Are frequent measurements in back pain research harmful? Two comparisons of back pain in groups with or without frequent follow-up.

Background: Frequent measures are becoming increasingly used to evaluate the course of spinal pain. However, it is not known whether this type of continuous follow-up in itself has implications for people's experience of pain. Therefore this article examines a potential impact of frequent follow-up using SMS reporting on the report of pain, based on results from two previous studies of spinal pain. Methods: We examined two sets of cohorts, where each set was comparable in all other aspects, but one cohort in each set had been followed with weekly SMS-questions about the presence of spinal pain for 6 years and 1 year, respectively, whereas the other cohort had not answered any questions for research purposes before. At the end of the follow-up period, two cohorts, consisting of pupils from 5th and 6th grade, completed the Young Spine Questionnaire about spinal pain, one cohort in 2010 and the other in 2014. The other set of cohorts, consisting of low back pain patients in primary care, completed an extensive questionnaire about their back pain (2011 to 2013). Results: In both sets of cohorts there was a statistically significant difference in pain intensity with the pupils/patients who had been subject to frequent follow-up over long periods of time reporting lower intensity of pain. Other differences were small and not statistically significant. Conclusion: Since the data were not optimally suited for the purpose of these analyses, the results should obviously be interpreted with caution, but they do not support a theory about increased attention leading to increased awareness, which in turn will lead to increased pain. On the contrary, participants reported lower levels of pain when belonging to the samples that had been subject to frequent follow-up by SMS-track over long periods of time.