Clinical trials in rheumatoid arthritis (RA) currently focus on measuring severity of functional disability, patient global assessment, pain, and morning stiffness1. However, the inclusion of patient-reported outcome measures (PROM) to assess the impact of illness has been recognized as an important development, and collaboration with patients in developing PROM is becoming mandatory2. While it is recognized that patients and professionals may have different values and priorities3, discussion continues about how to incorporate outcomes that are important to patients. Recent collaborations with patients in the conception of outcome measures have revealed 3 aspects of impact that require assessment. These are the severity of an outcome, its importance to the patient, and patient ability to self-manage (Figure 1). We provide 3 examples of how this impact triad emerged in recent RA research and discuss how the concept may influence the development of future instruments. Figure 1. The impact triad. The first example comes from extensive focus group data exploring a patient definition of flare in RA4. The emergent definition included 3 components: as symptom intensity increased (i.e., severity), symptoms were sufficiently different from normal background variations (i.e., became important), and the actions patients took to deal with them failed (i.e., self-management). This resulted in a tipping point being reached where medical help was sought for uncontrolled flare. The patients’ complex model of flare goes beyond a simple increase in the number of swollen joints or the intensity of pain, to include these additional considerations. Therefore, the future development of a flare instrument will require not only items on the severity of flare-related symptoms, but also items on how these are different from patients’ perceptions of normal background symptoms and items on the controllability of symptoms. The second example comes from the development of a set of … Address correspondence to Prof. S.E. Hewlett, Academic Rheumatology, Bristol Royal Infirmary, Bristol BS2 8HW. E-mail: Sarah.Hewlett{at}uwe.ac.uk