Background: Patient-reported outcomes are expected to play an important role in patient-centred health care. To capture patients’ perspectives, patient involvement in the development of patient-reported outcome (PRO) instruments is essential, but often lacking. This qualitative study explored the perspectives of patients with low back pain, to gain an understanding of how to qualify a patient-centred consultation by using PROs. This was done by exploring patients’ perspectives regarding the assessment of functioning and disability as part of the development of a new PRO instrument based on the International Classification of Functioning, Disability and Health Core Set. Methods: Semi-structured focus group interviews with seven patients with low back pain were conducted. Data were analysed by drawing on the Interpretive Description methodology. Results: The analysis revealed three core themes: simplicity, individuality and application. Simplicity represented keeping items to a minimum and avoiding overlaps; individuality implied the need for individualized answers; and application signified that PROs should be utilized during the consultation, and that they can provide useful information for clinical decision-making. Conclusions: The study provides essential knowledge about elements of importance to patients with low back pain when aiming for a patient-centred consultation using PROs. Furthermore, it underlines the importance of involving patients in PRO development because their perspectives improved the new PRO instrument.