Skin prick testing (SPT) is the cornerstone of IgE-mediated allergy diagnosis,¹ due to its high sensitivity and specificity.² However, a uniform method for wheal measurement does not exist. Ansotegui et al.² recommends to measure wheals in millimeters with a ruler, in many centers they are outlined with a pen and transfer by tape to a paper and then measured. Subsequently, the specialist is able to manually measure the maximum (MD) and orthogonal diameter (OD) of the wheal. This procedure is time consuming and makes reproducible measurements difficult.^{2, 3} Knowing the wheal's area could help make a more accurate diagnosis.⁴ Over the last 30 years, many attempts have been made to develop a device to measure the size of SPT.³ Nexkin DSPT® (Figure S1A,B) is a novel mechatronic system based on 3D laser technology, that automatically locates allergen's wheal and measures its size (MD, OD and area in square millimeters) (Figure S1C).

A prospective clinical trial was conducted at Clínica Universidad de Navarra (NCT05284565) to evaluate the level of agreement in wheal size measures between this new device and the manual procedure, to assess the test–retest reliability for both procedures, and to compare reading value variations between both measurement approaches. Methods details are shown in Appendix S1.

A total of 108 individuals were screened during the study period (Figure S2) and 93 patients were finally included for analysis. SPT was performed with positive (histamine) and negative (saline solution) controls. Fifteen minutes later, two consecutive readings with the device and two manual readings were performed by two separate nurses. Comparisons between first and second readings are shown in Table S1.

Correlations between the manual procedure and the device (Figure 1) showed a relatively strong association, and all of them were statistically significant (Area: r = .742, p < .001; MD, r = .700, p < .001; OD, r = .644, p < .001). The intraclass correlation coefficient (ICC) values showed poor to moderate agreement between the manual procedure and the device [0.49 (95% CI: 0.26–0.65) to 0.70 (95% CI: 0.53–0.81)]. Test–retest reliability (Figure S3) was found to be moderate to good for the manual procedure (ICC values ranged from 0.57 [95% CI: 0.42–0.70] to 0.80 [95% CI: 0.71–0.86], corresponding to OD and area evaluations, respectively) and good to excellent for the device (the ICC values were 0.88 [95% CI: 0.83–0.92] in area, 0.85 [95% CI: 0.79–0.90] in MD, and 0.85 [95% CI: 0.78–0.90] in OD). The consistency of Nexkin DSPT® readings appeared to be greater than those of the manual procedure. Reading variations in area (Figure 2) for Nexkin DSPT® (2.02 mm²; SD = 3.42) were lower than those of the manual procedure (4.94 mm²; SD = 4.14) (p < .001). Similar results were obtained for MD and OD of wheals. Additional results are included in Appendix S1.

Overall, the agreement between the device and manual procedure was moderate. Although no gold standard method exists,⁵ the automatic measurement system of the device seems to be more appropriate to yield less variable measurements than the manual procedure, as the results from the device are regardless of the individual who performs SPT and/or the thickness of the pen used to outline the wheals.⁶ The discussion was expanded in Appendix S1.

The results suggest a higher reliability of the electro-medical device Nexkin DSPT® for the measurement of wheal area in SPT, compared to the manual procedure. This device has potential for improving the uniformity of the reading phase of the SPT and, therefore, it may favour standardization, upgrade, and innovation of the current SPT technique.

皮肤点刺试验 (SPT) 是 IgE 介导的过敏诊断的基石¹ ，因为它具有高灵敏度和特异性。²然而，不存在统一的风团测量方法。Ansotegui 等人。²建议用尺子测量以毫米为单位的风团，在许多中心，他们用笔勾勒出轮廓，然后用胶带转移到纸上，然后进行测量。随后，专家能够手动测量风团的最大 (MD) 和正交直径 (OD)。此过程非常耗时，并且难以进行可重复的测量。^{2, 3}了解风团的面积有助于做出更准确的诊断。^4个 Over the last 30 years, many attempts have been made to develop a device to measure the size of SPT.³ Nexkin DSPT® (Figure S1A,B) is a novel mechatronic system based on 3D laser technology, that automatically locates allergen's wheal and measures its size (MD, OD and area in square millimeters) (Figure S1C).

A prospective clinical trial was conducted at Clínica Universidad de Navarra (NCT05284565) to evaluate the level of agreement in wheal size measures between this new device and the manual procedure, to assess the test–retest reliability for both procedures, and to compare reading value variations between both measurement approaches. Methods details are shown in Appendix S1.

A total of 108 individuals were screened during the study period (Figure S2) and 93 patients were finally included for analysis. SPT was performed with positive (histamine) and negative (saline solution) controls. Fifteen minutes later, two consecutive readings with the device and two manual readings were performed by two separate nurses. Comparisons between first and second readings are shown in Table S1.

Correlations between the manual procedure and the device (Figure 1) showed a relatively strong association, and all of them were statistically significant (Area: r = .742, p < .001; MD, r = .700, p < .001; OD, r = .644, p < .001). The intraclass correlation coefficient (ICC) values showed poor to moderate agreement between the manual procedure and the device [0.49 (95% CI: 0.26–0.65) to 0.70 (95% CI: 0.53–0.81)]. Test–retest reliability（图 S3）被发现对于手动程序来说是中等到好的（ICC 值范围从 0.57 [95% CI：0.42-0.70] 到 0.80 [95% CI：0.71-0.86]，分别对应于 OD 和面积评估) 和设备的良好到优秀（ICC 值在面积上为 0.88 [95% CI：0.83–0.92]，在 MD 上为 0.85 [95% CI：0.79–0.90]，以及 0.85 [95% CI：0.78–0.90]在外径）。Nexkin DSPT® 读数的一致性似乎优于手动程序。Nexkin DSPT® 的面积读数变化（图 2）（2.02 mm ²；SD = 3.42）低于手动程序（4.94 mm ²；SD = 4.14）（p  < .001）。风团的 MD 和 OD 获得了类似的结果。附加结果包含在附录 S1 中。

总体而言，设备和手动程序之间的一致性适中。尽管不存在黄金标准方法，⁵该设备的自动测量系统似乎比手动程序更适合产生更少的可变测量值，因为该设备的结果与执行 SPT 的个人和/或厚度无关用来勾勒风团轮廓的笔。⁶讨论在附录 S1 中进行了扩展。

结果表明，与手动程序相比，用于测量 SPT 风团面积的电子医疗设备 Nexkin DSPT® 具有更高的可靠性。该装置具有提高SPT读取相位均匀性的潜力，有利于现有SPT技术的标准化、升级和创新。