Background Data from the health care system has been recommended for research and surveillance of interpersonal violence (IPV). However, data from the health care system often lack information regarding the counterpart of IPV. Reliable information about the counterpart is important for distinguishing between different types of IPV such as family violence involving family members (partners, children, elderly) and community violence involving unrelated persons (strangers, acquaintances). Since 2014, Odense University Hospital in Denmark has routinely registered information about the counterpart for all victims of IPV admitted to the emergency department.

Objective To evaluate the completeness of routine registration of information about the counterpart of IPV revealed by victims admitted to an urban emergency department.

Methods We included 11,200 victims of IPV admitted to the emergency department at Odense University Hospital, Denmark 2014–2021. We extracted data from the routine patient registration system. We estimated the proportions of missing information regarding the counterpart stratified by age group and gender of the victims, type of incidents, weapon use, and severity of the lesions.

Results Information about the counterpart was registered in 91.5% of all cases. In 43.1% (CI: 42.2–44.0) of the cases, the counterpart was unknown to the victim, in 24.3% (CI: 23.5–25.1) the counterpart was an acquaintance, in 10.5% (CI: 10.0–11.1) the counterpart was a partner, and in 4.2% (CI: 3.8–4.5) the counterpart was another family member. The proportion of cases with no information about the counterpart varied slightly with gender, age group, time of violence, place of violence, and severity of injury. Only half of the victims injured with firearms (46.2%, CI: 30.1–62.8) and one-fourth of the victims injured with knives (25.9%, CI: 21.9–30.2) did not reveal information about the counterpart.

Conclusions The study showed that the vast majority of victims of IPV admitted to an urban emergency department reveal information about the counterpart. The proportions of victims revealing no information varied only slightly with age, gender, type and time of violence, and severity. Information about the counterpart of IPV make data from the health care system an important tool for research and surveillance of IPV.