Serum concentration of tIgE and mite sIgE/tIgE ratio in patients with AR, AS, AD, and their multimorbidities. (a) Serum concentration of tIgE in patients with AR+AS/CVA+AD/eczema was higher than AR+AS/CVA; Serum concentrations of tIgE of AR or AS/CVA were lower than their multimorbidities; Serum concentration of tIgE of AD/eczema was lower than AR and AR multimorbidities, and AR higher than AS/CVA. (b) D. pteronyssinus sIgE/tIgE ratio was higher in patients with upper airway allergic multimorbidities, such as AR co-occurring with AS/CVA or AD/eczema, and lower in patients only have AS/CVA or AD/eczema. The ratio in AR was higher than in AS/CVA or AD. (c) D. farinae sIgE/tIgE ratio pattern was similar to D. pteronyssinus. *: p < 0.05; **: p < 0.01; ***: p < 0.001.