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Reliability Analysis of Two Short Medication Adherence Questionnaires

February 19 2016 12:34 PM ET via RheumReports RheumReports

At CRA 2016, Raquel Sweezie presented an analysis of the reliability of two short medication adherence questionnaires in patients with rheumatoid arthritis.

Adherence is defined as the extent to which a patient takes a medication as prescribed by their health care provider. In rheumatology, adherence rates have been reported to be as low as 30%. The most commonly used questionnaire to assess adherence in rheumatology is the19-item Compliance Questionnaire Rheumatology (CQR-19).

Recently, two shorter questionnaires have been developed including a 5-item Compliance Questionnaire Rheumatology (CQR-5) and the 9-item Medication Adherence Rating Scale (MARS-9).

The reliability analysis was conducted in a group of randomly selected patients with rheumatoid arthritis (RA) from a group of patients at Sunnybrook Hospital in Toronto. The researches recruited 100 patients, with a mean age of 61, the vast majority were female, and the patients were highly educated with 78% having at least some post-secondary education.

The CQR-5 and MARS-9 medication adherence questionnaires were administered to the group. The questionnaires were completed at three time points: at baseline, 2 weeks, and 3 months.

Between baseline and the 2-week visit, the Intra-Class Correlation Coefficient (ICC) for the CQR-5 was 0.78. This is considered to be an acceptable ICC. Between baseline and 3 months, the ICC was fairly stable at 0.73. Interestingly, this ICC was identical to the data published for the original CQR-19. This suggests the CQR-5 is stable over time.

The ICC for the MARS-9 was 0.57 measured between baseline and 2 weeks, and 0.43 between baseline and 3 months.

In summary, the CQR-5 appears to be more reliable than the MARS-9 as measured by the ICC. Furthermore, test-retest reliability of the CQR-5 was similar to the original CQR-19.

Challenges with medication compliance questionnaires remain prevalent. Medication compliance questionnaire scores have been positively correlated with semi-structured interviews. However, questionnaires and interviews do not correlate well with electronic medication measures or with medication possession ratios (MPRs). Medication compliance questionnaires likely under-report the true level of adherence. If in doubt about a patient's adherence, call the pharmacy. It isn't perfect but it is the best we have.


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About the Author

Dr. Andy Thompson
Dr. Andy Thompson

Dr. Andy Thompson is an Associate Professor at Western University and founder of Rheuminfo.com, Rheumtalks.com, and RheumReports.com.

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