Residency · Residency · Chronic Pain Management
Chronic Pain and Substance Use Disorders
Introduction
Chronic pain and substance use disorders (SUDs) are frequently co-occurring conditions. Roughly 40-60% of patients with opioid use disorder (OUD) report chronic pain, and up to 25% of chronic pain patients meet criteria for a substance use disorder. This overlap creates diagnostic complexity, treatment challenges, and heightened risk for overdose and death. Safe and effective management requires a framework of universal precautions, collaborative care with addiction medicine, and strong emphasis on non-opioid strategies.
Prevalence and Epidemiology of Co-Occurring Disorders
The overlap between chronic pain and substance use disorders is striking across multiple substances. Alcohol use disorder affects 15-28% of chronic pain populations, and cannabis use disorder affects 12-20%. Adverse childhood experiences (ACEs) are independent risk factors for both chronic pain and SUD, pointing to shared developmental vulnerabilities. At the neurobiological level, both conditions involve dysregulation of the mesolimbic dopamine system, stress-response circuits (the HPA axis), and endogenous opioid tone, and both involve central sensitization and maladaptive neuroplasticity. Patients with co-occurring chronic pain and SUD consistently show higher rates of psychiatric comorbidity (depression, PTSD, anxiety), greater functional disability, and increased healthcare utilization compared to patients with either condition alone.
Universal Precautions in Pain Medicine
The universal precautions approach, adapted from infection control principles, applies standardized risk assessment and monitoring to all patients receiving controlled substances. By treating every patient the same way, it reduces stigma while improving safety.
Ten Steps of Universal Precautions
The framework involves ten steps applied systematically. First, establish a pain diagnosis supported by objective findings, with an appropriate differential. Second, perform a psychological assessment screening for comorbid psychiatric disorders and SUD risk factors. Third, obtain informed consent documenting risks, benefits, alternatives, and expectations for controlled substance therapy. Fourth, create a written treatment agreement outlining monitoring expectations, single prescriber and pharmacy requirements, and grounds for discontinuation. Fifth, assess pain and function before and after interventions using validated tools such as the PEG scale or Brief Pain Inventory. Sixth, conduct an appropriate trial of opioid therapy with or without adjunctive medications, defining treatment goals and a reassessment timeline. Seventh, reassess using the 5 A's: Analgesia, Activity, Adverse effects, Aberrant behaviors, and Affect. Eighth, regularly assess the 4 D's: Dysphoria, Dysfunction, Drug misuse, and Dose escalation. Ninth, periodically review the pain diagnosis and comorbidities to determine whether ongoing controlled substance therapy remains indicated. Tenth, document thoroughly, including risk-benefit analysis, monitoring results, and clinical decision-making.
Risk Stratification Tools
| Tool | Items | Purpose | Timing | Key Features |
|---|---|---|---|---|
| Opioid Risk Tool (ORT) | 5 items | Predict aberrant drug behaviors | Before initiating opioids | Brief; family/personal history of substance abuse, age, psychiatric history |
| SOAPP-R | 24 items | Predict aberrant behaviors | Before initiating opioids | Validated; self-administered; higher sensitivity than ORT |
| DIRE Score | 4 domains | Assess appropriateness of long-term opioid therapy | Before initiating opioids | Diagnosis, Intractability, Risk, Efficacy; clinician-rated |
| COMM | 17 items | Monitor ongoing aberrant behaviors | During opioid therapy | Self-administered; assesses current misuse behaviors |
Several validated tools help stratify risk. The Opioid Risk Tool (ORT) is a brief 5-item screening instrument for predicting aberrant drug behaviors. The Screener and Opioid Assessment for Patients with Pain (SOAPP-R) is a 24-item validated predictor of aberrant behaviors. The DIRE Score (Diagnosis, Intractability, Risk, Efficacy) guides the appropriateness of long-term opioid therapy. The Current Opioid Misuse Measure (COMM) monitors ongoing aberrant behaviors in patients already receiving opioids.
<image>Flowchart depicting the universal precautions approach to opioid prescribing in chronic pain, starting with comprehensive assessment (pain diagnosis, psychological screening, SUD risk stratification using ORT/SOAPP-R), progressing through informed consent and treatment agreement, then entering a monitoring cycle of prescription drug monitoring program checks, urine drug testing, pill counts, and clinical reassessment using the 5 A's framework, with decision nodes for continuing therapy, modifying treatment, or referring to addiction medicine based on findings at each monitoring point.</image>
Monitoring Strategies
Prescription Drug Monitoring Programs (PDMPs)
PDMPs are mandatory in most states before prescribing Schedule II-V controlled substances. Checking the PDMP identifies doctor shopping, concurrent benzodiazepine prescriptions, and overlapping opioid prescriptions. These checks should be performed at every prescribing visit, not just the initial prescription, and integration with electronic health records improves compliance and efficiency.
Urine Drug Testing (UDT)
Urine drug testing provides objective data on medication adherence and substance use. Immunoassay screening at the point of care is rapid and inexpensive but has high false-positive and false-negative rates. Confirmatory testing with liquid chromatography-tandem mass spectrometry (LC-MS/MS) provides quantitative, definitive identification and should be used for unexpected results. Expected findings include the presence of prescribed substances and their appropriate metabolites. Unexpected findings -- the absence of a prescribed medication (suggesting diversion or non-adherence), the presence of non-prescribed substances, or illicit drugs -- require clinical follow-up. Understanding opioid metabolism is critical for interpretation: hydrocodone metabolizes to hydromorphone, and codeine metabolizes to morphine via CYP2D6. Testing frequency should be risk-stratified: minimum annually for low-risk patients, quarterly for moderate-risk, and monthly for high-risk patients.
Behavioral Monitoring
Aberrant behaviors exist on a spectrum. Less concerning behaviors include requesting specific medications, occasional early refill requests, and hoarding during good periods. More concerning behaviors include prescription forgery, stealing medications, concurrent illicit drug use, injection of oral formulations, and recurrent claims of lost or stolen prescriptions. Documenting behavioral observations is essential for medicolegal protection.
Buprenorphine for Dual Diagnosis
Pharmacology
Buprenorphine is a partial mu-opioid agonist with high receptor affinity and a ceiling effect on respiratory depression. Its kappa-opioid antagonist properties may provide antidepressant and anti-dysphoric effects. Its long half-life (24-42 hours) allows once-daily dosing. Available formulations include sublingual tablets and films (with or without naloxone), buccal film, subcutaneous implant (Probuphine), and extended-release subcutaneous injection (Sublocade).
Advantages in Co-Occurring Pain and OUD
Buprenorphine simultaneously treats opioid use disorder and chronic pain with a single medication, which is a significant advantage in dual-diagnosis patients. Its ceiling effect on respiratory depression provides a wider safety margin than full agonists. It reduces illicit opioid use by 75-80% and decreases overdose mortality. For analgesic purposes, twice- or thrice-daily sublingual dosing (for example, 4-8 mg every 8 hours) provides more consistent analgesia than once-daily dosing. Buprenorphine's high receptor affinity may also improve pain by stabilizing opioid receptor occupancy and reducing opioid-induced hyperalgesia.
Clinical Considerations
The elimination of the X-waiver requirement in 2023 means any DEA-licensed prescriber can now prescribe buprenorphine for OUD. Induction requires careful timing to avoid precipitated withdrawal; the traditional method waits until the Clinical Opiate Withdrawal Scale (COWS) score exceeds 12. The microdosing approach (Bernese method) allows initiation of buprenorphine without discontinuing full agonists, thereby avoiding precipitated withdrawal entirely. Split dosing (twice or thrice daily) is recommended for analgesic efficacy in dual-diagnosis patients. Methadone is an alternative for patients who fail buprenorphine but requires enrollment in an opioid treatment program (OTP).
<image>Pharmacological comparison diagram showing buprenorphine (partial agonist) versus full opioid agonists (morphine, fentanyl) at the mu-opioid receptor, with dose-response curves illustrating the ceiling effect on respiratory depression and euphoria for buprenorphine while maintaining analgesic efficacy, alongside a receptor binding diagram showing buprenorphine's high affinity displacing full agonists and blocking exogenous opioid effects, with clinical implications for pain management and addiction treatment annotated at key points on the curves.</image>
Non-Opioid Strategies for Pain in SUD Patients
Pharmacological
Duloxetine and venlafaxine are first-line choices for neuropathic pain with co-occurring depression or anxiety. Gabapentin and pregabalin are effective for neuropathic pain but carry emerging abuse potential (gabapentin is Schedule V in some states), so they require careful monitoring in SUD patients. Topical agents -- lidocaine, diclofenac, and capsaicin -- have an excellent safety profile with no abuse potential. Acetaminophen and NSAIDs on a scheduled basis provide baseline analgesia, though hepatotoxicity must be monitored in patients with alcohol use disorder or hepatitis C. Ketamine infusions have emerging evidence for chronic pain and co-occurring depression, with NMDA antagonism addressing central sensitization. Low-dose naltrexone (1-4.5 mg/day) produces paradoxical analgesic effects through upregulation of endogenous opioid tone, though this dose does not treat OUD.
Non-Pharmacological
Exercise therapy releases endogenous opioids and endocannabinoids while improving mood and function. Cognitive-behavioral therapy can address both pain coping and relapse prevention simultaneously. Mindfulness-based relapse prevention integrates mindfulness techniques with addiction recovery principles. Acupuncture has growing evidence for chronic pain, with battlefield acupuncture used in military and VA settings. Peer support and recovery coaching can be integrated with pain self-management programs.
Collaborative Care with Addiction Medicine
Integrated care models that co-locate pain and addiction services improve outcomes for both conditions. Regular communication between pain providers, addiction specialists, and behavioral health clinicians is essential, as are shared treatment plans that address both pain and recovery goals. Harm reduction approaches -- naloxone co-prescribing, safer use counseling, and supervised injection sites -- should be part of the treatment framework. Naloxone should be prescribed to all patients on opioids with a history of SUD, as well as to their household contacts.
<image>Organizational diagram of a collaborative care model for co-occurring chronic pain and substance use disorder, showing three integrated clinical teams (pain medicine, addiction medicine, behavioral health) sharing a unified electronic health record, conducting joint case conferences, and following shared protocols for risk assessment, urine drug testing interpretation, buprenorphine management, crisis intervention, and outcome tracking, with the patient at the center receiving coordinated services and community recovery support resources connected at the periphery.</image>
Clinical Pearls
Universal precautions should be applied to all patients receiving controlled substances, not selectively to those perceived as high-risk; selective application is stigmatizing and misses cases. An unexpected urine drug test result is a clinical finding that requires a conversation, not an automatic discharge from care -- abandoning patients with SUD increases overdose risk. Buprenorphine dosed twice or three times daily provides superior analgesia compared to once-daily dosing in patients with co-occurring pain and OUD. Gabapentinoids have emerging abuse potential and should be monitored with the same vigilance as opioids in SUD populations. Pain management and addiction treatment should be integrated rather than sequential; treating one condition while ignoring the other leads to failure of both.
References
- Gourlay DL, Heit HA, Almahrezi A. Universal precautions in pain medicine: a rational approach to the treatment of chronic pain. Pain Medicine. 2005;6(2):107-112.
- Speed TJ, Parekh V, Engstrom A, et al. Comorbid chronic pain and opioid use disorder: literature review and potential treatment innovations. International Review of Psychiatry. 2018;30(5):136-146.
- Manhapra A, Arias AJ, Ballantyne JC. The conundrum of opioid tapering in long-term opioid therapy for chronic pain: a commentary. Substance Abuse. 2018;39(2):152-161.
- Volkow ND, McLellan AT. Opioid abuse in chronic pain — misconceptions and mitigation strategies. New England Journal of Medicine. 2016;374(13):1253-1263.
