The effect of written informed consent on detection of violence in the home

Studies of programmatic interventions for victims of violence in the home may require the use of informed consent. The use of informed consent may result in ascertainment bias, with victims of violence being less likely to participate.

To investigate the effect of written informed consent on the detection of violence in the home during emergency department (ED) screening.

The authors performed a nonrandomized, controlled trial of 3,466 patients at an urban university ED. On odd days, patients (n = 1,857) were read a brief scripted statement and screened using standardized questions. On even days, patients (n = 1,609) received standard written informed consent prior to the same screening questions (writ-IC). The main outcome was the number of cases of violence in the home detected using each screening protocol.

Fewer writ-IC patients participated in screening (82% vs 92%; p < 0.001). Despite a higher refusal rate in the writ-IC group, there was no difference in the number of victims detected by each screening method: choked/kicked/bit/punched? (writ-IC, 7.3 vs routine screen, 6.5%; p = 0.3); slapped/grabbed/shoved? (7.3 vs 6.7%; p = 0.4); threatened/actually used knife/gun to scare/hurt you? (8.3 vs 9.4%; p = 0.3); thrown object to harm you? (5.2 vs 4.6%; p = 0.4); forced sex? (5.8 vs 4.7%; p = 0.15); or afraid current/former intimate partner would hurt you physically? (13.9 vs 11.9%; p = 0.9).

A written informed consent process in screening for violence in the home is associated with a higher refusal rate than routine screening, but use of written informed consent does not result in a lower rate of detection for multiple forms of violence. The authors did not find any support for the hypothesis that the use of written informed consent would decrease detection of violence in the home.