## 4 Discussion  
In this study, we compared SPT results for HM food allergen extracts with results for commercially available extracts, in patients with reported food-specific allergic symptoms, e.g., OAS, GI symptoms, skin symptoms, and/or respiratory symptoms, after ingestion of the suspected food. We performed SPTs in 54 patients, using both the HM extract and the commercially available extract of the same food allergen, within the same patient, at the same time. We found a strong correlation between both extract methods for hazelnut and walnut, moderate correlation for peanut and apple, and weak correlation for almond \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Accuracy of Sensitization Measurements in Relation to Reported Symptoms**} \\ \hline \multicolumn{2}{c}{**Extract**} & \multicolumn{1}{c}{**Sensitivity**} & \multicolumn{1}{c}{**Specificity**} & \multicolumn{1}{c}{**PPV**} & \multicolumn{1}{c}{**NPV**} & \multicolumn{1}{c}{**LR+**} & \multicolumn{1}{c}{**LR\(-\)**} \\ \hline \multirow{3}{*}{Almond} & ALK & 1.00 & 0.25 & 0.73 & 1.00 & 1.33 & 0.00 \\ \cline{2-7}  & HM & 0.88 & 0.25 & 0.70 & 0.50 & 1.17 & 0.50 \\ \cline{2-7}  & slgE Almond & 0.44 & 0.20 & 0.25 & 0.38 & 0.56 & 2.78 \\ \hline \multirow{3}{*}{Apple} & ALK & 0.88 & 0.00 & 0.83 & 0.00 & 0.88 & NA \\ \cline{2-7}  & HM & 0.82 & 0.33 & 0.88 & 0.25 & 1.24 & 0.53 \\ \cline{2-7}  & Mal d1 & 0.88 & 0.00 & 0.88 & 0.00 & 0.88 & NA \\ \hline \multirow{3}{*}{Hazelnut} & ALK & 0.97 & 0.25 & 0.85 & 0.67 & 1.30 & 0.11 \\ \cline{2-7}  & HM & 0.97 & 0.13 & 0.83 & 0.50 & 1.11 & 0.23 \\ \cline{2-7}  & Cor a1 & 0.82 & 0.50 & 0.97 & 0.13 & 1.64 & 0.36 \\ \hline \multirow{3}{*}{Peach} & ALK & 0.19 & 0.83 & 0.75 & 0.28 & 1.13 & 0.98 \\ \cline{2-7}  & HM & 0.94 & 0.33 & 0.79 & 0.67 & 1.41 & 0.19 \\ \cline{2-7}  & Peru p1 & 0.75 & 0.50 & 0.94 & 0.17 & 1.50 & 0.50 \\ \hline \multirow{3}{*}{Peanut} & ALK & 0.82 & 0.23 & 0.47 & 0.60 & 1.06 & 0.79 \\ \cline{2-7}  & HM & 0.91 & 0.23 & 0.50 & 0.75 & 1.18 & 0.39 \\ \cline{2-7}  & Ara h2 & 1.00 & 0.65 & 0.36 & 1.00 & 2.86 & 0.00 \\ \cline{2-7}  & Ara h8 & 0.53 & 0.71 & 0.82 & 0.38 & 1.85 & 0.66 \\ \hline \multirow{3}{*}{Walnut} & ALK & 0.50 & 0.67 & 0.92 & 0.15 & 1.50 & 0.75 \\ \cline{2-7}  & HM & 0.50 & 1.00 & 1.00 & 0.21 & NA & 0.50 \\ \cline{2-7}  & Jug r1 & 1.00 & 0.14 & 0.10 & 1.00 & 1.16 & 0.00 \\ \hline \multirow{6}{*}{Walnut} & ALK = Allergy Laboratories Kopenhagen, Denmark; HM = homemade; PPV = positive predictive value; NPV = negative predictive value; LR+ = positive likelihood ratio; LR\(-\) = negative likelihood ratio; NA = not applicable. \\ \cline{2-7}  & ALK = Allergy Laboratories Kopenhagen, Denmark; HM = homemade; PPV = positive predictive value; NPV = negative predictive value; LR+ = positive likelihood ratio; LR\(-\) = negative likelihood ratio; NA = not applicable. \\ \cline{1-1} \cline{2-7}  & ALK = Allergy Laboratories Kopenhagen, Denmark; HM = homemade; PPV = positive predictive value; NPV = negative predictive value; LR+ = positive likelihood ratio; LR\(-\) = negative likelihood ratio; NA = not applicable. \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Accuracy of sensitization measurements in relation to reported symptoms. and peach. This indicates that these HM food allergen extracts are a good to moderate alternative in the absence of standardized commercially available extracts. We found comparable sensitivity and specificity results for HM and ALK food allergen extracts. As expected, the mean sensitivity was high (0.84 and 0.73, respectively), but the specificity is considerably low for both extracts (0.38 and 0.37, respectively). [PERSON] et al. described this low specificity earlier for food allergen extracts [14]. In particular, the hazelnut extract performed poorly in both extracts. One reason might be that we compared the results with doctor-diagnosed allergies without performing DBPCFCs. Another reason might be that most patients are sensitized to Cor a1, and consequently we lose these labile proteins during extraction.