J Manipulative Physiol Ther. 2016 (Feb); 39 (2): 6375 ~ FULL TEXT
William B Weeks, MD, PhD, MBA, Brent Leininger, DC, James M Whedon, DC, MS,
Jon D Lurie, MD, MS, Tor D Tosteson, ScD, Rand Swenson, DC, MD, PhD,
Alistair J OMalley, PhD, Christine M Goertz, PhD, DC
The Geisel School of Medicine at Dartmouth,
The Dartmouth Institute for Health Policy and Clinical Practice,
Director, Health Services and Clinical Research, Palmer College of Chiropractic,
Palmer Center for Chiropractic Research,
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.
KEYWORDS:   Chiropractic; Manipulation; Medicare; Propensity Score; Retrospective Studies
From the FULL TEXT Article:
Controlling the growth of healthcare costs continues to be a critical health policy issue. An aging population and advances in the ability to extend life and manage chronic disease have conspired to produce approximately 75 million people in the US who have multiple concurrent chronic conditions [1, 2]: 62% of Americans over age 65 have multiple chronic conditions,  and 23% of Medicare beneficiaries have 5 or more chronic conditions.  The care of individuals with chronic conditions is estimated to account for 78% of US healthcare spending, and Medicare beneficiaries with more than 1 chronic condition account for 95% while those with more than 5 chronic conditions account for 66% of all Medicare spending.  The likelihood that patients will use expensive health care resources such as hospital care increases substantially when comorbidities are present, [5, 6] and resource consumption increases dramatically if patients are also depressed.  The Strategic Framework on Multiple Chronic Conditions has called for development of new models of care for multiply comorbid Medicare beneficiaries. 
In addition, it has become increasingly evident that chronic pain is associated with high rates of diagnosable psychopathology,  and that unrecognized and untreated psychopathology can interfere with rehabilitation.  Because anxiety can decrease pain thresholds and tolerance,  emotional distress can magnify medical symptoms,  and depression can worsen chronic pain treatment outcomes,  psychiatric comorbidities may be implicated in perpetuating pain-related dysfunction. 
Among older US adults, back pain is common and associated with co-morbidities and self-reported difficulty with most functional tasks.  Medicare data from the 1990s indicated that low back pain (LBP) diagnoses and related expenditures increased disproportionately,  the use of lumbar and facet injections for LBP increased dramatically,  and there was intensive use of pharmaceutical agents among LBP patients.  The escalating prevalence of LBP among Medicare beneficiaries, the increasing costs of its treatment, and the high use and costs of pharmaceuticals suggest a critical need to identify appropriate, cost-effective, and conservative treatments for older patients with LBP. Further, the tenacity and cost of chronic pain disorders, and the very high rates of comorbid depression, [19, 20] undiagnosed mood disorders (reaching levels of 75% among those with cLBP), [21, 22] and anxiety disorders [19, 20, 23] with chronic pain disorders suggest that exploring ways to disrupt the vicious cycle of pain, stress, and emotional dysfunction are warranted. Since simultaneous pharmacological treatment of pain symptoms and major depression has led to improved function and quality of life,  and longitudinal analyses have shown that changes in pain and depression symptoms influence 1 another, [25, 26] it makes sense that concurrent treatment of both conditions is recommended. 
Most LBP in older adults can be managed non-surgically,  and randomized controlled clinical trials have demonstrated that chiropractic manipulative treatment (CMT) is an effective, conservative treatment option for LBP [27-30] that has been recommended for back pain in older adults by a variety of advisory bodies. [31, 32] While CMT has been shown to result in slightly better pain and function outcomes compared to other active treatments for chronic LBP, a number of researchers have questioned the clinical importance of these findings. From a healthcare system or societal perspective, small differences in clinical outcomes may be important if associated with minimal additional costs, or cost savings. Studies examining differences in healthcare expenditures between CMT users and non-users show that CMT users are younger, wealthier, and healthier than non-users. [33-35] After propensity score matching to adjust for such differences, 1 study of the Medical Expenditure Panel Survey found that chiropractic care was associated with a lower use of medical resources, overall.  However, to date, propensity score methods have not been applied to claims data for the purposes of evaluating costs of care for multiply-comorbid patients seeking CMT for treatment of LBP.
Therefore, to explore whether older Medicare fee-for-service beneficiaries with an episode of LBP and multiple comorbidities who obtained CMT during their episode had lower costs than those who did not, we used Medicare files and a propensity score weighting methodology to adjust for confounders and create equivalent groups for comparison. [37-40] Further, we sought to determine whether, for particular diagnostic mixes within these treatment groups, reduced expenditures on psychiatric care or pain medications might be associated with CMT
We examined 4 clinical treatment patterns for older, Medicare fee-for-service enrolled, multiply-comorbid patients who had a discrete episode of cLBP. After propensity score weighting that addressed differences in demographics across the treatment groups (including the finding that CMT patients had lower illness burdens), we found that 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, although most cost differences were due to differences in inpatient care cost; Medicare part B and D expenditures for patients who used any conventional medical care for their cLBP were similar, as were compound annual expenditure growth rates. While costs of care, and annual growth of healthcare costs, were generally lower for patients who used only CMT, that advantage might be offset somewhat by higher rates of later treatment for chronic LBP within a year of the episodes completion in this group.
A high proportion of CMT users had 13 or more chiropractic visits. Others have found substantial variation in the number and duration of episodes of chiropractic care and the number of visits associated with those episode. [43, 47] However, the potential overall (and particularly pain medication) cost savings that we found when only DCs provided back pain treatment for patients with cLBP might warrant further exploration of a new role for DCs in managing such multiply-comorbid patients. [48, 49]
In contrast to other studies results, [42, 43] we did not find that order of treatment was associated with large differences in treatment costs of care when both CMT and conventional medical care were used during an episode of care. This might be attributable to the fact that we examined a multiply-comorbid cohort of patients. We did find modestly higher daily Part B and Part D costs for patients who used conventional medical care before they used CMT, but this cost advantage was offset by longer episode lengths when CMT was obtained first.
We sought evidence that CMT might reduce expenditures for psychiatric care or pain medications among older Medicare fee-for-service beneficiaries with a cLBP episode who had an additional NMS diagnosis and anxiety, depression, or both. However, we found no reductions in psychiatric expenditures associated with CMT. While we found reductions in overall and pain medication expenditures associated with CMT at the episode level, these disappeared when examining those expenditures on a per-episode-day basis. We did find evidence that patients with osteoarthritis were less likely, and those with other NMS diagnoses were more likely, to use CMT; however, this may reflect that doctors of chiropractic and doctors of medicine have different coding practices.
Clinical and Policy Application
Our findings suggest that, from a Medicare cost standpoint, CMT may be a cost-efficient first line treatment choice for older, multiply-comorbid patients with cLBP. If policymakers encouraged DCs to have a greater role in initially managing such patients, patients may have episodes of care that were shorter and less costly (both overall and per episode day), and they might have lower pharmaceutical expenditures for pain medications. Further, should such management require the addition of conventional medical care after an initial course of CMT, policymakers might expect that overall costs might be similar to those for episodes wherein CMT was added after conventional medical care.
Limitations and Future Studies
Our study has several limitations. First, findings from the multiply-comorbid group that we examined may not be generalizable either to the larger Medicare fee-for-service population or to the US population. Second, we were constrained by the use of large Medicare datasets. While these datasets generated relatively large numbers of patients in the 4 treatment groups and reflect actual care utilization patterns, we were unable to determine whether care provided was justified or resulted in better health outcomes, as determined by patients. Third, when patients choose a particular treatment, there exists the potential for selection bias due to unmeasured confounders. While we attempted to address selection bias through inverse propensity score weighting, ours is not a randomized controlled trial, and so there is no guarantee that the distributions of any unmeasured risk factors do not vary between the weighted groups. Therefore, all findings are referred to as associations and do not necessarily imply causality. Finally, we analyzed discrete, defined episodes of cLBP; analyses that use other definitions of cLBP may generate different results.
Studies such as ours provide initial evidence that CMT use is associated with lower expenditures among Medicare beneficiaries with cLBP and multiple co-morbidities. While the study design limits our ability to make strong conclusions, future exploration of causation through randomized controlled trials is warranted; such studies might be a reasonable next step in determining the most effective and efficient treatment for this multiply-comorbid and costly group of patients. Also, while we did not find reductions in expenditures for psychiatric or pain medication associated with CMT in this population, that patients who used only CMT had lower overall and per day Part A and Part B expenditures suggests that cost savings might be found in other areas. Future work should examine broader and younger populations, where such cost savings might be more readily found. Finally, future studies should attempt to examine patient centered health outcomes so that cost-effectiveness analyses could be conducted.
We 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.
Among older, multiply-comorbid Medicare beneficiaries with a chronic low back pain episode, chiropractic manipulative treatment was associated with lower overall episode costs and lower episode costs per day.
Most multiply-comorbid chronic low back patients who used any chiropractic manipulative treatment had at least 6 chiropractic visits; most of those who exclusively used chiropractic manipulative treatment had more than 12 visits.
Use of chiropractic manipulative treatment was associated with lower total Part A and Part D Medicare cost growth for multiply-comorbid patients with chronic low back pain episodes over the time period examined.
While we found overall Medicare cost-savings associated with use of chiropractic care, we found no evidence of lower psychiatric or pain medication expenditures associated with chiropractic manipulative treatment within diagnostic subgroups.
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