Chiropractic spinal manipulation and likelihood of tramadol prescription in adults with radicular low back pain: a retrospective cohort study using US data

Abstract

Objectives: Patients receiving chiropractic spinal manipulation (CSM) for low back pain (LBP) are less likely to receive any opioid prescription for subsequent pain management. However, the likelihood of specifically being prescribed tramadol, a less potent opioid, has not been explored. We hypothesised that adults receiving CSM for newly diagnosed radicular LBP would be less likely to receive a tramadol prescription over 1-year follow-up, compared with those receiving usual medical care.

Design: Retrospective cohort study.

Setting: US medical records-based dataset including >115 million patients attending academic health centres (TriNetX, Inc), queried 9 November 2023.

Participants: Opioid-naive adults aged 18-50 with a new diagnosis of radicular LBP were included. Patients with serious pathology and tramadol use contraindications were excluded. Variables associated with tramadol prescription were controlled via propensity matching.

Interventions: Patients were divided into two cohorts dependent on treatment received on the index date of radicular LBP diagnosis (CSM or usual medical care).

Primary and secondary outcome measures: Risk ratio (RR) for tramadol prescription (primary); markers of usual medical care utilisation (secondary).

Results: After propensity matching, there were 1171 patients per cohort (mean age 35 years). Tramadol prescription was significantly lower in the CSM cohort compared with the usual medical care cohort, with an RR (95% CI) of 0.32 (0.18 to 0.57; p<0.0001). A cumulative incidence graph demonstrated that the reduced incidence of tramadol prescription in the CSM cohort relative to the usual medical care cohort was maintained throughout 1-year follow-up. Utilisation of NSAIDs, physical therapy evaluation and lumbar imaging was similar between cohorts.

Conclusions: This study found that US adults initially receiving CSM for radicular LBP had a reduced likelihood of receiving a tramadol prescription over 1-year follow-up. These findings should be corroborated by a prospective study to minimise residual confounding.

Keywords: complementary medicine; pain management; rehabilitation medicine.

Figure 1

Study design. The vertical arrow represents the index date of diagnosis of radicular LBP. Assessment windows to the left of this arrow represent time windows occurring before the index date over a period of days (#,#). ‘∞’ indicates that the time window extends as far retrospectively as data permit per patient. The follow-up window occurring after the index date is shown by a green striped rectangle. Image by Robert Trager using a Creative Commons template from Schneeweiss et al. LBP, low back pain.

Figure 2

Cumulative incidence graph. Incidence curves of tramadol prescription in the chiropractic spinal manipulation cohort (CSM; blue) and usual medical care cohort (orange) are shown over the 1-year follow-up window (365 days). Shaded regions indicate 95% CIs.