Cultural Adaptation of a Compliance Questionnaire for Patients with Rheumatoid Arthritis to a Korean Version

BACKGROUND/AIMS: The Compliance Questionnaire-Rheumatology (CQR) is a validated scale to evaluate patient compliance for anti-rheumatic medications. We developed a Korean version of the CQR (KCQR) and confirmed its reliability and validity. METHODS: We prepared the KCQR by translating and back-translating the original CQR with modifications to adapt it to Korean culture. Fifty Korean patients with rheumatoid arthritis (RA) were enrolled in this study. The test-retest reliability of the KCQR was evaluated at a 2-week interval using the intraclass correlation coefficient (ICC). The validity of the KCQR was assessed by identifying associations between KCQR scores and patient compliance, measured using pharmacy refill data. RESULTS: The reliability of the KCQR was adequate, with an ICC of 0.71 for test-retest reliability. With respect to validity, the summed score of the weighted KCQR showed a significant correlation with pharmacy refill data (r2 = 0.57) on multiple regression analysis. CONCLUSIONS: Our results indicate that the KCQR is a reliable, valid instrument to evaluate compliance of Korean patients for RA medications.

Risk Factors of Drug Interaction between Warfarin and Nonsteroidal Anti-Inflammatory Drugs in Practical Setting

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to interact with the oral anticoagulant warfarin and can cause a serious bleeding complication. In this study, we evaluated the risk factors for international normalized ratio (INR) increase, which is a surrogate marker of bleeding, after addition of an NSAID in a total of 98 patients who used warfarin. Patient age, sex, body mass index, maintenance warfarin dose, baseline INR, coadministered medications, underlying diseases, and liver and kidney functions were evaluated for possible risk factors with INR increase > or =15.0% as the primary end-point. Of the 98 patients, 39 (39.8%) showed an INR elevation of > or =15.0% after adding a NSAID to warfarin therapy. Multivariate analysis showed that high maintenance dose (>40 mg/week) of warfarin (P=0.001), the presence of coadministered medications (P=0.024), the use of meloxicam (P=0.025) and low baseline INR value (P=0.03) were the risk factors for INR increase in respect to NSAID-warfarin interaction. In conclusion, special caution is required when an NSAID is administered to warfarin users if patients are taking warfarin >40 mg/week and other medications interacting with warfarin.

Dosage Adjustment before and after Warfarin - Rifampin Combination Therapy / 대한흉부외과학회지

BACKGROUND: Warfarin is used as an anticoagulant and it is mainly excreted by the liver metabolism (the R-form is mainly metabolized by cytochrome p450 3A4, and the S form by cytochrome p450 2C9). Rifampin is usually used for tuberculosis or endocarditis, and it is a representative drug that induces the CYP families, including 3A4 and 2C9. The anticoagulation effect of warfarin decreases through the increased metabolism that's due to the induction of enzymes, and this iscaused by rifampin when patients take these two medicines together. No one has suggested appropriate guidelines regarding this drug interaction even though an appropriate adjustment of warfarin's dosage is needed. We examined the drug interaction in patients who received warfarin - rifampin combination therapy according to the time interval, and the factors affecting drug interaction were analyzed. Based on the data, we tried to determine the clinically available warfarin dosage guidelines before and after taking this drug combination. MATERIAL AND METHOD: We reviewed the OO University Hospital anticoagulation service team's follow up sheets that were filled out from Jan 1998 to Sep 2006 for the patient who took warfarin - rifampin combination therapy (n=15). RESULT: The average INR of all the patient before rifampin administration was 2.25+/-0.52 (mean+/-SD), and that value for the first 100 days after rifampin administration was 1.98+/-0.28. The p value for these two sets of data showed no correlation (paired t-test, p>0.05). The average INR of all the patient before rifampin cessation was 2.19+/-0.34, and the value after rifampin cessation was 2.49+/-0.43. The p value of these two showed correlation (paired t-test, p<0.05) but the average INR falls between the therapeutic INR range. CONCLUSION: The warfarin dose adjustment equation of before and after warfarin - rifampin combination therapy was derived based on this study's results because the warfarin dosage adjustment of the anticoagulation service team was considered appropriate.