An ambulatory care classification system: design, development and evaluation.

A medical classification system for coding a patient's reason for visit has been developed for use in the National Ambulatory Medical Care Survey and for ambulatory care settings. The code is developed in a modular structure and includes modules for Symptoms; Diseases; Diagnostic, Screening and Preventive Procedures; Therapeutic Procedures, Process Problems and Counseling; Injuries and Adverse Effects; Follow-ups for Test Results; and Administrative Reasons for Visits. The system was evaluated in coding tests, through review by medical societies representing the major specialties, and by other health care providers. An extensive coding index is available.