Cost of chiropractic versus medical management of adults with spine-related musculoskeletal pain: a systematic review

Background The cost of spine-related pain in the United States is estimated at $134.5 billion. Spinal pain patients have multiple options when choosing healthcare providers, resulting in variable costs. Escalation of costs occurs when downstream costs are added to episode costs of care. The purpose of this review was to compare costs of chiropractic and medical management of patients with spine-related pain. Methods A Medline search was conducted from inception through October 31, 2022, for cost data on U.S. adults treated for spine-related pain. The search included economic studies, randomized controlled trials and observational studies. All studies were independently evaluated for quality and risk of bias by 3 investigators and data extraction was performed by 3 investigators. Results The literature search found 2256 citations, of which 93 full-text articles were screened for eligibility. Forty-four studies were included in the review, including 26 cohort studies, 17 cost studies and 1 randomized controlled trial. All included studies were rated as high or acceptable quality. Spinal pain patients who consulted chiropractors as first providers needed fewer opioid prescriptions, surgeries, hospitalizations, emergency department visits, specialist referrals and injection procedures. Conclusion Patients with spine-related musculoskeletal pain who consulted a chiropractor as their initial provider incurred substantially decreased downstream healthcare services and associated costs, resulting in lower overall healthcare costs compared with medical management. The included studies were limited to mostly retrospective cohorts of large databases. Given the consistency of outcomes reported, further investigation with higher-level designs is warranted. Supplementary Information The online version contains supplementary material available at 10.1186/s12998-024-00533-4.


Introduction
Spine-related musculoskeletal pain is the leading cause of disability worldwide and one of the most common reasons for missed work [1].In the United States (U.S.), healthcare costs for low back and neck pain are rising and as of 2016 were the highest for any condition, with an estimated $134.5 billion for care related to spinal pain [2].
There are many options for treatment of acute or chronic spine-related pain.These range from conservative therapies, such as manual or behavioral therapies, to medications, injection procedures and surgery [3,4].Approaches to management of spine-related musculoskeletal pain differ by type of provider, such as chiropractors, physical therapists, primary care medical physicians and medical specialists such as orthopedists and neurologists [5].In the U.S., chiropractic care is one of the most commonly utilized approaches to treatment of spine-related musculoskeletal pain [6].Chiropractic care guidelines are concordant with the American College of Physicians' recommendations for initial management of low back pain (LBP) using non-pharmaceutical treatment [7,8].
In the midst of rising healthcare costs, it is important to examine not only clinical outcomes but also the cost of intervention strategies for spine-related pain.Although most cases of spine-related musculoskeletal pain can be effectively managed with conservative guideline-concordant non-pharmacological and noninvasive approaches, frequently a patient's course of care is unnecessarily escalated by use of more invasive, hazardous, and/or costly procedures [9].The escalation of care for spine-related musculoskeletal pain may include emergency department visits, medical specialist visits, diagnostic imaging, hospitalization, surgery, interventional pain medicine techniques, prescription of drugs with high risk for addiction or abuse, and encounters for complications of spine care (e.g., adverse drug events) [9].The escalation of spine-related musculoskeletal pain management is closely associated with increased downstream costs.
Gold et al. defined "downstream" costs as those that "may have changed, intentionally or unintentionally, as a result of the implementation strategy and intervention." [10] p.3 Downstream costs may include those associated with healthcare utilization, patient and caregiver costs, productivity costs and costs to other sectors.For spine-related musculoskeletal pain, most often LBP, an emerging body of evidence suggests that downstream costs are significantly affected by the specialty of the initiating care provider [5].Such costs typically include diagnostic tests, particularly advanced imaging [11], surgery, specialist care and medication use [12].
The opioid epidemic.For patients with spine-related musculoskeletal disorders, among the most important escalations of care associated with downstream human and societal costs that are receiving recent attention are opioid use, abuse and overdose.In 2017, the U.S. government declared the opioid epidemic to be a Public Health Emergency [13].This epidemic is still on the rise, with drug overdose deaths increased by 31% in a single year, 2019-2020 [14].
It is not certain which combination of provider and/or therapy offers the most cost-effective approach to managing spine-related musculoskeletal pain.A 2015 systematic review compared the costs of chiropractic care to those of other types of health care [15].The costs were generally lower when musculoskeletal spine care was managed by chiropractors, though the included studies contained methodological limitations [15].The purpose of this review was to update, summarize, and evaluate the evidence for the cost of chiropractic care compared to conventional medical care for management of spinerelated musculoskeletal pain [15].

Methods
Our team followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol to conduct the review and registered it with PROSPERO in December 2022 prior to data abstraction (CRD42022383145).We elected a priori not to pursue meta-analysis due to heterogeneity of the included studies.Most of the included studies are cohort studies which by their nature can only show associations, cannot prove causation, and are of a lower level of evidence than RCTs, which are the study design usually included in meta-analyses.We conducted the searches and quality assessments from July through December 2022 and data abstraction from January through March 2023.The primary aim of our systematic review was to address the research question: Is chiropractic management of spine-related musculoskeletal pain in U.S. adults associated with lower overall healthcare costs as compared to medical care?
To answer the research question, we formulated PICO elements (Population, Intervention, Comparison, Outcome) as follows:

P: U.S. adults with spine-related musculoskeletal pain I: Chiropractic management C: Medical care O: Healthcare costs and use of procedures estimated to increase downstream costs involved in escalation of care
Costs in a controlled setting are not often comparable to usual and customary costs in a clinical setting [16].
Therefore, in addition to randomized controlled trials, we also included economic and cohort studies that collected data specifically on cost, whether or not treatment outcomes were considered.

Eligibility criteria Inclusion criteria
• Published in peer-reviewed journal and available in Medline from inception through 10/31/2022 • English language • Study population comprised of US adults treated for spine-related musculoskeletal pain • Compared chiropractic management to medical care • Cost data for treatment of spine-related musculoskeletal pain were provided • Designs were randomized controlled trial, cohort study or economic evaluation.

Exclusion criteria
• Reviews, commentaries, abstracts from conference proceedings, theses, cross-sectional descriptive surveys and gray literature.• Systematic reviews were not used as part of quality assessment or data abstraction.They were retrieved only to identify eligible studies which were not found in the literature search.

Literature search
We developed a search strategy based on the PICO terms, with a health sciences librarian working with the other investigators.We made several "trial runs" to refine the strategy to be sure it was as inclusive as possible while screening out obviously non-relevant citations.Our search was conducted exclusively in Medline, as relevant high-quality articles were more likely to be found in journals indexed there.We developed a search strategy with keyword clusters based on our PICO.Most publications about spine-related pain study adults (our P) and "adult" was not helpful as a limiter.Intervention (I) cluster terms were selected from a previously published search string of complementary and alternative medicine terms [17].
The Outcome (O) cluster started with terms used in a prior cost-effectiveness study [18], with the subsequent addition of indexing terms found during early search trial runs.The MeSH heading Cost-Effectiveness Analysis was not yet available at the time of our search.The complete search strategy is shown in Additional File 1.
Retrieved citations were downloaded into an End-Note library (v.20).Using Rayyan https:// rayyan.ai/, [19] online systematic review software, at least two investigators screened titles and abstracts for eligibility and resolved disagreements by discussion.At least two investigators checked the references included in all relevant systematic reviews found in the literature search and added any eligible citations not identified in our literature search to the library.At least two investigators did full-text screening of the titles remaining after title/ abstract screening was completed, and disagreements were again resolved by discussion.All authors contributed during the process in review of eligible citations.

Evaluation of risk of bias
We evaluated randomized controlled trials (RCTs) using a checklist modeled after those of the Scottish Intercollegiate Guideline Network (SIGN) [20], which we have used elsewhere [3].An article was rated as "high quality, low risk of bias, " "acceptable quality, moderate risk of bias, " "low quality, high risk of bias, " or "unacceptable" quality.For studies analyzing treatment costs (e.g., economic studies), we developed a checklist with similar format to those of SIGN checklists [20].
For cohort studies, it was difficult to identify a single appropriate checklist because most seemed designed to be more appropriate to assess prospective cohort studies, and the most recent relevant studies related to our topic are retrospective cohort studies using large datasets.We therefore developed a checklist for prospective cohort studies after reviewing other existing checklists [20].For retrospective or cross-sectional cohort studies, we developed a checklist combining some features of the SIGN checklist for cohort studies [20] and the NIH tool for observational cohort and cross-sectional studies [21].These checklists included items assessing comparability of the included cohort groups, as part of the risk of bias assessment.Three investigators (RF, CH and JW), one of whom is an author of a number of cohort studies, piloted and then refined this form with a sample of studies.
Two or more investigators rated each article.Disagreements were resolved by including additional reviewers and discussing differences in ratings until they reached agreement.
Because of the large number of cohort studies, which are considered to have an inherent risk of bias due to their design, we only included studies which the investigators agreed were at minimum "acceptable quality, moderate risk of bias" using the SIGN quality criteria.We excluded any studies that the investigators found to be "low quality, high risk of bias" or "unacceptable quality."

Data extraction
Because it has been found that data extraction errors are frequent in systematic reviews, we followed the recommendations on data extraction in a review of data extraction guidelines and methods [22].Before starting the process, we listed all the items we thought were necessary for answering our research question.Then we drafted a data extraction form with these items and two investigators (RF and CH) piloted it on a sample of studies.We then provided brief, online training on use of the forms with the 3 investigators who did the data extraction (RF, CH, DT).This included instructions on how disagreements would be resolved, which was to recheck the source paper and provide it to the other reviewer(s).Two investigators (RF and CH) did independent parallel extraction for all studies, and DT then reviewed the drafted tables; thus the data extraction was triple-checked.We did not attempt to subcategorize patient populations from the included studies.

Results
We concluded the search in November 2022 and retrieved 2247 citations.Figure 1 shows the PRISMA flow chart, showing reasons for exclusions.Nine articles were identified by reference tracking and expert consultation to make the total number of articles for screening 2256.Title and abstract screening of these resulted in 93 articles for full-text screening, with 49 excluded (see Additional File 2 for citations) and 44 remaining for quality assessment and data extraction.Please refer to Table 5 for a summary of findings including a quick-view color coded identification format related to each accepted paper.For ease of viewing, we divided the papers using

Data extraction and summary
Because of the large number of studies, we separated the data extraction into two tables, using 2017, the year the U.S. declared the opioid epidemic [13], as the dividing line.[15] were retrospective/crosssectional cohort studies, with 1 prospective cohort study and 1 economic/cost study.From 1991 to 2017, most [16] were economic/cost studies, with 7 retrospective/crosssectional cohort studies, 3 prospective cohort studies and 1 randomized controlled trial.

Summary of cost factors
Table 4 summarizes the findings of all included studies, by year of publication.Below we have grouped these by type of cost and factors affecting cost.Table 5 depicts chiropractic services versus comparisons in terms of higher, lower or no difference in association for each of the identified types of costs and downstream utilization of factors affecting costs.All of the included studies newer than 2009 demonstrated associations that favored chiropractic services in regard to lower costs and lower utilization of services.

Type of costs
• Total costs Ten studies found that Doctor of Chiropractic (DC) care had lower overall costs [5,12,38,41,42,51,52,55,58,62].No studies found that DC care had higher overall costs.• Costs per episode of care Six studies found that DC care had lower costs per episode [35,38,41,49,59,62], and two found that it had higher cost per episode [23,56].• Insurance/compensation costs Four studies found DC care had lower insurance and compensation payment costs [49,53,55,57].No studies found higher costs.• Long-term healthcare costs Two studies found lower long-term healthcare costs associated with DC care [36,42].No studies found higher costs.• Office visit costs One study found reduced costs for DC office visits [12]; four studies found that DC care had higher costs for office visits [47][48][49]61].Two of these studies noted that chiropractic office costs were higher only when referral costs were not included in the calculation.When referral costs were included, chiropractic office visit costs did not differ significantly from medical care costs [48,61].

Prospective cohort studies
Carey [23] The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons A Elder [24] Comparative effectiveness of usual care with or without chiropractic care in patients with recurrent musculoskeletal back and neck Pain A Graves [25] Factors associated with early magnetic resonance imaging utilization for acute occupational low back pain: a population-based study from Washington State workers' compensation A Keeney [26] Early predictors of lumbar spine surgery after occupational back injury: results from a prospective study of workers in Washington State

A
Cohort studies (retrospective/cross-sectional) Anderson [27] Three patterns of spinal manipulative therapy for back pain and their association with imaging, injection procedures, and surgery: a cohort study of insurance claims A Anderson [28] Risk of treatment escalation in recipients vs nonrecipients of spinal manipulation for musculoskeletal cervical spine disorders: analysis of insurance claims H Bezdjian [29] Efficiency of primary spine care as compared to conventional primary care: a retrospective observational study at an Academic Medical Center H Davis [30] The effect of reduced access to chiropractic care on medical service use for spine conditions among older adults H Davis [31] Access to chiropractic care and the cost of spine conditions among older adults H Fritz [32] Importance of the type of provider seen to begin health care for a new episode low back pain: associations with future utilization costs

H
Hong [33] Clinician-level predictors for ordering low-value imaging H Hurwitz [34] Variations in patterns of utilization and charges for neck pain in North Carolina, 2000 to 2009: a statewide claims' data analysis H Hurwitz [35] Variations in patterns of utilization and charges for the care of low back pain in North Carolina, 2000 to 2009: a statewide claims' data analysis H Jin [36] Healthcare resource utilization in management of opioid-naive patients with newly diagnosed neck pain H Kazis [37] Observational retrospective study of the association of initial healthcare provider for new-onset low back pain with early and long-term opioid use H Liliedahl [38] Cost of care for common back pain conditions initiated with chiropractic doctor vs medical doctor/doctor of osteopathy as first physician: experience of one Tennessee-based general health insurer H Louis [39] Association of initial provider type on opioid fills for individuals with neck pain H Rhon [12] The influence of a guideline-concordant stepped care approach on downstream healthcare utilization in pts with spine and shoulder pain H Weeks [40] Cross-sectional analysis of per capita supply of doctors of chiropractic and opioid use in younger Medicare beneficiaries H Weeks [41] The association between use of chiropractic care and costs of care among older Medicare patients with chronic low back pain and multiple comorbidities H Whedon [9] Initial choice of spinal manipulation reduces escalation of care for chronic low back pain among older Medicare beneficiaries H Whedon [42] Long-Term Medicare Costs Associated With Opioid Analgesic Therapy vs Spinal Manipulative Therapy for Chronic Low Back Pain in a Cohort of Older Adults H Whedon [43] Initial choice of spinal manipulative therapy for treatment of chronic low back pain leads to reduced long-term risk of adverse drug events among older Medicare beneficiaries H Whedon [44] Association between utilization of chiropractic services for treatment of low back pain and use of prescription opioids H Whedon [45] Impact of chiropractic care on use of prescription opioids in patients with spinal pain H Whedon [40] Association between chiropractic care and use of prescription opioids among older Medicare beneficiaries with spinal pain: a retrospective observational study H

Cost studies
Grieves [47] Cost minimization analysis of low back pain claims data for chiropractic vs medicine in a managed care organization A Haas [48] Cost-effectiveness of medical and chiropractic care for acute and chronic low back pain H Harwood [5] Where to start?A two-stage residual inclusion approach to estimating influence of the initial provider on healthcare utilization and costs for low back pain in the US H Jarvis [49] Cost per case comparison of back injury claims of chiropractic versus medical management for conditions with identical diagnostic codes A Kominski [50] Economic evaluation of four treatments for low-back pain: results from a randomized controlled trial A • Emergency department (ED) visits Two studies, both published from 2018 through 2022, found that fewer ED visits were associated with DC care [9,28].

Discussion
The purpose of this systematic review was to address our primary research question: Is chiropractic management of spine-related musculoskeletal pain in U.S. adults associated with lower overall healthcare costs as compared to medical care?This is the first systematic review of this type performed since 2015.In that review, Dagenais et al. found that health care costs were generally lower among patients whose spine pain was managed with chiropractic care.Due to the heterogeneity of patient populations and sample sizes each paper was evaluated by three separate reviewers using the checklists previously described in the Methods Sect.[15] As the literature review progressed, we found that in studies published within the past few years, an important aspect of cost began to emerge that went beyond the immediate per episode cost: the type of initial provider was strongly associated with lower downstream costs.Downstream costs are often incurred after the initial provider has completed the episode of care.Downstream financial costs include expensive and invasive procedures such as hospitalization, surgery, injection procedures and advanced imaging.There are additional financial and non-financial downstream costs associated with the long-term consequences of addiction to opioid analgesics, including work absenteeism, decreased quality of life, psychological distress, and death due to drug overdose.
Bise et al. continued pursuing this concept in a 2023 cohort study, finding an association between the first choice of provider and future healthcare utilization [64].His team concluded that both chiropractors and physical therapists provide nonpharmacologic and nonsurgical interventions, and that their early use appears to be associated with a decrease in immediate and long-term utilization of healthcare resources.This study adds further confidence in the emerging body of evidence on provider-related cost differentials and provides a compelling case for the influence of conservative care providers as the first provider managing for spine-related musculoskeletal pain.It follows logically that if downstream interventions are reduced, lower healthcare system costs will follow.
nonpharmacologic and nonsurgical interventions, and that their early use appears to be associated with a decrease in immediate and long-term utilization of healthcare resources.This study adds further confidence in the emerging body of evidence on provider-related cost differentials and provides a compelling case for the influence of conservative care providers as the first provider managing for spine-related musculoskeletal pain.It follows logically that if downstream interventions are reduced, lower healthcare system costs will follow.
The potential human and societal cost savings of avoiding overuse of opioid analgesics, with the possibility of * A, acceptable quality, moderate risk of bias; H, high quality, low risk of bias          overdoses and addiction, is another important emerging concept in the literature.We found that 10 studies published since the U.S. government declared the opioid epidemic in 2017 found reduced dispensing of opioid prescriptions when DCs were the first provider [5,12,29,36,37,39,[43][44][45][46].Only one study published in the earlier time period (1991-2017) included opioid prescribing as a comparison [41].
Overall, as summarized in Table 4, diagnostic imaging, opioid utilization, surgery, hospitalizations, injection procedures, specialist visits and emergency department visits were all reduced where chiropractors were involved early in the case.We did not subcategorize the patient populations (e.g., general population, Medicare, insurance claims) within any of tables.

Limitations of the study
First, most of the included studies were retrospective cohort studies using large databases.Observational studies can only show associations, not prove causation, so definitive conclusions cannot be made about costs.However, their findings were so consistent that they warrant further scrutiny using higher-level study designs.Second, most of the included studies were retrospective cohort studies and therefore not the highest level of evidence.Third, we did not use any single validated checklist to assess study quality.We evaluated several checklists (e.g., SIGN, CHESS, MMAT) before determining that modification of validated checklists was necessary.Existing checklists seemed better-suited to prospective cohort designs and not as well-suited to the included retrospective cohort designs.The included studies were so variable in design and patient populations that it was not possible to pool the results for meta-analysis.Fourth, some large established datasets contained limited cost outcome variables.This made important factors such as pharmaceutical use and costs unavailable if they were not included in the dataset.Fifth, some observational studies using claims data and electronic health records do not provide enough detailed clinical information to determine whether opioid prescriptions were filled, or if filled, were actually used by the patient.Lastly, we searched only the MEDLINE database, and it is possible we missed other relevant articles not indexed there.

Strengths
Although there are few randomized controlled trials available on this topic, there were many well-conducted cohort studies that provided analyses of large datasets with cost and care data identified by provider type.
While there are certainly other factors affecting cost of care, this paper included the most common cost escalators associated with typical care for LBP, including opioids, injection procedures, surgery, specialist visits and emergency department visits.
Based on the substantial body of evidence published since 1991, a trend is developing in US healthcare systems to include chiropractors as an integral part of the medical/healthcare team, as exemplified by the Veterans Administration (VA) chiropractic clinics across the country [65,66].
Recommendations.When considering this evidence, it may be in society's best interest for U.S. healthcare organizations and governmental agencies to consider modifying benefit designs to reduce barriers to access to chiropractic providers.Modifying or eliminating preauthorization requirements, medical doctor gatekeepers, arbitrary visit limits, co-pays and deductibles may all be considered.Eliminating these barriers would allow easier access to chiropractic services, which based on currently available evidence consistently demonstrate reduced downstream services and associated costs.

Conclusion
Patients with spine-related musculoskeletal pain who consulted a chiropractor as their initial provider incurred substantially decreased downstream healthcare services and associated costs, resulting in lower overall healthcare costs compared with medical management.A primary limitation was related to the heterogeneity and sample sizes of the populations and retrospective data sets.While observational studies cannot prove causation, the recurrent theme of the data seems to support the utilization of chiropractors as the initial provider for an episode of spine-related musculoskeletal pain.Future studies using randomized designs will be helpful in clarifying and validating this trend.

Table 1
Included studies, by study design and first author

Table 2
Summary of included studies 2018-2022

Table 2 (
continued) Study designs: CO Retrospective/cross-sectional cohort study; CS Cost study/economic evaluation; PCO prospective cohort study AC Acupuncturist; ADE Adverse drug event; APRN Advanced practice registered nurse; cLBP Chronic low back pain; CT Computed tomography; DC Chiropractor; DO Osteopathic physician; ED Emergency department; EHR Electronic healtth record; EM Emergency room medical physician; LBP Low back pain; MC Medicare; MD Medical doctor; MRI Magnetic resonance imaging; MT Manual therapy; OAT Opioid analgesic therapy; OR Odds ratio; Ortho Orthopedist/orthopedic surgeon; PCP/PCMD Primary care medical physician; PM&R Physical medicine and rehabilitation medical physician; PT Physical therapist; RN Registered nurse; SMT Spinal manipulative therapy

Table 3
Summary of included studies 1991-2017

Table 3
(continued) Study design: CO, retrospective or cross-sectional cohort study; CS, cost study; PCO, prospective cohort study; RCT, randomized controlled trial AC Acupuncturist; cLBP Chronic low back pain; CLBP Complicated low back pain; CMT Chiropractic manipulative treatment; CNP Complicated neck pain; DC Chiropractor or chiropractic care; DO Osteopathic physician or osteopathic care; ED Emergency department; EM Emergency medicine; HEA Home exercise advice; HMO Health maintenance organization; LBP Low back pain; MD Medical physician or medical care; MRI Magnetic resonance imaging; Neuro Neurosurgeon; NMSK Neuromusculoskeletal; Occmed Occupational medicine; OMT Osteopathic manipulative therapy; OR Odds ratio; Ortho Orthopedist/orthopedic surgeon; PCMD primary care medical physician; PM Physical modalities; PMPY Per member per year; PT Physical therapist or physical therapy care; QALY Quality-adjusted Life Year; SMT Spinal manipulative therapy; SRE Supervised rehabilitative exercise; ULBP Uncomplicated low back pain; UNP Uncomplicated neck pain