Association between patient beliefs regarding assigned treatment and clinical response: reanalysis of data from the...

To reanalyze data from a 2002 study by the Hypericum Depression Trial Study Group to determine whether patients who believed they were receiving active therapy rather than placebo obtained greater improvement, independent of treatment.

Three hundred forty adults with major depressive disorder (according to the Structured Clinical Interview for DSM-IV) and baseline scores of ≥ 20 on the 17-item Hamilton Depression Rating Scale (HDRS-17) were randomized to Hypericum perforatum 900-1,500 mg/d, sertraline 50-100 mg/d, or placebo and were asked to guess their assigned treatment after 8 weeks. This reanalysis of data was performed from October 1, 2009, to April 15, 2011. The intent-to-treat sample included 207 subjects (mean age = 44 years) who had (1) at least 1 postbaseline visit; (2) adherence data based on serum levels of hyperforin, sertraline, and desmethylsertraline; and (3) guess data. Univariate factorial analysis of variance was used to determine whether treatment assignment affected clinical improvement according to HDRS-17 score and whether this effect was moderated by patient guess of sertraline, Hypericum, or placebo. Analysis of covariance was used to determine whether side effects mediated improvement in the context of patient guess and assigned treatment. χ₂ analyses compared response rates (≥ 50% decrease in HDRS-17 score) between the guess groups and between the treatment groups within each guess group.

Assigned treatment had no significant effect on clinical improvement (P = .65), but patient guess was significantly associated with improvement (P < .001), and treatment and guess interacted significantly (P = .005). Among subjects who guessed placebo, clinical improvement was small and did not differ significantly across treatments. Among subjects who guessed Hypericum, improvement was large and did not differ significantly across treatments. Among subjects who guessed sertraline, those who received placebo or sertraline had large improvements, but those who received Hypericum had significantly less improvement (P < .001). Similar findings were obtained for response rates.

Patient beliefs regarding treatment may have a stronger association with clinical outcome than the actual medication received, and the strength of this association may depend upon the particular combination of treatment guessed and treatment received.