Biochemical profiles. Applications in ambulatory screening and preadmission testing of adults.

Evidence bearing on the utility of biochemical profiles for ambulatory care screening and preadmission testing was reviewed, and recommendations were formulated. Certain biostatistical principles relevant to this analysis include the concepts of regression to the mean, the meaning of biochemical "normality" (particularly as it relates to multiple testing), and the effects of disease prevalence on the post-test probability of disease for individual test results. Applying these principles to a typical 12-test battery in asymptomatic adults, one would expect a low yield of unanticipated diagnoses and a high proportion of false-positive results. For the typical test battery, the empirical evidence supports these expectations in ambulatory care screening. In addition, routine preadmission use of biochemical profiles is not supported by studies examining their impact on patient care, hospital costs, or lengths of stay. Whereas components of these profiles can be endorsed for screening or preadmission testing, we recommend that the routine use of the entire profile be abandoned in these settings.