Variation of response to questionnaires in the two weeks before surgery for lumbar disc herniation

Abstract

Background: The Core Outcome Measures Index (COMI) is one of many patient-reported outcome measures developed and validated in the field of spinal surgery. In order to evaluate the reliability of this instrument, thorough and routine testing and validation is required. Methods: The investigators analysed preoperative COMI questionnaires of individuals undergoing surgery for lumbar disc herniation, collected in two different moments, approximately two weeks apart, during which time their symptomatology was not expected to change significantly. Results: Preoperative questionnaires from 56 patients were analysed. The mean final score was 7.98 for the first questionnaire and 8.20 for the second (p=0.176, mean difference: -0.214), 62.5% of subjects reported feeling overall similar, over the course of those two weeks, and 26.8% reported a slight worsening, although these findings had no correlation with the variation demonstrated by the final COMI score. Four specific questions, regarding patient satisfaction, quality of life, and impact on everyday life, had statistically different results from the first to the second interview. Current smokers had a higher variation between the two questionnaires, with a mean variation of 0.941, versus -0.103 in non-smokers (p=0.003). Conclusions: The COMI questionnaire demonstrated good internal validity and reproducibility, when applied to patients whose symptoms were not expected to have changed significantly. Even amongst subjects who felt their symptomatology had worsened slightly, the questionnaire did not demonstrate significant variations. Further investigation could be pursued in order to address the effect of smoking on the variation of responses to the questionnaire.