Spanish transcultural adaptation and validation of the English version of the compliance questionnaire in rheumatology

Abstract

To perform a transcultural adaptation and validation of a Spanish version of the compliance questionnaire in rheumatology (sCQR). In this transversal study of transcultural adaptation of the sCQR, validity was evaluated in patients with rheumatoid arthritis (RA) and a minimum 6-month follow-up by determining compliance with the electronic prescription system in consuming steroids or nonbiologic disease-modifying antirheumatic drugs. A two-week retest was proposed to all patients. All patients completed the health assessment questionnaire (HAQ), and the Morisky-Green test was also performed. Reliability was analyzed using Cronbach's alpha and the intraclass correlation coefficient (ICC). Convergent construct validity was tested in the electronic prescription system using discriminative analysis, and divergent construct validity was tested by comparing it to the HAQ. Sensitivity, specificity and ROC curves were evaluated for the sCQR and the Morisky-Green test. Of 123 recruited patients, 101 fulfilled the inclusion criteria, and 61 were on biologic therapy. 23 performed the retest. Test-retest reliability (ICC) was 0.76 (Cronbach's alpha 0.86). Multiple regression analysis showed correlation with each item of the sCQR as independent variables (r = 0.60). No correlation was seen between total score punctuation of the sCQR and the HAQ (r = 0.22). Discriminative analysis weighting each sCQR item showed a cutoff point of - 0.9991 (sensibility and 58.8%, specificity 98.3%). The likelihood ratio of the sCQR to detect ≤ 80% adherence with electronic prescriptions was 35.3. The Morisky-Green test revealed sensibility and specificity were 29.4 and 83.3%, respectively. This study validates the transcultural adaptation of sCQR in RA patients. A high reliability of sCQR for measuring adherence was found. Its predictive value suggests that it could be used as a screening instrument.

Adherence to Treatment in Patients with Rheumatoid Arthritis from Spain

“… 14 This study was conducted using a highly reliable and specific tool, being the only rheumatology-specific adherence measure, 8 , 9 that has been recently validated for its use in Spanish RA population. 12 It must also be stressed the special effort that was made when selecting centers to participate in the study, having into account geographical distribution and other variables, such as population density and public health expenditure for each region, in order to obtain a representative sample of Spain. Results obtained in this study can be extrapolated to the total Spanish population.…”

“…Study population was not selected based on disease activity, participants reflected real-life RA population treated in routine clinical practice. Another disadvantage is the use of a self-reported questionnaire to test for adherence, even though it is a highly specific method with a highly predictive value, 12 this method is relatively insensitive, since patients may claim to be adherent to avoid caregiver disapproval. 8 Despite this, the use of indirect methods as the one used in this study is a more simple and feasible way to evaluate adherence and due to its highly predictive value, it can be used as a screening instrument.…”

“… 8 Despite this, the use of indirect methods as the one used in this study is a more simple and feasible way to evaluate adherence and due to its highly predictive value, it can be used as a screening instrument. 12 …”

“…To calculate sample size, results obtained in the preliminary study of the transcultural adaptation of sCQR were considered, where a 78% adherence to treatment was established. 12 Estimating a similar proportion of therapeutic adherence and having in mind that the prevalence of RA in Spanish population is 0.5% 13 and Spanish population is 46,439,864 inhabitants, for an alpha error of 5% and an accuracy of 3% it was estimated that the necessary sample would be 730 patients. Assuming a loss percentage of 15%, a total population of 859 patients was determined to be necessary.…”

“…To adjust its weight, a coefficient was applied to each item, to generate a Z score (Z K ): Z K = a + W 1 X 1K + W 2 X 2K + … + W 19 X 19K , where Z K is the discriminant Z score for patient K, a is a constant, W i is the discriminant weight for item i and patient K. A cutoff point allowed classifying patients into those with satisfactory compliance or unsatisfactory compliance. 12 …”