A unidimensional pain/disability measure for low-back pain syndromes

A new measure is presented, suitable for documenting severity and response to treatment in chronic low-back pain syndromes. It is self-administered and combines two pain and seven mobility items. These were selected from pre-existing validated instruments on the basis of their sensitivity to change after treatment. Their Italian validated translation was adopted. The measure was administered to 32 chronic low-back pain Italian patients, all refractory to previous conservative treatments. In most cases they presented with herniation or protrusion of 1–3 lumbar discs. Patients were treated with 3–6 sessions of autotraction over a 5- to 15-day period. Scores on the scale were recorded at admission, discharge and follow-up, 1–3 months after treatment. At discharge and at follow-up, patients were asked if, overall, they felt improved, the same or worse. At follow-up, 20 patients out of 32 reported overall improvement. Scalometric properties of the measure were tested using Rasch analysis. For admission and follow-up, items followed a consistent hierarchical relationship along a unidimensional pain/disability variable, which is being called back illness. The items were not redundant, in that they spread well along a wide range of difficulty/severity. The hierarchy matched well with the expected expression of the conditions of the patients. A study was conducted on 34 chronic back pain patients, showing satisfactory test-retest reliability. Depending on the various items, Cohen's unweighted K ranged from 0.27 to 0.78, with ten of the 11 items above the 0.45 level of acceptability, while intraclass correlation coefficients ranged from 0.42 to 0.89. At follow-up, changes in BACKILL of plus 15% or more, with respect to admission, were consistent with patients' reports of improvement in 19 out of 20 cases. Changes in BACKILL of less than 15% were consistent with patients reports of being the same or worse in 11 out of 12 cases.