What is the clinical relevance of the Numerical rating scale for pain?

Abstract

The landmark paper discussed in this chapter is ‘Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale’, published by Farrar et al. in 2001. The numerical rating scale is now the standard instrument used in chronic pain studies to measure pain intensity. Farrar et al. determined the changes in pain intensity that were clinically significant for studies of chronic pain while measuring the patient’s global impression of change. The paper used pooled data from ten recent studies of pregabalin in 2,724 subjects. The authors reported a consistent relationship between pain intensity and patient global impression of change, regardless of study, disease type, age, sex, study result, or treatment group. A reduction of approximately two points on the numerical rating scale, or of 30% in the global impression of change of pain intensity, represented a clinically important difference.