Guns, Suicide, and Homicide
Authors: Andrew Anglemyer
Journal: Annals of Internal Medicine (2014)

Letters17 June 2014Guns, Suicide, and HomicideAndrew Anglemyer, PhDAndrew Anglemyer, PhDFrom University of California, San Francisco, San Francisco, California.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L14-5012 SectionsAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:In Hemenway's editorial (1), he correctly suggests that our systematic review and meta-analysis (2) “provides too conservative an estimate of the relationship among guns and suicide and homicide at a societal level” (1). Although we agree that our methods have probably underestimated the true relationship between guns and suicide or homicide victimization, our inclusion of only studies that assessed the individual's personal firearm experience does provide an estimate of the minimum likely risk.The narrative around studies of firearm ownership and harms usually discredits causality assumptions, and causal inference is particularly problematic in ecologic studies. Critics are quick to point out conflicting “evidence” from various sources of rates and their interpretations. In fact, a commonly cited review of ecologic data by Kates and Mauser (3) only adds fodder to the ongoing debate. We purposefully excluded ecologic data, in part, to obviate this common critique regarding the interpretability of population-level data.Hemenway also correctly points out that most individuals commit suicide with a firearm from their own home, thus potentially justifying the use of aggregate population-level data to determine suicide outcomes. Unfortunately, this would probably not be enough to convince doubters that rate data can be used to assert correlations between firearm access and suicide. More important, we had 2 primary outcomes of interest in our review: suicide and homicide victimization. Although we can make a reasonable assumption that the firearms used in suicides were obtained from the home (albeit still an assumption that we wanted to avoid), we cannot reasonably make that same assumption about the firearms used in homicides. Hemenway even writes “most perpetrators [of homicides] do not use a gun from the victim's home” (1). We feel that using different inclusion criteria for different outcomes would not have been prudent (that is, including ecologic data for suicide outcomes and not for homicide outcomes) because the focus of our review was access to firearms among cases, not among perpetrators, and the result focuses on the home. Moreover, our results may help households understand the risks of keeping a firearm in the home, particularly if there is a household member who is depressed or a violent relationship; results from ecologic studies may be better for evaluating policies.Notwithstanding our review, ecologic studies are a good source of data for establishing trends and positing relationships. We agree that a potential future methodological review could compare the summary estimates we obtained from individual-level data with those that would have been obtained if ecologic data been included. Operationally, of course, a reviewer would need to consider many issues: the rates of ownership to use (such as regional rates, state rates, or city rates), the time frame (that is, the most recent or most reliable data), and the types of suicide (for example, should only firearm-related suicides be included?). For these reasons, among others, ecologic data are seldom seen in meta-analyses of individual-level data. Assuming that the reviewer was able to overcome the operational obstacles of disparate rates over disparate regions describing dissimilar outcomes, he or she would have to ensure that the interpretation of the results from such a review are truly reflective of aggregated population-level data and not of individual-level data. Of course, there are conceptual steps to calculate ecologic relative risk estimates so that conclusions about individual-level behavior can be inferred, although there are inherent assumptions (4). The reviewer could pool these new “individual-level” relative risk estimates to get a pooled rate from ecologic studies.To compare results from the meta-analysis of ecologic studies with those from the individual-level data we summarize, there are many approaches a reviewer could use. Namely, he or she could pool the results together to get a summary estimate from both ecologic and individual-level data, although combining estimates that were derived from different sources with different assumptions can be problematic. He or she could also perform a sensitivity analysis comparing the pooled estimates with and without ecologic data. Or he or she could perform a subgroup analysis comparing the pooled estimates from ecologic data with those from individual-level data separately. We feel that there are indeed benefits from reviewing ecologic data, and Hemenway's suggestion for future research will complement our current review nicely. The 2 reviews together could provide a more nuanced understanding of the true relationship between access to firearms and harms outcomes.Andrew Anglemyer, PhDUniversity of California, San FranciscoSan Francisco, CaliforniaReferences1. Hemenway D. Guns, suicide, and homicide: individual-level versus population-level studies [Editorial]. Ann Intern Med. 2014;160:134-5. [PMID: 24592499] LinkGoogle Scholar2. Anglemyer A, Horvath T, Rutherford G. The accessibility of firearms and risk for suicide and homicide victimization among household members: a systematic review and meta-analysis. Ann Intern Med. 2014;160:101-10. [PMID: 24592495] LinkGoogle Scholar3. Kates DB, Mauser G. Would banning firearms reduce murder and suicide? A review of international and some domestic evidence. Harv J Law Public Policy. 2007;30:649-94. Google Scholar4. Schuessler AA. Ecological inference. Proc Natl Acad Sci U S A. 1999;96:10578-81. [PMID: 10485866] CrossrefMedlineGoogle Scholar Comments0 CommentsSign In to Submit A Comment Author, Article, and Disclosure InformationAffiliations: From University of California, San Francisco, San Francisco, California.Disclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L14-0158. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoGuns, Suicide, and Homicide: Individual-Level Versus Population-Level Studies David Hemenway Guns, Suicide, and Homicide: Individual-Level Versus Population-Level Studies David Hemenway Guns, Suicide, and Homicide Robert B. Sklaroff Guns, Suicide, and Homicide David Hemenway Guns, Suicide, and Homicide Robert B. Sklaroff Guns, Suicide, and Homicide David Hemenway Metrics 17 June 2014Volume 160, Issue 12Page: 876KeywordsBehaviorConflicts of interestDisclosureFirearm injuriesForecastingHomicideInformation storage and retrievalSuicideSystematic reviews ePublished: 17 June 2014 Issue Published: 17 June 2014 CopyrightCopyright © 2014 by American College of Physicians. All Rights Reserved.PDF DownloadLoading ...