Major Diagnostic Categories
The Major Diagnostic Categories (MDC) are formed by dividing all possible principal diagnoses from ICD-9-CM into 25 mutually exclusive diagnosis areas. The diagnoses in each MDC correspond to a single organ system or etiology and in general are associated with a particular medical specialty.
- MDC 1 to MDC 23 are grouped according to principal diagnoses.
- Patients are assigned to MDC 24 (Multiple Significant Trauma) with at least two significant trauma diagnosis codes (either as principal or secondaries) from different body site categories.
- Patients assigned to MDC 25 (HIV Infections) must have a principal diagnosis of an HIV Infection or a principal diagnosis of a significant HIV related condition and a secondary diagnosis of an HIV Infection.
Detailed information about MDCs is available from the National Bureau of Economic Research and the Agency for Healthcare Research and Quality.
|Ear, Nose, Mouth, And Throat|
|Hepatobiliary System and Pancreas|
|Musculoskeletal System and Connective Tissue|
|Skin, Subcutaneous Tissue, and Breast|
|Endocrine, Nutritional, and Metabolic System|
|Kidney and Urinary Tract|
|Male Reproductive System|
|Female Reproductive System|
|Pregnancy, Childbirth, and Puerperium|
|Newborn and Other Neonates (Perinatal Period)|
|Blood and Blood Forming Organs and Immunological Disorders|
|Myeloproliferative Diseases and Disorders (Poorly Differentiated Neoplasms)|
|Infectious and Parasitic Diseases and Disorders|
|Mental Diseases and Disorders|
|Alcohol/Drug Use or Induced Mental Disorders|
|Injuries, Poison, and Toxic Effect of Drugs|
|Factors Influencing Health Status|
|Multiple Significant Trauma|
|Human Immunodeficiency Virus (HIV) Infection|