Trends in documenting and coding of child physical abuse in hospitalised children and adolescents in Germany: a nationwide administrative data analysis

Hospital administrative data are widely used to monitor child physical abuse (CPA), but coding is often inconsistent. We described the national frequency and distribution of CPA-related coding in German administrative data and assessed how ICD-10-GM indicators and procedural coding influence ascertainment and temporal trends. We analysed aggregated German hospital data from the InEK data browser (2019-2024, ages 0-17 years), comparing T74.1 with broader indicator sets (a validated algorithm adapted to ICD-10-GM and an extended German set) and capturing procedural safeguarding documentation (OPS 1-945.x). We summarised principal diagnoses among hospitalisations with CPA-related coding and quantified CPA-related coding among admissions with predefined abuse-relevant injuries (fractures, haematomas) in children aged 0-2 years, a group at increased risk of physical abuse. CPA-related diagnostic coding remained rare (< 0.5% of annual admissions excluding procedural codes) but increased from 2019 to 2024, driven mainly by assessment- and psychosocial-context indicators (particularly Z04.5 and Z65), whereas T74.1 was stable or declining. Several low-frequency codes showed pronounced year-to-year variability. OPS 1-945.x-a child-protection assessment of suspected endangerment rather than confirmed abuse-had the highest counts and increased, with a decline in 2022. CPA-related indicators were mainly associated with head injuries, most often traumatic subdural haemorrhage and concussion. Among children with abuse-relevant fractures and haematomas, explicit T74.1 coding occurred in only a small minority, whereas OPS 1-945.x was more frequent. CONCLUSION: These findings highlight the need for standardised coding guidance, validation of broader code sets, and training on administrative documentation to improve the surveillance value of hospital data. WHAT IS KNOWN: • CPA is under-coded in hospital administrative data; T74.1 is rarely used. • Broader ICD/procedure-based definitions can increase case capture. WHAT IS NEW: • German national discharge data (2019-2024) show stable/declining T74.1 with rising Z04.5/Z65 and increasing procedural codes OPS 1-945.x. • Including the broader indicator and procedural codes (e.g., Z04.5, Z65, OPS 1-945.x) reveals a marked shift in how concerns about CPA are documented, with these codes increasingly used alongside or instead of T74.1, particularly among children admitted with abuse-relevant injuries.