Dosing of lumbar spinal manipulative therapy and its association with escalated spine care: A cohort study of insurance claims.

OBJECTIVE: The objective of this study was to evaluate the relationship between three distinct spinal manipulative therapy dose groups and escalated spine care by analyzing insurance claims from a cohort of patients with low back pain. METHODS: We compared three distinct spinal manipulative therapy dose groups (low = 1 SMT visits, moderate = 2-12 SMT visits, high = 13+ SMT visits), to a control group (no spinal manipulative therapy) regarding the outcome of escalated spine care. Escalated spine care procedures include imaging studies, injection procedures, emergency department visits, surgery, and opioid medication use. Propensity score matching was performed to address treatment selection bias. Modified Poisson regression modeling was used to estimate the relative risk of spine care escalation among three spinal manipulative therapy doses, adjusting for age, sex, retrospective risk score and claim count. RESULTS: 83,025 claims were categorized into 11,114 unique low back pain episodes; 8,137 claims had 0 spinal manipulative therapy visits, with the remaining episodes classified as low dose (n = 404), moderate dose (n = 1,763) or high dose (n = 810). After propensity score matching, 5,348 episodes remained; 2,454 had 0 spinal manipulative therapy visits with the remaining episodes classified as low dose (n = 404), moderate dose (n = 1,761), or high dose (n = 729). The estimated relative risk (vs no spinal manipulative therapy) for any escalated spine care was 0.45 (95% confidence interval 0.38, 0.55, p <0.001), 0.58 (95% confidence interval 0.53, 0.63, p <0.001), and 1.03 (95% confidence interval 0.95, 1.13, p = 0.461) for low, moderate, and high dose spinal manipulative therapy groups, respectively. CONCLUSIONS: For claims associated with initial episodes of low back pain, low and moderate dose spinal manipulative therapy groups were associated with a 55% and 42% reduction, respectively, in the relative risk of any escalated spine care.

Association between cervical artery dissection and spinal manipulative therapy -a medicare claims analysis.

BACKGROUND: Cervical artery dissection and subsequent ischemic stroke is the most serious safety concern associated with cervical spinal manipulation. METHODS: We evaluated the association between cervical spinal manipulation and cervical artery dissection among older Medicare beneficiaries in the United States. We employed case-control and case-crossover designs in the analysis of claims data for individuals aged 65+, continuously enrolled in Medicare Part A (covering hospitalizations) and Part B (covering outpatient encounters) for at least two consecutive years during 2007-2015. The primary exposure was cervical spinal manipulation; the secondary exposure was a clinical encounter for evaluation and management for neck pain or headache. We created a 3-level categorical variable, (1) any cervical spinal manipulation, 2) evaluation and management but no cervical spinal manipulation and (3) neither cervical spinal manipulation nor evaluation and management. The primary outcomes were occurrence of cervical artery dissection, either (1) vertebral artery dissection or (2) carotid artery dissection. The cases had a new primary diagnosis on at least one inpatient hospital claim or primary/secondary diagnosis for outpatient claims on at least two separate days. Cases were compared to 3 different control groups: (1) matched population controls having at least one claim in the same year as the case; (2) ischemic stroke controls without cervical artery dissection; and (3) case-crossover analysis comparing cases to themselves in the time period 6-7 months prior to their cervical artery dissection. We made each comparison across three different time frames: up to (1) 7 days; (2) 14 days; and (3) 30 days prior to index event. RESULTS: The odds of cervical spinal manipulation versus evaluation and management did not significantly differ between vertebral artery dissection cases and any of the control groups at any of the timepoints (ORs 0.84 to 1.88; p > 0.05). Results for carotid artery dissection cases were similar. CONCLUSION: Among Medicare beneficiaries aged 65 and older who received cervical spinal manipulation, the risk of cervical artery dissection is no greater than that among control groups.

Association between chiropractic care and use of prescription opioids among older medicare beneficiaries with spinal pain: a retrospective observational study.

BACKGROUND: The burden of spinal pain can be aggravated by the hazards of opioid analgesics, which are still widely prescribed for spinal pain despite evidence-based clinical guidelines that identify non-pharmacological therapies as the preferred first-line approach. Previous studies have found that chiropractic care is associated with decreased use of opioids, but have not focused on older Medicare beneficiaries, a vulnerable population with high rates of co-morbidity and polypharmacy. The purpose of this investigation was to evaluate the association between chiropractic utilization and use of prescription opioids among older adults with spinal pain. METHODS: We conducted a retrospective observational study in which we examined a nationally representative multi-year sample of Medicare claims data, 2012-2016. The study sample included 55,949 Medicare beneficiaries diagnosed with spinal pain, of whom 9,356 were recipients of chiropractic care and 46,593 were non-recipients. We measured the adjusted risk of filling a prescription for an opioid analgesic for up to 365 days following diagnosis of spinal pain. Using Cox proportional hazards modeling and inverse weighted propensity scoring to account for selection bias, we compared recipients of both primary care and chiropractic to recipients of primary care alone regarding the risk of filling a prescription. RESULTS: The adjusted risk of filling an opioid prescription within 365 days of initial visit was 56% lower among recipients of chiropractic care as compared to non-recipients (hazard ratio 0.44; 95% confidence interval 0.40-0.49). CONCLUSIONS: Among older Medicare beneficiaries with spinal pain, use of chiropractic care is associated with significantly lower risk of filling an opioid prescription.

Initial Choice of Spinal Manipulation Reduces Escalation of Care for Chronic Low Back Pain Among Older Medicare Beneficiaries.

STUDY DESIGN: We combined elements of cohort and crossover-cohort design. OBJECTIVE: The objective of this study was to compare longterm outcomes for spinal manipulative therapy (SMT) and opioid analgesic therapy (OAT) regarding escalation of care for patients with chronic low back pain (cLBP). SUMMARY OF BACKGROUND DATA: Current evidence-based guidelines for clinical management of cLBP include both OAT and SMT. For long-term care of older adults, the efficiency and value of continuing either OAT or SMT are uncertain. METHODS: We examined Medicare claims data spanning a five-year period. We included older Medicare beneficiaries with an episode of cLBP beginning in 2013. All patients were continuously enrolled under Medicare Parts A, B, and D. We analyzed the cumulative frequency of encounters indicative of an escalation of care for cLBP, including hospitalizations, emergency department visits, advanced diagnostic imaging, specialist visits, lumbosacral surgery, interventional pain medicine techniques, and encounters for potential complications of cLBP. RESULTS: SMT was associated with lower rates of escalation of care as compared to OAT. The adjusted rate of escalated care encounters was approximately 2.5 times higher for initial choice of OAT vs. initial choice of SMT (with weighted propensity scoring: rate ratio 2.67, 95% confidence interval 2.64-2.69, P < .0001). CONCLUSION: Among older Medicare beneficiaries who initiated long-term care for cLBP with opioid analgesic therapy, the adjusted rate of escalated care encounters was significantly higher as compared to those who initiated care with spinal manipulative therapy.Level of Evidence: 3.

Long-Term Medicare Costs Associated With Opioid Analgesic Therapy vs Spinal Manipulative Therapy for Chronic Low Back Pain in a Cohort of Older Adults.

OBJECTIVES: The purpose of this study was to compare Medicare healthcare expenditures for patients who received long-term treatment of chronic low back pain (cLBP) with either opioid analgesic therapy (OAT) or spinal manipulative therapy (SMT). METHODS: We conducted a retrospective observational study using a cohort design for analysis of Medicare claims data. The study population included Medicare beneficiaries enrolled under Medicare Parts A, B, and D from 2012 through 2016. We assembled cohorts of patients who received long-term management of cLBP with OAT or SMT (such as delivered by chiropractic or osteopathic practitioners) and evaluated the comparative effect of OAT vs SMT upon expenditures, using multivariable regression to control for beneficiary characteristics and measures of health status, and propensity score weighting and binning to account for selection bias. RESULTS: The study sample totaled 28,160 participants, of whom 77% initiated long-term care of cLBP with OAT, and 23% initiated care with SMT. For care of low back pain specifically, average long-term costs for patients who initiated care with OAT were 58% lower than those who initiated care with SMT. However, overall long-term healthcare expenditures under Medicare were 1.87 times higher for patients who initiated care via OAT compared with those initiated care with SMT (95% CI 1.65-2.11; P < .0001). CONCLUSIONS: Adults aged 65 to 84 who initiated long-term treatment for cLBP via OAT incurred lower long-term costs for low back pain but higher long-term total healthcare costs under Medicare compared with patients who initiated long-term treatment with SMT.

Temporal Trends and Geographic Variations in the Supply of Clinicians Who Provide Spinal Manipulation to Medicare Beneficiaries: A Serial Cross-Sectional Study.

OBJECTIVE: Spinal manipulation (SM) is recommended for first-line treatment of patients with low back pain. Inadequate access to SM may result in inequitable spine care for older US adults, but the supply of clinicians who provide SM under Medicare is uncertain. The purpose of this study was to measure temporal trends and geographic variations in the supply of clinicians who provide SM to Medicare beneficiaries. METHODS: Medicare is a US government-administered health insurance program that provides coverage primarily for older adults and people with disabilities. We used a serial cross-sectional design to examine Medicare administrative data from 2007 to 2015 for SM services identified by procedure code. We identified unique providers by National Provider Identifier and distinguished between chiropractors and other specialties by Physician Specialty Code. We calculated supply as the number of providers per 100 000 beneficiaries, stratified by geographic location and year. RESULTS: Of all clinicians who provide SM to Medicare beneficiaries, 97% to 98% are doctors of chiropractic. The geographic supply of doctors of chiropractic providing SM services in 2015 ranged from 20/100 000 in the District of Columbia to 260/100 000 in North Dakota. The supply of other specialists performing the same services ranged from fewer than 1/100 000 in 11 states to 8/100 000 in Colorado. Nationally, the number of Medicare-active chiropractors declined from 47 102 in 2007 to 45 543 in 2015. The count of other clinicians providing SM rose from 700 in 2007 to 1441 in 2015. CONCLUSION: Chiropractors constitute the vast majority of clinicians who bill for SM services to Medicare beneficiaries. The supply of Medicare-active SM providers varies widely by state. The overall supply of SM providers under Medicare is declining, while the supply of nonchiropractors who provide SM is growing.

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.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: Opioid Analgesic Therapy (OAT) and Spinal Manipulative Therapy (SMT) are evidence-based strategies for treatment of chronic low back pain (cLBP), but the long-term safety of these therapies is uncertain. The objective of this study was to compare OAT versus SMT with regard to risk of adverse drug events (ADEs) among older adults with cLBP. SUMMARY OF BACKGROUND DATA: We examined Medicare claims data spanning a 5-year period on fee-for-service beneficiaries aged 65 to 84 years, continuously enrolled under Medicare Parts A, B, and D for a 60-month study period, and with an episode of cLBP in 2013. We excluded patients with a diagnosis of cancer or use of hospice care. METHODS: All included patients received long-term management of cLBP with SMT or OAT. We assembled cohorts of patients who received SMT or OAT only, and cohorts of patients who crossed over from OAT to SMT or from SMT to OAT. We used Poisson regression to estimate the adjusted incidence rate ratio for outpatient ADE among patients who initially chose OAT as compared with SMT. RESULTS: With controlling for patient characteristics, health status, and propensity score, the adjusted rate of ADE was more than 42 times higher for initial choice of OAT versus initial choice of SMT (rate ratio 42.85, 95% CI 34.16-53.76, P < 0.0001). CONCLUSION: Among older Medicare beneficiaries who received long-term care for cLBP the adjusted rate of ADE for patients who initially chose OAT was substantially higher than those who initially chose SMT.Level of Evidence: 2.

Spinal Manipulation vs Prescription Drug Therapy for Chronic Low Back Pain: Beliefs, Satisfaction With Care, and Qualify of Life Among Older Medicare Beneficiaries.

OBJECTIVE: The objective of this study was to compare patients' perspectives on the use of spinal manipulative therapy (SMT) compared to prescription drug therapy (PDT) with regard to health-related quality of life (HRQoL), patient beliefs, and satisfaction with treatment. METHODS: Four cohorts of Medicare beneficiaries were assembled according to previous treatment received as evidenced in claims data: SMT, PDT, and 2 crossover cohorts (where participants experienced both types of treatments). A total of 195 Medicare beneficiaries responded to the survey. Outcome measures used were a 0-to-10 numeric rating scale to measure satisfaction, the Low Back Pain Treatment Beliefs Questionnaire to measure patient beliefs, and the 12-item Short Form Health Survey to measure HRQoL. RESULTS: Recipients of SMT were more likely to be very satisfied with their care (84%) than recipients of PDT (50%; P = .002). The SMT cohort self-reported significantly higher HRQoL compared to the PDT cohort; mean differences in physical and mental health scores on the 12-item Short Form Health Survey were 12.85 and 9.92, respectively. The SMT cohort had a lower degree of concern regarding chiropractic care for their back pain compared to the PDT cohort's reported concern about PDT (P = .03). CONCLUSION: Among older Medicare beneficiaries with chronic low back pain, long-term recipients of SMT had higher self-reported rates of HRQoL and greater satisfaction with their modality of care than long-term recipients of PDT. Participants who had longer-term management of care were more likely to have positive attitudes and beliefs toward the mode of care they received.

Cost comparison of two approaches to chiropractic care for patients with acute and sub-acute low Back pain care episodes: a cohort study.

BACKGROUND: Low back pain (LBP) imposes a costly burden upon patients, healthcare insurers, and society overall. Spinal manipulation as practiced by chiropractors has been found be cost-effective for treatment of LBP, but there is wide variation among chiropractors in their approach to clinical care, and the most cost-effective approach to chiropractic care is uncertain. To date, little has been published regarding the cost effectiveness of different approaches to chiropractic care. Thus, the current study presents a cost comparison between chiropractic approaches for patients with acute or subacute care episodes for low back pain. METHODS: We employed a retrospective cohort design to examine costs of chiropractic care among patients diagnosed with acute or subacute low back pain. The study time period ranged between 07/01/2016 and 12/22/2017. We compared cost outcomes for patients of two cohorts of chiropractors within health care system: Cohort 1) a general network of providers, and Cohort 2) a network providing conservative evidence-based care for rapid resolution of pain. We used generalized linear regression modeling to estimate the comparative influence of demographic and clinical factors on expenditures. RESULTS: A total of 25,621 unique patients were included in the analyses. The average cost per patient for Cohort 2 (mean allowed amount $252) was lower compared to Cohort 1 (mean allowed amount $326; 0.77, 95% CI 0.75-0.79, p < .001). Patient and clinician related factors such as health plan, provider region, and sex also significantly influenced costs. CONCLUSIONS: This study comprehensively analyzed cost data associated with the chiropractic care of adults with acute or sub-acute low back pain cared by two cohorts of chiropractic physicians. In general, providers in Cohort 2 were found to be significantly associated with lower costs for patient care as compared to Cohort 1. Utilization of a clinical model characterized by a patient-centered clinic approach and standardized, best-practice clinical protocols may offer lower cost when compared to non-standardized clinical approaches to chiropractic care.

Implementation of the Primary Spine Care Model in a Multi-Clinician Primary Care Setting: An Observational Cohort Study.

OBJECTIVE: The objective of this investigation was to compare the value of primary spine care (PSC) with usual care for management of patients with spine-related disorders (SRDs) within a primary care setting. METHODS: We retrospectively examined existing patient encounter data at 3 primary care sites within a multi-clinic health system. Designated clinicians serve in the role as PSC as the initial point of contact for spine patients, coordinate, and follow up for the duration of the episode of care. A PSC may be a chiropractor, physical therapist, or medical or osteopathic physician who has been trained to provide primary care for patients with SRDs. The PSC model of care had been introduced at site I (Lebanon, New Hampshire); sites II (Bedford, New Hampshire) and III (Nashua, New Hampshire) served as control sites where patients received usual care. To evaluate cost outcomes, we employed a controlled quasi-experimental design for analysis of health claims data. For analysis of clinical outcomes, we compared clinical records for PSC at site I and usual care at sites II and III, all with reference to usual care at site I. We examined clinical encounters occurring over a 24-month period, from February 1, 2016 through January 31, 2018. RESULTS: Primary spine care was associated with reduced total expenditures compared with usual care for SRDs. At site I, average per-patient expenditure was $162 in year 1 and $186 in year 2, compared with site II ($332 in year 1; $306 in year 2) and site III ($467 in year 1; $323 in year 2). CONCLUSION: Among patients with SRDs included in this study, implementation of the PSC model within a conventional primary care setting was associated with a trend toward reduced total expenditures for spine care compared with usual primary care. Implementation of PSC may lead to reduced costs and resource utilization, but may be no more effective than usual care regarding clinical outcomes.

Trends in Insurance Coverage for Complementary Health Care Services.

Introduction: Complementary health care professionals deliver a substantial component of clinical services in the United States, but insurance coverage for many such services may be inadequate. The objective of this project was to follow up on an earlier single-year study with an evaluation of trends in reimbursement for complementary health care services over a 7-year period. Methods: The authors employed a retrospective serial cross-sectional design to analyze health insurance claims for services provided by licensed acupuncturists, chiropractors, and naturopaths in New Hampshire (NH) from 2011 to 2017. They restricted the analyses to claims in nonemergent outpatient settings for Current Procedural Terminology code 99213, which is one of the most commonly used clinical procedure codes across all specialties. They evaluated by year the likelihood of reimbursement, as compared with primary care physicians as the gold standard. A generalized estimating equation model was used to account for within-person correlations among the separate claim reimbursement indicators for individuals used in the analysis, using an exchangeable working covariance structure among claims for the same individual. Reimbursement was defined as payment >0 dollars. Results: The total number of clinical services claimed was 26,725 for acupuncture, 8317 for naturopathic medicine, 2,539,144 for chiropractic, and 1,860,271 for primary care. Initially, likelihood of reimbursement for naturopathic physicians was higher relative to primary care physicians, but was lower from 2014 onward. Odds of reimbursement for both acupuncture and chiropractic claims remained lower throughout the study period. In 2017, as compared with primary care the likelihood of reimbursement was 77% lower for acupuncturists, 72% lower for chiropractors, and 64% lower for naturopaths. Conclusion: The likelihood of reimbursement for complementary health care services is significantly lower than that for primary care physicians in NH. Lack of insurance coverage may result in reduced patient access to such services.

Regarding: "Insurance Reimbursement for Complementary Healthcare Services".

In the article, "Insurance Reimbursement for Complementary Healthcare Services," we reported that the likelihood of reimbursement for complementary health care services in New Hampshire was significantly lower as compared with services of primary care physicians. The relatively low likelihood of reimbursement for integrative health care suggests that many patients who want such services must pay for them out of pocket. Affordable access to these services may be similarly limited in other states; certainly the utilization of integrative health care services varies significantly across the US states, and such variation may be tied to likelihood of reimbursement. Unwarranted geographic variation in reimbursement for integrative health care services is likely to compound inequities in access to health care in general, particularly for people of lower socioeconomic status. The aspirational value of Health Justice asserts the obligation of societies to attend to the basic health needs of all, with particular attention to the disadvantaged. A new project under development, The Atlas of Integrative Healthcare, is intended to support the advancement of health justice. The Atlas project is expected to support the policy goals of the integrative health care community with regard to helping patients access the high-value integrative health care services that they need and want.

Association Between Utilization of Chiropractic Services for Treatment of Low-Back Pain and Use of Prescription Opioids.

OBJECTIVE: Pain relief resulting from services delivered by doctors of chiropractic may allow patients to use lower or less frequent doses of opioids, leading to reduced risk of adverse effects. The objective of this investigation was to evaluate the association between utilization of chiropractic services and the use of prescription opioid medications. DESIGN: The authors used a retrospective cohort design to analyze health insurance claims data. SETTING: The data source was the all payer claims database administered by the State of New Hampshire. The authors chose New Hampshire because health claims data were readily available for research, and in 2015, New Hampshire had the second-highest age-adjusted rate of drug overdose deaths in the United States. SUBJECTS: The study population comprised New Hampshire residents aged 18-99 years, enrolled in a health plan, and with at least two clinical office visits within 90 days for a primary diagnosis of low-back pain. The authors excluded subjects with a diagnosis of cancer. OUTCOME MEASURES: The authors measured likelihood of opioid prescription fill among recipients of services delivered by doctors of chiropractic compared with nonrecipients. They also compared the cohorts with regard to rates of prescription fills for opioids and associated charges. RESULTS: The adjusted likelihood of filling a prescription for an opioid analgesic was 55% lower among recipients compared with nonrecipients (odds ratio 0.45; 95% confidence interval 0.40-0.47; p < 0.0001). Average charges per person for opioid prescriptions were also significantly lower among recipients. CONCLUSIONS: Among New Hampshire adults with office visits for noncancer low-back pain, the likelihood of filling a prescription for an opioid analgesic was significantly lower for recipients of services delivered by doctors of chiropractic compared with nonrecipients. The underlying cause of this correlation remains unknown, indicating the need for further investigation.

The Association Between Use of Chiropractic Care and Costs of Care Among Older Medicare Patients With Chronic Low Back Pain and Multiple Comorbidities.

OBJECTIVE: The purpose of this study was to determine whether use of chiropractic manipulative treatment (CMT) was associated with lower healthcare costs among multiply-comorbid Medicare beneficiaries with an episode of chronic low back pain (cLBP). METHODS: We conducted an observational, retrospective study of 2006 to 2012 Medicare fee-for-service reimbursements for 72326 multiply-comorbid patients aged 66 and older with cLBP episodes and 1 of 4 treatment exposures: chiropractic manipulative treatment (CMT) alone, CMT followed or preceded by conventional medical care, or conventional medical care alone. We used propensity score weighting to address selection bias. RESULTS: After propensity score weighting, total and per-episode day Part A, Part B, and Part D Medicare reimbursements during the cLBP treatment episode were lowest for patients who used CMT alone; these patients had higher rates of healthcare use for low back pain but lower rates of back surgery in the year following the treatment episode. Expenditures were greatest for patients receiving medical care alone; order was irrelevant when both CMT and medical treatment were provided. Patients who used only CMT had the lowest annual growth rates in almost all Medicare expenditure categories. While patients who used only CMT had the lowest Part A and Part B expenditures per episode day, we found no indication of lower psychiatric or pain medication expenditures associated with CMT. CONCLUSIONS: This study found that older multiply-comorbid patients who used only CMT during their cLBP episodes had lower overall costs of care, shorter episodes, and lower cost of care per episode day than patients in the other treatment groups. Further, costs of care for the episode and per episode day were lower for patients who used a combination of CMT and conventional medical care than for patients who did not use any CMT. These findings support initial CMT use in the treatment of, and possibly broader chiropractic management of, older multiply-comorbid cLBP patients.

Racial Disparities in Use of Chiropractic Services by Medicare Beneficiaries Aged 65 to 99 in Los Angeles County, California.

Racial and ethnic disparities in utilization of chiropractic services have been described at the state level, but little is known about such local disparities. We analyzed Medicare data for the year 2008 to evaluate by ZIP code for utilization of chiropractic services among older adults in Los Angeles County, California. We evaluated for availability and use of chiropractic services by racial/ethnic category, quantified geographic variations by coefficient of variation, and mapped utilization by selected racial/ethnic categories. Among 7502 beneficiaries who used chiropractic services, 72% were white, 12% Asian, 1% black, 1% Hispanic, and 14% other/unknown. Variation in the number of beneficiaries per ZIP code who used chiropractic services was highest among Hispanics, blacks, and Asians. We found evidence of racial disparities in use of chiropractic services at the local level in Los Angeles County. Older blacks and Hispanics in Los Angeles County may be underserved with regard to chiropractic care.

Comparing Propensity Score Methods for Creating Comparable Cohorts of Chiropractic Users and Nonusers in Older, Multiply Comorbid Medicare Patients With Chronic Low Back Pain.

OBJECTIVE: Patients who use complementary and integrative health services like chiropractic manipulative treatment (CMT) often have different characteristics than do patients who do not, and these differences can confound attempts to compare outcomes across treatment groups, particularly in observational studies when selection bias may occur. The purposes of this study were to provide an overview on how propensity scoring methods can be used to address selection bias by balancing treatment groups on key variables and to use Medicare data to compare different methods for doing so. METHODS: We described 2 propensity score methods (matching and weighting). Then we used Medicare data from 2006 to 2012 on older, multiply comorbid patients who had a chronic low back pain episode to demonstrate the impact of applying methods on the balance of demographics of patients between 2 treatment groups (those who received only CMT and those who received no CMT during their episodes). RESULTS: Before application of propensity score methods, patients who used only CMT had different characteristics from those who did not. Propensity score matching diminished observed differences across the treatment groups at the expense of reduced sample size. However, propensity score weighting achieved balance in patient characteristics between the groups and allowed us to keep the entire sample. CONCLUSIONS: Although propensity score matching and weighting have similar effects in terms of balancing covariates, weighting has the advantage of maintaining sample size, preserving external validity, and generalizing more naturally to comparisons of 3 or more treatment groups. Researchers should carefully consider which propensity score method to use, as using different methods can generate different results.

Risk of stroke after chiropractic spinal manipulation in medicare B beneficiaries aged 66 to 99 years with neck pain.

OBJECTIVE: The purpose of this study was to quantify risk of stroke after chiropractic spinal manipulation, as compared to evaluation by a primary care physician, for Medicare beneficiaries aged 66 to 99 years with neck pain. METHODS: This is a retrospective cohort analysis of a 100% sample of annualized Medicare claims data on 1 157 475 beneficiaries aged 66 to 99 years with an office visit to either a chiropractor or primary care physician for neck pain. We compared hazard of vertebrobasilar stroke and any stroke at 7 and 30 days after office visit using a Cox proportional hazards model. We used direct adjusted survival curves to estimate cumulative probability of stroke up to 30 days for the 2 cohorts. RESULTS: The proportion of subjects with stroke of any type in the chiropractic cohort was 1.2 per 1000 at 7 days and 5.1 per 1000 at 30 days. In the primary care cohort, the proportion of subjects with stroke of any type was 1.4 per 1000 at 7 days and 2.8 per 1000 at 30 days. In the chiropractic cohort, the adjusted risk of stroke was significantly lower at 7 days as compared to the primary care cohort (hazard ratio, 0.39; 95% confidence interval, 0.33-0.45), but at 30 days, a slight elevation in risk was observed for the chiropractic cohort (hazard ratio, 1.10; 95% confidence interval, 1.01-1.19). CONCLUSIONS: Among Medicare B beneficiaries aged 66 to 99 years with neck pain, incidence of vertebrobasilar stroke was extremely low. Small differences in risk between patients who saw a chiropractor and those who saw a primary care physician are probably not clinically significant.

Risk of traumatic injury associated with chiropractic spinal manipulation in Medicare Part B beneficiaries aged 66 to 99 years.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: In older adults with a neuromusculoskeletal complaint, to evaluate risk of injury to the head, neck, or trunk after an office visit for chiropractic spinal manipulation compared with office visit for evaluation by primary care physician. SUMMARY OF BACKGROUND DATA: The risk of physical injury due to spinal manipulation has not been rigorously evaluated for older adults, a population particularly vulnerable to traumatic injury in general. METHODS: We analyzed Medicare administrative data on Medicare B beneficiaries aged 66 to 99 years with an office visit in 2007 for a neuromusculoskeletal complaint. Using a Cox proportional hazards model, we evaluated for adjusted risk of injury within 7 days, comparing 2 cohorts: those treated by chiropractic spinal manipulation versus those evaluated by a primary care physician. We used direct adjusted survival curves to estimate the cumulative probability of injury. In the chiropractic cohort only, we used logistic regression to evaluate the effect of specific chronic conditions on likelihood of injury. RESULTS: The adjusted risk of injury in the chiropractic cohort was lower than that of the primary care cohort (hazard ratio, 0.24; 95% confidence interval, 0.23-0.25). The cumulative probability of injury in the chiropractic cohort was 40 injury incidents per 100,000 subjects compared with 153 incidents per 100,000 subjects in the primary care cohort. Among subjects who saw a chiropractic physician, the likelihood of injury was increased in those with a chronic coagulation defect, inflammatory spondylopathy, osteoporosis, aortic aneurysm and dissection, or long-term use of anticoagulant therapy. CONCLUSION: Among Medicare beneficiaries aged 66 to 99 years with an office visit risk for a neuromusculoskeletal problem, risk of injury to the head, neck, or trunk within 7 days was 76% lower among subjects with a chiropractic office visit than among those who saw a primary care physician. LEVEL OF EVIDENCE: 3.

Medicare's demonstration of expanded coverage for chiropractic services: limitations of the demonstration and an alternative direct cost estimate.

OBJECTIVE: The purposes of this study were to examine the direct costs associated with Medicare's 2005-2007 "Demonstration of Expanded Coverage of Chiropractic Services" (Demonstration) and their drivers, to explore practice pattern variation during the Demonstration, and to describe scenarios of cost implications had provider behavior and benefit coverage been different. METHODS: Using Medicare Part B data from April 1, 2005, and March 31, 2007, and 2004 Rural Urban Continuum Codes, we conducted a retrospective analysis of traditionally reimbursed and expanded chiropractic services provided to patients aged 65 to 99 years who had a neuromusculoskeletal condition. We compared chiropractic care costs, supply, and utilization patterns for the 2-year periods before, during, and after the Demonstration for 5 Chicago area counties that participated in the Demonstration to those for 6 other county aggregations-urban or rural counties that participated in the Demonstration; were designated comparison counties during the Demonstration; or were neither participating nor comparison counties during the Demonstration. RESULTS: When compared with other groups, doctors of chiropractic in 1 region (Chicago area counties) billed more aggressively for expanded services and were reimbursed significantly more for traditionally reimbursed chiropractic services provided before, during, and after the Demonstration. Costs would have been substantially lower had doctors of chiropractic in this 1 region had responded similarly to those in other demonstration counties. CONCLUSION: We found widespread geographic variation in practice behavior and patterns. Our findings suggest that Medicare might reduce the risk of accelerated costs associated with the introduction of a new benefit by applying appropriate limits to the frequency of use and overall costs of those benefits, particularly in highly competitive markets.

Trends in the use and cost of chiropractic spinal manipulation under Medicare Part B.

BACKGROUND CONTEXT: Concern about improper payments to chiropractic physicians prompted the US Department of Health and Human Services to describe chiropractic services as a "significant vulnerability" for Medicare, but little is known about trends in the use and cost of chiropractic spinal manipulation provided under Medicare. PURPOSE: To quantify the volume and cost of chiropractic spinal manipulation services for older adults under Medicare Part B and identify longitudinal trends. STUDY DESIGN/SETTING: Serial cross-sectional design for retrospective analysis of administrative data. PATIENT SAMPLE: Annualized nationally representative samples of 5.0 to 5.4 million beneficiaries. OUTCOME MEASURES: Chiropractic users, allowed services, allowed charges, and payments. METHODS: Descriptive statistics were generated by analysis of Medicare administrative data on chiropractic spinal manipulation provided in the United States from 2002 to 2008. A 20% nationally representative sample of allowed Medicare Part B fee-for-service claims was merged, based on beneficiary identifier, with patient demographic data. The data sample was restricted to adults aged 65 to 99 years, and duplicate claims were excluded. Annualized estimates of outcome measures were extrapolated, per beneficiary and per user rates were estimated, and volumes were stratified by current procedural terminology code. RESULTS: The number of Medicare beneficiaries who used chiropractic spinal manipulation grew 13% from 2002 to 2004, remained flat through 2007, and then declined 5% through 2008. An estimated 1.7 million beneficiaries (6.9%) used 18.6 million allowed chiropractic services in 2008. In inflation-adjusted dollars, allowed charges per user increased 4% through 2005 and then declined by 17% through 2008; payments per user increased by 5% from 2002 to 2005 and then declined by 18% through 2008. Expenditures for chiropractic in 2008 totaled an estimated $420 million. Longitudinal trends in allowed claims for spinal manipulation varied by procedure: the relative frequency of treatment of one to two spinal regions declined from 43% to 29% of services, treatment of three to four regions increased from 48% to 62% of services, and treatment of five regions remained flat at 9% of services. CONCLUSIONS: Chiropractic claims account for less than 1/10th of 1% of overall Medicare expenditures. Allowed services, allowed charges, and fee-for-service payments for chiropractic spinal manipulation under Medicare Part B generally increased from 2002, peaked in 2005 and 2006, and then declined through 2008. Per user spending for chiropractic spinal manipulation also declined by 18% from 2006 to 2008, in contrast to 10% growth in total spending per beneficiary and 16% growth in overall Medicare spending.