Classification of nonspecific low back pain. II. Clinical diversity of organic forms

A classification study was conducted in an unselected sample of outpatient subjects with localized nonspecific low back pain. The heterogeneity of a subgroup of patients without a psychiatric disorder according to the DSM-III classification (axis I), and whose low back pain may be labeled as 'purely organic' (see part 1 of the study in the companion paper), led to further evaluation of this group by correspondence and cluster analysis. A seven-cluster population structure emerged from the cluster analysis. Comprehensive description of these clusters suggests at least four well-differentiated clinical entities or 'syndromes.' Although no satisfactory correlation with pre-existing 'pathoanatomic' classification or hypotheses was found, this variable clinical presentation suggests different etiological or physiopathologic patterns for low back pain (and possibly more specific management of this condition). More comprehensive descriptions and evaluations of clinical symptoms and syndromes appear necessary in order to elaborate a clinical classification of LBP.