Efficacious application of laboratory testing in internal medicine

Abstract

Laboratory testing plays a major role in internal medicine, especially in diagnosing diseases. In order to use laboratory testing most effectively, several conditions need to be met. Firstly, only tests that contribute to patient management should be performed. Otherwise, overtesting occurs. It leads to unnecessary costs and can be a burden on patients. In this thesis, several examples of overtesting were investigated. We found a high rate of unnecessary repetitions of laboratory tests when patients are referred to the outpatient clinic. We also found that when patients are admitted on the ward, laboratory testing is performed far more often than recommended. Secondly, test results need to be available when required. In this thesis, we found that in the emergency department, a shorter turnaround time, defined as the time from ordering of the tests and the results’ becoming available, is associated with a shorter length of stay. Shorter turnaround times also allow laboratory testing to be performed directly before visits to the outpatient clinic. We found that pre-visit testing lead to more patients receiving a diagnosis on their first visit. Thirdly, test results need to be interpreted correctly. We found that in the setting of patients receiving checkpoint inhibitors for cancer, routinely measured hematological tests can aid in the diagnosis of auto-immune toxicity. Increased automation and decision support systems using artificial intelligence may be able to help increase the efficacy of laboratory testing.