Coding multiple drug use in ICD-10 and ICD-11

Background:

Polydrug use is common, it’s the main reason for deadly drug overdose in Norway, but the ICD-10 code for multiple drug use (F19) seems to be under-reported. Correct and consistent recording of multiple drug use is important to improve estimations of risk, prognosis and treatment needs.

Methods:

We reviewed the hospital journal for N=147 residential substance use disorder patients at Oslo University Hospital, and registered the ICD-10 codes for mental and behavioural disorders due to psychoactive substance use (F10 – F19).

Results:

All the patients (100%) had one or more F10 – F19 code, 79% had two or more, and 61% had three or more codes for substance use. The F19 code for multiple drug use was recorded for 15% of the patients, but it applied to 35% when manually revised.

Conclusions:

The ICD-10 code for multiple drug use (F19) is under-reported in our treatment site. The clinicians seem to prefer separate diagnosis for each drug, because this gives information regarding what substances the patient is addicted to. Using the future ICD-11 definition for “disorders due to use of multiple specified psychoactive substances” (6C4F), 79% of the subjects fit the 6C4F-code. We urge the developers of ICD-11 to make it possible to “post-code” the specific drugs the patient use, enabling clinicians to communicate dual drug use in the main code and specify substance in the post-code.