Metered-dose inhaler adherence in a clinical trial.
We studied patterns of inhaler usage in a sample of participants from two centers in the Lung Health Study clinical trial. The inhaler, containing either ipratropium bromide or a placebo, was prescribed to be taken as two inhalations three times daily. For 4 months we recorded adherence by both self-report (n = 95) and canister weight change (n = 70). We compared these results with data obtained from a microprocessor monitoring device, the Nebulizer Chronolog (NC), which records the date and time of each inhaler actuation. Seventy-three percent of the participants reported using the inhaler an average of three times daily; however, NC data showed that only 15% of the participants actually used the inhaler an average of 2.5 or more times per day. Canister weight overestimated adherence because only 62% of the NC sets contained the prescribed two actuations. Fourteen percent showed a pattern of actuation of their inhalers more than 100 times in a 3-h interval. We interpret this usage pattern to reflect deliberate emptying of inhalers to appear to be in good compliance with the prescribed program. We conclude that self-report and weighing of inhaler canisters overestimate adherence to the prescribed regimens. Furthermore, a substantial number of monitored inhaler users appear to deliberately dump their medication prior to follow-up visits.
Rand
C S
CS
Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
Wise
R A
RA
Nides
M
M
Simmons
M S
MS
Bleecker
E R
ER
Kusek
J W
JW
Li
V C
VC
Tashkin
D P
DP
D000280:Administration, Inhalation; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D005260:Female; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D010349:Patient Compliance
D009241:Ipratropium