Are preferences for cyclooxygenase-2 inhibitors influenced by the certainty effect?
OBJECTIVE
To test whether the widespread use of cyclooxygenase-2 (COX-2) inhibitors may be mediated in part by the certainty effect, i.e., by a perception that COX-2 inhibitors eliminate the risk of serious gastrointestinal (GI) events in contrast to merely reduce their risk.


METHODS
Patients' preferences for conventional nonsteroidal antiinflammatory drugs (NSAID) and COX-2 inhibitors for treatment of arthritis were predicted across a range of absolute risks of GI events using an Adaptive Conjoint Analysis survey.


RESULTS
Preferences for COX-2 inhibitors were much stronger when the risk of serious GI events was eliminated in contrast to reduced, even though the absolute risk reduction (ARR) was the same. Few patients (22%) preferred COX-2 inhibitors when the risk associated with NSAID and COX-2 inhibitors was 4% and 2%, respectively (ARR = 2%). In contrast, the majority (90%) preferred COX-2 inhibitors when the risk associated with NSAID and COX-2 inhibitors was 2% and 0%, respectively (ARR = 2%). We obtained similar findings regardless of the ARR.


CONCLUSIONS
The willingness shown by older adults to pay for COX-2 inhibitors may reflect a misperception of the risk of toxicity associated with these medications.
VA Connecticut Healthcare System, West Haven, Connecticut 06520-8031, USA. liana.fraenkel@yale.edu
Liana
L
Fraenkel
Dick R
DR
Wittink
John
J
Concato
Terri
T
Fried
D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects*; D016861:Cyclooxygenase Inhibitors / Q000009:adverse effects*; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000188:drug therapy*; D017060:Patient Satisfaction; D010465:Perception; D011237:Predictive Value of Tests; D012306:Risk
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors