A comparison of fixed and disposable head Heaf guns

The objective of the study was to compare the newly introduced Model 2000 disposable-head Heaf gun with the currently used fixed-head gun. The study simultaneously Heaf-tested 1410 school children on both forearms using a different gun on each arm; the tests were read blind. The results were similar for both Heaf guns. The fixed-head gun gave a stronger reaction in 202 (14%) children by one Heaf grade. The disposable head gun gave a stronger reaction in 116 (8%) children, by one Heaf grade in 113 and 2 Heaf grades in 3 children. kappa = 0.607 (95% confidence interval [CI] = +/- 0.038), indicating good agreement between the tests. chi 2 = 0.177, d.f. = 1, P = 0.7 NS. Given the practical advantages of Heaf skin testing for primary screening, it is likely that practitioners will replace the fixed-head gun with one that avoids sterilisation problems. The small variation between the tests was not considered clinically important, while the advantages of the new test were considerable. It is therefore recommended that the Model 2000 Heaf gun replace the fixed-head gun for primary screening.