Goldberg and McGee BMC Public Health 2011, 11:770 http://www.biomedcentral.com/1471-2458/11/770 advisory boards such as the Institute of Medicine com- mittee which produced in July 2011 the report Relieving Pain in America[4]. What we see in this landmark report is a reframing of the agenda for pain including a social transformation of pain diagnosis, treatment, and care. Yet even though this report argues that pain ought to be framed as a public health issue, it fails to articulate what ought to be as understood as most important about pain from the perspectives of social justice, health inequities, or even the global burdens and causes of disease. There are multiple reasons for regarding pain as a public health priority. The first and foremost is the staggering prevalence of pain. Because pain is a multivalent, dynamic, and ambiguous phenomenon, it is notoriously difficult to quantify, and therefore caution is warranted in issuing broad assessments regarding the epidemiology of chronic pain across the globe. Yet, even with such limitations, there is little question regarding its high prevalence and incidence. 10% of the world’s population - approximately 60 million people - endure chronic pain,[1] and fairly reli- able estimates in individual countries and regions indicate chronic pain prevalence closer to 20-25%[5-7]. Primary care settings in Asia, Africa, Europe, and in the Americas had patients reporting persistent pain prevalence of 10 to 25%. Consistent estimates of chronic pain prevalence in the U.S. range from 12 to 25%, and prevalence of 20% has been noted in Europe [7-9]. Although there are few esti- mates of the incidence of global chronic pain, WHO has estimated that as many as 1 in 10 adult individuals are newly diagnosed with chronic pain each year [1]. Moreover, aside from the prevalence and incidence of chronic pain, both the severity of such pain and the extent of any accompanying disability are also key factors in assessing its burden. The evidence suggests that mod- erate-to-severe pain is prevalent even in resource-rich settings,[10,11] and that the combination of persistent pain and comorbid psychological disorders produce sig- nificant disability across the globe (as measured by impairment of daily activities) [12]. Ultimately, as one commentator recently concluded, the evidence is strong that “for millions of people across the globe, excruciating pain is an inescapable reality of life.”[13] This is true for both the developed and the devel- oping world. Pain is therefore a global health problem, one that significantly affects both the global North and the glo- bal South. However, akin to the general global burden of disease, pain and its treatment are distributed highly unequally in both the global North and the global South, with those most disadvantaged bearing higher burdens of persistent pain and lesser likelihood of effective treatment. Such inequities render the equitable treatment of pain an ethical imperative consistent with mandates of social justice. While the ethical implications of the inequitable distribution of global chronic pain is properly regarded as Page 2 of 5 a top priority in global health ethics, a full explication is beyond the scope of the current project. Here, we argue simply that pain ought to be regarded as a global public health priority, a point which establishes a baseline for future ethical analyses. Second, akin to many other chronic non-communic- able diseases (NCDs) across the globe, chronic pain is typically accompanied by substantial comorbidities. The roster of chronic NCDs that are positively correlated with chronic pain are myriad,[14] including but not lim- ited to diabetes,[15,16] arthritis,[17] depression,[18,19] and asthma,[20] among others. Chronic NCDs account for over 60 percent of the global burden of mortality,[21] with generally increasing epidemiologic trajectories across the globe [22,23]. Because these NCDs can be expected to increase the incidence and ultimately the prevalence of global chronic pain, the matter of incidence and the larger context regarding comorbid (chronic) NCDs also justifies the treatment of chronic pain as a global public health priority. A Public Health Approach to Pain Understanding pain as a public health priority helps to explain its tight linkage with social and economic determi- nants of health. The social epidemiologic evidence sug- gests strongly that patterns of NCDs from the hyperlocal to the global level are powerfully determined by the condi- tions in which people and communities live, work, and play [23]. Given the aforementioned comorbid relationship between a variety of NCDs and chronic pain, one would predict that chronic pain should correlate with some of these social determinants of health. This prediction is borne out in research that links with chronic pain a num- ber of such determinants, including mental and physical stress at work,[24,25] socioeconomic status,[26] rurality, [27] occupational status,[28] neighborhood,[29] race, [29,30] and education [31]. One of the most promising theories regarding the cau- sal pathways between such social factors and poor NCD and all-cause health outcomes is the allostatic load hypothesis [32,33]. This theory posits that persistent exposure to deleterious social and economic conditions activates the human body’s fight-or-flight response to a state of perpetuity. In turn, the persistent accumulation of stress hormones such as cortisol has been robustly correlated with a number of diseases and negative health outcomes [33]. Under this theoretical framework, one would predict a direct relationship between increased social disadvantage and either or both the frequency and the severity of chronic pain. Several recent analyses bear this prediction out [34-36]. Dorner et al. found that even at the same intensity of pain, those lowest on the social gradient reported feeling two to three times as disabled as compared to the highest group [34].