Reliability and clinical utility of the chronic pain classification in the 11th Revision of the International Classification of Diseases from a global perspective: results from India, Cuba, and New Zealand.

Chronic pain affects 1 in 5 persons and contributes substantially to the global burden of disease. The 11th Revision of the International Classification of Diseases (ICD-11) includes a comprehensive classification of chronic pain. The aim of this ecological implementation field study was to evaluate the classification's interrater reliability and clinical utility in countries with different income levels.