Linguistic adaptation and validation into Spanish of the ARTS questionnaire, a self reported instrument designed to measure four osteoarthritis treatment satisfaction dimensions: treatment advantages, treatment convenience, apprehension about treatment and satisfaction with medical care.
Adaptation was performed using conceptual equivalence, supervised by a panel of 6 experts and 4 independent translators, who were in charge of performing translation and back-translation of the items. A sample of patients suffering from knee, hip or column osteoarthritis was used to estimate the psychometric properties of feasibility, reliability, validity and sensitivity to change. Three groups were identified: adequate analgesic effect and tolerability, treatment-switch because of a weak analgesic effect, and treatment- switch due to poor tolerability. The ARTS was administered at baseline, 1 week later for retest, and after 4 weeks of treatment with NSAIDs or Cox II-inhibitors.
A sample of 163 patients was formed (67.7 [9.2] years old). No floor or ceiling effects were found, items were well understood and non- response rates were below 1%. Cronbach's alpha for the total scales was 0.85, and the intraclass correlation coefficient was 0.81. Exploratory factor analysis yielded 4 dimensions which were coherent with those proposed by the original authors. Concurrent validity was measured with SF-36, a pain VAS instrument, a treatment compliance VAS, and the Morisky-Green compliance questionnaire. The adapted instrument showed a good discriminatory validity, and it was able to distinguish between patients needing a change in treatment and those who did not need it. It was also sensitive to changes in patients' treatment effectiveness after a 30 days follow up.
A psychometrically valid and conceptually equivalent ARTS questionnaire has been produced to explore satisfaction with treatment in patients with osteoarthritis in Spanish speaking countries.