Effect of a ban on carrying firearms on homicide rates in 2 Colombian cities

Context Homicide is a leading cause of death in Colombia, with much of the fatal interpersonal violence concentrated in the country's largest cities. Firearms are involved in as much as 80% of homicides in Colombia. Objective To evaluate the effect of an intermittent police-enforced ban on carrying firearms on the incidence of homicide in urban Colombia. Design Interrupted time-series study with multiple replications. Setting Cali, Colombia, during 1993 and 1994 and Bogota, Colombia, from 199 5 through August 1997. Participants The populations of Cali and Bogota. Intervention Carrying of firearms was banned on weekends after paydays, on holidays, and on election days, Enforcement included establishment of polic e checkpoints and searching of individuals during traffic stops and other r outine law enforcement activity. Main Outcome Measure Homicide rates during intervention days were compared with rates during similar days without the intervention; estimates were bas ed on comparisons within the same month, day of week, and time of day. Results There were 4078 homicides in Cali during 1993 and 1994 (114.6 per 1 00 000 person-years). In Bogota, 9106 homicides occurred from 1995 through August 1997 (61 per 100 000 person-years). The incidence of homicide was lo wer during periods when the firearm-carrying ban was in effect compared wit h other periods (multivariate-adjusted rate ratio, 0.86 [95% confidence int erval {CI}, 0.76-0.97] for Cali, and 0.87 [95% CI, 0.77-0.98] for Bogota). Conclusion An intermittent citywide ban on the carrying of firearms in 2 Co lombian cities was associated with a reduction in homicide rates for both c ities.