Perceived medication assignment during a placebo-controlled laboratory study of
varenicline: temporal associations of treatment expectancies with smoking-related
outcomes.
Author(s): Correa JB(1), Heckman BW, Marquinez NS, Drobes DJ, Unrod M, Roetzheim RG, Brandon
TH.
Affiliation(s): Author information:
(1)Department of Psychology, University of South Florida, Tampa, FL, USA.
Publication date & source: 2014, Psychopharmacology (Berl). , 231(13):2559-66
RATIONALE: Expectancies regarding treatment assignment may influence outcomes in
placebo-controlled trials above and beyond actual treatment assignment. For
smoking pharmacotherapies, guessing enrollment in the active medication treatment
is associated with higher abstinence rates. However, placebo-controlled trials of
smoking pharmacotherapies rarely assess perceived treatment assignment and those
that do only collect this information after reaching full dosage.
OBJECTIVES: To determine the temporal relationship between treatment expectancies
and smoking-related variables, we assessed the impact of treatment guess during a
placebo-controlled laboratory study of varenicline on measures of craving,
smoking reward, and smoking reinforcement. We hypothesized that treatment guess
at mid-titration would influence smoking-related measures at full dosage, above
and beyond actual medication effects. We also explored factors related to guess
stability and differences in blind fidelity between mid-drug titration and full
dosage.
METHODS: Eighty-eight participants completed laboratory assessments at baseline,
mid-titration, and full dosage that involved self-report and behavioral measures
of tonic craving, cue-provoked craving, smoking reward, and smoking
reinforcement. Participants guessed treatment assignment at mid-titration and
full dosage.
RESULTS: Generalized linear models confirmed that, beyond actual treatment
assignment, treatment guess improved model fit for both self-report and
behavioral smoking-related measures. Further, accuracy of treatment guess
improved from titration to full dosage, and specific demographic factors (e.g.,
gender, race) were associated with type of treatment guess and guess stability
across time.
CONCLUSIONS: These results reinforce the importance of assessing perceived
treatment assignment repeatedly during placebo-controlled trials and suggest that
treatment expectancies during titration can affect outcomes once full dosage has
been reached.
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