Longer-term chiropractic care outcomes for US active-duty military personnel with low back pain: secondary analysis of a pragmatic clinical trial

Few trials have directly evaluated outcomes of adding chiropractic care to usual medical care, and prior work has been limited to short-term follow-up. The objective of this work is to address these gaps by evaluating outcomes from the addition of chiropractic care to usual medical care in active-duty U.S. military members with low back pain (LBP) over 52 weeks. A multi-site, pragmatic clinical trial allocated 750 U.S. active-duty military personnel with LBP to usual medical care plus chiropractic care or usual medical care alone with the primary endpoint at 12 weeks. The final 154 participants enrolled in the study were asked to provide longer-term follow-up data. We used inverse probability weighting to account for missing outcome data and analyzed data using linear mixed-effects regression models over all follow-up time points. We report between-group mean differences at 12 and 52 weeks adjusted by baseline age, sex, site, pain duration, worst pain intensity, and interaction terms for site differences by group over time. Primary outcomes were disability (Roland-Morris Disability Questionnaire: RMDQ) and pain intensity (NRS). Secondary outcomes were PROMIS-29: pain interference, physical function, fatigue, sleep disturbance, and social role. A total of 144 participants provided outcome data after 12 weeks. Overall, the mean participant age was 33 years, 113 (78%) were male, 54 (38%) were non-white race, 18 (13%) were Hispanic or Latino ethnicity, and 71 (49%) had chronic LBP. At 12 weeks, moderate between-group difference in RMDQ (2.2 points, 95% CI 0.4 to 4.0) favored chiropractic care with small difference in NRS (0.6, -0.1 to 1.2). At 52 weeks, RMDQ difference was small (1.7, -0.2 to 3.7) and NRS difference was negligible (0.2, -0.5 to 1.0). Improvement in PROMIS domains varied, with many diminishing over the course of follow-up; sleep disturbance demonstrated the greatest longer-term difference in improvement at 52 weeks (3.6, 0.5 to 6.7). Adding chiropractic care to usual medical care for active-duty U.S. military members with low back pain resulted in a small difference in pain-related disability and a meaningful difference in sleep disturbance but not pain intensity at 52 weeks. Differences in pain interference, physical function, and social role estimates also favored the addition of chiropractic care over the longer-term follow-up. This trial was first posted for registration on clinicaltrials.gov (NCT01692275) on 09/06/12.