How little pain and disability do patients with low back pain have to experience to feel that they have recovered?

Epidemiological and clinical studies of people with low back pain (LBP) commonly measure the incidence of recovery. The pain numerical rating scale (NRS), scores from 0 to 10, and Roland Morris disability questionnaire (RMDQ), scores from 0 to 24, are two instruments often used to define recovery. On both scales higher scores indicate greater severity. There is no consensus, however, on the cutoff scores on these scales that classify people as having recovered. The aim of this study was to determine which cutoff scores most accurately classify those who had recovered from LBP. Subjects from four clinical studies were categorized as 'recovered' or 'unrecovered' according to their self-rating on a global perceived effect scale. Odd ratios were calculated for scores of 0, 1, 2, 3 and 4 on the NRS and RMDQ to predict perceived recovery. Scores of 0 on the NRS and <or=2 on the RMDQ most accurately identify patients who consider themselves completely recovered. The diagnostic odds ratio (OR) for predicting recovery was 43.9 for a score of 0 on the NRS and 17.6 for a score of <or=2 on the RMDQ. There was no apparent effect of LBP duration or length of follow-up period on the optimal cutoff score. OR for the NRS were generally higher than those for RMDQ. Cutoffs of 0 on the NRS and 2 on the RMDQ most accurately classify subjects as recovered from LBP. Subjects consider pain more than disability when determining their recovery status.