Multiple biochemical blood testing as a case-finding tool in ambulatory medical patients

The usefulness and costs of multiple biochemical blood tests as a case-finding tool in ambulatory medical patients are not well known. Recommendations are lacking or based upon results of screening asymptomatic persons. We designed a study to determine prospectively the yield, potential disadvantages, and patient charges of routine biochemical testing at our medical outpatient clinic.

Twenty-three biochemical parameters were evaluated in 493 consecutive patients. Parameters not considered indicated for diagnostic or management purposes by the staff physicians at the first visit were classified as routine tests. The main outcome measures were the number and the nature of new diagnoses leading to a new management, the number of additional tests and visits, and patient charges.

New diagnoses resulting in new management were found in 25 patients (5%). They were mainly lipid disorders. Seven additional visits and 74 further tests were caused by abnormal results of routine tests. The net charges for the detection of the new diagnoses leading to new management were $12,682. Secondary analysis revealed that the determination of only three routine tests (cholesterol, glucose, alanine aminotransferase) would have detected all clinically important diagnoses and would have reduced the charges by 30%.

Routine biochemical testing is a useful case-finding tool with acceptable costs in middle-aged medical outpatients of a university teaching setting. However, the spectrum of newly detected disorders leading to changes in patient management is small. The results suggest that a reduced routine battery consisting of cholesterol, glucose, and alanine aminotransferase might be preferable because it will detect the clinically important diagnoses and lead to a substantial reduction of patient charges.