Spending on social and public health services and its association with homicide in the USA: an ecological study.

Objective: To examine whether state-level spending on social and public health services is associated with lower rates of homicide in the USA.

Design: Ecological study.

Setting: USA.

Participants: All states in the USA and the District of Columbia for which data were available (n=42).

Primary Outcome Measure: Homicide rates for each state were abstracted from the US Department of Justice Federal Bureau of Investigation's Uniform Crime Reporting.

Results: After adjusting for potential confounding variables, we found that every $10 000 increase in spending per person living in poverty was associated with 0.87 fewer homicides per 100 000 population or approximately a 16% decrease in the average homicide rate (estimate=-0.87, SE=0.15, p<0.001). Furthermore, there was no significant effect in the quartile of states with the highest percentages of individuals living in poverty but significant effects in the quartiles of states with lower percentages of individuals living in poverty.

Conclusions: Based on our findings, spending on social and public health services is associated with significantly lower homicide rates at the state level. Although we cannot infer causality from this research, such spending may provide promising avenues for homicide reduction in the USA, particularly among states with lower levels of poverty.