## 3 Results
### Skin Prick Tests  
One hundred and seventy-four SPTs were performed with the six included food allergens: 27 (16%) with almond, 21 (12%) with apple, 44 (25%) with hazelnut, 23 (13%) with peach, 28 (16%) with peanut, and 31 (18%) with walnut.  
The mean HEP index with ALK food allergen extracts vs. HM extracts was; 0.96 vs. 0.51 for almond, 0.47 vs. 0.38 for apple, 1.40 vs. 1.61 for hazelnut, 0.11 vs. 0.83 for peach, 0.86 vs. 1.13 for peanut, and 0.42 vs. 0.39 for walnut, respectively. P-values for the comparison of the number of positive SPTs (\(\geq\) 3 mm) were: 0.5 for almond, 0.5 for apple, 1.0 for hazelnut, <0.001 for peach, 0.63 for peanut, and 1.0 for walnut. The SPT-HEP results and ICC of the six food allergens are shown in Table 3.  
The differences in the SPT-HEP results with both extracts are also depicted in Figure 1.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Symptoms Per Food Allergen**} \\ \hline  & **Almond** & **Apple** & **Hazelnut** & **Peach** & **Peanut** & **Walnut** & **Total** \\ \hline \(n\) (\%) & 27 (16) & 21 (12) & 44 (25) & 23 (13) & 28 (16) & 31 (18) & 174 (100) \\  & \(n\) (\%) & \(n\) (\%) & \(n\) (\%) & \(n\) (\%) & \(n\) (\%) & \(n\) (\%) & \(n\) (\%) \\ Consuming/ & 8 (30) & 3 (14) & 7 (16) & 6 (26) & 13 (46) & 3 (10) & 40 (23) \\ no symptoms & NA (strict diet) & 3 (11) & 1 (5) & 1 (2) & 1 (4) & 4 (14) & 6 (19) & 16 (9) \\ Symptoms: & & & & & & & \\ GI/OAS & 12 (44) & 12 (57) & 23 (52) & 12 (52) & 5 (18) & 14 (45) & 78 (45) \\ Skin & 0 & 0 & 1 (2) & 0 & 1 (4) & 0 & 2 (1) \\ Lung & 1 (4) & 0 & 0 & 0 & 0 & 0 & 1 (1) \\ GI/OAS + Skin & 1 (4) & 1 (5) & 2 (5) & 1 (4) & 0 & 1 (3) & 6 (3) \\ GI/OAS + Lung & 2 (7) & 3 (14) & 8 (18) & 3 (13) & 2 (7) & 5 (16) & 23 (13) \\ GI/OAS + Skin + Lung & 0 & 1 (5) & 2 (5) & 0 & 2 (7) & 2 (6) & 7 (4) \\ \hline Skin + Lung & 0 & 0 & 0 & 0 & 1 (4) & 0 & 1 (1) \\ \hline \multicolumn{6}{c}{SPT = skin prick test; \(n\) = number; NA = not applicable because of patient on a strict diet free from the food allergen; GI = gastro-intestinal symptoms; OAS = oral allergy syndrome; skin = skin symptoms; lung = respiratory symptoms.} \\ \end{tabular}
\end{table}
Table 2: Symptoms per food allergen.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**SPT Results Per Food Allergen**} \\ \hline  & & **Almond** & **Apple** & **Hazelnut** & **Peach** & **Peanut** & **Walnut** & **Total** \\ \hline  & Positive \(\geq\)3 mm & 24 & 19 & 41 & 4 & 21 & 14 & 123 \\ ALK & 89 & 90 & 93 & 17 & 75 & 45 & 71 \\  & Mean HEP index & 0.96 & 0.47 & 1.40 & 0.11 & 0.86 & 0.42 & \\  & Range HEP & 0–4.05 & 0–1.14 & 0–18.85 & 0–1.42 & 0–5.17 & 0–2.57 & \\  & positive \(\geq\)3 mm & 22 & 17 & 42 & 20 & 23 & 14 & 138 \\ HM & 81 & 81 & 95 & 87 & 82 & 45 & 79 \\  & Mean HEP index & 0.51 & 0.38 & 1.61 & 0.83 & 1.13 & 0.39 & \\  & Range HEP & 0–1.37 & 0–1.44 & 0–11.44 & 0–1.91 & 0–6.07 & 0–2.31 & \\  & ICC & 0.36 & 0.74 & 0.79 & 0.17 & 0.66 & 0.78 & \\
95\% CI for ICC & 0 to 0.65 & 0.47 to 0.89 & 0.65 to 0.88 & 0 to 0.49 & 0.39 to 0.82 & 0.59 to 0.89 & \\ \(p\)-value HEP & 0.03 & \textless{}0.0001 & \textless{}0.0001 & 0.015 & \textless{}0.0001 & \textless{}0.0001 & \\ Strength of ICC & weak & moderate & strong & weak & moderate & strong \\ \hline  & \multicolumn{6}{c}{SPT = Skin Prick Test; \(n\) = number; HEP = Histamine Equivalent Prick test; ALK = Allergy Laboratories; Kopenhagen, Denmark; HM = homemade; ICC = intra-class correlation coefficient.} \\ \end{tabular}
\end{table}
Table 3: Skin prick test results per food allergen.  
The ICCs between the SPT-HEP results for both extract methods, HM and commercial, were all significant; 0.36 (weak) for almond, 0.74 (moderate) for apple, 0.79 (strong) for hazelnut, 0.17 (weak) for peach, 0.66 (moderate) for peanut, and 0.78 (strong) for walnut.