[A cost-effectiveness analysis of a pre-visit testing system for new outpatients in primary care medicine]

We evaluated cost-effectiveness parameters of common diagnostic test panels advocated by the Japan Society of Clinical Pathology in order to determine the validity of pre-visit testing of these test panels for new outpatients with some defined symptoms. The "Essential Laboratory Tests(ELT) (2)" panel was universally applied to 540 new outpatients who visited the Comprehensive Medicine Clinics in the National Defense Medical College and its affiliated hospital. A "useful result(UR)", the unit of usefulness of the ELT, was assigned by assessing the impact of its results on physician's diagnosis- or decision-making. Patients were classified into 7 major symptom groups according to their chief complaint, and clinical effectiveness(UR/patient), economic efficiency(cost/UR) and cost-effectiveness(delta cost/delta UR) were analyzed in each patient group. Clinical effectiveness ranged from 1.38(renal/urinary tract symptoms) to 0.27 UR/patient(neurological symptoms) with a cost disparity from yen 1,222 to yen 5,946/UR between these patient groups. Substantial decreases in clinical effectiveness were demonstrated in all patient groups with the ELT(1)-testing alone in a simulation study; however, cost-effectiveness parameters still remain in excellent values in the renal/urinary tract symptom and infection/inflammation-related symptom groups(1.13 and 0.77 UR/patient at a cost of yen 836 and yen 1,181/UR, respectively). The addition of some ELT(2)-specific test items such as AST, ALT to the ELT(1) baseline panel improved clinical effectiveness of the ELT(1) in lassitude/exhaustive symptom group at a minimal cost increment. This study verified the validity of the ELT(1) as a panel for pre-visit testing in patients with renal/urinary tract symptoms and infection/inflammation-related symptoms, but not in those with other symptoms.