Which organization maintains the diagnosis classifications in volumes 1 and 2 of ICD-9?

The organization that maintains the diagnosis classifications in volumes 1 and 2 of ICD-9 is the National Center for Health Statistics (NCHS). NCHS is responsible for the development and maintenance of the International Classification of Diseases (ICD) codes, which include the classifications for various diseases and health-related conditions. Volumes 1 and 2 of ICD-9 specifically address diagnosis codes and provide a comprehensive framework for coding the diagnoses and reasons for healthcare encounters.

This organization's role is essential for ensuring that the coding system remains relevant and up-to-date with the evolving medical landscape, providing standardized terminology that can be used by health professionals globally. By overseeing these classifications, NCHS helps facilitate the collection, analysis, and interpretation of health data, ultimately contributing to advancements in public health and healthcare delivery.

While other organizations like CMS (Centers for Medicare & Medicaid Services), AHIMA (American Health Information Management Association), and AHA (American Hospital Association) play significant roles in healthcare coding, policy-making, and education, it is NCHS that directly maintains the specific classification system in volumes 1 and 2 of ICD-9.