The time measurement has a 4-min resolution, and at least 6 months of data can be stored in volatile solid-state memory before the battery requires changing. The dates and times of approximately 4,000 actuations can be stored in memory, which exceeds the number of inhalations needed to empty all four of the dispensed canisters. The NC data are easily downloaded through an external interface into an IBM-compatible computer where they are stored as a database file and can be printed at any time.
The ancillary study began approximately at the midpoint of recruiting for the Lung Health Study. Two-hundred fifty-one consecutive participants were enrolled in the NC study at the time they entered the smoking cessation group program. Attendance at the meeting where inhalers were initially dispensed to special intervention participants was the only criterion for inclusion in the NC study. Groups ranged in size from 8 to 18 participants, and each group member was assigned to the same condition, either feedback or control. The first 49 participants (4 groups) at University of California at Los Angeles and 62 participants (5 groups) at Johns Hopkins were enrolled in the control condition for a total of 111, while the next 42 participants (3 groups) at University of California at Los Angeles and 98 participants (7 groups) at Johns Hopkins were enrolled in the feedback condition for a total of 140.
Control Condition: Participants in the control group were told that the NC was an electronic device that recorded the amount of inhaled drug used. No specific information was provided about the ability of the NC to record patterns of use. While participants were not explicitly instructed in the full capability of the NC, all participant questions were answered candidly. Three control participants included in this study did have questions about the specific function of the device or otherwise conveyed to the investigators their awareness of the NC measurement capability.