Maladaptive LTOT dependence and Opioid Induced Chronic Pain Syndrome (OICP):
Despite the best intentions and efforts by patients and providers, adaptive LTOT dependence that provides functional improvement and pain control can and often does evolve over time into maladaptive LTOT dependence or CPOD accompanied by the clinical phenomenology of OICP irrespective of whether LTOT is continued or discontinued.45 OICP often mimics the worsening of musculoskeletal and other diseases associated with chronic pain and seemingly unrelated medical and psychiatric diseases, thus potentially causing providers and patients to fail to recognize the clinical impact of OICP. Attributing worsening OICP to musculoskeletal deterioration can encourage reliance on inappropriate tests and clinical evaluations that can lead to ineffective and harmful treatments, including polypharmacy and initiation or dose escalation of other potentially addictive substances.52,53,65 These ineffective methods of treating OICP may worsen overall health and function. Polysubstance use and polypharmacy, especially with addictive medications like gabapentin, benzodiazepines, and stimulants, can substantially increase clinical complexity and patient distress. OICP has become more prominent with the recent embracing of opioid tapering as a treatment of ineffective and unsafe LTOT. In our clinical experience, treatment of the medical and psychiatric conditions associated with OCIP may be futile and reinstatement of opioid dose, albeit as a treatment of opioid dependence, is often necessary.52,66
The insidious development of maladaptive LTOT dependence with OICP can evade usual pain focused clinical evaluations because of confounding clinical presentations. This raises the need for close follow up of patients on LTOT to assess for development of OICP using specific criteria. Thus, the increased recognition that patients on LTOT can develop a paradoxical persistent pain syndrome raises the need for a set of criteria for the identification of OICP.70 We propose the following criteria enumerated in Box 2 as a starting point. These criteria for identifying OICP should be revised with further research and accumulation of clinical expertise and OICP can be perhaps developed into a formal diagnostic terminology.
It is important not to confuse or equate OICP, a common clinical phenomenon observed in clinical practice presumably driven largely by non-nociceptive mechanisms, with opioid induced hyperalgesia (OIH), a rare clinical phenomenology driven by nociceptive mechanisms. Allostatic opponent effect is the shared theoretical explanation for both OICP and OIH. 45,71 However, OIH is the clinical expression of allostatic opponent effect confined to the nociceptive components of pain experience that is associated with increased pain related to hyperalgesia (a higher sensitivity to nociceptive stimuli).45,71 Prior authors have used the term hyperkatefia to described the pain experience associated with allostatic opponent effect on the non-nociceptive components of pain.69 OICP is conceptualized as the increased global experience of pain, other associated symptoms like depression, anxiety, fatigue and debility mediated by non-nociceptive mechanisms and is not typically associated with hyperalgesia in clinical practice.45
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