The role of inexperience in measuring tuberculin skin reaction (Mantoux test) by the pen or palpation technique.

We have shown previously that experienced readers can use the palpation or pen method for reading the Mantoux tuberculin skin test with accuracy. In order to investigate if the inexperienced reader can use both methods with the same degree of accuracy, we performed Mantoux tests in 539 healthy subjects, aged 20-57 years (mean 33 years), using the PPD-RT 23 in dose 2 I.U. (1/5000). In random order and a double-blind fashion, an experienced and an inexperienced reader measured the induration after 48 h by the palpation method initially and then by the pen method, without knowing the identity of the subject. Results of the study did not show any significant difference in any range of measurements by the two readers, using either the pen or palpation method (P greater than 0.1). A highly statistically significant linear relationship was found between the measurements by the pen method used by experienced and inexperienced readers (r = 0.823, P less than 0.0001) and between the palpation measurements by the two readers (r = 0.939, P less than 0.0001). We conclude that the effects of an inexperienced examiner in the measurement of of tuberculin skin induration are minimal. Inexperienced readers can use the pen method as accurately as the traditional palpation method.