Adherence rates during a randomized controlled trial evaluating the use of blinded acetaminophen and ibuprofen in children with asthma

William J. Sheehan, Ian M. Paul, David T. Mauger, James N. Moy, Stanley J. Szefler, Daniel J. Jackson, Anne M. Fitzpatrick, Michael D. Cabana, Ronina Covar, Rachel G. Robison, Wanda Phipatanakul

Research output: Contribution to journalArticlepeer-review


Background/aims: When conducting clinical trials comparing over-the-counter (OTC) medications, the wide availability of these treatments are a potential challenge to maintaining study integrity. We seek to describe adherence to a study protocol involving widely available OTC medications. Methods: To prospectively evaluate associations between acetaminophen use and asthma in 300 children aged 1–5 years, we conducted a double blind, randomized, controlled trial where parents administered blinded forms of either acetaminophen or ibuprofen as needed to their children over a 48 week period. Written and verbal instructions encouraged the exclusive use of the blinded study medication and discouraged OTC use. Adherence was determined by evaluating the frequency of use of per-protocol blinded study medication compared to off-protocol use of OTC medications. Results: 4195 doses of acetaminophen or ibuprofen were received by children during the study which included 3664 doses (87.3%) of blinded study medication adhering to the protocol and 531 doses (12.7%) of OTC products deviating from the protocol with better adherence among those randomized to ibuprofen as compared to acetaminophen (89.5% vs. 85.5% of doses, p < 0.01). Individually, 227 participants (75.7%) remained fully adherent by not receiving any OTC medications. Pre-study preference for either acetaminophen or ibuprofen by the participants' families was not associated with differential rates of adherence to the blinded medication. Conclusion: This parallel study demonstrated greater than 85% of acetaminophen or ibuprofen doses were blinded study medications adhering to the protocol while less than 15% were OTC deviations from the protocol. This successfully implemented study design provides a template to comparatively evaluate these and other OTC medications.

Original languageEnglish (US)
Article number106334
JournalContemporary Clinical Trials
StatePublished - May 2021
Externally publishedYes


  • Acetaminophen
  • Asthma
  • Children
  • Ibuprofen
  • Randomized controlled trial

ASJC Scopus subject areas

  • Pharmacology (medical)


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