Evolution of Outcome Assessment in Chronic Low Back Pain Clinical Trials Throughout the 20th and 21st Centuries: A Scoping Review

OBJECTIVE: To identify, map, and synthesise the outcomes reported in patients with Chronic Low Back Pain (CLBP) and describe how these outcomes have changed over time throughout the 20th and 21st centuries. METHODS: A scoping review was conducted according to the Joanna Briggs Institute methodology and reported following the PRISMA-ScR guidelines. Four electronic databases (PubMed, Embase, PEDro, and Google Scholar) were searched for clinical trials published between 1975 and 2025. Five independent reviewers screened studies, extracted data, and categorised reported outcomes into conceptually related domains. Outcomes and measurement instruments were synthesised descriptively and narratively according to four chronological periods. RESULTS: A total of 708 clinical trials met the eligibility criteria. Pain intensity remained the only outcome consistently reported throughout the entire study period. Over time, outcome assessment progressively expanded to include disability, physical function, physical performance, psychological health, quality of life, work-related outcomes, sleep, fatigue, physical activity, healthcare utilization, and patient-reported outcomes. Measurement instruments also evolved from predominantly symptom-oriented scales to standardized multidimensional questionnaires and, more recently, objective digital technologies. Overall, outcome assessment shifted from a predominantly biomedical approach toward comprehensive biopsychosocial evaluation. CONCLUSIONS: Outcome assessment in CLBP clinical trials has undergone a marked conceptual evolution over the past 5 decades. These findings support the adoption of standardized, multidimensional, and patient-centred outcome frameworks to improve the methodological quality, comparability, and clinical relevance of future clinical trials.