Violence Prevention Research Program, Department of Emergency Medicine, University of California Davis School of Medicine, Sacramento, California, USA.
Center for Gun Policy and Research, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA.
Inj Prev. 2018 Dec;24(6):431-436. doi: 10.1136/injuryprev-2017-042475. Epub 2017 Oct 6.
Comprehensive background check (CBC) policies are hypothesised to reduce firearm-related violence because they extend background checks to private party firearm sales, but no study has determined whether these policies actually increase background checks, an expected intermediary outcome. We evaluate the association between CBC policies and the rates of firearm background checks in three states that recently implemented these policies: Delaware (July 2013), Colorado (July 2013) and Washington (December 2014).
We used the synthetic control group method to estimate the difference from estimated counterfactual postintervention trends in the monthly rate of background checks per 1 00 000 people for handguns, long guns and both types combined, using data for January 1999 through December 2016. Inference was based on results from permutation tests. We conducted multiple sensitivity analyses to assess the robustness of our results.
Background check rates increased in Delaware, by 22%-34% depending on the type of firearm, following enactment of its CBC law. No overall changes were observed in Washington and Colorado. Our results were robust to changes in the comparison group and statistical methods.
The enactment of CBC policies was associated with an overall increase in firearm background checks only in Delaware. Data external to the study suggest that Washington experienced a modest, but consistent, increase in background checks for private party sales, and Colorado experienced a similar increase in checks for sales not at gun shows. Non-compliance may explain the lack of an overall increase in background checks in Washington and Colorado.
综合背景调查（CBC）政策假设可以减少与枪支有关的暴力行为，因为它们将背景调查扩大到私人枪支销售，但没有研究确定这些政策是否实际上增加了背景调查，这是预期的中间结果。我们评估了最近实施这些政策的三个州（特拉华州（2013 年 7 月）、科罗拉多州（2013 年 7 月）和华盛顿州（2014 年 12 月））的 CBC 政策与枪支背景调查率之间的关联。
我们使用合成对照组方法，根据 1999 年 1 月至 2016 年 12 月的数据，估计了每月每 10 万人的手枪、长枪和两种枪支组合的背景检查率的实际干预后趋势的差异。推断基于随机排列测试的结果。我们进行了多次敏感性分析，以评估结果的稳健性。
在特拉华州，自其 CBC 法颁布以来，手枪的背景检查率增加了 22%-34%，取决于枪支的类型。华盛顿州和科罗拉多州没有观察到总体变化。我们的结果在比较组和统计方法发生变化时仍然稳健。
CBC 政策的颁布仅在特拉华州与枪支背景检查的总体增加有关。研究以外的数据表明，华盛顿州私人枪支销售的背景检查略有增加，但持续增加，科罗拉多州在枪支展览之外的枪支销售中也有类似的增加。不遵守规定可能解释了华盛顿州和科罗拉多州背景检查总体增加的缺乏。
