Risk of Opioid Overdose Associated With Concomitant Use of Opioids and Skeletal Muscle Relaxants: A Population-Based Cohort Study

Comparative Risk of Injury with Concurrent Use of Opioids and Skeletal Muscle Relaxants

Concurrent use of skeletal muscle relaxants (SMRs) and opioids has been linked to an increased risk of injury. However, it remains unclear whether the injury risks differ by specific SMR when combined with opioids. We conducted nine retrospective cohort studies within a US Medicaid population. Each cohort consisted exclusively of person-time exposed to both an SMR and one of the three most dispensed opioids-hydrocodone, oxycodone, and tramadol. Opioid users were further divided into three cohorts based on the initiation order of SMRs and opioids-synchronically triggered, opioid-triggered, and SMR-triggered. Within each cohort, we used Cox proportional hazard models to compare the injury rates for different SMRs compared to methocarbamol, adjusting for covariates. We identified 349,543, 139,458, and 218,967 concurrent users of SMRs with hydrocodone, oxycodone, and tramadol, respectively. In the oxycodone-SMR-triggered cohort, the adjusted hazard ratios (HRs) were 1.86 (95% CI, 1.23-2.82) for carisoprodol and 1.73 (1.09-2.73) for tizanidine. In the tramadol-synchronically triggered cohort, the adjusted HRs were 0.69 (0.49-0.97) for metaxalone and 0.62 (0.42-0.90) for tizanidine. In the tramadol-SMR-triggered cohort, the adjusted HRs were 1.51 (1.01-2.26) for baclofen and 1.48 (1.03-2.11) for cyclobenzaprine. All other HRs were statistically nonsignificant. In conclusion, the relative injury rate associated with different SMRs used concurrently with the three most dispensed opioids appears to vary depending on the specific opioid and the order of combination initiation. If confirmed by future studies, clinicians should consider the varying injury rates when prescribing SMRs to individuals using hydrocodone, oxycodone, and tramadol.

Potentially Life-Threatening Interaction between Opioids and Intrathecal Baclofen in Individuals with a Childhood-Onset Neurological Disorder: A Case Series and Review of the Literature

BACKGROUND

 Spasticity and dystonia are movement impairments that can occur in childhood-onset neurological disorders. Severely affected individuals can be treated with intrathecal baclofen (ITB). Concomitant use of ITB and opioids has been associated with central nervous system (CNS) depression. This study aims to describe the clinical management of this interaction, based on a case series and review of literature.

METHODS

 Four individuals with childhood-onset CNS disorders (age 8-24) and CNS-depressant overdose symptoms after the concomitant use of ITB and opioids are described. The Drug Interaction Probability Scale (DIPS) was calculated to assess the cause-relationship (doubtful <2, possible 2-4, probable 5-8, and highly probable >8) of the potential drug-drug interaction. A literature review of similar previously reported cases and the possible pharmacological mechanisms of opioid-baclofen interaction is provided.

RESULTS

 After ITB and opioid co-administration, three out of four patients had decreased consciousness, and three developed respiratory depression. DIPS scores indicated a possible cause-relationship in one patient (DIPS: 4) and a probable cause-relationship in the others (DIPS: 6, 6, and 8). Discontinuation or adjusting ITB or opioid dosages resulted in clinical recovery. All patients recovered completely. In the literature, two articles describing nine unique cases were found.

CONCLUSION

 Although the opioid-ITB interaction is incompletely understood, concomitant use may enhance the risk of symptoms of CNS-depressant overdose, which are potentially life-threatening. If concomitant use is desirable, we strongly recommend to closely monitor these patients to detect interaction symptoms early. Awareness and monitoring of the potential opioid-ITB interaction is essential to reduce the risk of severe complications.

Coprescribing of opioids and psychotropic medications among Medicare-enrolled older adults on long-term opioid therapy

BACKGROUND

Pressures to reduce opioid prescribing have potential to incentivize coprescribing of opioids (at lower dose) with psychotropic medications. Evidence concerning the extent of the problem is lacking. This study assessed trends in coprescribing and characterized coprescribing patterns among Medicare-enrolled older adults with chronic noncancer pain (CNCP) receiving long-term opioid therapy (LTOT).

METHODS

A cohort study was conducted using 2012-2018 5% National Medicare claims data. Eligible beneficiaries were continuously enrolled and had no claims for cancer diagnoses or hospice use, and ≥ 2 claims with diagnoses for CNCP conditions within a 30-day period in the 12 months before the index date (LTOT initiation). Coprescribing was defined as an overlap between opioids and any class of psychotropic medication (antidepressants, benzodiazepines, antipsychotics, anticonvulsants, muscle relaxants, and nonbenzodiazepine hypnotics) based on their prescription fill dates and days of supply in a given year. The occurrence of coprescribing, coprescribing intensity, and number of days of overlap with psychotropic medications were calculated for each calendar year.

RESULTS

The eligible study population of individuals on LTOT ranged from 2038 in 2013 to 1751 in 2018. The occurrence of coprescribing among eligible beneficiaries decreased from 73.41% in 2013 to 70.81% in 2015 and then increased slightly to 71.22% in 2018. Among eligible beneficiaries with at least one overlap day, the coprescribing intensity with any class of psychotropic medications showed minimal variation throughout the study period: 74.73% in 2013 and 72.67% in 2018. Across all the years, the coprescribing intensity was found to be highest with antidepressants (2013, 49.90%; 2018, 50.33%) followed by benzodiazepines (2013, 25.42%; 2018, 19.95%).

CONCLUSION

Coprescribing was common among older adults with CNCP who initiated LTOT but did not rise substantially in the period studied. Future research should investigate drivers behind coprescribing and safety of various patterns of use.

Preoperative Opioid Prescribers and Lumbar Fusion: Their Effect on Clinical Outcomes and Postoperative Opioid Usage

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the impact of multiple preoperative opioid prescribers on postoperative patient opioid usage and patient-reported outcome measures after single-level lumbar fusion.

SUMMARY OF BACKGROUND DATA

Prior literature has identified opioid prescriptions from multiple postoperative providers increase opioid usage rates. However, there is limited evidence on how multiple preoperative opioid prescribers affect postoperative opioid usage or clinical outcomes after a single-level lumbar fusion.

PATIENTS AND METHODS

A retrospective review of single-level transforaminal lumbar interbody fusion or posterolateral lumbar fusions between September 2017 and February 2020 at a single academic institution was performed. Patients were excluded if they were not identifiable in our state's prescription drug-monitoring program. Univariate comparisons and regression analyses identified factors associated with postoperative clinical outcomes and opioid usage.

RESULTS

Of 239 patients, 160 (66.9%) had one or fewer preoperative prescribers and 79 (33.1%) had >1 prescribers. On regression analysis, the presence of multiple preoperative prescribers was an independent predictor of increased improvement in Visual Analog Scale (∆VAS) Back (β=-1.61, P =0.012) and the involvement of a nonoperative spine provider was an independent predictor of increased improvement in ∆VAS Leg (β = -1.53, P = 0.034). Multiple preoperative opioid prescribers correlated with an increase in opioid prescriptions postoperatively (β = 0.26, P = 0.014), but it did not significantly affect the amount of morphine milligram equivalents prescribed (β = -48.79, P = 0.146). A greater number of preoperative opioid prescriptions predicted worse improvements in VAS Back, VAS Leg, and Oswestry Disability Index and predicted increased postoperative opioid prescriptions, prescribers, and morphine milligram equivalents.

CONCLUSIONS

Multiple preoperative opioid prescribers predicted increased improvement in postoperative back pain, whereas preoperative involvement of a nonoperative spine provider predicted improvements in leg pain after surgery. The number of preoperative opioid prescriptions was a better metric for predicting poor postoperative outcomes and increased opioid consumption compared with the number of preoperative opioid prescribers.

Does adding muscle relaxant make post-operative pain better? a narrative review of the literature from US and European studies

Centrally acting skeletal muscle relaxants (CASMR) are widely prescribed as adjuncts for acute and chronic pain. Given the recent interest in multimodal analgesia and reducing opioid consumption, there has been an increase in its use for perioperative/postoperative pain control. The mechanism of action, pharmacodynamics, and pharmacokinetics of these drugs vary. Their use has been studied in a wide range of operative and non-operative settings. The best evidence for the efficacy of CASMRs is in acute, nonoperative musculoskeletal pain and, in the operative setting, in patients undergoing total knee arthroplasty and abdominal surgery, including inguinal herniorrhaphy and hemorrhoidectomy. The risk of complications and side effects, coupled with the limited evidence of efficacy, should prompt careful consideration of individual patient circumstances when prescribing CASMRs as part of perioperative pain management strategies.

Human IPSC-Derived PreBötC-Like Neurons and Development of an Opiate Overdose and Recovery Model

Opioid overdose is the leading cause of drug overdose lethality, posing an urgent need for investigation. The key brain region for inspiratory rhythm regulation and opioid-induced respiratory depression (OIRD) is the preBötzinger Complex (preBötC) and current knowledge has mainly been obtained from animal systems. This study aims to establish a protocol to generate human preBötC neurons from induced pluripotent cells (iPSCs) and develop an opioid overdose and recovery model utilizing these iPSC-preBötC neurons. A de novo protocol to differentiate preBötC-like neurons from human iPSCs is established. These neurons express essential preBötC markers analyzed by immunocytochemistry and demonstrate expected electrophysiological responses to preBötC modulators analyzed by patch clamp electrophysiology. The correlation of the specific biomarkers and function analysis strongly suggests a preBötC-like phenotype. Moreover, the dose-dependent inhibition of these neurons' activity is demonstrated for four different opioids with identified IC50's comparable to the literature. Inhibition is rescued by naloxone in a concentration-dependent manner. This iPSC-preBötC mimic is crucial for investigating OIRD and combating the overdose crisis and a first step for the integration of a functional overdose model into microphysiological systems.

Potentially harmful drug-drug interactions in the therapeutic regimens of persons with spinal cord injury

OBJECTIVES

Individuals with spinal cord injury deal with multiple health complications that require them to use many medications. The purpose of this paper was to find the most common potentially harmful drug-drug interactions (DDIs) in therapeutic regimens of persons with spinal cord injury, and the risk factors associated with it. We further highlight the relevance of each of the DDIs specific to spinal cord injury population.

DESIGN

Observational design and cross-sectional analysis.

SETTING

Community; Canada.

PARTICIPANTS

Individuals with spinal cord injury (n = 108).

MAIN OUTCOME MEASURES/ANALYSIS

The main outcome was the presence of one or more potential DDIs that can lead to an adverse outcome. All the reported drugs were classified as per the World Health Organization's Anatomical Therapeutic Chemical Classification system. Twenty potential DDIs were selected for the analysis based on the most common medications prescribed to people with spinal cord injury and severity of clinical consequences. The medication lists of study participants were analyzed for selected DDIs.

RESULTS

Among the 20 potential DDIs analyzed in our sample, the top 3 prevalent DDIs were Opioids + Skeletal Muscle Relaxants, Opioids + Gabapentinoids, and Benzodiazepines + ≥ 2 other central nervous system (CNS)-active drugs. Of the total sample of 108 respondents, 31 participants (29%) were identified with having at least one potential DDI. The risk of having a potential DDI was highly associated with polypharmacy, though no associations were found between the presence of a drug interaction and age, sex, level of injury, time since injury, or cause of injury among the study sample.

CONCLUSION

Almost three out of ten individuals with spinal cord injury were at risk of having a potentially harmful drug interaction. Clinical and communication tools are needed that facilitate identification and elimination of harmful drug combinations in the therapeutic regimens of patients with spinal cord injury.

Comparative Study of Opioid Initiation With Tramadol, Short-acting Hydrocodone, or Short-acting Oxycodone on Opioid-related Adverse Outcomes Among Chronic Noncancer Pain Patients

OBJECTIVE

To compare the safety profiles of low and high-dose tramadol, short-acting hydrocodone, and short-acting oxycodone therapies among chronic noncancer pain individuals.

MATERIALS AND METHODS

A retrospective cohort study of individuals with back/neck pain/osteoarthritis with an initial opioid prescription for tramadol, hydrocodone, or oxycodone was conducted using IQVIA PharMetrics Plus claims for Academics database (2006 to 2020). Two cohorts were created for separately studying opioid-related adverse events (overdoses, accidents, self-inflicted injuries, and violence-related injuries) and substance use disorders (opioid and nonopioid). Patients were followed from the index date until an outcome event, end of enrollment, or data end. Time-varying exposure groups were constructed and Cox regression models were estimated.

RESULTS

A total of 1,062,167 (tramadol [16.5%], hydrocodone [61.1%], and oxycodone [22.4%]) and 986,809 (tramadol [16.5%], hydrocodone [61.3%], and oxycodone [22.2%]) individuals were in the adverse event and substance use disorder cohorts. All high-dose groups had elevated risk of nearly all outcomes, compared with low-dose hydrocodone. Compared with low-dose hydrocodone, low-dose oxycodone was associated with a higher risk of opioid overdose (hazard ratio: 1.79 [1.37 to 2.33]). No difference in risk was observed between low-dose tramadol and low-dose hydrocodone (hazard ratio: 0.85 [0.64 to 1.13]). Low-dose oxycodone had higher risks of an opioid use disorder, and low-dose tramadol had a lower risk of accidents, self-inflicted injuries, and opioid use disorder compared with low-dose hydrocodone.

DISCUSSION

Low-dose oxycodone had a higher risk of opioid-related adverse outcomes compared with low-dose tramadol and hydrocodone. This should be interpreted in conjunction with the benefits of pain control and functioning associated with oxycodone use in future research.

Potentially clinically significant drug-drug interactions in older patients admitted to the hospital: A cross-sectional study

Background: An international consensus list of potentially clinically significant drug-drug interactions (DDIs) in older people has been recently validated. Our objective was to describe the prevalence and characteristics of drug combinations potentially causing clinically significant DDIs identified in the medication history of older patients admitted to the hospital and the prevalence and characteristics of manifest DDIs-DDIs involved in adverse drug events present at hospital admission, DDIs that contributed to ADE-related hospital admissions, and DDIs involved in drug-related laboratory deviations. Methods: The data were obtained from our previous study that examined the drug-relatedness of hospital admissions to University Hospital Hradec Králové via the department of emergency medicine in the Czech Republic. Patients ≥ 65 years old were included. Drug combinations potentially causing clinically significant DDIs were identified using the international consensus list of potentially clinically significant DDIs in older people. Results: Of the 812 older patients admitted to the hospital, 46% were exposed to drug combinations potentially causing clinically significant DDIs. A combination of medications that affect potassium concentrations accounted for 47% of all drug combinations potentially causing clinically significant DDIs. In 27 cases, potentially clinically significant DDIs were associated with drug-related hospital admissions. In 4 cases, potentially clinically significant DDIs were associated with ADEs that were present at admissions. In 4 cases, the potentially clinically significant DDIs were associated with laboratory deviations. Manifest DDIs that contributed to drug-related hospital admissions most frequently involved antithrombotic agents and central nervous system depressants. Conclusion: The results confirm the findings from the European OPERAM trial, which found that drug combinations potentially causing clinically significant DDIs are very common in older patients. Manifest DDIs were present in 4.3% of older patients admitted to the hospital. In 3.3%, manifest DDIs contributed to drug-related hospital admissions. The difference in the rates of potential and manifest DDIs suggests that if a computerized decision support system is used for alerting potentially clinically significant DDIs in older patients, it needs to be contextualized (e.g., take concomitant medications, doses of medications, laboratory values, and patients' comorbidities into account).

High opioid doses, naloxone, and central nervous system active medications received by Medicare-enrolled adults

BACKGROUND

A limited number of studies have analyzed prescribing among Medicare-enrolled adults at risk for opioid overdoses. The objectives of this study were to evaluate prescribing for naloxone and central nervous system (CNS) active medications and to determine the relationships of patient characteristics with exposure to these medications.

METHODS

This was a retrospective cross-sectional analysis of a Medicare-enrolled medication therapy management eligible cohort. Patients were stratified into two cohorts, individuals with a mean daily morphine milligram equivalent (MME) dose <50 and individuals with MME ≥50. Medications assessed included benzodiazepines, skeletal muscle relaxants (SMR), hypnotics, gabapentanoids, selective-serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), tricyclic antidepressants (TCA), antipsychotics, barbiturates, other antiepileptics, hydroxyzine, and naloxone. Chi-square with odds ratios and logistic regressions determined the relationships of medications and patient characteristics with mean daily MME ≥50. Relationship between medications and opioid dose was adjusted for age and sex.

RESULTS

There were 3452 patients with a daily MME <50 and 1116 with a daily MME ≥50. After adjusting for age and sex, patients with a daily MME ≥50 were more likely to be prescribed hypnotics (OR: 1.41, 95% CI 1.17-1.70), SNRIs (OR: 1.39, 95% CI 1.17-1.64), and naloxone (OR: 3.21, 95% CI 2.49-4.12) (p < 0.001). Nine percent of eligible patients received naloxone. Age groups of persons <85 years of age had 1.58-4.04 (p ≤ 0.004) times the odds of being prescribed a mean daily MME ≥50.

CONCLUSION

Nearly one-fourth of patients were prescribed a mean daily opioid therapy of MME ≥50. These patients were more likely to be prescribed hypnotics, SNRIs, and naloxone. Patients receiving chronic high-dose opioid therapy were more likely to be in age groups of persons <85 years. Naloxone may be underprescribed among eligible adults. Targeted medication services may ensure optimal prescribing among Medicare patients with chronic opioid therapies.

Opioid Coprescribing with Sedatives after Implant-Based Breast Reconstruction

BACKGROUND

Skeletal muscle relaxants and benzodiazepines are thought to mitigate against postoperative muscle contraction. The Centers for Disease Control and Prevention and the Food and Drug Administration warn against coprescribing them with opioids because of increased risks of overdose and death. The authors evaluated the frequency of coprescribing of opioids with skeletal muscle relaxants or benzodiazepines after implant-based reconstruction.

METHODS

The authors examined health care claims to identify women (18 to 64 years old) who underwent implant-based breast reconstruction between January of 2008 and June of 2019 to determine the frequency of coprescribing, factors associated with coprescribing opioids and skeletal muscle relaxants or benzodiazepines, and the impact on opioid refills within 90 days of reconstruction.

RESULTS

A total of 86.7 percent of women ( n = 7574) who had implant-based breast reconstruction filled an opioid prescription perioperatively. Of these, 27.7 percent of women filled prescriptions for opioids and benzodiazepines, 14.4 percent for opioids and skeletal muscle relaxants, and 2.4 percent for opioids, benzodiazepines, and skeletal muscle relaxants. Risk factors for coprescribing opioids and benzodiazepines included use of acellular dermal matrix, immediate reconstruction, and history of anxiety. Women who filled prescriptions for opioids and skeletal muscle relaxants, opioids and benzodiazepines, and opioids with skeletal muscle relaxants and benzodiazepines were significantly more likely to refill opioid prescriptions, even when controlling for preoperative opioid exposure.

CONCLUSIONS

Nearly half of women filled an opioid prescription with a benzodiazepine, skeletal muscle relaxant, or both after implant-based breast reconstruction. Coprescribing of opioids with skeletal muscle relaxants may potentiate opioid use after surgery and should be avoided given the risks of sedation. Identifying strategies that avoid sedatives to manage pain after breast reconstruction is critical to mitigate high-risk prescribing practices.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Identifying Clinically Relevant Drug-Drug Interactions With Methadone and Buprenorphine: A Translational Approach to Signal Detection

Methadone and buprenorphine have pharmacologic properties that are concerning for a high risk of drug-drug interactions (DDIs). We performed high-throughput screening for clinically relevant DDIs with methadone or buprenorphine by combining pharmacoepidemiologic and pharmacokinetic approaches. We conducted pharmacoepidemiologic screening via a series of self-controlled case series studies (SCCS) in Optum claims data from 2000 to 2019. We included persons 18 years or older who experienced an outcome of interest during target drug treatment. Exposures were all overlapping medications (i.e., the candidate precipitants) during target drug treatment. Outcomes were opioid overdose, non-overdose adverse effects, and cardiac arrest. We used conditional Poisson regression to calculate rate ratios, accounting for multiple comparisons with semi-Bayes shrinkage. We explored the impact of key study design choices in analyses that varied the exposure definitions of the target drugs and the candidate precipitant drugs. Pharmacokinetic screening was conducted by incorporating published data on CYP enzyme metabolism into an equation-based static model. In SCCS analysis, 1,432 events were included from 248,069 new users of methadone or buprenorphine. In the primary analysis, statistically significant DDIs included gabapentinoids with either methadone or buprenorphine; baclofen with methadone; and benzodiazepines with methadone. In sensitivity analysis, additional statistically significant DDIs included methocarbamol, quetiapine, or simvastatin with methadone. Pharmacokinetic screening identified two moderate-to-strong potential DDIs (clonidine and fluconazole with buprenorphine). The combination of clonidine and buprenorphine was also associated with a significantly increased risk of opioid overdose in pharmacoepidemiologic screening. These DDI signals may be the most important targets for future confirmation studies.

FORWARDS-1: an adaptive, single-blind, placebo-controlled ascending dose study of acute baclofen on safety parameters in opioid dependence during methadone-maintenance treatment-a pharmacokinetic-pharmacodynamic study

Background

Treatment of opiate addiction with opiate substitution treatment (e.g. methadone) is beneficial. However, some individuals desire or would benefit from abstinence but there are limited options to attenuate problems with opiate withdrawal. Preclinical and preliminary clinical evidence suggests that the GABA-B agonist, baclofen, has the desired properties to facilitate opiate detoxification and prevent relapse. This study aims to understand whether there are any safety issues in administering baclofen to opioid-dependent individuals receiving methadone.

Methods

Opiate-dependent individuals (DSM-5 severe opioid use disorder) maintained on methadone will be recruited from addiction services in northwest London (NHS and third sector providers). Participants will be medically healthy with no severe chronic obstructive pulmonary disease or type 2 respiratory failure, no current dependence on other substances (excluding nicotine), no current severe DSM-5 psychiatric disorders, and no contraindications for baclofen or 4800 IU vitamin D (placebo). Eligible participants will be randomised in a 3:1 ratio to receive baclofen or placebo in an adaptive, single-blind, ascending dose design. A Bayesian dose-escalation model will inform the baclofen dose (10, 30, 60, or 90 mg) based on the incidence of ‘dose-limiting toxicity’ (DLT) events and participant-specific methadone dose. A range of respiratory, cardiovascular, and sedative measures including the National Early Warning Score (NEWS2) and Glasgow Coma Scale will determine DLT. On the experimental day, participants will consume their usual daily dose of methadone followed by an acute dose of baclofen or placebo (vitamin D3) ~ 1 h later. Measures including oxygen saturation, transcutaneous CO₂, respiratory rate, QTc interval, subjective effects (sedation, drug liking, craving), plasma levels (baclofen, methadone), and adverse events will be obtained using validated questionnaires and examinations periodically for 5 h after dosing.

Discussion

Study outcomes will determine what dose of baclofen is safe to prescribe to those receiving methadone, to inform a subsequent proof-of-concept trial of the efficacy baclofen to facilitate opiate detoxification. To proceed, the minimum acceptable dose is 30 mg of baclofen in patients receiving ≤ 60 mg/day methadone based on the clinical experience of baclofen’s use in alcoholism and guidelines for the management of opiate dependence.

Trial registration

Clinicaltrials.gov NCT05161351. Registered on 16 December 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06821-9.

Comparative Risk of Opioid Overdose With Concomitant use of Prescription Opioids and Skeletal Muscle Relaxants

BACKGROUND AND OBJECTIVES

The concomitant use of prescription opioids and skeletal muscle relaxants has been associated with opioid overdose, but little data exist on the head-to-head safety of these drug combinations. The objective of this study was to compare the risk of opioid overdose among patients on long-term opioid therapy who concurrently initiate skeletal muscle relaxants.

METHODS

We conducted an active comparator cohort study spanning 2000 to 2019 using healthcare utilization data from four US commercial and public insurance databases. Individuals were required to have at least 180 days of continuous enrollment and at least 90 days of continuous prescription opioid use immediately before and on the date of skeletal muscle relaxant initiation. Exposures were the concomitant use of prescription opioids and skeletal muscle relaxants, and the main outcome was the hazard ratio (HR) and bootstrapped 95% confidence interval (CI) of opioid overdose resulting in an emergency visit or hospitalization. The primary analysis quantified opioid overdose risk across seven prescription opioid-skeletal muscle relaxant therapies and a negative control outcome (sepsis) to assess potential confounding by unmeasured illicit opioid use. Secondary analyses evaluated two- and five-group comparisons in patients with similar baseline characteristics; individuals without prior recorded substance abuse; and subgroups stratified by baseline opioid dosage, benzodiazepine co-dispensing, and oxycodone or hydrocodone use.

RESULTS

Weighted HR of opioid overdose relative to cyclobenzaprine was 2.52 (95% CI 1.29-4.90) for baclofen; 1.64 (95% CI 0.81-3.34) for carisoprodol; 1.14 (95% CI 0.53-2.46) for chlorzoxazone/orphenadrine; 0.46 (95% CI 0.17-1.24) for metaxalone; 1.00 (95% CI 0.45-2.20) for methocarbamol; and 1.07 (95% CI 0.49-2.33) for tizanidine in the 30-day intention-to-treat analysis. Findings were similar in the as-treated analysis, two- and five-group comparisons, and in patients without prior recorded substance abuse. None of the therapies relative to cyclobenzaprine were associated with sepsis, and no subgroups indicated increased risk of opioid overdose.

DISCUSSION

Concomitant use of prescription opioids and baclofen relative to cyclobenzaprine is associated with opioid overdose. Clinical interventions may focus on prescribing alternatives in the same drug class or providing access to opioid antagonists if treatment with both medications is necessary for pain management.

Coprescribing of opioids and high-risk medications in the USA: a cross-sectional study with data from national ambulatory and emergency department settings

OBJECTIVE

Describe trends in opioid plus high-risk medication coprescribing in the USA.

DESIGN

Analyses of serial, cross-sectional, nationally representative data of the National Ambulatory Medical Care Survey (NAMCS) over 2007-2016 and the National Hospital Ambulatory Medical Care Survey (NHAMCS) over 2007-2018.

SETTING

US ambulatory (NAMCS) and emergency department (ED, NHAMCS) settings.

PARTICIPANTS

Patient visits in which the patient was 18 years and older with an opioid prescription in the NAMCS or NHAMCS databases.

PRIMARY AND SECONDARY OUTCOME MEASURES

Frequency of opioid plus high-risk medication coprescribing.

RESULTS

From a combined sample of 700 499 visits over 2007-2018, there were 105 720 visits (15.1%) where opioids were prescribed. n=31 825 were from NAMCS and n=73 895 were from NHAMCS. The mean prevalence of coprescription of opioids and high-risk medications for the combined NAMCS and NHAMCS sample was 18.4% in 2007, peaked at 33.2% in 2014 and declined to 23.8% in 2016. Compared with adults receiving opioid prescriptions alone, those coprescribed opioids and high-risk medications were older, more likely female, white and using private or Medicare insurance (p<0.0001).

CONCLUSIONS

Coprescribing is more common in ambulatory than ED settings and has been declining, yet one in four patient visits where opioids were prescribed resulted in coprescribed, high-risk medications in 2016. Efforts and research to help lower the rates of high-risk prescribing are needed.

Opioid Drug-Drug-Drug Interactions and Unintentional Traumatic Injury: Screening to Detect Three-Way Drug Interaction Signals

Growing evidence suggests that drug interactions may be responsible for much of the known association between opioid use and unintentional traumatic injury. While prior research has focused on pairwise drug interactions, the role of higher-order (i.e., drug-drug-drug) interactions (3DIs) has not been examined. We aimed to identify signals of opioid 3DIs with commonly co-dispensed medications leading to unintentional traumatic injury, using semi-automated high-throughput screening of US commercial health insurance data. We conducted bi-directional, self-controlled case series studies using 2000-2015 Optum Data Mart database. Rates of unintentional traumatic injury were examined in individuals dispensed opioid-precipitant base pairs during time exposed vs unexposed to a candidate interacting precipitant. Underlying cohorts consisted of 16-90-year-olds with new use of opioid-precipitant base pairs and ≥1 injury during observation periods. We used conditional Poisson regression to estimate rate ratios adjusted for time-varying confounders, and semi-Bayes shrinkage to address multiple estimation. For hydrocodone, tramadol, and oxycodone (the most commonly used opioids), we examined 16,024, 8185, and 9330 drug triplets, respectively. Among these, 75 (0.5%; hydrocodone), 57 (0.7%; tramadol), and 42 (0.5%; oxycodone) were significantly positively associated with unintentional traumatic injury (50 unique base precipitants, 34 unique candidate precipitants) and therefore deemed potential 3DI signals. The signals found in this study provide valuable foundations for future research into opioid 3DIs, generating hypotheses to motivate crucially needed etiologic investigations. Further, this study applies a novel approach for 3DI signal detection using pharmacoepidemiologic screening of health insurance data, which could have broad applicability across drug classes and databases.

Concurrent use of prescription gabapentinoids with opioids and risk for fall-related injury among older US Medicare beneficiaries with chronic noncancer pain: A population-based cohort study

BACKGROUND

Gabapentinoids are increasingly prescribed to manage chronic noncancer pain (CNCP) in older adults. When used concurrently with opioids, gabapentinoids may potentiate central nervous system (CNS) depression and increase the risks for fall. We aimed to investigate whether concurrent use of gabapentinoids with opioids compared with use of opioids alone is associated with an increased risk of fall-related injury among older adults with CNCP.

METHODS AND FINDINGS

We conducted a population-based cohort study using a 5% national sample of Medicare beneficiaries in the United States between 2011 and 2018. Study sample consisted of fee-for-service (FFS) beneficiaries aged ≥65 years with CNCP diagnosis who initiated opioids. We identified concurrent users with gabapentinoids and opioids days' supply overlapping for ≥1 day and designated first day of concurrency as the index date. We created 2 cohorts based on whether concurrent users initiated gabapentinoids on the day of opioid initiation (Cohort 1) or after opioid initiation (Cohort 2). Each concurrent user was matched to up to 4 opioid-only users on opioid initiation date and index date using risk set sampling. We followed patients from index date to first fall-related injury event ascertained using a validated claims-based algorithm, treatment discontinuation or switching, death, Medicare disenrollment, hospitalization or nursing home admission, or end of study, whichever occurred first. In each cohort, we used propensity score (PS) weighted Cox models to estimate the adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) of fall-related injury, adjusting for year of the index date, sociodemographics, types of chronic pain, comorbidities, frailty, polypharmacy, healthcare utilization, use of nonopioid medications, and opioid use on and before the index date. We identified 6,733 concurrent users and 27,092 matched opioid-only users in Cohort 1 and 5,709 concurrent users and 22,388 matched opioid-only users in Cohort 2. The incidence rate of fall-related injury was 24.5 per 100 person-years during follow-up (median, 9 days; interquartile range [IQR], 5 to 18 days) in Cohort 1 and was 18.0 per 100 person-years during follow-up (median, 9 days; IQR, 4 to 22 days) in Cohort 2. Concurrent users had similar risk of fall-related injury as opioid-only users in Cohort 1(aHR = 0.97, 95% CI 0.71 to 1.34, p = 0.874), but had higher risk for fall-related injury than opioid-only users in Cohort 2 (aHR = 1.69, 95% CI 1.17 to 2.44, p = 0.005). Limitations of this study included confounding due to unmeasured factors, unavailable information on gabapentinoids' indication, potential misclassification, and limited generalizability beyond older adults insured by Medicare FFS program.

CONCLUSIONS

In this sample of older Medicare beneficiaries with CNCP, initiating gabapentinoids and opioids simultaneously compared with initiating opioids only was not significantly associated with risk for fall-related injury. However, addition of gabapentinoids to an existing opioid regimen was associated with increased risks for fall. Mechanisms for the observed excess risk, whether pharmacological or because of channeling of combination therapy to high-risk patients, require further investigation. Clinicians should consider the risk-benefit of combination therapy when prescribing gabapentinoids concurrently with opioids.

Multimodal Analgesia in the Era of the Opioid Epidemic

This article attempts to review the key components of a multimodal analgesic regimen for the treatment of acute pain. Adhering to these key components will help reduce the opioid burden to surgical patients while reducing acute pain. As well, this regimen is intended to reduce further negative contributions to the opioid crisis.

Are Symptoms of Spasticity, Pain, and Fatigue Related in People With Stroke?

PURPOSE

The purpose of this study was to determine whether symptoms of spasticity, pain, and fatigue are correlated in people with stroke.

DESIGN

A longitudinal-correlation, mixed-method design was used.

METHODS

Spasticity, pain, and fatigue symptoms were explored in 22 patients with stroke admitted to three different rehabilitation units certified by the Commission on Accreditation of Rehabilitation Facilities. Data were obtained upon admission, postdischarge, and 1 month after discharge. Demographics, numeric ratings, and a semistructured interview were used to determine associations over time.

RESULTS

Symptoms of spasticity, pain, and fatigue were quite variable. Fatigue was more likely to impair recovery. Spasticity appears to contain pain experiences. Pain does not appear to be a major factor over time.

CONCLUSIONS

In this sample of patients with stroke, symptoms of spasticity, pain, and fatigue were correlated.

CLINICAL RELEVANCE

In managing poststroke spasticity, pain, and fatigue, nurses should recognize that these symptoms are correlated.

Utilization Patterns of Skeletal Muscle Relaxants Among Commercially Insured Adults in the United States from 2006 to 2018

OBJECTIVE

To examine the prevalence and duration of skeletal muscle relaxant (SMR) treatment among commercially insured adults in the United States.

METHODS

We used the MarketScan Research Database to identify a cohort of adults 18 to 64 years who had ≥2-year continuous enrollment between 2005 and 2018. We estimated the prevalence of SMR treatment using a repeated cross-sectional design and derived treatment duration using the Kaplan-Meier method. Analyses were stratified by age group, sex, geographic region, individual SMR agent, and musculoskeletal disorder.

RESULTS

48.7 million individuals were included. Treatment prevalence ranged from 61.5 to 68.3 per 1,000. About one-third of users did not have a preceding musculoskeletal disorder diagnosis. Cyclobenzaprine was the dominant agent accounting for >50% of prescriptions. The considerable growth in the use of baclofen, tizanidine, and methocarbamol paralleled with a decline in carisoprodol and metaxalone use. The prevalence was highest in the South while lowest in the Northeast. The median treatment duration was 14 days with 4.0%, 1.9%, and 1.0% of individuals using SMRs for more than 90, 180, and 365 days, respectively. Compared with cyclobenzaprine, patients initiating baclofen, tizanidine, and carisoprodol had longer treatment duration.

CONCLUSIONS

SMRs are widely used in the United States. Their use slightly increased in recent years, but trends varied among individual agents, patient groups, and geographic regions. Despite limited evidence to support efficacy, a sizable number of U.S. adults used SMRs for long-term and off-label conditions. Further study is needed to understand determinants of treatment as well as outcomes associated with such use.

Assessing opioid overdose risk: a review of clinical prediction models utilizing patient-level data

Drug, and specifically opioid-related, overdoses remain a major public health problem in the United States. Multiple studies have examined individual risk factors associated with overdose risk, but research developing clinical risk prediction tools for overdose has only emerged in the last few years. We conducted a comprehensive review of the literature on patient-level factors associated with opioid-related overdose risk, with an emphasis on clinical risk prediction models for opioid-related overdose in the United States. Studies that developed and/or validated clinical prediction models were closely reviewed and evaluated to determine the state of the field. We identified 12 studies that reported risk prediction models for opioid-related overdose risk. Published models were developed from a variety of data sources, including Veterans Health Administration data, Medicare data, commercial insurance data, and statewide linked datasets. Studies reported model performance using measures of discrimination, usually at good-to-excellent levels, though they did not always assess calibration. C-statistics were better for models that included clinical predictors (c-statistics: 0.75-0.95) compared to models without them (c-statistics: 0.69-0.82). External validation of models was rare, and we found no studies evaluating implementation of models or risk prediction tools into clinical practice. A common feature of these models was a high rate of false positives, largely because opioid-related overdose is rare in the general population. Thus, efforts to implement prediction models into practice should take into account that published models overestimate overdose risk for many low-risk patients. Future prediction models assessing overdose risk should employ external validation and address model calibration. In order to translate findings from prediction models into clinical public health benefit, future studies should focus on developing clinical prediction tools based on prediction models, implementing these tools into clinical practice, and evaluating the impact of these models on treatment decisions, patient outcomes, and, ultimately, opioid overdose rates.

Coprescription of Opioids With Other Medications and Risk of Opioid Overdose

Polypharmacy is common among patients taking prescription opioids long-term, and the codispensing of interacting medications may further increase opioid overdose risk. To identify nonopioid medications that may increase opioid overdose risk in this population, we conducted a case-crossover-based screening of electronic claims data from IBM MarketScan and Optum Clinformatics Data Mart spanning 2003 through 2019. Eligible patients were 18 years of age or older and had at least 180 days of continuous enrollment and 90 days of prescription opioid use immediately before an opioid overdose resulting in an emergency room visit or hospitalization. The main analysis quantified the odds ratio (OR) between opioid overdose and each nonopioid medication dispensed in the 90 days immediately before the opioid overdose date after adjustment for prescription opioid dosage and benzodiazepine codispensing. Additional analyses restricted to patients without cancer diagnoses and individuals who used only oxycodone for 90 days immediately before the opioid overdose date. The false discovery rate (FDR) was used to account for multiple testing. We identified 24,866 individuals who experienced opioid overdose. Baclofen (OR 1.56; FDR < 0.01; 95% confidence interval (CI), 1.29 to 1.89), lorazepam (OR 1.53; FDR < 0.01; 95% CI, 1.25 to 1.88), and gabapentin (OR 1.16; FDR = 0.09; 95% CI, 1.04 to 1.28), among other nonopioid medications, were associated with opioid overdose. Similar patterns were observed in noncancer patients and individuals who used only oxycodone. Interventions may focus on prescribing safer alternatives when a potential for interaction exists.

Houston Cocktail: Driving under influence of hydrocodone, alprazolam, and carisoprodol

Concurrent use of opioids, benzodiazepines, and skeletal muscle relaxants potentiates the drug effect and respiratory depression via interactions of μ-opioid and GABAA receptors. In the early 2000s when abuse of prescription drugs began to spike, a potent combination including hydrocodone, alprazolam, and carisoprodol, aka the "Houston Cocktail" or "Holy Trinity", emerged that may give users heroin-like euphoria. This research evaluated driving while intoxicated (DWI) cases that tested positive for hydrocodone, alprazolam, and carisoprodol, between 2015 and 2019. The blood samples were collected from drivers and submitted by the Houston Police Department (HPD). They were subsequently analyzed for alcohol and drugs by reference laboratories or Houston Forensic Science Center (HFSC). Toxicological findings, demographic information, and observed impairment were evaluated for the Houston Cocktail-positive DWI cases. A total of 80 DWI/DUID cases positive for hydrocodone, alprazolam, and carisoprodol in blood in which the traffic offense occurred between May 2015 and December 2019 were identified. Among these Houston Cocktail cases, the mean (median, range) concentrations were 75 (61, 6.9-322) ng/mL for hydrocodone, 58 (48, 5.8-180) ng/mL for alprazolam, and 3.9 (3.0, 0.3-14; n = 68) µg/mL for carisoprodol; 80 (100%) and 23 (29%) cases were also positive for meprobamate (mean 13; range 1.2-41 µg/mL) and hydromorphone (1.8; 1.0-3.3 ng/mL), respectively; carisoprodol and meprobamate in 12 of the cases were qualitatively detected. Forty six percent of those cases were females and 54% were males; 44% were Blacks, 46% were Whites, and 10% were other races as identified by the arresting officer. Mean (median) age of the drivers was 36 (34) years, ranged from 22 to 60 years. Twenty eight percent of the cases were positive for the Houston Cocktail only; 21% had one other drug/metabolite, 28% two, 14% three, and 10% had four or more additional drugs/metabolites. Of the 80 cases, cannabinoids were the most frequently detected analytes (35%), followed by codeine (11%). The drivers exhibited driving problems related to lane position, vigilance, judgment, speed, and/or braking. Many of the drivers (70-84%) had red/glassy eyes, slurred speed, poor balance, HGN and impaired divided attention. The present study showed that despite a traffic safety risk, drivers in Houston continue to use this dangerous drug combination. The risk is further exacerbated by the fact that the many drivers had yet other drugs in the system besides the three drugs.

Keeping the Pharmacology in Pharmacoepidemiology

The treatment of many medical conditions requires the use of multiple drugs. A study published recently in this journal nicely illustrates the need to consider the pharmacology of potentially interacting drugs when conducting pharmacoepidemiologic studies of patient safety outcomes associated with such interactions. By examining multiple streams of data, we can piece together the risks and the mechanisms of action underlying those risks, and provide useful information for clinicians and patients to use multiple pharmacotherapies safely.

Screening to identify signals of opioid drug interactions leading to unintentional traumatic injury

BACKGROUND

Efforts to minimize harms from opioid drug interactions may be hampered by limited evidence on which drugs, when taken concomitantly with opioids, result in adverse clinical outcomes.

OBJECTIVE

To identify signals of opioid drug interactions by identifying concomitant medications (precipitant drugs) taken with individual opioids (object drugs) that are associated with unintentional traumatic injury DESIGN: We conducted pharmacoepidemiologic screening of Optum Clinformatics Data Mart, identifying drug interaction signals by performing confounder-adjusted self-controlled case series studies for opioid + precipitant pairs and injury.

SETTING

Beneficiaries of a major United States-based commercial health insurer during 2000-2015 PATIENTS: Persons aged 16-90 years co-dispensed an opioid and ≥1 precipitant drug(s), with an unintentional traumatic injury event during opioid therapy, as dictated by the case-only design EXPOSURE: Precipitant-exposed (vs. precipitant-unexposed) person-days during opioid therapy.

OUTCOME

Emergency department or inpatient International Classification of Diseases discharge diagnosis for unintentional traumatic injury. We used conditional Poisson regression to generate confounder adjusted rate ratios. We accounted for multiple estimation via semi-Bayes shrinkage.

RESULTS

We identified 25,019, 12,650, and 10,826 new users of hydrocodone, tramadol, and oxycodone who experienced an unintentional traumatic injury. Among 464, 376, and 389 hydrocodone-, tramadol-, and oxycodone-precipitant pairs examined, 20, 17, and 16 (i.e., 53 pairs, 34 unique precipitants) were positively associated with unintentional traumatic injury and deemed potential drug interaction signals. Adjusted rate ratios ranged from 1.23 (95 % confidence interval: 1.05-1.44) for hydrocodone + amoxicillin-clavulanate to 4.21 (1.88-9.42) for oxycodone + telmisartan. Twenty (37.7 %) of 53 signals are currently reported in a major drug interaction knowledgebase.

LIMITATIONS

Potential for reverse causation, confounding by indication, and chance CONCLUSIONS: We identified previously undescribed and/or unappreciated signals of opioid drug interactions associated with unintentional traumatic injury. Subsequent etiologic studies should confirm (or refute) and elucidate these potential drug interactions.

Assessment of Physician Prescribing of Muscle Relaxants in the United States, 2005-2016

IMPORTANCE

Little is known to date about national trends in the prescribing of skeletal muscle relaxants (SMRs), the use of which is associated with important safety concerns, especially in older adults and in those who use concomitant opioids.

OBJECTIVE

To measure national trends in SMR prescribing over a 12-year period.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the National Ambulatory Medical Care Survey from January 2005 to December 2016. Data were analyzed from August 21, 2018, to July 18, 2019. The study included patients with ambulatory care visits who had encounters with non-federally funded, office-based physicians in the United States.

EXPOSURES

SMR use, categorized as newly prescribed or continued therapy at the office visit.

MAIN OUTCOMES AND MEASURES

Ambulatory care visits-overall and stratified by calendar year, geographic region, and patient age, sex, and race-in which an SMR was newly prescribed or continued were quantified. Among office visits in which an SMR was newly prescribed, diagnoses were assessed. Concomitant medications were quantified for all office visits, stratified by new or continued therapy. Survey visit weights were used to estimate nationally representative measures, and age-standardized rates were generated by geographic region using US Census data.

RESULTS

This study included a total of 314 970 308 office visits (mean [SD] age, 53.5 [15.2] years; 194 621 102 [61.8%] men and 120 349 206 [38.2%] women). In 2016, there were 30 730 262 (95% CI, 30 626 464-30 834 060) US ambulatory care visits in which an SMR was either newly prescribed or continued as ongoing therapy. Patients in these visits were most frequently female (58.2% [95% CI, 57.9%-58.6%]), white (53.7% [95% CI, 53.4%-54.0%]), and aged 45 to 64 years (48.5% [95% CI, 48.2%-48.9%]). During the study period, office visits with a prescribed SMR nearly doubled from 15.5 million (95% CI, 15.4-15.6 million) in 2005 to 30.7 million (95% CI, 30.6-30.8 million) in 2016. Although visits for new SMR prescriptions remained stable, office visits with continued SMR drug therapy tripled from 8.5 million (95% CI, 8.4-8.5 million) visits in 2005 to 24.7 million (95% CI, 24.6-24.8 million) visits in 2016. Older adults accounted for 22.2% (95% CI, 21.8%-22.6%) of visits with an SMR prescription. Concomitant use of an opioid was recorded in 67.2% (95% CI, 62.0%-72.5%) of all visits with a continuing SMR prescription.

CONCLUSIONS AND RELEVANCE

This study found that SMR use increased rapidly between 2005 and 2016, which is a concern given the prominent adverse effects and limited long-term efficacy data associated with their use. These findings suggest that approaches are needed to limit the long-term use of SMRs, especially in older adults, similar to approaches to limit long-term use of opioids and benzodiazepines.