The Fourth Edition, published in 1993, provided many refinements, including the Diagnosis-Related Estimates (DRE) or “injury” model for the evaluation of spinal injuries, alternative approaches to assessing lower-extremity impairment, and a pain chapter. The DRE model was unique in allowing for the assignment of an impairment rating based solely on the diagnosis, even if maximum medical improvement (MMI) had not been achieved.
The Fourth Edition is still used in Alabama, Arkansas, Maine, Maryland, Texas, and West Virginia.
