P-017 - (Poster #17) Opioid Use Disorder Outcomes of Chronic Low Back Pain Patients Transitioned from Oral Schedule II Short-Acting Opioids to Belbuca or Oral Schedule II Long-Acting Opioids: A Retrospective US Commercial Claims Analysis

Chronic low back pain (cLBP) is a leading cause of disability in the United States, affecting millions of adults and often resulting in significant personal and societal costs. Opioids are commonly prescribed for cLBP, especially when other treatments have failed. However, the evidence supporting their long-term benefits is limited as prolonged use is associated with substantial health risks, including tolerance, dependence, and misuse. A major concern with long-term opioid therapy is the development of opioid use disorder (OUD), as patients may misuse medications to manage pain or withdrawal symptoms. Despite tremendous efforts, such as urine drug testing and prescription drug monitoring, opioid misuse and overdose rates have not significantly declined. Buprenorphine, a partial µ-opioid agonist, appears to offer a safety profile which may be advantageous relative to full agonists for use in those at risk of OUD.

Purpose/Objectives:

The primary aim of this study is to explore outcomes associated with OUD among US patients with cLBP receiving oral Schedule II short-acting opioids (SAO) and transitioning to Belbuca® (buprenorphine buccal film) or oral Schedule II long-acting opioids (LAO). Opioid Risk Tool (ORT) is a scientific literature-based tool with high sensitivity and specificity levels for predicting the probability of a patient displaying aberrant behaviors when prescribed opioids for chronic pain. The ORT measures the risk factors associated with substance abuse (personal and family history of substance abuse, age, history of preadolescent sexual abuse, and certain psychological diseases) and calculates total scores that indicate the probability of patients displaying opioid-related aberrant behaviors. Based on the final ORT scores, patients were categorized as low-risk (≤3 points), moderate-risk (4-7 points), or high-risk cases (≥8 points). In addition, this study investigates the most relevant factors associated with occurrence of OUD in a real-world setting.

Methods:

This retrospective study was performed in the Merative MarketScan® database of commercially insured US patients from January 2019 to December 2023. The index date was the first date of Belbuca® or oral Schedule II LAO. Observational period consisted of the 6-month pre-index and 12-month follow-up periods. Patients were adults, required to have ≥2 low back pain diagnoses and ≥1 oral Schedule II SAO prescription claims in the 6-month pre-index. Patients with a healthcare/pharmaceutical coverage gap and with cancer/HIV diagnoses during the observation were excluded. Switching between Belbuca® and LAO medications was prohibited.

Study outcomes were OUD-related measures in the pre-index and follow-up periods, ORT results, and binary logistic regression findings. Duration for capturing ORT factors in patient history was extended, starting from the first date of continuous coverage until the index date, with a minimum duration of 6 months. The regression analysis was performed among the sample of non-matched patients with   independent variables including all demographic and clinical characteristics, considering the choice of index treatment. The odds ratio (OR) was presented for the most reliable risk factors. Propensity-score matching (PSM) was employed to balance patients’ characteristics.

Results:

The final sample of non-matched population consisted of 3,350 patients (1,331 in Belbuca® and 2,019 in the LAO cohort). After the PSM analysis, the final sample of matched population had 964 patients in both cohorts.

In the non-matched sample, a significantly higher proportion of Belbuca®-treated patients had positive OUD histories vs. LAO cohort (22.8% vs. 19.7%, p=0.030), while the rates of patients with OUD in the follow-up period were similar (18.9% vs. 19.2%, p=0.796). For patients without positive OUD history, a significantly higher proportion of Belbuca® patients had high OUD risk (1.6% vs. 0.5%, p=0.005). There were no differences in the proportion of patients with low and moderate OUD risk (90.7% in Belbuca® vs. 91.4% in LAO and 7.7% vs. 8.1%, both p≥0.050, respectively). A numerically lower rate of patients with OUD during the follow-up period was observed with Belbuca®, but statistical significance was not achieved (9.7% vs. 10.7%, p=0.441). The rate of all-grade opioid abuse/dependence was significantly lower during Belbuca® vs. LAO treatment (163.02 vs. 210.03 events per 1,000 person-years, p=0.041). Regression analysis revealed that region (West vs. Non-West regions; OR 2.01, p< 0.001), cerebrovascular disease (yes vs. no; OR 1.81, p=0.047), anxiety (yes vs. no; OR 1.72, p< 0.001), age (18-43 years vs. 44-65 years; OR 1.48, p=0.006), and joint pain (yes vs. no; OR 1.33, p=0.033) were significant risk factors for OUD occurrence.

In the matched study sample, a similar proportion of patients in study cohorts had positive OUD histories (23.0% in Belbuca® vs. 20.0% in LAO, p=0.108), with a similar proportion of patients who had OUD in the follow-up period (18.5% vs. 18.0%, p=0.814). Considering only patients without positive OUD histories there were no differences between Belbuca® and LAO in the proportion of patients with low (91.5% vs. 90.9%, p=0.686), moderate (7.0% vs. 8.6%, p=0.260), and high OUD risk (1.5% vs. 0.5%, p=0.071). It was demonstrated that a numerically lower number of Belbuca® patients had OUD in the follow-up period (8.8% vs. 10.2%, p=0.325), with a similar rate of all-grade opioid abuse/dependence (162.70 in Belbuca® vs. 203.06 events per 1,000 person-years in LAO cohort, p=0.172, respectively).

Conclusions/Implications for future research and/or clinical care:

This US real-world analysis among cLBP patients who were treated with oral Schedule II SAO and transitioned to Belbuca® or oral Schedule II LAO demonstrated that region of residence (West vs. other regions), cerebrovascular disease, anxiety, age (18-43 years vs. 44-65 years), and joint pain had a significant impact on OUD occurrence.

In addition, it was shown that Belbuca® patients had a higher risk for OUD development based on the pre-index comorbidities evaluated via ORT. Despite the higher OUD risk, there was no difference shown in the OUD rates during the treatment between Belbuca® vs. LAO patients.

The main study limitations are related to the restrictions of coding systems due to the nature and characteristics of real-world insurance claims. The influence of this limitation has been minimized by performing thorough data cleaning, a careful patient selection process, and bias-controlling methods such as PSM. Second, the chronicity and severity of low back pain could not be determined in the retrospective claims database.