The purpose of this study is investigating variables affecting the numbers of clinical laboratory tests.

Data about the number of clinical laboratory tests, hospital characteristics, and the number of patients between January 1999 and December 1999 was collected. Data resources were Statistical Yearbook, Standardization Audit by Korean Hospital Association and Internal Data Set of each hospital. Hospital characteristics were hospital ownership, tertiary care hospital, duration since opening, licensed hospital beds, the rates of medical inpatient and outpatient. Multiple regression analysis was applied to find factors affecting the number of clinical laboratory tests. Models for WBC, RBC, Hb, Hct, PLT, LDC, PT, PTT, AST, ALT, and GLU were statistically adequate.

As the results, hospital ownership, duration since opening, licensed hospital beds, the rate of medical outpatient were statistically significant. Private hospitals showed higher numbers than public hospitals, hospitals within 5 years since opening showed higher numbers than others. The licensed hospital beds was positively correlated with the numbers of the tests, whereas the rates of medical outpatient was negatively correlated.

In conclusion, hospital characteristics affect the numbers of clinical laboratory tests. It could be a clue why the costs of medical services were different among medical facilities.