Acute Flares of Knee Osteoarthritis (the ACT-FLARE Study): Protocol for a Web-Based Case-Crossover Study in Community-Dwelling Adults

Abstract

Background The cardinal feature of osteoarthritis (OA) is pain. Although heterogeneity in pain and function have been demonstrated in the long-term course of OA, the more proximate determinants of acute flare-ups remain less clear. How short-term intermittent or transient exposures trigger acute flare-ups has important implications for effective and sustainable self-management strategies. Objective The primary objective of this study is to identify potential triggers of acute flares in knee OA. Secondary objectives are to determine their course and consequences and describe high-risk participant profiles. Methods We carried out a Web-based case-crossover study. This study aims to recruit 620 community-dwelling adults aged ≥40 years, resident in England, and who have knee pain, with or without a recorded diagnosis of knee OA, and no preexisting diagnosis of inflammatory arthropathy. Participants will be recruited via 3 routes: (1) general practice registers, (2) offline community advertisement, and (3) online social media advertisement. By using questionnaires comparing periods before participants’ self-reported flare-up episodes (hazard periods) with periods during the study when their knee OA symptoms are stable (control periods), triggers preceding flare-ups will be identified and examined using conditional logistic regression. Time-to-resolution of flare-up will be examined by monitoring people’s daily pain, bothersomeness, and medication usage until the participant reports when their flare-up episode ends. Rates of flare-ups will be examined across different participant and flare characteristics using regression models to identify high-risk participant profiles. A study-specific Patient Advisory Group (PAG) is providing suggestion, input, and ongoing support for all stages of the research process. Results Participant recruitment opened in July 2018 and is anticipated to continue for 6 months. The study results will be disseminated through a number of channels, including relevant national or international conferences and peer-reviewed publication in a medical journal, via advocacy or charity organizations, such as Versus Arthritis and across social media. Findings will be fed back to members of our PAG, study participants, and clinicians from participating primary care general practices. The PAG will also take an active role in the overall dissemination strategy. Conclusions This study will provide empirical evidence to help patients identify common knee OA flare triggers and provide health care professionals with questions to identify patients at most risk of frequent flare-ups. International Registered Report Identifier (IRRID) DERR1-10.2196/13428

Triggers for acute flare in adults with, or at risk of, knee osteoarthritis: a web-based case-crossover study in community-dwelling adults

“…Adults aged ≥40 years who were resident in England with knee pain, with or without a recorded knee OA diagnosis, with daily access to the internet, and ability to complete questionnaires in English were invited to take part in a 13-week web-based case-crossover study 15 , 16 . Exclusions included inflammatory arthropathies (including gout), fibromyalgia, joint replacement in the flaring knee or knee surgery in the last 3 months.…”

“…Participants who experienced a flare were invited to complete an Event-Driven questionnaire, designed to capture information about the flare and the same potential trigger exposures as in the Scheduled questionnaires, during the day of the flare and the 3 days prior 15 . The Event-Driven questionnaire also invited participants to answer ‘yes/no’ to a question asking if the flare was unexpected.…”

“…They were then invited to complete a Daily questionnaire on pain intensity 30 , bothersomeness 24 , medication use and participant judgement of flare resolution each day until their flare ended. Resolution was defined a priori as return to pre-flare ‘normal’ state for two consecutive days 15 , however this was relaxed to one confirmation due to the lower than expected proportion (36%) meeting the initial definition.…”

“…A Patient Advisory Group confirmed OA flares to be a research priority, provided advice and suggestion across all aspects of preliminary feasibility and pilot work, and inputted to procedures and processes for this full-scale study from inception to dissemination 15 , 16 . Engagement was via workshops and remote correspondence.…”

“…In OA, modifiable excessive or aberrant load exposures to weight-bearing joints are important drivers of etiopathogenesis 14 . In this study, we postulate that intermittent or transient activity-related exposures, including high joint loading activities, are causes of recurrent flares with important implications for acute symptom management and long-term self-management 15 .…”