Compelling evidence has long shown that diagnostic imaging for low back pain does not improve care in the absence of suspicion of serious pathology. However, the effect of imaging use on clinical outcomes has not been investigated in patients presenting to chiropractors. The aim of this study was to determine if diagnostic imaging affects clinical outcomes in patients with low back pain presenting for chiropractic care.
A matched observational study using prospective longitudinal observational data with a one-year follow-up was performed in primary care chiropractic clinics in Denmark. Data were collected from November 2016 to December 2019. Participants included low back pain patients presenting for chiropractic care, who were either referred or not referred for diagnostic imaging at their initial visit. Patients were excluded if they were younger than 18 years, had a diagnosis of underlying pathology, or had previously had imaging relevant to their current clinical presentation. Coarsened exact matching was used to match participants referred for diagnostic imaging with participants not referred for diagnostic imaging on baseline variables including participant demographics, pain characteristics, and clinical history. Mixed linear and logistic regression models were used to assess the effect of imaging on back pain intensity and disability at two weeks, three months, and one year, and on global perceived effect and satisfaction with care at two weeks.
A total of 2162 patients were included, and 24.1% of them were referred for imaging. Near perfect balance between matched groups was achieved for baseline variables except for age and leg pain. Participants referred for imaging had slightly higher back pain intensity at two weeks (0.4, 95%CI: 0.1, 0.8) and one year (0.4, 95%CI: 0.0, 0.7), and disability at two weeks (5.7, 95%CI: 1.4, 10.0), but these differences are unlikely to be clinically meaningful. No difference between groups was found for the other outcome measures. Similar results were found when a sensitivity analysis, adjusted for age and leg pain intensity, was performed.
The authors concluded that diagnostic imaging did not result in better clinical outcomes in patients with low back pain presenting for chiropractic care. These results support that current guideline recommendations against routine imaging apply equally to chiropractic practice.
This study confirms what most experts suspected all along and what many chiropractors vehemently denied for years. One could still argue that the outcomes do not differ much and therefore imaging does not cause any harm. This argument would, however, be wrong. The harm it causes does not affect the immediate clinical outcomes. Needless imaging is costly and increases the cancer risk.