摘要：Objectives . We compared chiropractic practice volume in areas of high versus areas of low or no shortages of primary care providers. Methods . Using data from a cross-sectional survey of US chiropractors and data from the Bureau of Health Professions’ Area Resource File, we conducted multiple linear and logistic regression modeling of the effects of rural or Health Professional Shortage Area location on chiropractic practice volume and wait times. Results . Chiropractors in rural and high-shortage areas have busier, higher-volume practices than do those in other locales (after control for other chiropractors in the same market service area). Conclusions . Chiropractic providers render a substantial amount of care to underserved and rural populations. Health policy planners should consider the full complement of providers available to improve access to care. (Am J Public Health. 2002;92:2001–2009) Complementary and alternative medicine (CAM) use in the United States has grown markedly. 1– 3 Evidence suggests that lifetime CAM use increases with age across age cohorts and that half of all CAM patients continue to use CAM for many years. 4 Such documented trends have raised awareness and interest in the CAM disciplines, 5– 7 thus driving further research and discussion about CAM patients’ use and utilization of medical or preventive services, 1, 8, 9 the inclusion of CAM in private insurance and managed care, 10– 12 and the actual or potential roles of CAM practitioners as additional nonphysician primary care providers in the US health workforce. 13– 20 Chiropractic health care is among the largest and most high-profile of the established nonallopathic singular health care disciplines, and chiropractic users consistently represent the largest share in surveys of CAM users overall. 2, 9 A substantial body of rigorous scientific evidence supports the efficacy and effectiveness of spinal manipulation for various conditions. 21– 27 Additionally, the chiropractic profession has established structures and processes for further developing and disseminating that evidence base and for fostering effective, evidence-based education, training, and practice. 28– 33 Chiropractic education and clinical training in the 17 accredited chiropractic colleges in the United States combines discipline-specific chiropractic assessment and therapeutic procedures with standard medical diagnosis and procedures, excluding invasive or critical care procedures, pharmacology, and surgery. 29, 30 Hours of education and training required in chiropractic and medical school curricula are 4820 in the doctor of chiropractic (DC) program, compared with 4670 in the doctor of medicine (MD) program (not counting postgraduate clinical residency hours of MDs). Curricular differences include a greater emphasis on biomechanics, musculoskeletal function, and manual procedures for chiropractic students and a substantially longer mentored clinical experience for medical students in both undergraduate and postgraduate training. 34, 35 Ongoing interest and efforts relative to practice, research, and policy have been directed toward studying the characteristics of chiropractic patients and practice, the relationship between chiropractic and other health care providers, and the distribution, use, and utilization of chiropractic services. Patient characteristics associated with chiropractic use may include poorer health status, 36 older age, reportage of a greater number of chronic health problems, more frequent physician visits, and greater difficulty in obtaining an appointment with a physician. 37 Chiropractic patients in rural areas may be more likely than those in more urban locales to present with nonmusculoskeletal complaints. 38, 39 A high level of satisfaction with chiropractic care and a strong chiropractor–patient relationship 40– 44 may especially characterize chiropractic practices in rural, medically underserved areas. 45 Chiropractic patients may typically use a DC as a first point of contact with the health care system, 46 particularly in rural areas. 47 Most chiropractic patients self-report that they do not use other providers’ services while under chiropractic care 46 ; however, more than 97% of DCs report that they refer their patients for medical care as needed. 48– 51 Slightly more than half of surveyed family physicians report referring patients to DCs. 43, 49 Bidirectional referral relationships between MDs and DCs may be more active in rural areas, 38 among younger or newer practitioners, 48, 52 and among MDs who feel informed about chiropractic care. 52 The majority of surveyed chiropractors convey a self-perception of practicing in a primary care capacity 53 ; they also report that they provide primary care services such as health history assessments and physical examinations of their patients on a routine basis. 51, 53 An interdisciplinary expert focus group (DCs, MDs, physician assistants, and nurse practitioners) concurred that DCs are able to make diagnoses in more than 90%—and therapeutic contributions in more than half—of primary care activities, although more DCs than other participants perceived a need for physician involvement in primary care activities. 54 The position of the chiropractic profession is that prevention and health promotion are integral to chiropractic care, 28 and most DCs agree. 53, 55– 57 However, the actual provision of such services varies somewhat among chiropractic providers 53, 55 and may be related to where their practices are located. 45 High DC-to- population ratios are associated with smaller towns. 58 Half of surveyed DCs practice in communities with populations under 50 000, 53, 55 and most rural-practicing DCs also originally come from rural areas. 38 Findings on the relationship between locale and chiropractic utilization have been mixed. Hawk 59 and Cote et al. 60 reported higher rural and higher urban use of chiropractic care, respectively, and Shekelle and Brook 61 reported both. Whereas an early ecological-level analysis of 4 regions ranked chiropractic utilization rates in the same order as chiropractors per population, 62 a more recent study comparing regions that varied by geography and DC-to-population ratios found no relation between DC density and visit rates, although patterns of treatment (amount of care provided per episode) did vary significantly across geographic sites. 61 In a cohort study of chiropractic utilization in a medically underserved rural Iowa area, no relation was found between level of access to physician services (measured as growth in the physician workforce) and the use of chiropractic services. 36 Given such a mix of intriguing and sometimes conflicting findings, further work is warranted to clarify our understanding of actual and potential roles of chiropractors in meeting the health care needs of underserved or rural populations. Such studies should include comprehensive and policy-relevant definitions of “underserved,” such as the Health Professional Shortage Area (HPSA) designation. Studies should also include and control for a number of other potential predictors of chiropractic service use (e.g., rurality or DC and population densities) to sort out their differential effects. It is also important to embed study of chiropractic use within relevant conceptual frameworks and to apply the appropriate methodologies of health services research. For instance, as a dimension of access to health care, wait times (both before and during scheduled and walk-in visits) may be used to measure time barriers or organizational barriers to patients. 63 For both conceptual and methodological reasons, consideration of provider-specific market service areas as a useful unit or level of analysis is fundamental, whether as a means of studying issues relative to workforce capacity or access or as the context for studies of provider competition or collaboration. 64– 70 In an earlier study, 71 we surveyed Missouri chiropractors, comparing chiropractic practices serving high- or whole-shortage HPSAs with those serving low-, part- or nonshortage areas. Chiropractic practices serving high-shortage areas had significantly higher practice volumes (numbers of weekly visits and of annual new patients), even after control for DC density and rural location. Although rural location was a significant predictor of annual new patients, it was not significantly related to number of weekly visits. As a follow-up to an earlier preliminary single-state survey, our study surveyed a national sample of active, licensed DCs. Specifically, that survey tested (1) the hypothesized relationship between chiropractic practice volume and location in HPSAs or rural areas, and controlled for various characteristics of DCs or their practice environments that might also affect practice volumes, and (2) whether there were differences in wait times between chiropractic practices in high-shortage versus low- or no-shortage HPSAs, or in rural versus nonrural locations.
