Interexaminer reliability and discriminant validity of inclinometric measurement of lumbar rotation in chronic low-back pain patients and subjects without low-back pain.

The interexaminer reliability of an inclinometer procedure to measure lumbar rotation was evaluated by two chiropractic clinicians who examined 25 chronic (greater than 6 months) low-back pain patients and 25 subjects without low-back pain. These groups were compared for differences in mean left, right, and total rotation. Patients who had lumbar spinal surgery were excluded. Twenty-eight men and 22 women, ranging in age from 28-38 years, were evaluated. Reliability between examiners was evaluated by Pearson's correlation coefficient and the intraclass correlation coefficient. All coefficients were significant (P less than 0.01). Errors in prediction and examiner disagreement were evaluated by the standard error of estimate and the interexaminer measurement error. The standard errors of estimate (range: 1.4-4.4) and the interexaminer measurement errors (range: 3.8-10.4) were large compared to the scale of measurement. An analysis of variance of differences between the chronic low-back pain patients and asymptomatics revealed significantly more left rotation in the asymptomatic subjects (F = 8.4; df = 1; P less than 0.006). Also, there was significantly more total rotation in the asymptomatic subjects (F = 4.143; df = 1; P less than 0.048). However, because of the large error attributed to this procedure, it is not possible to say whether the difference between the two groups is a result of the large error or some "real" difference. Therefore, the procedure described in this study should not be used as a clinical outcome measure.