J Rheum Dis 2019; 26(3): 179-185  
Nonsteroidal Anti-inflammatory Drugs-sparing Effect of Symptomatic Slow-acting Drugs for Osteoarthritis in Knee Osteoarthritis Patients
Soo-Kyung Cho1, Hyoungyoung Kim1, Ha-Rim Park1, Wooseok Choi2, Seongmi Choi2, Sun-Young Jung3, Eun Jin Jang4, Yoon-Kyoung Sung1
1Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, Seoul, 2Department of Statistics, Kyungpook National University, Daegu, 3College of Pharmacy, Chung-Ang University, Seoul, 4Department of Information Statistics, Andong National University, Andong, Korea
Correspondence to: Yoon-Kyoung Sung http://orcid.org/0000-0001-6691-8939
Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea. E-mail:sungyk@hanyang.ac.kr
Received: December 26, 2018; Revised: March 13, 2019; Accepted: March 13, 2019; Published online: July 1, 2019.
© Korean College of Rheumatology. All rights reserved.

This is a open Access article, which permits unrestricted non-commerical use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objective. To evaluate the nonsteroidal anti-inflammatory drugs (NSAID)-sparing effect of symptomatic slow-acting drugs for osteoarthritis (SYSADOA) in knee osteoarthritis (OA) patients. Methods. A retrospective study was conducted on a cohort of knee OA patients who visited a single academic referral hospital from 2013 to 2014. Among all patients, NSAID users in their first visit were extracted and divided into SYSADOA users and SYSADOA non-users. All patients were observed from their first visit with knee OA to their last visit, NSAID discontinuation, or the date of data collection, July 2017 (mean observational periods: 369.1 days). To evaluate the NSAID-sparing effect of SYSADOA, Cox regression analysis was performed after adjusting for confounding factors. Results. Patients for this study (n=212) were divided into SYSADOA users (n=57) and SYSADOA non-users (n=155). The mean age (68.8 vs. 66.6 years old, p=0.31) and the number of comorbidities (p=0.73) were comparable between the two groups. The SYSADOA users showed higher Kellgren–Lawrence (KL) grade (66.7% of patients with more than KL grade 3) than SYSADOA non-users (42.6% of patients with more than KL grade 3) (p=0.02). In treatment, the frequency of intra-articular injection was higher in the SYSADOA user group than the SYSADOA non-user group (33.3% vs. 9.0%, p<0.01). In Cox regression analysis, SYSADOA use contributed to NSAID discontinuation in knee OA patients (hazard ratio 2.97, 95% confidential interval 1.42∼6.22). Conclusion. This real-world analysis demonstrated that SYSADOA use combined with NSAIDs had a significant effect on NSAID discontinuation in patients with knee OA.
Keywords: Osteoarthritis, Symptomatic slow-acting drugs for osteoarthritis, Nonsteroidal anti-inflammatory drugs

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