The effect of applied force and device design on skin prick test performance.

Background: Skin prick tests (SPTs) are difficult to standardize, and SPT performance mainly relies on the clinician's expertise. So far, the effect of various factors such as device types, shape, variety of material type, and applied force on the performance of SPT has not been extensively investigated.

Objective: To investigate the effect of various factors, including type or shape of devices, material type, and applied force, on the performance of SPT.

Methods: Four SPT devices with different shapes and materials were applied on 12 subjects under 3 different applied forces (30, 45, and 60 g). The results were compared with standard method using an ALK lancet pricked by an experienced clinician.

Results: A total of 480 pricks were conducted on 12 subjects. The wheal sizes and sensitivities of all devices increased with higher applied forces. The thinner lancets with a long sharp tip had relatively higher analytical sensitivities and provided 100% sensitivity at applied forces of 45 g and above. The pain scores of all devices at applied forces of 30 to 60 g ranged from 1.00 to 1.81 with minimal incidences of bleeding (0%-4.17%), whereas the pain score of the standard method by the ALK lancet was 2.08 with much higher incidences of bleeding at 27.08%.

Conclusion: The type/shape of the SPT device and applied force are the essential factors affecting the performance of SPT. The study result could pave the way toward higher performance and standardized SPT.

Trial Registration: The Thai Clinical Trials Registry identification number: TCTR20220627004 (https://www.thaiclinicaltrials.org/show/TCTR20220627004).