Table 4. Mean emitted dose per discharge score at quality control (n = 1036), and frequency per discharge score of all used and returned Twincers (total n = 8544; for discharge score 2–5 than n = 6963).

Discharge score	N in quality control	Mean emitted dose in mg (SD)	Frequency in the 8544 returned Twincers in %
2	202	50.9 (1.5)	14.6
3	671	44.2 (3.5)	56.7
4	147	36.3 (5.8)	9.7
5	16	19.6 (10.4)	0.5

The discharge scores were classified as follows: 1 = very good discharge, classifiers exceptional clean; 2 = good discharge, light smearing in blister and/or classifiers; 3 = adequate discharge, moderate smearing of little agglomerates in blister and classifiers; 4 = moderate discharge, agglomerates in blister and/or bypass channel and/or above average smearing of classifiers; 5 = inadequate discharge, complete blockage of powder channel.

A discharge score of ‘1’ was never found during in vitro quality checks. Although the determination of the discharge score is somewhat subjective, a discharge score of ‘1’ of the used and retrieved Twincers often will be the consequence of poorly sealed packaging (minigrip bag) and subsequent liquefaction of the powder by hygroscopy. This score is, therefore, considered an artefact.