FRI0422 HOW MANY OA PATIENTS WILL BE OVERTREATED IF TREATED WITH DMOADS? ANALYSIS OF OSTEOARTHRITIS INITIATIVE DATA
Authors: I. Shirinsky, V. Shirinsky
Journal: Annals of the Rheumatic Diseases (2020)

Background: Significant research effort is currently put on discovering drugs able to slow structural progression of osteoarthritis (OA). In many patients OA shows little or no increase in pain or function deterioration over time. Thus, giving disease-modifying OA drugs (DMOAD) for long periods to this subset of patients can be considered as overtreatment. There is a lack of studies directly evaluating how many patients with diagnosed OA experience no impact of the disease during long-term follow up and thus probably do not need any disease modification. Objectives: To assess proportions of patients with diagnosed symptomatic knee OA or frequent knee pain that does not result in sustained pain and limitation of function during long-term follow up. Methods: For the current study we used 8-year longitudinal data obtained from the Osteoarthritis Initiative (OAI) progression (n= 1390) and incidence (n = 3284) subcohorts, which are publically available at https://oai.nih.gov . For the analyses we included knees having frequent knee symptoms in the past 12 months before the baseline for at least one month. Thus the analyzed group comprised patients fulfilling the definition of symptomatic knee OA (frequent symptoms + Kellgren-Lawerence (KL) grade ≥ II) and people who might have early OA (frequent symptoms + KL grade &lt; II) in accordance with the proposed draft classification criteria [1]. The proportion of knees experiencing no impact of OA at the 8 years follow-up was assessed. No impact of OA was defined if a knee fulfilled all the following criteria: 1. WOMAC pain score within normative values 2. WOMAC disability score within normative values 3. Absence of joint replacement. We used previously reported reference population age and gender adjusted values for WOMAC knee pain and WOMAC knee function [2]. It is unlikely that any OA treatment is capable to improve WOMAC pain and function measures above these reference ranges in a given person [2]. Results: We included 3092 knees from 2147 participants in the analysis. The mean age of participants was 61.16 years, the mean BMI was 28.59. Almost half of symptomatic knees with baseline KL grades 0-I were not impacted by the disease at 8 year follow up. Every fifth knee with symptomatic knee OA (KL grades ≥ II) had no impact of the disease at the end of follow up. Every third knee with symptomatic KL grade II OA did not develop pain or disability outside the reference range. The percentage of symptom-free knees at year 8 declined progressively with higher KL grades (Table). Table. Percentage of knees with no impact of OA on 8 year follow up depending on baseline KL grade. Baseline KL grade Total n of knees Percentage of knees with no impact of OA 0 894 47 % 45.78% I 469 43.1% II 923 31.31% 19% III 609 17.7% IV 197 7.1% Conclusion: If given DMOADs, a substantial proportion of OA patients would be overtreated, especially those with early OA. References: [1]Luyten FP, Bierma-Zeinstra S, Dell’Accio F, Kraus VB, Nakata K, Sekiya I, Arden NK, Lohmander LS: Toward classification criteria for early osteoarthritis of the knee. Semin Arthritis Rheum 2018, 47(4):457-463. [2]Bellamy N, Wilson C, Hendrikz J: Population-based normative values for the Western Ontario and McMaster (WOMAC) Osteoarthritis Index: part I. Semin Arthritis Rheum 2011, 41(2):139-148. Disclosure of Interests: None declared