Major Diagnostic Category (MDC)
The Major Diagnostic Categories (MDC) are formed by dividing all possible principal diagnoses (from ICD-9) 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.
