Arthritis is a common cause of severe pain and functional limitation that affects hundreds of millions of individuals worldwide [1]. The growing prevalence of obesity has lead to a global increase in arthritis. In developing nations specifically, the improved ability to treat infectious diseases and prevent other causes of early mortality has lengthened life expectancy and increased the burden of chronic conditions including arthritis [2]. While disease-modifying antirheumatic drugs slow the progression of rheumatoid arthritis (RA), no such therapeutics are currently available for osteoarthritis (OA), the most prevalent form of arthritis. For both conditions, total joint replacement (TJR) is the treatment of choice for individuals with advanced structural damage, severe pain and functional limitation [3-13].

Total joint replacement is frequently performed in the US, with over one million hip and knee replacements operations carried out annually [14]. Research on TJR outcomes in developed countries suggests that patients with worse functional status at the time of surgery tend to have worse outcomes [15, 16]. Studies also document marked gender and racial disparities in access to and preference for surgery: women tend to present for surgery at a more advanced stage of functional decline [17, 18] and rates of TJR are significantly higher among white patients as compared with African American patients of similar disease status [19]. In developing countries, however, access to TJR is constrained by the limited resources and availability of trained surgeons, and outcome data are scarce. To address these gaps in technical expertise, medical relief organizations have begun to launch programs to perform TJR on resident populations in developing countries. These programs educate host facilities about the procedure with the eventual goal of enabling them to develop autonomous joint replacement programs. Similar initiatives are occurring in other fields of medicine [20]. The clinical results of these medical service and education initiatives have not yet been critically evaluated. Such outcome data would be useful to determine whether patients treated by these relief organizations experience outcomes comparable to those achieved in developed countries. These data would also establish a benchmark for comparison of outcomes as programs evolve toward greater independence of the host surgeons and care teams.

The goal of this paper is to document the outcomes of TJR performed on a cohort of Dominican patients by surgeons of Operation (Op) Walk Boston, a not for profit medical relief organization that performs joint replacements upon approximately 45 Dominican patients annually with advanced hip or knee arthritis. In March 2009 and March 2010, OpWalk Boston operated upon a total of 88 patients. We obtained data on pre-operative pain and functional for these patients and analogous post-operative data one year following TJR for members of the 2009 cohort. In this paper, we report on pre-operative severity and changes in status in this joint replacement population. We also assess the internal consistency of the scales used to measure pain and functional status in order to validate the use of these scales in this developing world context. Through empirical evaluation of the effects of TJR on health-related quality of life in this cohort, we hope to set a benchmark for future initiatives to transfer TJR to the developing world setting.

To the best of our knowledge, this is the first study to critically assess the pre-operative health status and to evaluate the effects of TJR on self-reported health status for patients in a developing country receiving care from a medical relief service organization. Prior research has suggested that factors such as low pre-operative functional status and poorly controlled co-morbidities are associated with worse final results and thus may mitigate against good outcomes on such patients [15, 16, 31]. For example, a prospective cohort study of 175 patients with OA undergoing total hip or knee replacement found that patients with worse pre-operative health status did not achieve the same improvement in function and pain assessed by the SF-36 and WOMAC scales measured six months and two years post-operatively, as compared to patients starting with better pre-operative health statuses [15, 31]. Another study of 860 patients undergoing total knee arthroplasty found that low pre-operative scores and a higher number of co-morbidities were predictors of worse scores on pain and function assessed by the WOMAC and SF-36 scales one and two years post-operatively [16]. However, we document that the patients in our cohort achieved significant gains in physical function, experienced dramatic reductions in pain and reported high satisfaction with the overall results of the operation. Specifically, our patients’ level of improvement of an average of 50 points on the WOMAC pain scale and 60 points on the WOMAC and SF-36 physical function scales is high in comparison to several other prospective cohort studies. For example, in the prospective cohort study of 860 patients described above [16], the average one year post-operative improvement in WOMAC pain and function scales was approximately 35 points and 30 points, respectively. Similarly, in the study of 175 patients undergoing total hip and knee replacement, patients improved in the SF-36 physical function scale by approximately 37 points and 28 points, respectively [15]. Thus the dramatic improvement in pain, function, and health status in our cohort suggests that poor pre-operative status and socioeconomic factors may not preclude good outcomes on patients participating in medical relief initiatives.

Our study builds upon prior research on the effect of TJR in developed countries, extending many of the findings documented in the United States, the United Kingdom and Australia to the Dominican Republic, to a small cohort of patients in the Dominican Republic.

Studies have consistently shown that women present for TJR at a later stage of functional decline and with greater pain than their male counterparts [5, 16-18, 36] For example, in a study involving 323 patients undergoing total hip or knee replacement in the United States, women undergoing reported worse physical functional status, as measured by the Intermediate Activity of Daily Living (IADL) scale, than their male counterparts for both procedures. Specifically, women scored on average 9.1 points lower than males for knee surgery and 19.7 points lower for hip surgery on the 0 – 100 IADL scale (100 is best) [18]. Researchers have hypothesized that this discrepancy is due to gender differences in preference for or access to TJR [17, 18]. That is, women may wait until they have suffered from greater functional deterioration due to arthritis before electing to undergo surgery and TJR may be offered less readily to women than to men. In our cohort of Dominican patients, we also found that women had worse pain and functional status at the time of surgery. These differences were statistically significant and were greater than the established minimally clinical important differences (MCID) for each of the subscales (7.5 for WOMAC pain, 7.2 for WOMAC stiffness, 6.7 for WOMAC function, and 7.8 for SF-36 physical function) [37]. Explanations in addition to the ones proposed above in developed countries may help to explain this discrepancy. For example, Dominican women may have stronger social support networks that help them to compensate for their functional limitations. In addition, the tasks that they need to compensate for may be less physically demanding than those performed by men. Further research is needed to explore the cultural factors that mediate this discrepancy.

Our study also provides further support for the internal consistency of the WOMAC pain, function and stiffness scales and the SF-36 physical function and mental health subscales. Prior research using these measures in developed countries has demonstrated high internal consistency with Cronbach alpha values ranging from 0.95 to 0.97 for WOMAC scales [38] and values greater than 0.90 for the SF-36 subscales [39]. The somewhat lower Cronbach alpha values in our sample (Table 1) appear to be related in part to educational attainment. At baseline, the internal consistency for each of the scales was higher for those who achieved at least a secondary school education compared to those who did not. Still, Cronbach alpha values for all scales are above 0.7 suggesting that these measures are acceptable for reliable assessment of pain, function and mental health status in Dominican participants. Further research on cultural differences in how patients report health status and on the cultural-specific ways that arthritis affects patients’ lives may help to tailor scales for patients in a developing country.

Our study was limited by the involvement of 81 patients including only 28 evaluated at both baseline and one year follow-up. In addition, patients were selected by the OpWalk team as those with the most advanced forms of arthritis and with substantial financial need. These patients may not be representative of the arthritic Dominican population. Both of these factors limit the generalizability of our results. However, since the patients in our cohort represent those with the most severe forms of arthritis, the outcomes reported in our study may be a conservative estimate of the gains that could be achieved following TJR if a greater proportion of patients with advanced arthritis in the Dominican Republic were able to participate in programs such as OpWalk.

Our study suggests that TJR performed by American surgeons participating in a medical relief organization is typically successful in relieving pain and restoring ability to perform functional activities for a small group of Dominican patients. These quantitative results provide a benchmark for evaluating outcomes achieved by such relief organizations. In addition, the significant gains in health-related quality of life documented in this pilot project justify larger studies of the outcome of TJR in developing world settings, with longer follow-up periods. Total joint replacement is currently largely unavailable to the majority of the population in developing countries such as the Dominican Republic. If the operation is shown to be successful as suggested by these data, efforts should be made to increase access to TJR. This would entail capacity building and design of care delivery systems that allow for host countries to perform these surgeries independently. In addition to the structural, operational and supply needs for successful delivery of this type of surgery, educating local care teams (surgeons, nurses, physical therapists and operating room personnel) is another important component of a sustainable solution to TJR in developing countries. Our work can serve as a standard to evaluate the performance of these programs each step of the way in the progression from medical relief program to autonomous TJR program staffed by the host facility. Lastly, arthritis is a paradigmatic chronic disease. As the global population ages and grows leading to an increased prevalence of chronic disease in developing nations, it will become ever more important to focus efforts on understanding and treating these conditions, including tailoring the efforts of medical relief organizations to best address the needs of these patients throughout the continuum of care.