Ambulatory Surgery - Appendix C: Data Notes

Who Submitted Data to the Council:

Ambulatory surgery data were submitted by 200 facilities. Inpatient data were submitted by 215 facilities.

The Identification and Classification of Cases for This Report:

Listed below, are the CPT-4 (Physician's Current Procedural Terminology, Fourth Edition) and ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) code ranges for collectable principal procedures by the Council. In summary, they include surgeries, endoscopies, chemotherapies and select cardiovascular procedures.

The method of identifying procedures in the inpatient setting was ICD-9-CM which is the standard coding method used to capture the medical diagnoses and procedures performed during the hospitalization for administrative data sets. The method(s) of identifying the principal procedure in the ambulatory surgery setting was mixed. Some facilities submitted cases to the Council using the ICD-9-CM coding method, others used the CPT-4 coding method.

For this analysis, CPT-4 codes were cases included in this report were those with a principal procedure within the range mandated by the Council for the ambulatory surgery setting. The ambulatory surgery setting includes both the freestanding ambulatory surgery centers and the short procedure units of hospitals. Not all outpatient procedures are required to be submitted to the Council. The mandate focuses primarily on treatment procedures and, to a lesser degree, select diagnostic procedures. For this report, the same procedures as those required in the ambulatory surgery setting were captured in the inpatient setting. It is important to understand that people often undergo multiple procedures during the same inpatient stay. This approach does not capture every occurrence of a given procedure, just when it is the principal. We have intentionally captured similar cases for comparative purposes.

The cases were then categorized according to the first two digits of the ICD-9-CM code in the principal procedure position of the patient discharge record. The first two digits identify the specific organ site or in some cases, specific class of procedures to an organ or anatomic site. Categorizing in this manner allows for a summary presentation of what would otherwise be an cumbersome presentation. A small portion (2%) of the records were excluded from analysis due to invalid codes or CPT-4 codes that do not have an equivalent ICD-9-CM code.