The ARthritis Treatment Satisfaction (ARTS) questionnaire specifically assesses patients' satisfaction with osteoarthritis treatment. However, its usefulness is limited since its criterion validity is unknown. The goal of this research was to analyse the criterion validity of the questionnaire in order to identify a cut-off value able to differentiate patients who are satisfied and those who are unsatisfied with osteoarthritis treatment and to establish the possible need for switching therapy.
We used responses to the ARTS questionnaire from outpatients with osteoarthritis included in an open-label, non-controlled, naturalistic, prospective switching therapy study. In addition, patients' responses to two questions on satisfaction with treatment and osteoarthritis-related health status were recorded. Receiver operative characteristic (ROC) curve analyses with estimators of validity were determined. The correlation between responses to the ARTS questionnaire, the question regarding satisfaction with treatment, and the osteoarthritis-related health status assessment were also analysed.
A total of 1756 male and female subjects were enrolled in the study. ROC curve analysis identified a cut-off point of >or=61 points as optimal for the criterion validity estimators of sensitivity (0.86), specificity (0.83), and positive (0.87) and negative (0.81) predictive values. This threshold value was used to identify patients satisfied with treatment and patients with a need to switch therapy (kappa coefficient of agreement 0.68 and 0.66, respectively). ARTS questionnaire scoring correlated with satisfaction with treatment (p < 0.0001), and with patient (r = 0.655, p < 0.0001) and investigator (r = 0.565, p < 0.0001) health status assessments.
The ARTS questionnaire was able to identify patients satisfied with treatment and those with a need to switch their osteoarthritis therapy.