Inflammatory back pain: the United States perspective.

Inflammatory back pain (IBP) is a relatively recent and well-accepted concept whose precise definition remains elusive. The definition of IBP varies by criteria set, as does its sensitivity and specificity regarding screening and case ascertainment in various clinical or epidemiologic settings. This article reviews the history of efforts to define IBP, particularly the criteria sets that have been built around its measurement, describes assessment of IBP in the clinical setting, and illustrates how IBP has been used in epidemiologic and clinical research.