Non-essential blood tests in the intensive care unit: a prospective observational study

Non-essential blood testing in the acute care setting can be a prominent source of morbidity, patient discomfort, increased workload for the healthcare provider, and wasteful spending. The magnitude of such non-essential blood testing has not been well described. We aimed to measure the extent of unnecessary blood testing in a 33-bed intensive care unit (ICU) at a tertiary-care teaching hospital in Ontario, Canada.

Over a period of four weeks, all ICU attending physicians were asked to select, from a comprehensive list, blood tests that they deemed essential to the appropriate care for each of their patients on the following day. The actual tests processed on the following day were recorded. Descriptive statistics were used to determine what proportion of all processed tests were deemed essential blood tests. The association between patient characteristics and the total cost of unnecessary tests was assessed using the Wilcoxon rank-sum test and the Spearman correlation coefficient, as appropriate.

Nine attending physicians provided input for a total of 81 patient days. In 65 (80%) of these days, at least one test was considered non-essential. Physicians deemed only 338 (48.7%) of 694 processed blood tests as essential, which amounted to $2,243.41 (46.0%) out of an overall cost of $4,882.11. Patients' age, sex, mechanical ventilation status, and treatment with vasoactive drugs on the study day were not associated with the number of non-essential tests.

Attending physicians deemed a substantial proportion of the blood tests processed in a tertiary care ICU setting as unnecessary. Furthermore, the non-essential tests incurred substantial additional cost. Further work is required to gain a better understanding of the underlying factors contributing to these wasteful practices.