Concordance of lateral flow and skin prick tests in the assessment of allergen sensitisation in the epidemiological field in children.

BACKGROUND

A new lateral flow test (LFT) for office use provides information about sensitisation to common allergens. Concordance between LFT and skin-prick test (SPT) has not been assessed in epidemiological studies. The aim of this study is to determine LFT-SPT concordance in this field.

METHODS

Plasma samples (n = 270) from children aged 9-12 years previously SPT tested were used for the analysis. We selected 180 samples from children SPT positive to any of the 6 allergens which were common to SPT and LFT (cat, birch, timothy-grass, olive, pellitoryand Dermatophagoides pteronyssinus), and 90 samples from children SPT negative. The intensity of the LFT colour line which indicates a positive reaction was rated from 0 to 4.

RESULTS

Only results on cat, olive and D. pteronyssinus were analysed, as only these had an acceptable number of individuals. When atopy was defined as at least 1 wheal with a mean diameter > or =3 mm, agreement was excellent (Cohen's kappa = 0.81) when a lightly visible line was considered positive in the LFT, and dropped substantially (Cohen's kappa = 0.68) when this value of LFT was considered negative. The correlation between the SPT wheal diameter and the intensity of the LFT line was 0.71 for cat, 0.81 for olive and 0.78 for D. pteronyssinus.

CONCLUSIONS

As compared to SPT, LFT is a reliable method to screen for sensitisation to cat dander, olive pollen and D. pteronyssinus in the epidemiological field among schoolchildren. There is a good correlation between the SPT wheal diameter and the intensity of the LFT line.