Characterising flare-ups of knee osteoarthritis in community-dwelling adults: who gets them and how long do they last?

Talk Code: 
R.10
Presenter: 
Martin J Thomas
Co-authors: 
Martin J Thomas, Trishna Rathod-Mistry, Emma L Parry, Christopher Pope, Tuhina Neogi, George Peat
Author institutions: 
Primary Care Centre Versus Arthritis, School of Primary, Community and Social Care, Keele University, Midlands Partnership NHS Foundation Trust, Keele Clinical Trials Unit, Keele University, Boston University School of Medicine

Problem

Acute flare-ups are experienced by a substantial proportion of adults with osteoarthritis (OA), but these events remain poorly understood. As part of a wider programme of research, the current study aimed to (i) identify participant or knee symptom characteristics associated with higher risk of flare-ups, (ii) describe the time course and consequences of flare-ups of knee OA to provide better information for healthcare professionals and patients on the likely short-term prognosis.

Approach

The ACT-FLARE study (ACuTe FLAREs in knee OA) is a 13-week web-based case-crossover study of knee pain in people aged ≥40 years resident in England, with or without a recorded diagnosis of knee OA, and no inflammatory arthropathy. Participants were recruited from 15 general practice registers, and from the community via distributed flyers/posters and online social media advertisement. After completing a baseline questionnaire, participants were encouraged to self-report a flare-up at any time during the study period via the website. A flare-up was defined as the sudden onset of worsening signs and symptoms, sustained for ≥24 hours. After characterising their flare-up, from notification date through to flare-up resolution participants completed four daily questions about the last 24 hours: i) average pain (0-10 NRS), ii) level of bothersomeness, iii) pain medication use, and iv) whether the flare-up had resolved. Associations between selected participant and knee symptom characteristics at baseline and the occurrence of flare-ups were estimated using Poisson regression and expressed as unadjusted incidence rate ratios (IRR; 95%CI). Flare-up characteristics, course and consequences were analysed descriptively.

Findings

Of 744 participants recruited between July 2018 and February 2019 (mean age (SD) 62.1 (10.2) years; 60% female, body mass index 29.2 (5.7) kg/m2), 493 participants reported 714 flare-ups. Among participants who engaged throughout study follow-up, 242 (51%) reported ≥1 flare-up. Flare-ups were more common in younger ages (IRR 0.98: 95%CI 0.97, 0.99), females (1.85: 1.43, 2.39), and those with severe frequent knee pain at baseline (2.06: 1.17, 3.63). Associations with prior knee injury/surgery and socioeconomic status were weak or absent. Among those whose end dates were known, number of flare-ups per participant ranged between 1 and 6 (mean (SD) 1.32 (0.64)) and median (IQR) flare-up duration was 5 (3, 8) days. Knee changes noticed since flare-up onset included: stiffness (64%), limping (58%), increased difficulty with everyday activities (57%), sleep disturbance (48%) and swelling (33%). Levels of pain, bothersomeness and medication usage reduced over the period between flare-up onset and resolution.

Consequences

Knee OA flare-ups are most commonly reported by working age adults, females and those with more persistent pain patterns. Most flare-ups appear to last between 3 and 8 days.

Submitted by: 
Martin Thomas
Funding acknowledgement: 
MJT is joint-funded by a Health Education England (HEE) and National Institute for Health Research (NIHR) Integrated Clinical Academic Programme Clinical Lectureship (ICA-CL-2016-02-014) for this research project. ELP received funding from an NIHR In-Practice Fellowship (IPF-2014-08-03) and an NIHR Academic Clinical Fellowship and is currently supported by an NIHR School for Primary Care Research GP Progression Fellowship. TN is funded by NIH K24 AR070892, R01 AG066010 and P30 AR072571. This conference abstract presents independent research funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, HEE or the Department of Health and Social Care.