Chronic low back pain can remain difficult to control even after years of conventional treatment. This five-year analysis followed 241 treatment-refractory patients using inhaled medical cannabis and found sustained improvements in patient-reported pain and related outcomes over long-term follow-up. The study is notable for its duration and real-world clinical setting, offering a much longer view than most cannabis pain research. The findings suggest that inhaled cannabis may provide durable benefit for some patients with chronic low back pain who have not responded adequately to standard therapies.
“Background/Objectives: Chronic low back pain (CLBP) affects approximately 20% of the global population and is a leading cause of years lived with disability. Long-term, real-world evidence for inhaled cannabis in patients refractory to conventional multimodal therapy remains scarce. We assessed the five-year efficacy and safety of inhaled cannabis in CLBP patients who had documented failure of ≥1 year of opioid analgesics, anticonvulsants, antidepressants, NSAIDs, and physiotherapy, with each patient serving as their own historical control.
Methods: We analyzed prospectively collected clinical data from 241 consecutive adults with treatment-refractory CLBP (mean age 49.3 ± 14.9 years; 37.8% female; mean pain duration 15.1 years) initiated on inhaled medical cannabis (predominantly smoking, THC 4-22%, CBD 2-22%) in a single-center tertiary orthopedic clinic between 2020 and 2025 (Hasharon Hospital, Rabin Medical Center, Israel; IRB protocols 0807-21-RMC and 0634-25-RMC). Year-0 outcomes during conventional therapy were compared with outcomes at Years 1-5 on cannabis. Primary outcomes were the Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), and Brief Pain Inventory severity/interference (BPI-S/BPI-I). Concomitant-medication trajectories were a secondary outcome. The primary analysis was a mixed model for repeated measures (MMRM) with random intercept and slope, REML estimation, and time as a categorical fixed effect. Multiple imputation (MAR, m = 20, Rubin’s rules) was the primary missing-data approach; complete-case and tipping-point pattern-mixture sensitivity analyses were used. A multivariate Hotelling T2 provided a joint test across the four correlated PROMs. Concomitant-medication discontinuation was modeled with GEE logistic regression and exact McNemar tests. Time to discontinuation was estimated by Kaplan-Meier and Cox regression. The Bonferroni-adjusted significance threshold for the four primary outcomes was α = 0.0125. BioWell gas-discharge-visualization (GDV) parameters were exploratory only.
Results: Of 241 patients, 238 (98.8%) provided Year-5 data and 224 (92.9%) remained on cannabis at Year 5; only five patients (2.1%) discontinued for adverse events or inefficacy. All four primary PROMs improved markedly and durably. MMRM-estimated Year-5 minus Year-0 changes were: NRS -5.36 (95% CI -5.65, -5.07), ODI -17.68 (95% CI -19.73, -15.63), BPI-S -6.73 (95% CI -6.99, -6.47), and BPI-I -3.41 (95% CI -3.65, -3.16); all four contrasts had |z| ≥ 16.9 and p < 10-20. MI-pooled estimates were within 0.05 of MMRM (FMI < 0.03 for all outcomes). Hotelling T2 was F(4, 232) = 872.8, p < 10-20. At Year 5, 89.2% achieved ≥30% NRS reduction, 77.2% ≥ 50%, and 93.4% met the NRS minimum clinically important difference (MCID); ODI MCID 65.6%, BPI-S MCID (≥1 pt) 98.3%, BPI-I MCID (≥1 pt) 91.3%. Concomitant opioid use fell from 100% at baseline to 4.6% at Year 5 (within-patient absolute risk reduction 95.4%, McNemar exact p = 1.16 × 10-69), NSAID from 100% to 7.1%, SSRI/SNRI from 80.5% to 5.4%, and gabapentinoid from 38.6% to 2.5%. The ARR-derived NNT for opioid discontinuation was 1.05; this NNT is referenced to each patient’s own documented maximal-conventional-therapy state and is not equivalent to a between-arm randomized-trial NNT. Cannabis dose × time interaction was consistent with no pharmacological tolerance (β = -0.0044 per gram-month per year, p = 0.074). Across 1205 patient-years of cannabis exposure (calculated as 241 patients × 5 follow-up years from Year 1 through Year 5; baseline Year 0 represents pre-cannabis state and is not included in person-time on cannabis), 1338 organ-system AE events were recorded at 1.110/patient-year (Poisson 95% CI 1.05-1.17); 99.8% of graded events were mild (grade 1), with ocular (476 events, 0.40/PY), cognitive (460, 0.38/PY), and gastrointestinal (368, 0.31/PY) reactions predominating. The Year-3 retention dip reflected a documented telemedicine-clinic phenomenon during 2022-2024, with patients returning to in-person follow-up by Year 4-5. BioWell GDV discriminated NRS ≥ 4 only at chance level (BWS AUC 0.574, 95% CI 0.54-0.60; BWV AUC 0.51).
Conclusions: In a treatment-refractory CLBP cohort with five-year longitudinal follow-up, inhaled cannabis was associated with large, sustained, and statistically robust improvements in pain, disability, and pain interference, accompanied by near-total displacement of opioids, NSAIDs, antidepressants, and gabapentinoids. These observational associations, although mechanically less susceptible to bias for the binary medication-discontinuation outcomes than for self-reported PROMs, cannot be interpreted causally in the absence of a concurrent randomized control arm and may reflect a combination of pharmacological effect, regression to the mean from a high pre-treatment baseline, expectancy and self-selection effects intrinsic to an actively chosen open-label therapy, and secular trends in pain reporting. The within-patient benefit-risk profile-ARR-derived NNT ≈ 1 for opioid sparing against a predominantly mild adverse-event burden-supports consideration of cannabis as a potentially clinically meaningful, opioid-sparing option in patients who have failed multimodal conventional therapy, pending confirmation in randomized comparative trials.”
https://pubmed.ncbi.nlm.nih.gov/42351683
“Inhaled medical cannabis has emerged as a candidate analgesic for refractory chronic-pain syndromes.
Mechanistically, exogenous Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) modulate the endocannabinoid system through CB1- and CB2-receptor signaling, with downstream effects on descending pain modulation, peripheral nociceptor sensitization, and affective dimensions of suffering.”
“These data support consideration of inhaled cannabis as a potentially clinically meaningful, opioid-sparing option for patients who have failed conventional multimodal therapy.”