Core outcome measurement instruments for clinical trials in nonspecific low back pain

To standardize outcome reporting in clinical trials of patients with non-specific low back pain (LBP), an international multidisciplinary panel recommended physical functioning, pain intensity, and health-related quality of life (HRQoL) as core outcome domains. Given the lack of consensus on measurement instruments for these three domains in patients with LBP, this study aimed to generate such consensus. The measurement properties of 17 patient-reported outcome measures for physical functioning, three for pain intensity, and five for HRQoL were appraised in three systematic reviews following COSMIN methodology. Researchers, clinicians and patients (n = 207) were invited in a two-round Delphi survey to generate consensus ( ≥ 67% agreement among participants) on which instruments to endorse. Response rates were 44% and 41%, respectively. In Round 1, consensus was achieved on the Oswestry Disability Index version 2.1a (ODI 2.1a) for physical functioning (78% agreement) and the Numeric Rating Scale (NRS) for pain intensity (75% agreement). No consensus was achieved on any HRQoL instrument, although the Short Form 12 (SF12) approached the consensus threshold (64% agreement). In Round 2, consensus was reached on a NRS version with a 1-week recall period (96% agreement). Various participants requested one free-to-use instrument per domain. Considering all issues together, recommendations on core instruments were formulated: ODI 2.1a or 24-item Roland-Morris Disability Questionnaire for physical functioning, NRS for pain intensity, SF12 or 10-item PROMIS Global Health form for HRQoL. Further studies need to fill the evidence gaps on the measurement properties of these and other instruments.