Background“Flare” is a word often used by Sjögren’s patients and medical professionals, without any official definition or consensus on what it means. In addition, the heterogeneous nature of Sjögren’s symptoms means that the definition of a “flare” will vary greatly from patient to patient. As part of the European Necessity project,www.necessity-h2020.eu,7 Sjögren’s patients from the Patient Advisory Group (PAG) addressed this issue and hereby present our definition of a Sjögren’s flare from the patient perspective.ObjectivesTo provide a common definition of a flare in Sjögren’s despite the heterogeneity and subjectivity of symptoms and provide patients and medical professionals with a mutual, basic understanding of flares.MethodsThe Necessity PAG Members discussed which symptoms should be included in the definition of a flare. Flares are as heterogeneous and variable as the disease, but some symptoms appear more prominent than others. The symptoms selected by the PAG were compared with findings from the 2021 U.S. Sjögren’s Foundation survey. The 9 symptoms determined as the most commonly reported by patients were: dryness, fatigue, morning stiffness, global pain (joints, muscles, nerves, headache), forgetfulness and brain fog, depression and anxiety and sleep disorders. It was agreed that these are among the symptoms most likely to worsen the patient’s condition from the patient’s perspective.Not all of these symptoms are included in the usual assessment indices, such as the ESSDAI* or ESSPRI*. However, the different impairments experienced by patients should be taken into account when defining and assessing a flare. In addition, it is also important to clarify and mention that a flare is not necessarily systemic. It may relate to only one of the symptoms, e.g. the dryness, without necessarily leading to a worsening of the other symptoms.ResultsThe PAG agreed on the following definition: “A flare is the temporary and sudden onset of symptoms that become significantly worse before resolving and, on average, last at least 3 days.”ConclusionThe PAG considers agreement on how the term “flare” is used to be important for clinical trials as well as for patients and clinical management. For trials, use of a tool to measure flares as a patient reported outcome (PRO) would add value in gauging the patient experience in a global way and provide another potential index for evaluating treatments. Further discussion and validation is needed, however, as the high variability and subjectivity of symptoms makes establishing such a tool especially difficult. Nevertheless, patients need to be aware of flares so they can identify potential organ damage and obtain the best care possible. A flare assessment tool can allow the patient to be better informed, to better monitor their condition and to facilitate communication with their doctor.