LAUSR

Importance Structural racism has resulted in long-standing disinvestment and dilapidated environmental conditions in Black neighborhoods. Abandoned houses signal neglect and foster stress and fear for residents, weakening social ties and potentially contributing to poor health and safety. Objective To determine whether abandoned house remediation reduces gun violence and substance-related outcomes and increases perceptions of safety and use of outdoor space. Design, Setting, and Participants This cluster randomized trial was conducted from January 2017 to August 2020, with interventions occurring between August 2018 and March 2019. The study included abandoned houses across Philadelphia, Pennsylvania, and surveys completed by participants living nearby preintervention and postintervention. Data analysis was performed from March 2021 to September 2022. Interventions The study consisted of 3 arms: (1) full remediation (installing working windows and doors, cleaning trash, weeding); (2) trash cleanup and weeding only; and (3) a no-intervention control. Main Outcomes and Measures Difference-in-differences mixed-effects regression models were used to estimate the effect of the interventions on multiple primary outcomes: gun violence (weapons violations, gun assaults, and shootings), illegal substance trafficking and use, public drunkenness, and perceptions of safety and time outside for nearby residents. Results A master list of 3265 abandoned houses was randomly sorted. From the top of this randomly sorted list, a total of 63 clusters containing 258 abandoned houses were formed and then randomly allocated to 3 study arms. Of the 301 participants interviewed during the preintervention period, 172 (57.1%) were interviewed during the postintervention period and were included in this analysis; participants were predominantly Black, and most were employed. Study neighborhoods were predominantly Black with high percentages of low-income households. Gun violence outcomes increased in all study arms, but increased the least in the full remediation arm. The full housing remediation arm, compared with the control condition, showed reduced weapons violations by -8.43% (95% CI, -14.68% to -1.19%), reduced gun assaults by -13.12% (95% CI, -21.32% to -3.01%), and reduced shootings by a nonsignificant -6.96% (95% CI, -15.32% to 3.03%). The trash cleanup arm was not associated with a significant differential change in any gun violence outcome. Instances of illegal substance trafficking and use and public drunkenness outcomes were not significantly affected by the housing remediation or trash cleanup treatment. Perceptions of neighborhood safety and time spent outside were unaffected by the intervention. The study arms did differ in a baseline characteristic and some preintervention trends, which raises questions regarding other potential nonmeasured differences between study arms that could have influenced estimates. No evidence of displacement of gun violence outcomes was found. Conclusions and Relevance In this cluster randomized controlled trial among low-income, predominantly Black neighborhoods, inexpensive, straightforward abandoned housing remediation was directly linked to significant relative reductions in weapons violations and gun assaults, and suggestive reductions in shootings. Trial Registration isrctn.org Identifier: ISRCTN14973997.