AB0791 ONE VERSUS TWO INJECTIONS OF INTRA-ARTICULAR HIGHLY CROSS-LINKED HYALURONAN YEARLY IN PATIENTS WITH KNEE OSTEOARTHRITIS: INSIGHTS FROM ROUTINE CLINICAL PRACTICE
Authors: Tsvetoslav Georgiev, Rumen Stoilov
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Hyaluronic acid (HA) is a natural polysaccharide, which is an important structural component of synovial fluid and cartilage. There are different injectable forms of HA used for clinical application. Highly cross-linked/high-molecular-weight hyaluronans (HMWHA) provide additional stability and improve functionality [1], resulting in longer bioavailability in the knee joint and promoting viscoinduction [2]. A direct comparison between the two most common injection protocols of HMWHA in our routine practice is of great practical interest, since viscosupplementation is among the most commonly used treatment modalities for patients with knee osteoarthritis (KOA) in Bulgaria [3]. <h3>Objectives:</h3> Our aim was to compare the clinical effectiveness of two different regimens for injecting intra-articular HMWHA in KOA patients under 'real-world' conditions in routine clinical practice. <h3>Methods:</h3> This prospective, open-label, observational study included 50 patients with KOA who were followed for a period of 1 year. They were divided into two therapeutic arms according to their preselected treatment regimen: patients injected once with HMWHA (n = 25; group 1) at baseline and patients injected twice 6 months apart with HMWHA (n = 25; group 2). A 100-mm visual analogue scale (VAS) for pain, disease-specific (Western Ontario &amp; McMaster Universities Osteoarthritis index [WOMAC]) and generic (health assessment questionnaire – disability index [HAQ-DI]) questionnaires were used to evaluate patients at baseline, three months, six months, and one year later. Standardized radiographs were obtained at baseline and after one year. The response to the treatment was determined using the OMERACT-OARSI set of responder criteria [4]. <h3>Results:</h3> A single injection of HMWHA resulted in a statistically significant improvement in pain even at 12 months (ΔVAS = 10.12 ± 14.5 mm, p &lt; 0.05), although the effect progressively decreased after the third month when ΔVAS was 18 ± 14.31 mm, p &lt; 0.05 (Figure 1). If the two regimens of HA injections were directly compared, the mean difference of pain improvement for the year of follow-up was about 9 mm in favor of group 2, but this result was not "statistically" significant (10.12 vs 19.16 mm, p &gt; 0.05). Physical function was statistically improved in both groups (p &lt; 0.05) without any statistically significant difference. Responders in the first group in the end of the year were 40% (10/25) and 60% (15/25) in group 1 and group 2, respectively (p &gt; 0.05). In the end of the follow-up period HAQ-DI did only statistically improve among patients in group 2. <h3>Conclusion:</h3> If maximal symptomatic relief is our primary goal, it would be logical to choose a two-injection regimen. However, if we take into account the financial aspect, we may be satisfied with a single injection of highly cross-linked HA over a year. <h3>References</h3> [1] Bowman S, awad ME, Hamrick MW, Hunter M, Fulzele S. Recent advances in hyaluronic acid based therapy for osteoarthritis. Clinical and translational medicine. 2018Dec;7(1):6. doi: 10.1186/s40169-017-0180-3 [2] Divine JG, Zazulak BT, Hewett TE. Viscosupplementation for knee osteoarthritis: a systematic review. Clin Orthop Relat Res. 2007;455:113–122. [3] Georgiev T, Stoilov R. Bulgarian rheumatology: science and practice in a cost-constrained environment. Rheumatology international. 2018Nov9:1-3. doi: 10.1007/s00296-018-4202-2 [4] Pham T, van der Heijde DM, altman RD, anderson JJ, Bellamy N, Hochberg M, Simon L, Strand V, Woodworth T, Dougados M. OMERACT-OARSI initiative: Osteoarthritis Research Society international set of responder criteria for osteoarthritis clinical trials revisited. Osteoarthritis and Cartilage. 2004May1;12(5):389-99. <h3>Disclosure of interests:</h3> Tsvetoslav Georgiev: None declared, Rumen Stoilov Speakers bureau: abbvie, Pfizer, amgen, UCB, Novartis