Outpatients with low back pain: An analysis of the rate per day of pain improvement that may be expected and factors affecting improvement

Objective: To determine, only for those who improved, the rate per day of improvement expected for outpatients with low back pain and to identify factors influencing pain improvement: pain duration before assessment, pain and physical functioning levels before assessment, age, sex, and affective factors. It was presupposed that affective factors would have an appreciable effect. Design: The LIFEware System^SM database was used. Analysis was performed on 1292 records for the Painfree measure and 1562 records for the LIFEware System Visual Analog Scale. Measures for pain, physical functioning, and affective well-being were analyzed for 0-30 days vs. >30 days of pain duration before assessment using classification and regression trees analysis. Results: In both Painfree and LIFEware System Visual Analog Scale, 73% improved and 27% did not improve. Of those who improved, outpatients with 0-30 days of pain duration before assessment had higher per day rates of improvement than the >30 days group. Factors affecting improvement were, in descending order, more initial pain, younger age, and positive affective well-being; physical functioning did not affect rate of improvement. Factors affecting improvement for outpatients with >30 days since onset were, in descending order, more initial pain and better initial physical functioning; age and affective well-being were not factors. For all, neither sex nor the "satisfaction with life in general" question affected low back pain rate of improvement. Conclusion: Findings may be useful for clinical application because the actual rate of improvement may be compared with the expected rate. There was only a weak relationship shown between affective factors and pain improvement.