State anger and the risk of injury: a case-control and case-crossover study

Previous studies have examined anger at a given moment (state anger) and proxies for injury, or anger as a trait and injuries per se. Findings have been inconsistent. We sought to define further the relationship between state anger and risk of injury.

We conducted a case-control and case-crossover study in all 3 emergency departments in 1 county in Missouri. Cases were patients seeking care for an acute injury. They were compared with 2 controls: the patient himself or herself 24 hours before, and an individual recruited by telephone from the community and matched for age-group, sex, and time. Self-reported anger was assessed with 3 Likert scale items. Anger just before the injury was compared in case-crossover analyses with the respondent's own level of anger 24 hours before, and in standard case-control analyses with community participants' level of anger at the same hour the same day of the week in a subsequent week.

Of 2,517 patients, 2,446 provided data on anger just before the injury, and 2,117 reported data for 24 hours before injury. Of 1,856 community individuals, 1,533 provided complete data. Anger was prevalent. Of injured patients, 9%, 7%, and 4% reported feeling "quite a bit" or "extremely" "irritable," "angry," and "hostile," respectively, just before injury. Odds ratios for risk of injury were notably higher for greater degrees of anger; for example, for "angry," they were 1.8 (95% confidence interval, 1.1-2.7) for "quite a bit" and 7.2 (3.9-13) for "extremely." Odds ratios in women were substantially lower than those in men. Anger was not associated with fall and traffic injuries, but anger was strongly associated with intentional injuries inflicted by another person in both men and women.

High levels of self-reported state anger increase the risk of injury, especially among men, and specifically the risk of intentional injury in both sexes.