adults: a nationwide cohort study. Am J Geriatr Psychiatry. 2014 Jan;22(1):25-33. doi: 10.1016/j.jagp.2012.08.008. PubMed Central PMCID: PMC3844115
2: Bouvy PF, Liem M. Antidepressants and lethal violence in the Netherlands 1994-2008. Psychopharmacology (Berl). 2012 Aug;222(3):499-506. doi: 10.1007/s00213-012-2668-2. Epub 2012 Mar 7. PubMed PMID: 22395429; PubMed Central PMCID: PMC3395354