Transition from acute to chronic postsurgical pain: risk factors and protective factors

Abstract

Most patients who undergo surgery recover uneventfully and resume their normal daily activities within weeks. Nevertheless, chronic postsurgical pain develops in an alarming proportion of patients. The prevailing approach of focusing on established chronic pain implicitly assumes that information generated during the acute injury phase is not important to the subsequent development of chronic pain. However, a rarely appreciated fact is that every chronic pain was once acute. Here, we argue that a focus on the transition from acute to chronic pain may reveal important cues that will help us to predict who will go on to develop chronic pain and who will not. Unlike other injuries, surgery presents a unique set of circumstances in which the precise timing of the physical insult and ensuing pain are known in advance. This provides an opportunity, before surgery, to identify the risk factors and protective factors that predict the course of recovery. In this paper, the epidemiology of chronic postsurgical pain is reviewed. The surgical, psychosocial, socio-environmental and patient-related factors that appear to confer a greater risk of developing chronic postsurgical pain are described. The genetics of chronic postsurgical pain are discussed with emphasis on known polymorphisms in human genes associated with chronic pain, genetic studies of rodent models of pain involving surgical approaches, the importance of developing accurate human chronic postsurgical pain phenotypes and the expected gains for chronic postsurgical pain medicine in the post-genomic era. Evidence is then reviewed for a preventive multimodal analgesic approach to surgery. While there is some evidence that chronic postsurgical pain can be minimized or prevented by an analgesic approach involving aggressive perioperative multimodal treatment, other studies fail to show this benefit. The transition of acute postoperative pain to chronic postsurgical pain is a complex and poorly understood developmental process, involving biological, psychological and social-environmental factors.

Preventive Analgesia and Novel Strategies for the Prevention of Chronic Post-Surgical Pain

“…Elsewhere we have argued that the true power of preventive, multimodal treatment to impact the trajectory of postsurgical pain can only be realized by the integration of psychological interventions into the patients' pre-and postsurgical care [8]. Pain after surgery-in the aftermath of incision, intra-operative tissue damage and the ensuing inflammatory cascade-is subject to a host of psychosocial influences, including those related to mood and attention [92].…”

“…Psychosocial risk factors of particular concern with respect to CPSP include pre-surgical depression, anxiety, surgical fear [93], and emotional numbing [94]. Pain catastrophizing (rumination, magnification, and helplessness) after surgery may confer added risk of CPSP, although findings have been mixed and may be surgeryspecific [8]. Innovative research from our group has identified subgroups of patients with distinct post-surgical pain trajectories.…”

“…Despite the effectiveness of these programs in terms of the patient's quality of life, chronic pain patients often have difficulty accessing them until pain is well established and all other medical options have been exhausted. In contrast, for most surgeries, the nature of the injury and time of onset of pain are known in advance and patients are accessible through the hospital system [8]. Surgery therefore offers a unique opportunity to reach patients early-even before surgery-to influence psychological variables such as pre-surgical anxiety.…”

“…Moreover, many patients with objective signs of nerve injury do not develop CPSP [7]. The development of CPSP is a complex process which involves biologic, psychosocial, and environmental mechanisms that have yet to be fully understood [8].…”

Acute pain after total hip arthroplasty does not predict the development of chronic postsurgical pain 6 months later

“…Neuropathic pain (pain arising as a direct consequence of a lesion or disease affecting the somatosensory system) [2] has been implicated as a major contributor to the development of neuropathic pain [3,4]. A prospective longitudinal study examining patients that experienced intense neuropathic pain in the acute hospital period found that 56Vo of these patients reported chronic neuropathic pain I year postdischarge [5].…”