Background and aims: Because of the unsatisfactory representation of chronic pain in the International Classification of Diseases (ICD-10), an IASP Task Force developed a new classification of chronic pain for ICD-11. The aim of the present study was to test – prior to the classification’s implementation – the coding process and whether the diagnoses are regarded clinically useful.

Method: Participants were 177 professionals (57.6% men; 43.8±11.1 years) who work with patients affected by chronic pain. The participants had to provide the correct diagnostic codes for particular diagnoses (line coding) or brief vignettes (case coding), reported whether they had encountered any problems and rated the clinical utility. The ICD-11 codes were measured against a gold standard and coding problems compared between ICD-10 and ICD-11. 

Results: In the line coding, ICD-11 diagnoses were more often assigned correctly than ICD-10 codes and fewer difficulties and ambiguities were encountered in the coding process. The specificity of the new diagnoses and their utility was judged to be very high: 4.3±0.90 on a scale from 0 (not at all) to 5 (very useful).
Conclusion: The new ICD-11 diagnoses outperformed the old ICD-10 codes in 
all respects and were uniformly judged to have a very high utility for communication, treatment management and documentation. Thus, the new diagnoses have shown themselves to be integrated easily in the coding process, possess satisfactory characteristics and were regarded as clinically useful by the relevant professionals. Further studies investigating their validity in clinical settings will be the next step.

RESULTS OF THE WHO FIELD TESTING FOR THE CLASSIFICATION OF CHRONIC PAIN FOR THE ICD-11