Patient preference in a crossover clinical trial of patients with osteoarthritis of the knee or hip: face validity of self-report questionnaire ratings.
OBJECTIVE
To analyze correlational validity of self-report responses regarding patient preference between 2 drugs at the conclusion of a crossover double-blind clinical trial in patients with osteoarthritis (OA) of the knee or hip.


METHODS
Patients were randomized to 6 weeks' treatment of diclofenac/misoprostol or acetaminophen, followed by crossover to 6 weeks of the other drug. Patient preference was queried at the final visit: "Please compare control of your arthritis during the first and second periods as 'much better' or 'better' in the first period, 'no different' or 'better' or 'much better' in the second period." Patient preference ratings were evaluated in comparisons with 4 independent self-report measures within each treatment period: (1) change in Western Ontario McMaster (WOMAC) questionnaire scores; (2) change in pain visual analog scale (VAS) on a multidimensional Health Assessment Questionnaire (MDHAQ); (3) patient ratings of drug efficacy; and (4) patient report of change in arthritis status, as well as investigator ratings of the more efficacious drug.


RESULTS
Among 173 patients, diclofenac/misoprostol was rated as "much better" by 54 and "better" by 45, acetaminophen was rated as "better" by 18 and "much better" by 17, and "no difference" by 39 patients. Spearman rank correlations for patient preferences were significant for changes in WOMAC scores, pain VAS, and independent patient ratings of drug efficacy and changes in arthritis status within each treatment period, as well as with physician ratings of the more efficacious drug (p < 0.001).


CONCLUSIONS
Significant correlational validity is documented for patient self-report of preferences between 2 drugs compared to independent measures within each treatment period in this crossover clinical trial in patients with OA of the knee or hip.
Pincus
Theodore
T
Division of Rheumatology and Immunology, Vanderbilt University School of Medicine, 203 Oxford House, Box 5, Nashville, TN 37232, USA. t.pincus@vanderbilt.edu
Wang
Xiaofei
X
Chung
Cecilia
C
Sokka
Tuulikki
T
Koch
Gary G
GG
D000082:Acetaminophen / Q000627:therapeutic use*; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004008:Diclofenac / Q000627:therapeutic use*; D004311:Double-Blind Method; D006801:Humans; D016595:Misoprostol / Q000627:therapeutic use*; D015207:Osteoarthritis, Hip / Q000188:drug therapy*; D020370:Osteoarthritis, Knee / Q000188:drug therapy*; D017060:Patient Satisfaction; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
D018712:Analgesics, Non-Narcotic; D000894:Anti-Inflammatory Agents, Non-Steroidal; D016595:Misoprostol; D004008:Diclofenac; D000082:Acetaminophen