The present study shows that in the United States, pain is as prevalent in ambulatory oncology patients with common solid tumors as it was more than 20 years ago, despite the fact that opioid prescribing in the United States has increased more than 10-fold since 1990.11
It is appropriate that a recent Institute of Medicine report has called for coordinated, national efforts to create a cultural transformation in the way the nation understands and approaches pain management and prevention.12
In the present study, two thirds of the patients who were determined to be at risk of pain reported having pain or receiving analgesic treatment, and one third of the patients who had pain or used analgesics received inadequate treatment for their pain. Furthermore, we found that the odds of inadequate analgesic prescribing are twice as high for minority patients compared with non-Hispanic white patients.
Pain control remains a serious issue in patients with cancer throughout the world, as rates of undertreatment have also been reported in studies from industrialized nations such as Canada and some European countries.13–15
That the magnitude and scope of pain treatment inadequacy has not decreased substantially in the past two decades in the United States despite a long-standing awareness of this problem is surprising. In the early 1990s, nearly 900 ECOG clinicians were surveyed about pain treatment barriers; approximately 50% of respondents believed their patients had good pain control, and a number of the surveyed clinicians cited concerns about pain assessment, opioid adverse effects, and the reluctance of patients to report pain and take medications.16
Several observational and survey-based studies from various oncology care settings in the United States and Europe17–19
have since confirmed the results of the earlier ECOG survey, namely, that pain is not a primary concern for many patients and that patients and clinicians have misgivings about the adverse effects of pain medications; the costs associated with opioids and the medications used to mitigate their adverse effects; and the perceived dangers of driving, operating machinery, or caring for children while using certain pain medications.
In contrast to the 1994 ECOG pain study,2
the present study did not reveal age and sex to be significant factors for pain treatment adequacy. Our analysis also included individual race and ethnicity variables, as well as follow-up data (data that were not collected in the earlier ECOG pain study). The present study corroborates others' findings about the inequality of pain treatment adequacy between minority patients and non-Hispanic white patients and shows that these findings persist at short-term follow-up. This finding of pain treatment disparity has also been observed across a variety of noncancer settings.20,21
Minority patient factors, such as beliefs about the value of stoicism, concerns about opioid addiction and adverse effects, and reluctance to report pain or request analgesics putatively influenced this disparity.21–23
Some studies have suggested that communication difficulties between non-Hispanic white physicians and minority patients are common and may lower mutual trust and thus quality of care.22,24–26
When communication and trust between minority patients and their physicians are problematic, concerns about opioid-associated deaths, opioid diversion problems, and recreational opioid use may exacerbate disparities in pain treatment adequacy. Of note, the observation that white patients were also more likely to be undertreated at minority sites suggests that system factors (eg, opioid availability) could also be contributing to the disparity.
The complexity of care and symptom burden that patients with cancer experience throughout the trajectory of their care pose particular concerns. In the present study, 40% of patients seen in outpatient oncology settings at any point in their illness had at least three concurrent moderate or severe symptoms. Cancer survivors, like patients actively being treated for their disease, have complex and often unmet needs, and pain assessment and treatment are poorly understood in this population.27
Patients with nonadvanced cancer who were not receiving cancer-directed treatment were especially likely to be undertreated for pain. This disparity may be explained in part by the fact that nearly 50% of these patients experienced symptoms that oncologists believed were not attributable to cancer or cancer therapy and thus were not treated aggressively. This potential gap in pain treatment could be bridged with improved coordination of care between oncologists and nononcology providers. For example, Temel et al28
described the benefits of the early integration of palliative care specialists for patients with lung cancer receiving initial chemotherapy, and the Indiana Cancer Pain and Depression trial29
demonstrated the value of symptom management collaboration between oncologists and other providers. Finally, the availability of effective pain medication that is not perceived to interfere with driving, work performance, social interactions, or bowel habits could improve adherence to pain treatment.
This study is the largest prospective evaluation of pain and other symptoms in outpatient oncology in the United States. The distribution of the four solid tumors is typical for outpatient cancer care, including the low relative proportion of patients with prostate cancer. This study had several potential limitations. First, these findings can be generalized to patients with common solid tumors who receive care at sites associated with a US clinical cooperative group, yet a significant number of ambulatory patients with cancer have less common solid tumors or hematologic malignancies and/or receive care at sites outside the cooperative group system. In addition, we did not collect data on patients' comorbidities, insurance status, or socioeconomic status or clinicians' attributes (eg, age, race, and sex); these factors may influence pain management practice. Also, 28% of the patients in the present study did not have complete PMI data at follow-up for treatment adequacy assessment. These data were not missing at random, as these patients tended to be healthier and were likely to be minority patients or patients enrolled at minority-based sites. This pattern of missing data is itself a unique observation with potential utility for planning future research. Yet the patterns of pain expression and analgesic prescribing at the initial assessment and follow-up as revealed by multivariable analysis were remarkably similar. Finally, although the PMI is the best available and most widely used instrument to measure pain treatment adequacy, it remains only a gross indicator of pain treatment adequacy because it focuses on opioid analgesic prescribing categories and does not reflect the dosing of opioids or use of nonopioid pain interventions.
In conclusion, pain remains a significant concern in ambulatory oncology. Non-Hispanic white patients and patients with the most obvious burden of illness are most likely to receive adequate cancer pain management. Innovative pain treatments and refined measures of pain management adequacy as well as the better integration of nononcology clinical resources into the oncology setting all hold promise for improving outcomes in outpatient care of patients with cancer. Improved communication between providers and all patients about pain and pain treatment holds promise to help formulate the most appropriate patient-centered treatment goals and maximize health outcomes.