Long-Term Cannabis Therapy for Chronic Low Back Pain: A10-Year Prospective Study

Introduction

Chronic low back pain (CLBP) affects approximately 25% of the global population, contributing to substantial personal, societal, and economic burdens. ¹ Traditional treatments—non-steroidal anti-inflammatory drugs, muscle relaxants, and opioids—often fail to provide sustained relief and carry significant risks, notably opioid dependency. ¹ Given these limitations, cannabis-based therapies are increasingly recognized for their potential in managing chronic pain and reducing opioid reliance, leveraging compounds like delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) that interact with the endocannabinoid system (ECS).^2,3

Cannabinoids modulate pain by acting on CB1 and CB2 receptors within the ECS, altering pain perception and reducing inflammation—a distinct mechanism from opioids. ⁴ Studies demonstrate THC’s efficacy in reducing pain intensity in chronic conditions, including CLBP, ⁵ while CBD is under investigation for its analgesic potential. ⁶ However, the diversity in individual responses and cannabis product heterogeneity necessitates comprehensive evaluation of its long-term therapeutic value. ⁷ Short-term data suggest promise: a 2-week study of 249 CLBP patients found THC-dominant edibles significantly reduced pain, ⁸ and observational studies link cannabis to decreased opioid use.^9–17

Despite these findings, long-term evidence remains scarce, and complexities arise with cannabis use disorder (CUD), which may increase risks during spinal surgeries, such as prolonged hospital stays and complications.^18,19 These risks highlight the need for personalized approaches, particularly given CLBP’s demographic and clinical variability. ²⁰ Systematic reviews note a paucity of controlled trials specific to cannabis for back pain, underscoring gaps in understanding its sustained efficacy and safety. ⁷

This prospective study addresses these gaps by evaluating cannabis therapy over 10 years in 168 CLBP patients with anatomical causes (e.g., disc herniation, spinal stenosis) at a specialized orthopedic clinic since 2013. We assessed pain severity (Visual Analogue Scale, VAS ²¹ ), disability (Oswestry Disability Index, ODI ²² ), quality of life (SF-12 ²³ ), patient perception (PGIC ²⁴ ), and opioid dependence, offering the longest follow-up to date. We hypothesized that cannabis would deliver durable pain relief, enhance function, and reduce opioid use, with an acceptable safety profile, contributing critical data to its role as a sustainable pain management option.

Materials and Methods

Results

Of 168 subjects (135 males, 80.4%; mean age 47 ± 19), females were older (50.3 ± 22 vs. males 42 ± 18.1, t-test, p < 0.025). Anatomical causes included disc herniation (139/168, 83%), spinal stenosis (70/168, 41%), vertebral fracture (20/168, 12%), and post-tumor resection (5/168, 3%) (Tables 1 and 2). Baseline VAS was 84.6 ± 14.8, ODI 61.7 ± 13.7, SF-12 PCS 36.5 ± 6.3, and MCS 36.6 ± 11.1 (Table 3).

VAS decreased significantly (ANOVA, p < 0.0001; Fig. 1). From 84.6 ± 14.8, it fell to 18.3 ± 12.1 at 24 months (difference 66.3, Tukey-Kramer, p < 0.0001), 17.4 ± 11.8 at 60 months (difference vs. 24 months 0.9, p = 0.09), and 7.0 ± 11.0 at 120 months (difference 77.6, p < 0.0001). ODI mirrored this trend (ANOVA, p < 0.0001; Fig. 2). From 61.7 ± 13.7, it dropped to 9.8 ± 7.9 at 24 months (difference 51.9, p < 0.0001) and 4.0 ± 6.0 at 120 months (difference 57.7, p < 0.0001); 24-to-60-month change was nonsignificant (p = 0.87).

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FIG. 1.

VAS scores variation over time (n = 168), LOCF of missing data.

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FIG. 2.

ODI scores variation over time (n = 168), LOCF of missing data.

PGIC rose from 1.0 ± 0 at baseline to 6.1 ± 0.9 at 120 months (Kruskal–Wallis, H = 751.48, df = 6, p < 0.0001; Fig. 3), with major gains by 3 months (5.8 ± 1.0). SF-12 PCS improved from 36.5 ± 6.3 to 57.6 ± 9.2 (difference 21.1, ANOVA, F[1,325] = 604.81, p < 0.0001; Figure 4), and MCS from 36.6 ± 11.1 to 57.7 ± 10.5 (difference 21.1, F[1,325] = 322.83, p < 0.0001; Figure 4), based on 327 observations (168 baseline, 159 at 120 months post-LOCF).

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FIG. 3.

PGIC scores variation over time (n = 168), LOCF of missing data.

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FIG. 4.

SF-12 PCS comparison of timepoint 0 with timepoint 120 months (n = 168), LOCF of missing data (left). SF-12 MCS comparison of timepoint 0 with timepoint 120 months (n = 168), LOCF of missing data (right).

Baseline opioid use (153/168, 91%; morphine equivalent daily dose, MEDD 30 ± 12 mg) declined to 13/159 (8.2%; MEDD 1 ± 3 mg) at 120 months (t-test, p < 0.001), with 5 on fentanyl (100 µg), 4 oxymorphone, and 4 oxycodone; their VAS (6.5 ± 10.8) matched the cohort. Six patients (3.6%) discontinued due to adverse effects (e.g., dizziness); 9 died; tolerance required adjustments in 22% (37/168). Principal component analysis showed ODI as the dominant factor, with the first component explaining 86.5% of variance (Fig. 5).

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FIG. 5.

Principal component analysis indicates ODI is responsible for most over-time variation (n = 168), LOCF of missing data.

Discussion

This 10-year study demonstrates that cannabis therapy (20% THC, 50 ± 10 g/month) significantly reduces pain (VAS: 84.6 ± 14.8 to 7.0 ± 11.0), disability (ODI: 61.7 ± 13.7 to 4.0 ± 6.0), and opioid use (91% to 8.2%) in 168 CLBP patients, with sustained quality-of-life improvements (SF-12 PCS: 36.5 ± 6.3 to 57.6 ± 9.2; MCS: 36.6 ± 11.1 to 57.7 ± 10.5). These findings extend short-term evidence ⁸ and align with 12-month observational data, ⁹ positioning cannabis as a viable, long-term alternative to traditional analgesics.

THC’s effects, mediated by CB1 receptors, ⁴ likely drove pain relief, while mental health gains (MCS) suggest broader benefits. The opioid reduction from 91% (153/168) to 8.2% (13/159; MEDD: 30 ± 12 to 1 ± 3 mg) corroborates shorter-term studies ⁹ and systematic reviews advocating cannabis as an opioid-sparing option. ⁷ This is critical amid the opioid epidemic, as cannabis targets distinct pain pathways without the addiction or overdose risks of opioids. ⁴

Integration with current knowledge reinforces these results. Recent meta-analyses suggest moderate-quality evidence for cannabinoids in chronic non-cancer pain, including CLBP, ⁷ through direct long-term CLBP studies are limited. ⁴ Our findings of sustained pain and functional improvement align with observational reports of inhaled ⁵ and CBD-focused ⁶ therapies, supporting cannabis’s role in personalized medicine. CLBP’s complexity—evident in our cohort’s anatomical diversity (e.g., disc herniation 83%) and prior treatments (e.g., surgery 47%) ¹ —underscores the need for tailored approaches, which cannabis’s variable pharmacokinetics may facilitate. ²⁰

Safety considerations include tolerance (dose adjustments in 22% by 60 months) and adverse effects leading to discontinuation in 6 patients (3.6%), such as dizziness or paranoia, consistent with broader literature. ⁷ Unlike opioids, no addiction-related mortality occurred, though CUD studies caution of surgical complications,^18,19 emphasizing patient selection and monitoring. Psychiatric risks (e.g., psychosis) warrant screening, particularly with THC-dominant therapy. ⁷ The slower improvement from 24 to 60 months (VAS: 18.3 ± 12.1 to 17.4 ± 11.8; ODI non-significant change) suggests a plateau, possibly due to CB1 receptor desensitization, ⁸ necessitating strategies like periodic breaks.

While improvements were sustained over 10 years, we cannot exclude contributions from natural history or unreported minor adjunctive interventions, though protocol adherence minimized these risks.

Limitations include the single-center design, lack of a control group, and LOCF imputation, which may overestimate effects. ²⁵ The focus on 20% THC limits CBD-specific insights, though CBD’s anti-inflammatory and anxiolytic roles are noted elsewhere. ⁶ A primary limitation is the lack of a control group, which precludes definitive attribution of improvements solely to cannabis therapy. Natural disease progression, placebo effects, or regression to the mean could contribute to observed outcomes, though the sustained reductions over 10 years suggest a treatment-specific effect beyond spontaneous recovery.

Reliance on self-reported diaries and returns introduces possible recall bias or underreporting, though refill records provided objective corroboration.

Nine deaths (unrelated to therapy) and 7 discontinuations (6 adverse effects, 1 unspecified) reduced the cohort to 159 by 120 months, yet per-protocol analysis supports robustness.

Future research should prioritize large-scale randomized controlled trials (RCTs) to confirm efficacy, compare administration methods (e.g., inhalation vs. edibles ⁵ ), and refine dosing to mitigate tolerance and adverse effects. ⁷ Detailed pharmacodynamic analyses and multimodal integration (e.g., with physiotherapy ¹ ) could optimize outcomes. Given cannabis’s opioid-sparing potential, ⁹ studies in diverse populations, including Arabic cultures, ²⁰ could broaden accessibility and application.

In conclusion, this study supports cannabis’s therapeutic potential for CLBP management, offering significant pain relief, functional improvement, and opioid reduction over 10 years. Future efforts should refine protocols to ensure safe, effective, and tailored pain management strategies.

Conclusions

Ten years of cannabis therapy (20% THC) yielded profound reductions in pain (VAS: 84.6 ± 14.8 to 7.0 ± 11.0), disability (ODI: 61.7 ± 13.7 to 4.0 ± 6.0), and opioid dependence (91% to 8.2%) in 168 CLBP patients, with significant quality-of-life gains (SF-12 PCS: 36.5 ± 6.3 to 57.6 ± 9.2; MCS: 36.6 ± 11.1 to 57.7 ± 10.5). These findings highlight cannabis as a viable long-term alternative to traditional analgesics, supporting its role in chronic pain management. While safe and effective for most, tolerance (dose adjustments in 22%) and psychiatric risks (discontinuation in 3.6%) require careful monitoring. Larger RCTs are essential to validate these results, compare administration methods, and optimize dosing to mitigate adverse effects. Multimodal approaches integrating cannabis with physiotherapy could further enhance outcomes.