The standard tuberculin skin test which, if positive, is taken as the definition of tuberculous infection is the Mantoux test.2One of its disadvantages over multiple puncture tests is that it must be performed and read by trained personnel. Clinical utilization of the Mantoux test is hampered by the difficulty and variability in quantifying the resultant intradermal reaction. The traditional method of measurement of induration is the palpation method. Even experienced observers have considerable difficulty and frequently fail to identify any induration or the margins of the indurated area.
Sokal stated that the “ball-point” technique of measuring the skin induration can be mastered by almost anyone, with little practice. He also noted substantial reduction of observer variation in measurements of skin test responses, but did not compare the ball-point technique with any other one. Recently, in a double-blind study of 135 bacteriologically proven tuberculous patients, comparing the palpation vs the pen method, it was found that the pen method yielded the same frequency of distributions as the palpation one, and that the pen method appeared to be the more sensitive.
Conversely, in a second prospective study of 806 healthy volunteers, a significant difference was noted between the two methods in the 5 to 14 mm range of induration.