An Ambulatory Service Weighting System: making sense out of millions of ambulatory claims

This paper describes a cost-based relative value scale to use in measuring the intensity and costs of hospital services, regardless of the place of service--inpatient or outpatient. The Pittsburgh Research Institute's AMBULATORY SERVICE WEIGHTING SYSTEM (ASWS) is a service-driven relative value scale. The major components of the system are: 1) a classification of services and procedures provided in ambulatory settings; 2) a cost-based relative intensity weight for each service; and 3) a computerized system that assigns a relative weight to each ambulatory patient based on the specific services recorded on the patient bill and rendered during a particular visit or in multiple encounters. Computerized decision rules are also incorporated as edits to adjust for inconsistent revenue or procedure coding practices. The system basically standardizes the millions of outpatient claims received by third party payors so that intensity can be measured consistently across providers, and payment systems can be modified accordingly. The ASWS identifies service intensity on the same relative value scale as inpatient care, and thus, it can serve as a site-neutral classification of health care services for prospective payment and utilization management as well as a measure of resource intensity.