Reliability of skin test results depends on when they are read

A study has determined that skin-prick test (SPT) results can be read up to forty minutes after being taken, but they are more reliable when read between 20 and 30 minutes after they have been taken. The study was required because most skin prick test results are read twenty minutes after being taken, however under certain circumstances, such as extant clinical duties or emergencies, there may be a delay in the readings.

The objective of the study was to compare SPT wheal and flare reactions at 10, 30 and 40 with the standard 20 minutes to determine whether the extended time between the reading being taken and being read interfered with clinical significance. The study involved 53 subjects who were undergoing a routine aeroallergen SPT for allergy symptoms were tested with allergen extracts, histamine and a negative control solution. The results show that SPT to determine IgE-mediated or immediate hypersensitivity can be read up to 30 minutes without significant loss of reliability.

Source – PubMed

First published in May 2011

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