Cancer pain management has always been difficult. This is especially true during periods of acute exacerbation that require a visit to the ED. Previous literature has helped elucidate the scope of the problem [1–3, 13], but a more in depth analysis of ED cancer pain management and associated outcomes is lacking. Prior studies have demonstrated limited improvement in pain management despite targeted interventions, highlighting the need for further study in this area [3]. We performed this study to better define the population at risk, the current status of pain management in the ED, and the associated outcomes, in an effort to identify future targets for intervention.
Cancer Types:
After stratifying pain scores by cancer type, we noted that breast, colorectal, and ENT cancers had both a high volume of initial severe pain presentations and a low median delta pain. As a result, these cancers were of particular interest because they seemed to be the least responsive to pain management in our cohort.
Pain from breast cancer is often a result of the dissemination to other organs, most commonly to bone [14]. Prior literature suggests that roughly 30–40% of breast cancer patients experience pain following surgical interventions, and that chronic pain thereafter is common [14, 15]. In a separate study investigating chronic pain prevalence in breast cancer survivors, 25.3% presented with neuropathic pain, 18.7% with nociceptive pain, and 15.4% with central sensitization pain [16]. A recent study reported that 30–50% of patients with breast and colon cancer presenting to community cancer centers did not report discussing, getting advice, or receiving desired help for pain, fatigue, or emotional distress, thereby highlighting an area of improvement in the management for these two cancers and beyond [17].
Patients with head and neck cancer often suffer from episodes of acute pain (commonly nociceptive or neuropathic in nature) superimposed on chronic pain throughout the duration of the illness [18, 19]. Chronic pain in long-term head and neck cancer survivors are generally classified as post-surgical pain syndromes (i.e., loss of sensation and function), radiation-induced pain (i.e., neural damage and osteoradionecrosis) and chemotherapy-induced pain (i.e., peripheral neuropathy) [20, 21]. Ultimately, the consequences of pain in this patient population can cause nutritional problems, decreased quality of life, reduced treatment response, and increased hospitalization.
Pain Character
When comparing differences in delta pain between admitted and discharged patients, we found that discharged patients tended to have higher delta pain scores, indicating greater improvement in their pain. Given that admitted patients and discharged patients had similar initial pain scores at presentation, it appears that refractory pain is associated with higher admission rates. Our analysis revealed that those patients with musculoskeletal pain encountered a significantly greater resistance to pain management than other pain types. This finding suggests that patients with bony metastases and other musculoskeletal complications may require more aggressive pain management strategies. Tumors that metastasize to bone induce skeletal remodeling, fractures, anemia and significant pain. Unfortunately, the actual mechanisms that drive cancer-related bone pain require further investigation [22]. Treatment of bone pain from metastases remains palliative at present, and typically involves a combination of systemic analgesics, anti-tumor agents, hormones, chemotherapy, steroids, local surgery, anesthesia, and/or external beam radiation [23]. To our knowledge there are no published protocols for the specific management of acute pain crises for cancer-related musculoskeletal pain. This serves as a critical target for future intervention.
Age and Severe Pain
We found that patients with severe pain on arrival to the ED tended to be younger than those who presented without severe pain. Though no causative explanation can be drawn, we suspect that possible explanations for this finding include generational differences in experiencing and reporting pain, different age groups being more susceptible to certain cancer types, or other potential pathophysiological differences. For instance, we suspect that younger patients may be predisposed to cancer types or variances of pain that present in an acute manner (i.e., short-term, sharp, spontaneous, etc.). Alternative characteristics reported in the literature include how aging decreases sensitivity to low intensity pain and increases pain thresholds [24]. One study specifically reported a correlation between decreasing cancer pain severity and increasing age [25]. As younger patients tend to have shorter-lasting cancers when compared to elderly patients, they are less likely to have acclimated to their condition. Elderly patients are more likely to experience chronic pain from other medical conditions and may thereby be less affected by cancer pain, especially in the initial stages [26]. Furthermore, elderly patients may be less likely to report pain because of attitudes of stoicism, fatalism, and resignation [26]. Younger patients may be less likely to visit the ED unless their pain escalates to a severe state, thereby reinforcing the trend of higher initial pain scores in this population. We encourage oncology and emergency teams to be acutely aware of how cancer-pain may be experienced and consequently reported incongruously between different age groups.
Using ECOG with Initial Pain Levels to Guide Patient Care
By analyzing patients’ functional status in conjunction with their pain scores, we found that patients who presented to the ED with a high ECOG status and severe initial pain had significantly less improvement in their pain than all other patient groups. We suggest that this vulnerable patient group may experience little improvement in pain not because of poor ED management but rather due to inherent qualities of their illness that are difficult to address in the acute setting. We encourage ED physicians to recognize this phenomenon, adjust their expectations for pain relief, and understand that even a minor decrease in pain may be difficult to achieve.
Given the apparent influence of ECOG on pain management outcomes, we also recommend that ECOG status be routinely documented in both the ED and oncologic settings for cancer patients; especially in those who are experiencing acute pain. Patients with a high ECOG status and severe initial pain could be flagged in EHR systems to alert the care team regarding the increased odds of refractory pain and hospital admission. This flag could also trigger the need for a palliative care consultation and guide clinicians towards more aggressive pain management protocols whether in a specialized ED observation unit or on an inpatient ward. This EMR strategy is an area of potential further study as discussed below.
Improving Analgesic Utilization
Our analysis identified that patients who experienced a significant delay in analgesic administration were more likely to be admitted to the hospital. Given the often busy and chaotic environment of the ED, delays in treatment are common [27]. Creating a culture that stresses the importance of cancer pain management with appropriate timing and dosing is imperative in improving patient care and decreasing admissions for cancer pain management.
Opioid Analgesics
Though several non-opioid treatment modalities are available, opioid analgesics have been the mainstay for treating patients with moderate-to-severe cancer-related pain [28]. Consistent with the literature, we identified that patients who received opioids had superior pain control relative to those that received non-opioid medications. Interestingly, we also found that patients who received IV opioids for pain management in the ED were more likely to be admitted than those who did not. There are several factors that may contribute to this phenomenon. First, patients that require stronger pain medication may be more ill at baseline and are therefore more likely to be admitted. Secondly, once IV opioids are initiated, it may be difficult for clinicians to transition these patients to oral regimens in a timely manner, thus requiring admission for observation.
Beyond the administration of IV opioids, we were also interested in analyzing the patient cohort that received a home opioid prescription upon ED disposition. We specifically analyzed the subgroup of patients who were not already taking opioids at home. As expected, we found that these patients were more likely to receive a home opioid prescription if they were given an opioid analgesic during their ED visit. In the literature, there has been discussion regarding the use of step 2 “weak opioids” and step 3 “strong opioids”, in which studies have indicated that opioid-naïve cancer patients with moderate pain are more likely to respond to low-dose morphine, a strong opioid, than to weak opioids [28–30]. This poses an interesting point for emergency physicians to consider when deciding on the strength and dosing of analgesic agents for patients with active cancer-related pain.
Limitations and Future Areas of Study
Due to the nature of retrospective studies, an inherent limitation is the inability to assume causation. Additionally, this study was performed at a specific region in the United States, and therefore may not be generalizable to other populations. Regarding areas of further study, future investigations into pain characteristics (i.e., duration, location, quality) may help identify a subgroup of pain that is more in need of targeted intervention. We believe that a more detailed survey of cancer types can help identify features that catalyze exacerbations of cancer-related pain. Another realm of further study should focus on visits involving severe initial pain at presentation to gain insight on potential risk factors. Lastly, a better understanding of differing cancer pain experiences between young and elderly patients may help formulate more tailored protocols for pain management and ideally decrease the number of preventable ED visits for cancer-related pain.