REPRODUCIBILITY OF SKIN PRICK TEST-RESULTS IN EPIDEMIOLOGIC STUDIES -A COMPARISON OF 2 DEVICES

The reproducibility of skin prick tests under field conditions is esse ntial for comparing prevalences between centers in epidemiologic multi center studies. This study aimed to evaluate and compare the reproduci bility of two widely used skin prick test devices: the Multi-Test and the ALK lancer. The subjects were 28 children, aged 6-14 years, with k nown sensitivities to Dermatophagoides pteronyssinus (D. pter.). Both devices were applied to each subject on two occasions, 1 week apart, b y different, randomly assigned fieldworkers, using histamine, negative control, and the D. pter. allergen extract. For all three tested solu tions, mean wheal sizes were larger for the Multi-Test than for the AL K lancet. The coefficient of variation for histamine was 21.8% for the Multi-Test and 17.3% for the ALK lancet. The coefficients of variatio n for the allergen D. pter, amounted to 47.4% for the Multi-Test and t o 24.6% for the ALK lancet. The percentage of concordant test results was 92.6% for the Multi-Test and 100.0% for the ALK lancet for a cutof f point of wheal size equal to or greater than 1 mm. The results of th is study suggest that the single ALK lancet performs slightly better t han the Multi-Test device with respect to reproducibility under condit ions of epidemiologic field studies.