Background

The International Classification of Disease version 10 (ICD-10) is widely regarded as the international standard for reporting diseases and hospital presentations. Previous UK studies have shown that hospital level ICD-10 coding poorly reflects the true numbers of presentations related to acute recreational drug toxicity (ARDT) leading to an underestimation of their burden when these data are collated at a national level. This study aims to determine how well ICD-10 data coding identifies ARDT presentations using cases identified through the European Drug Emergencies Network (Euro-DEN).

Methods

The Euro-DEN Plus project collects data on all ARDT presentations to 31 sentinel hospital centres in 21 European and neighbouring countries; the Euro-DEN database was retrospectively interrogated to identify all ARDT presentations to three centres (London, Basel and Copenhagen) between July 1st-December 31st 2015. The hospital coding departments provided the diagnostic ICD-10 codes that were applied to these identified presentations. Analysis was then undertaken to determine the proportion of cases that included diagnostic codes related to ARDT and the proportion of cases with no diagnostic code recorded.

Results

Of the 619 ARDT Euro-DEN presentations, only 191 (30.9%) had an ARDT-related ICD-10 diagnostic code; of these only 150 (70.4% of coded, 24.2% of all presentations) were assigned a related primary ICD-10 diagnostic code, and 41 (19.2%, 6.6%) a related secondary or subsequent code. 22 (10%, 3.6%) presentations had no ARDT-related codes, and 406 (65.6%) presentations received no code (Figure 1). The most common reason for non-coding was being medically discharged from the Emergency Department, in 236 (58.1%) cases.

Conclusions

Less than a third of this European cohort presenting to hospital with ARDT were assigned ICD-10 codes that would enable identification of the case as drug-related. This represents a missed opportunity to monitor the prevalence of harms associated with recreational drug use. We propose that changes are made to future ICD versions to include current recreational drugs and new and emerging psychoactive substances, and that further consideration is given to the capture and coding of cases discharged directly from the Emergency Department.