Adherence Assessment Using Medication Weight in a Phase IIb Clinical Trial of Difluoromethylornithine for the Chemoprevention of Skin Cancer

• Published in: Cancer epidemiology, biomarkers & prevention Vol. 14; no. 11; pp. 2579 - 2583
• Main Authors: HESS, Lisa M, SABODA, Kathylynn, MALONE, Daniel C, SALASCHE, Stuart, WARNEKE, James, ALBERTS, David S
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.11.2005
• Subjects: Adherence; Administration, Topical; Adult; Aged; Aged, 80 and over; Antineoplastic agents; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - therapeutic use; Biological and medical sciences; Chemoprevention; Chemotherapy; compliance; DFMO; Eflornithine - administration & dosage; Eflornithine - therapeutic use; Female; Glucocorticoids - administration & dosage; Glucocorticoids - therapeutic use; Humans; Male; Medical sciences; methodology; Middle Aged; Patient Compliance; Pharmacology. Drug treatments; Placebos; Skin Neoplasms - prevention & control; topical agents; Triamcinolone - administration & dosage; Triamcinolone - therapeutic use; Truth Disclosure; Tumors; United States; North America; America; Antineoplastic agent; Human; Drug; Skin disease; Chemoprophylaxis; Enzyme; Enzyme inhibitor; Lyases; Antimetastatic agent; Ornithine decarboxylase; Malignant tumor; Weight; Skin cancer; Drug compliance; Prevention; Carbon-carbon lyases; Cancerology; Treatment; Carboxy-lyases; Phase II trial; Treatment compliance; Public health
• ISSN: 1055-9965; 1538-7755
• DOI: 10.1158/1055-9965.EPI-05-0104

Objective: Adherence is a common and essential measurement in clinical trials. This study evaluates the association between participant self-reported study diary records and the weight of the medication vessel at each study visit, in the setting of a phase IIb topical chemoprevention trial. Methods: One hundred and twenty-four eligible participants were randomized to one of four arms [34 to difluoromethylornithine (DFMO) plus triamcinolone, 31 to DFMO plus placebo, 31 to placebo plus triamcinolone, and 28 to double placebo] for 6 months of treatment for actinic keratosis. Adherence was assessed at each clinic visit by weighing each tube of dispensed and returned medication and the participant's study diary. Results: Self-reported adherence was consistently higher than adherence measured by returned medication weight (96.5% versus 71.3%, 94.6% versus 82.4%, 95.3% versus 69.5%, and 95.8% versus 66.8% for DFMO, DFMO placebo, triamcinolone, and triamcinolone placebo, respectively; P < 0.001). Most participants (59.2%) recorded 100% adherence on the study diary; however, using the weight adherence, only 10.2% were completely adherent to the study regimen. Conclusions: Self-reported diary measures seem to overestimate adherence when compared with weighing the returned medication vessel. It is recommended that future clinical trials involving topical applications incorporate medication weights as a primary measure of adherence because it is objective, quantitative, inexpensive, noninvasive, and easy to use.