Assessment of a point-of-care test for paracetamol and salicylate in blood.

Background: Paracetamol and salicylate are commonly taken in acute overdose. Clinicians have a low threshold for excluding the presence of these two drugs, by ordering laboratory tests in any patient suspected of ingesting an overdose or with an altered mental state.

Aim: To test the effectiveness of a new point of care test that qualitatively detects paracetamol and salicylate in blood and to examine the potential time saved by its use.

Design: Prospective multicentre trial.

Methods: The new test was compared with laboratory analysis in a routine blood sample taken from patients presenting to emergency departments with suspected overdose.

Results: The test had sensitivities of 98.5% and 88.5%, and specificities of 74.7% and 92%, for paracetamol and salicylate, respectively, at cut-off levels of 25 mg/l and 100 mg/l, respectively The point of care test results were available 2 h before the laboratory result.

Discussion: This point-of-care test could be used to rule out an overdose with either of these two drugs, and could thus lead to earlier clinical decisions for suspected overdose patients. Recommendations have been made following this trial that the cut-off value for paracetamol should be reduced from 25 mg/l to 12.5 mg/l in order to increase its usefulness. To prevent the test being misread, we also suggest that each device should be embossed to remind users that the presence of a line indicates there is no drug present.