Vikram B. Patel

Bio: Vikram B. Patel is an academic researcher from Loyola University Chicago. The author has contributed to research in topics: Evidence-based medicine & Opioid. The author has an hindex of 11, co-authored 13 publications receiving 2873 citations.

A comprehensive review of opioid-induced hyperalgesia.

Abstract: Opioid-induced hyperalgesia (OIH) is defined as a state of nociceptive sensitization caused by exposure to opioids. The condition is characterized by a paradoxical response whereby a patient receiving opioids for the treatment of pain could actually become more sensitive to certain painful stimuli. The type of pain experienced might be the same as the underlying pain or might be different from the original underlying pain. OIH appears to be a distinct, definable, and characteristic phenomenon that could explain loss of opioid efficacy in some patients. Findings of the clinical prevalence of OIH are not available. However, several observational, cross-sectional, and prospective controlled trials have examined the expression and potential clinical significance of OIH in humans. Most studies have been conducted using several distinct cohorts and methodologies utilizing former opioid addicts on methadone maintenance therapy, perioperative exposure to opioids in patients undergoing surgery, and healthy human volunteers after acute opioid exposure using human experimental pain testing. The precise molecular mechanism of OIH, while not yet understood, varies substantially in the basic science literature, as well as clinical medicine. It is generally thought to result from neuroplastic changes in the peripheral and central nervous system (CNS) that lead to sensitization of pronociceptive pathways. While there are many proposed mechanisms for OIH, 5 mechanisms involving the central glutaminergic system, spinal dynorphins, descending facilitation, genetic mechanisms, and decreased reuptake and enhanced nociceptive response have been described as the important mechanisms. Of these, the central glutaminergic system is considered the most common possibility. Another is the hypothesis that N-methyl-D-aspartate (NMDA) receptors in OIH include activation, inhibition of the glutamate transporter system, facilitation of calcium regulated intracellular protein kinase C, and cross talk of neural mechanisms of pain and tolerance. Clinicians should suspect OIH when opioid treatment's effect seems to wane in the absence of disease progression, particularly if found in the context of unexplained pain reports or diffuse allodynia unassociated with the original pain, and increased levels of pain with increasing dosages. The treatment involves reducing the opioid dosage, tapering them off, or supplementation with NMDA receptor modulators. This comprehensive review addresses terminology and definition, prevalence, the evidence for mechanism and physiology with analysis of various factors leading to OIH, and effective strategies for preventing, reversing, or managing OIH.

Interventional Techniques: Evidence-based Practice Guidelines in the Management of Chronic Spinal Pain

Abstract: Background: The evidence-based practice guidelines for the management of chronic spinal pain with interventional techniques were developed to provide recommendations to clinicians in the United States. Objective: To develop evidence-based clinical practice guidelines for interventional techniques in the diagnosis and treatment of chronic spinal pain, utilizing all types of evidence and to apply an evidence-based approach, with broad representation by specialists from academic and clinical practices. Design: Study design consisted of formulation of essentials of guidelines and a series of potential evidence linkages representing conclusions and statements about relationships between clinical interventions and outcomes. Methods: The elements of the guideline preparation process included literature searches, literature synthesis, systematic review, consensus evaluation, open forum presentation, and blinded peer review. Methodologic quality evaluation criteria utilized included the Agency for Healthcare Research and Quality (AHRQ) criteria, Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria, and Cochrane review criteria. The designation of levels of evidence was from Level I (conclusive), Level II (strong), Level III (moderate), Level IV (limited), to Level V (indeterminate). Results: Among the diagnostic interventions, the accuracy of facet joint nerve blocks is strong in the diagnosis of lumbar and cervical facet joint pain, whereas, it is moderate in the diagnosis of thoracic facet joint pain. The evidence is strong for lumbar discography, whereas, the evidence is limited for cervical and thoracic discography. The evidence for transforaminal epidural injections or selective nerve root blocks in the preoperative evaluation of patients with negative or inconclusive imaging studies is moderate. The evidence for diagnostic sacroiliac joint injections is moderate. The evidence for therapeutic lumbar intraarticular facet injections is moderate for short-term and long-term improvement, whereas, it is limited for cervical facet joint injections. The evidence for lumbar and cervical medial branch blocks is moderate. The evidence for medial branch neurotomy is moderate. The evidence for caudal epidural steroid injections is strong for short-term relief and moderate for long-term relief in managing chronic low back and radicular pain, and limited in managing pain of postlumbar laminectomy syndrome. The evidence for interlaminar epidural steroid injections is strong for short-term relief and limited for long-term relief in managing lumbar radiculopathy, whereas, for cervical radiculopathy the evidence is moderate. The evidence for transforaminal epidural steroid injections is strong for short-term and moderate for long-term improvement in managing lumbar nerve root pain, whereas, it is moderate for cervical nerve root pain and limited in managing pain secondary to lumbar post laminectomy syndrome and spinal stenosis.

American Society of Interventional Pain Physicians (ASIPP) Guidelines for Responsible Opioid Prescribing in Chronic Non-Cancer Pain: Part 2 - Guidance

Abstract: RESULTS: Part 2 of the guidelines on responsible opioid prescribing provides the following recommendations for initiating and maintaining chronic opioid therapy of 90 days or longer. 1. A) Comprehensive assessment and documentation is recommended before initiating opioid therapy, including documentation of comprehensive history, general medical condition, psychosocial history, psychiatric status, and substance use history. (Evidence: good) B) Despite limited evidence for reliability and accuracy, screening for opioid use is recommended, as it will identify opioid abusers and reduce opioid abuse. (Evidence: limited) C) Prescription monitoring programs must be implemented, as they provide data on patterns of prescription usage, reduce prescription drug abuse or doctor shopping. (Evidence: good to fair) D) Urine drug testing (UDT) must be implemented from initiation along with subsequent adherence monitoring to decrease prescription drug abuse or illicit drug use when patients are in chronic pain management therapy. (Evidence: good) 2. A) Establish appropriate physical diagnosis and psychological diagnosis if available prior to initiating opioid therapy. (Evidence: good) B) Caution must be exercised in ordering various imaging and other evaluations, interpretation and communication with the patient, to avoid increased fear, activity restriction, requests for increased opioids, and maladaptive behaviors. (Evidence: good) C) Stratify patients into one of the 3 risk categories - low, medium, or high risk. D) A pain management consultation, may assist non-pain physicians, if high-dose opioid therapy is utilized. (Evidence: fair) 3. Essential to establish medical necessity prior to initiation or maintenance of opioid therapy. (Evidence: good) 4. Establish treatment goals of opioid therapy with regard to pain relief and improvement in function. (Evidence: good) 5. A) Long-acting opioids in high doses are recommended only in specific circumstances with severe intractable pain that is not amenable to short-acting or moderate doses of long-acting opioids, as there is no significant difference between long-acting and short-acting opioids for their effectiveness or adverse effects. (Evidence: fair) B) The relative and absolute contraindications to opioid use in chronic non-cancer pain must be evaluated including respiratory instability, acute psychiatric instability, uncontrolled suicide risk, active or history of alcohol or substance abuse, confirmed allergy to opioid agents, coadministration of drugs capable of inducing life-limiting drug interaction, concomitant use of benzodiazepines, active diversion of controlled substances, and concomitant use of heavy doses of central nervous system depressants. (Evidence: fair to limited) 6. A robust agreement which is followed by all parties is essential in initiating and maintaining opioid therapy as such agreements reduce overuse, misuse, abuse, and diversion. (Evidence: fair) 7. A) Once medical necessity is established, opioid therapy may be initiated with low doses and short-acting drugs with appropriate monitoring to provide effective relief and avoid side effects. (Evidence: fair for short-term effectiveness, limited for long-term effectiveness) B) Up to 40 mg of morphine equivalent is considered as low dose, 41 to 90 mg of morphine equivalent as a moderate dose, and greater than 91 mg of morphine equivalence as high dose. (Evidence: fair) C) In reference to long-acting opioids, titration must be carried out with caution and overdose and misuse must be avoided. (Evidence: good) 8. A) Methadone is recommended for use in late stages after failure of other opioid therapy and only by clinicians with specific training in the risks and uses. (Evidence: limited) B) Monitoring recommendation for methadone prescription is that an electrocardiogram should be obtained prior to initiation, at 30 days and yearly thereafter. (Evidence: fair) 9. In order to reduce prescription drug abuse and doctor shopping, adherence monitoring by UDT and PMDPs provide evidence that is essential to the identification of those patients who are non-compliant or abusing prescription drugs or illicit drugs. (Evidence: fair) 10. Constipation must be closely monitored and a bowel regimen be initiated as soon as deemed necessary. (Evidence: good) 11. Chronic opioid therapy may be continued, with continuous adherence monitoring, in well-selected populations, in conjunction with or after failure of other modalities of treatments with improvement in physical and functional status and minimal adverse effects. (Evidence: fair) DISCLAIMER: The guidelines are based on the best available evidence and do not constitute inflexible treatment recommendations. Due to the changing body of evidence, this document is not intended to be a "standard of care." Language: en

An update of comprehensive evidence-based guidelines for interventional techniques in chronic spinal pain. Part II: guidance and recommendations.

Abstract: Objective To develop evidence-based clinical practice guidelines for interventional techniques in the diagnosis and treatment of chronic spinal pain. Methodology Systematic assessment of the literature. Evidence I. Lumbar Spine • The evidence for accuracy of diagnostic selective nerve root blocks is limited; whereas for lumbar provocation discography, it is fair. • The evidence for diagnostic lumbar facet joint nerve blocks and diagnostic sacroiliac intraarticular injections is good with 75% to 100% pain relief as criterion standard with controlled local anesthetic or placebo blocks. • The evidence is good in managing disc herniation or radiculitis for caudal, interlaminar, and transforaminal epidural injections; fair for axial or discogenic pain without disc herniation, radiculitis or facet joint pain with caudal, and interlaminar epidural injections, and limited for transforaminal epidural injections; fair for spinal stenosis with caudal, interlaminar, and transforaminal epidural injections; and fair for post surgery syndrome with caudal epidural injections and limited with transforaminal epidural injections. • The evidence for therapeutic facet joint interventions is good for conventional radiofrequency, limited for pulsed radiofrequency, fair to good for lumbar facet joint nerve blocks, and limited for intraarticular injections. • For sacroiliac joint interventions, the evidence for cooled radiofrequency neurotomy is fair; limited for intraarticular injections and periarticular injections; and limited for both pulsed radiofrequency and conventional radiofrequency neurotomy. • For lumbar percutaneous adhesiolysis, the evidence is fair in managing chronic low back and lower extremity pain secondary to post surgery syndrome and spinal stenosis. • For intradiscal procedures, the evidence for intradiscal electrothermal therapy (IDET) and biaculoplasty is limited to fair and is limited for discTRODE. • For percutaneous disc decompression, the evidence is limited for automated percutaneous lumbar discectomy (APLD), percutaneous lumbar laser disc decompression, and Dekompressor; and limited to fair for nucleoplasty for which the Centers for Medicare and Medicaid Services (CMS) has issued a noncoverage decision. II. Cervical Spine • The evidence for cervical provocation discography is limited; whereas the evidence for diagnostic cervical facet joint nerve blocks is good with a criterion standard of 75% or greater relief with controlled diagnostic blocks. • The evidence is good for cervical interlaminar epidural injections for cervical disc herniation or radiculitis; fair for axial or discogenic pain, spinal stenosis, and post cervical surgery syndrome. • The evidence for therapeutic cervical facet joint interventions is fair for conventional cervical radiofrequency neurotomy and cervical medial branch blocks, and limited for cervical intraarticular injections. III. Thoracic Spine • The evidence is limited for thoracic provocation discography and is good for diagnostic accuracy of thoracic facet joint nerve blocks with a criterion standard of at least 75% pain relief with controlled diagnostic blocks. • The evidence is fair for thoracic epidural injections in managing thoracic pain. • The evidence for therapeutic thoracic facet joint nerve blocks is fair, limited for radiofrequency neurotomy, and not available for thoracic intraarticular injections. IV. Implantables • The evidence is fair for spinal cord stimulation (SCS) in managing patients with failed back surgery syndrome (FBSS) and limited for implantable intrathecal drug administration systems. V. ANTICOAGULATION • There is good evidence for risk of thromboembolic phenomenon in patients with antithrombotic therapy if discontinued, spontaneous epidural hematomas with or without traumatic injury in patients with or without anticoagulant therapy to discontinue or normalize INR with warfarin therapy, and the lack of necessity of discontinuation of nonsteroidal anti-inflammatory drugs (NSAIDs), including low dose aspirin prior to performing interventional techniques. • There is fair evidence with excessive bleeding, including epidural hematoma formation with interventional techniques when antithrombotic therapy is continued, the risk of higher thromboembolic phenomenon than epidural hematomas with discontinuation of antiplatelet therapy prior to interventional techniques and to continue phosphodiesterase inhibitors (dipyridamole, cilostazol, and Aggrenox). • There is limited evidence to discontinue antiplatelet therapy with platelet aggregation inhibitors to avoid bleeding and epidural hematomas and/or to continue antiplatelet therapy (clopidogrel, ticlopidine, prasugrel) during interventional techniques to avoid cerebrovascular and cardiovascular thromboembolic fatalities. • There is limited evidence in reference to newer antithrombotic agents dabigatran (Pradaxa) and rivaroxan (Xarelto) to discontinue to avoid bleeding and epidural hematomas and are continued during interventional techniques to avoid cerebrovascular and cardiovascular thromboembolic events. Conclusions Evidence is fair to good for 62% of diagnostic and 52% of therapeutic interventions assessed. Disclaimer The authors are solely responsible for the content of this article. No statement on this article should be construed as an official position of ASIPP. The guidelines do not represent "standard of care."

American Society of Interventional Pain Physicians (ASIPP) guidelines for responsible opioid prescribing in chronic non-cancer pain

Abstract: BACKGROUND Opioid abuse has continued to increase at an alarming rate since the 1990 s. As documented by different medical specialties, medical boards, advocacy groups, and the Drug Enforcement Administration, available evidence suggests a wide variance in chronic opioid therapy of 90 days or longer in chronic non-cancer pain. Part 1 describes evidence assessment. OBJECTIVES The objectives of opioid guidelines as issued by the American Society of Interventional Pain Physicians (ASIPP) are to provide guidance for the use of opioids for the treatment of chronic non-cancer pain, to produce consistency in the application of an opioid philosophy among the many diverse groups involved, to improve the treatment of chronic non-cancer pain, and to reduce the incidence of abuse and drug diversion. The focus of these guidelines is to curtail the abuse of opioids without jeopardizing non-cancer pain management with opioids. RESULTS 1) There is good evidence that non-medical use of opioids is extensive; one-third of chronic pain patients may not use prescribed opioids as prescribed or may abuse them, and illicit drug use is significantly higher in these patients. 2) There is good evidence that opioid prescriptions are increasing rapidly, as the majority of prescriptions are from non-pain physicians, many patients are on long-acting opioids, and many patients are provided with combinations of long-acting and short-acting opioids. 3) There is good evidence that the increased supply of opioids, use of high dose opioids, doctor shoppers, and patients with multiple comorbid factors contribute to the majority of the fatalities. 4) There is fair evidence that long-acting opioids and a combination of long-acting and short-acting opioids contribute to increasing fatalities and that even low-doses of 40 mg or 50 mg of daily morphine equivalent doses may be responsible for emergency room admissions with overdoses and deaths. 5) There is good evidence that approximately 60% of fatalities originate from opioids prescribed within the guidelines, with approximately 40% of fatalities occurring in 10% of drug abusers. 6) The short-term effectiveness of opioids is fair, whereas the long-term effectiveness of opioids is limited due to a lack of long-term (> 3 months) high quality studies, with fair evidence with no significant difference between long-acting and short-acting opioids. 7) Among the individual drugs, most opioids have fair evidence for short-term and limited evidence for long-term due to a lack of quality studies. 8) The evidence for the effectiveness and safety of chronic opioid therapy in the elderly for chronic non-cancer pain is fair for short-term and limited for long-term due to lack of high quality studies; limited in children and adolescents and patients with comorbid psychological disorders due to lack of quality studies; and the evidence is poor in pregnant women. 9) There is limited evidence for reliability and accuracy of screening tests for opioid abuse due to lack of high quality studies. 10) There is fair evidence to support the identification of patients who are non-compliant or abusing prescription drugs or illicit drugs through urine drug testing and prescription drug monitoring programs, both of which can reduce prescription drug abuse or doctor shopping. DISCLAIMER The guidelines are based on the best available evidence and do not constitute inflexible treatment recommendations. Due to the changing body of evidence, this document is not intended to be a \"standard of care.\

Opioid Epidemic in the United States

Abstract: Over the past two decades, as the prevalence of chronic pain and health care costs have exploded, an opioid epidemic with adverse consequences has escalated. Efforts to increase opioid use and a campaign touting the alleged undertreatment of pain continue to be significant factors in the escalation. Many arguments in favor of opioids are based solely on traditions, expert opinion, practical experience and uncontrolled anecdotal observations. Over the past 20 years, the liberalization of laws governing the prescribing of opioids for the treatment of chronic non-cancer pain by the state medical boards has led to dramatic increases in opioid use. This has evolved into the present stage, with the introduction of new pain management standards by the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) in 2000, an increased awareness of the right to pain relief, the support of various organizations supporting the use of opioids in large doses, and finally, aggressive marketing by the pharmaceutical industry. These positions are based on unsound science and blatant misinformation, and accompanied by the dangerous assumptions that opioids are highly effective and safe, and devoid of adverse events when prescribed by physicians. Results of the 2010 National Survey on Drug Use and Health (NSDUH) showed that an estimated 22.6 million, or 8.9% of Americans, aged 12 or older, were current or past month illicit drug users, The survey showed that just behind the 7 million people who had used marijuana, 5.1 million had used pain relievers. It has also been shown that only one in 6 or 17.3% of users of non-therapeutic opioids indicated that they received the drugs through a prescription from one doctor. The escalating use of therapeutic opioids shows hydrocodone topping all prescriptions with 136.7 million prescriptions in 2011, with all narcotic analgesics exceeding 238 million prescriptions. It has also been illustrated that opioid analgesics are now responsible for more deaths than the number of deaths from both suicide and motor vehicle crashes, or deaths from cocaine and heroin combined. A significant relationship exists between sales of opioid pain relievers and deaths. The majority of deaths (60%) occur in patients when they are given prescriptions based on prescribing guidelines by medical boards, with 20% of deaths in low dose opioid therapy of 100 mg of morphine equivalent dose or less per day and 40% in those receiving morphine of over 100 mg per day. In comparison, 40% of deaths occur in individuals abusing the drugs obtained through multiple prescriptions, doctor shopping, and drug diversion. The purpose of this comprehensive review is to describe various aspects of crisis of opioid use in the United States. The obstacles that must be surmounted are primarily inappropriate prescribing patterns, which are largely based on a lack of knowledge, perceived safety, and inaccurate belief of undertreatment of pain.

Neuropathic pain: quality-of-life impact, costs and cost effectiveness of therapy.

Abstract: A number of different diseases or injuries can damage the central or peripheral nervous system and produce neuropathic pain (NP), which seems to be more difficult to treat than many other types of chronic pain. As a group, patients with NP have greater medical co-morbidity burden than age- and sex-adjusted controls, which makes determining the humanistic and economic burden attributable to NP challenging. Health-related quality of life (HR-QOL) is substantially impaired among patients with NP. Patients describe pain-related interference in multiple HR-QOL and functional domains, as well as reduced ability to work and reduced mobility due to their pain. In addition, the spouses of NP patients have been shown to experience adverse social consequences related to NP. In randomized controlled trials, several medications have been shown to improve various measures of HR-QOL. Changes in HR-QOL appear to be tightly linked to pain relief, but not to the development of adverse effects. However, in cross-sectional studies, many patients continue to have moderate or severe pain and markedly impaired HR-QOL, despite taking medications prescribed for NP. The quality of NP treatment appears to be poor, with few patients receiving recommended medications in efficacious dosages. The substantial costs to society of NP derive from direct medical costs, loss of the ability to work, loss of caregivers' ability to work and possibly greater need for institutionalization or other living assistance. No single study has measured all of these costs to society for chronic NP. The cost effectiveness of various interventions for the treatment or prevention of different types of NP has been assessed in several different studies. The most-studied diseases are post-herpetic neuralgia and painful diabetic neuropathy, for which tricyclic antidepressants (both amitriptyline and desipramine) have been found to be either cost effective or dominant relative to other strategies. Increasing the use of cost-effective therapies such as tricyclic antidepressants for post-herpetic neuralgia and painful diabetic neuropathy may improve the HR-QOL of patients and decrease societal costs. Head-to-head clinical trials comparing NP therapies are needed to help assess the relative clinical efficacy of treatments, ideally using HR-QOL and utility outcomes. The full costs to society of NP, including productivity loss costs, have not been determined for chronic NP. Improved relative efficacy, utility and cost estimates would facilitate future cost-effectiveness research in NP.

Opioid Abuse in Chronic Pain — Misconceptions and Mitigation Strategies

Abstract: Chronic pain not caused by cancer is among the most prevalent and debilitating medical conditions but also among the most controversial and complex to manage. The urgency of patients’ needs, the demonstrated effectiveness of opioid analgesics for the management of acute pain, and the limited therapeutic alternatives for chronic pain have combined to produce an overreliance on opioid medications in the United States, with associated alarming increases in diversion, overdose, and addiction. Given the lack of clinical consensus and research-supported guidance, physicians understandably have questions about whether, when, and how to prescribe opioid analgesics for chronic pain without increasing public health risks. Here, we draw on recent research to address common misconceptions regarding the abuse-related risks of opioid analgesics and highlight strategies to minimize those risks.

A comprehensive review of opioid-induced hyperalgesia.

Abstract: Opioid-induced hyperalgesia (OIH) is defined as a state of nociceptive sensitization caused by exposure to opioids. The condition is characterized by a paradoxical response whereby a patient receiving opioids for the treatment of pain could actually become more sensitive to certain painful stimuli. The type of pain experienced might be the same as the underlying pain or might be different from the original underlying pain. OIH appears to be a distinct, definable, and characteristic phenomenon that could explain loss of opioid efficacy in some patients. Findings of the clinical prevalence of OIH are not available. However, several observational, cross-sectional, and prospective controlled trials have examined the expression and potential clinical significance of OIH in humans. Most studies have been conducted using several distinct cohorts and methodologies utilizing former opioid addicts on methadone maintenance therapy, perioperative exposure to opioids in patients undergoing surgery, and healthy human volunteers after acute opioid exposure using human experimental pain testing. The precise molecular mechanism of OIH, while not yet understood, varies substantially in the basic science literature, as well as clinical medicine. It is generally thought to result from neuroplastic changes in the peripheral and central nervous system (CNS) that lead to sensitization of pronociceptive pathways. While there are many proposed mechanisms for OIH, 5 mechanisms involving the central glutaminergic system, spinal dynorphins, descending facilitation, genetic mechanisms, and decreased reuptake and enhanced nociceptive response have been described as the important mechanisms. Of these, the central glutaminergic system is considered the most common possibility. Another is the hypothesis that N-methyl-D-aspartate (NMDA) receptors in OIH include activation, inhibition of the glutamate transporter system, facilitation of calcium regulated intracellular protein kinase C, and cross talk of neural mechanisms of pain and tolerance. Clinicians should suspect OIH when opioid treatment's effect seems to wane in the absence of disease progression, particularly if found in the context of unexplained pain reports or diffuse allodynia unassociated with the original pain, and increased levels of pain with increasing dosages. The treatment involves reducing the opioid dosage, tapering them off, or supplementation with NMDA receptor modulators. This comprehensive review addresses terminology and definition, prevalence, the evidence for mechanism and physiology with analysis of various factors leading to OIH, and effective strategies for preventing, reversing, or managing OIH.