The Risk of Bias and Sample Size of Trials of Spinal Manipulative Therapy for Low Back and Neck Pain: Analysis and Recommendations

Waste not, want not: call to action for spinal manipulative therapy researchers

BACKGROUND

Research waste is defined as research outcomes with no or minimal societal benefits. It is a widespread problem in the healthcare field. Four primary sources of research waste have been defined: (1) irrelevant or low priority research questions, (2) poor design or methodology, (3) lack of publication, and (4) biased or inadequate reporting. This commentary, which was developed by a multidisciplinary group of researchers with spinal manipulative therapy (SMT) research expertise, discusses waste in SMT research and provides suggestions to improve future research.

MAIN TEXT

This commentary examines common sources of waste in SMT research, focusing on design and methodological issues, by drawing on prior research and examples from clinical and mechanistic SMT studies. Clinical research is dominated by small studies and studies with a high risk of bias. This problem is compounded by systematic reviews that pool heterogenous data from varying populations, settings, and application of SMT. Research focusing on the mechanisms of SMT often fails to address the clinical relevance of mechanisms, relies on very short follow-up periods, and has inadequate control for contextual factors.

CONCLUSIONS

This call to action is directed to researchers in the field of SMT. It is critical that the SMT research community act to improve the way research is designed, conducted, and disseminated. We present specific key action points and resources, which should enhance the quality and usefulness of future SMT research.

Systematic Review and Meta-Analysis of Campylobacter Species Contamination in Poultry, Meat, and Processing Environments in South Korea

Campylobacter spp. constitute a significant global threat as a leading cause of foodborne illnesses, with poultry meat as a prominent reservoir for these pathogens. South Korea is known for its diverse poultry consumption habits, and continuous outbreaks make it a matter of concern to perform a meta-analysis to identify the primary source of contamination. This systematic review and meta-analysis aimed to assess and compare the prevalence of Campylobacter in various poultry and meat types while also considering the importance of environmental factors in South Korea. The meta-analysis revealed that duck meat exhibited the highest prevalence of Campylobacter, with a pooled estimate of 70.46% (95% CI: 42.80% to 88.38%), followed by chicken meat at a pooled prevalence of 36.17% (95% CI: 26.44% to 47.91%). Additionally, our analysis highlighted the predominance of C. jejuni and C. coli in South Korea. These findings underscore the importance of implementing rigorous food safety measures and establishing robust surveillance programs in the poultry industry to mitigate the risk of Campylobacter-related foodborne illnesses associated with meat consumption in South Korea.

Bias in the measurement of the outcome is associated with effect sizes in randomized clinical trials on exercise therapy for chronic low back pain: a meta-epidemiological study

OBJECTIVES

To explore the relationships between the risk of bias and treatment effect estimates for exercise therapy interventions on pain intensity and physical functioning outcomes in randomized controlled trials (RCTs) involving patients with chronic low back pain.

STUDY DESIGN AND SETTING

A cross-sectional meta-epidemiological study of the 230 RCTs (31,674 participants) in the 2021 'Exercise therapy for chronic low back pain' Cochrane Review were included. Study design characteristics, sample size, prospective trial registration, flowchart information, interventions, and comparisons were extracted. Independent pairs of reviewers assessed the risk of bias using the Cochrane Risk of Bias 2 tool.

RESULTS

The metaregression included 220 (pain intensity) and 203 (physical functioning) effect sizes. Unadjusted and adjusted metaregression models showed no significant associations between the bias domains and pain intensity effect sizes. Only domain 'bias in the measurement of the outcome' was significantly associated with physical functioning (standardized mean difference: -0.40, 95% confidence interval: -0.77 to -0.02) when adjusted for flowchart reported (yes/no), prospective trial registration, sample size, and comparator type.

CONCLUSION

The risk of bias in the measurement of the outcome could lead to slight overestimates of the effect size for physical functioning. Clinicians should consider this when they read and assess RCT results in this field. We encourage metaresearchers to replicate our findings using a consistent approach for evaluating the risk of bias (i.e., the RoB 2 tool) in other musculoskeletal conditions and interventions to investigate their generalizability.

Some conservative interventions are more effective than others for people with chronic non-specific neck pain: a systematic review and network meta-analysis

QUESTION

Which is the most effective conservative intervention for patients with non-specific chronic neck pain (CNSNP)?

DESIGN

A systematic review and network meta-analysis of randomised clinical trials.

PARTICIPANTS

Adults with CNSNP of at least 3 months duration.

INTERVENTIONS

All available pharmacological and non-pharmacological interventions.

OUTCOME MEASURES

The primary outcomes were pain intensity and disability. The secondary outcome was adverse events.

RESULTS

Overall, 119 RCTs (12,496 patients; 32 interventions) were included. Risk of bias was low in 50.4% of trials, unclear in 22.7% and high in 26.9%. Compared with inert treatment, a combination of active and/or passive multimodal non-pharmacological inventions (eg, exercise and manual therapy) were effective for pain on a 0-to-10 scale at 1 month (MD range 0.84 to 3.74) and at 3 to 6 months (MD range 1.06 to 1.49), and effective on disability on a 0-to-100 scale at 1 month (MD range 10.26 to 14.09) and 3 to 6 months (MD range 5.60 to 16.46). These effects ranged from possible to definite clinical relevance. Compared with inert treatment, anti-inflammatory drugs alone or in combination with another non-pharmacological treatment did not reduce pain at 1 month or 3 to 6 months. At 12 months, no superiority was found over inert treatment on both outcomes. Most mild adverse events were experienced following acupuncture/dry needling intervention. On average, the evidence varied from low to very low certainty.

CONCLUSIONS

While multimodal non-pharmacological interventions may reduce pain and disability for up to 3 to 6 months of follow-up when compared with inert treatment, the evidence was very uncertain about their effects. Better quality and larger trials are needed to improve the certainty of evidence.

REGISTRATION

PROSPERO CRD42019124501.

Sham treatment effects in manual therapy trials on back pain patients: a systematic review and pairwise meta-analysis

OBJECTIVE

To assess the effects and reliability of sham procedures in manual therapy (MT) trials in the treatment of back pain (BP) in order to provide methodological guidance for clinical trial development.

DESIGN

Systematic review and meta-analysis.

METHODS AND ANALYSIS

Different databases were screened up to 20 August 2020. Randomised controlled trials involving adults affected by BP (cervical and lumbar), acute or chronic, were included.Hand contact sham treatment (ST) was compared with different MT (physiotherapy, chiropractic, osteopathy, massage, kinesiology and reflexology) and to no treatment. Primary outcomes were BP improvement, success of blinding and adverse effect (AE). Secondary outcomes were number of drop-outs. Dichotomous outcomes were analysed using risk ratio (RR), continuous using mean difference (MD), 95% CIs. The minimal clinically important difference was 30 mm changes in pain score.

RESULTS

24 trials were included involving 2019 participants. Very low evidence quality suggests clinically insignificant pain improvement in favour of MT compared with ST (MD 3.86, 95% CI 3.29 to 4.43) and no differences between ST and no treatment (MD -5.84, 95% CI -20.46 to 8.78).ST reliability shows a high percentage of correct detection by participants (ranged from 46.7% to 83.5%), spinal manipulation being the most recognised technique.Low quality of evidence suggests that AE and drop-out rates were similar between ST and MT (RR AE=0.84, 95% CI 0.55 to 1.28, RR drop-outs=0.98, 95% CI 0.77 to 1.25). A similar drop-out rate was reported for no treatment (RR=0.82, 95% 0.43 to 1.55).

CONCLUSIONS

MT does not seem to have clinically relevant effect compared with ST. Similar effects were found with no treatment. The heterogeneousness of sham MT studies and the very low quality of evidence render uncertain these review findings.Future trials should develop reliable kinds of ST, similar to active treatment, to ensure participant blinding and to guarantee a proper sample size for the reliable detection of clinically meaningful treatment effects.

PROSPERO REGISTRATION NUMBER

CRD42020198301.

The effect of spinal manipulative therapy on pain relief and function in patients with chronic low back pain: an individual participant data meta-analysis

BACKGROUND

A 2019 review concluded that spinal manipulative therapy (SMT) results in similar benefit compared to other interventions for chronic low back pain (LBP). Compared to traditional aggregate analyses individual participant data (IPD) meta-analyses allows for a more precise estimate of the treatment effect.

PURPOSE

To assess the effect of SMT on pain and function for chronic LBP in a IPD meta-analysis.

DATA SOURCES

Electronic databases from 2000 until April 2016, and reference lists of eligible trials and related reviews.

STUDY SELECTION

Randomized controlled trials (RCT) examining the effect of SMT in adults with chronic LBP compared to any comparator.

DATA EXTRACTION AND DATA SYNTHESIS

We contacted authors from eligible trials. Two review authors independently conducted the study selection and risk of bias. We used GRADE to assess the quality of the evidence. A one-stage mixed model analysis was conducted. Negative point estimates of the mean difference (MD) or standardized mean difference (SMD) favors SMT.

RESULTS

Of the 42 RCTs fulfilling the inclusion criteria, we obtained IPD from 21 (n=4223). Most trials (s=12, n=2249) compared SMT to recommended interventions. There is moderate quality evidence that SMT vs recommended interventions resulted in similar outcomes on pain (MD -3.0, 95%CI: -6.9 to 0.9, 10 trials, 1922 participants) and functional status at one month (SMD: -0.2, 95% CI -0.4 to 0.0, 10 trials, 1939 participants). Effects at other follow-up measurements were similar. Results for other comparisons (SMT vs non-recommended interventions; SMT as adjuvant therapy; mobilization vs manipulation) showed similar findings. SMT vs sham SMT analysis was not performed, because we only had data from one study. Sensitivity analyses confirmed these findings.

LIMITATIONS

Only 50% of the eligible trials were included.

CONCLUSIONS

Sufficient evidence suggest that SMT provides similar outcomes to recommended interventions, for pain relief and improvement of functional status. SMT would appear to be a good option for the treatment of chronic LBP. Systematic Review Registration Number PROSPERO CRD42015025714.

Sample size, study length, and inadequate controls were the most common self-acknowledged limitations in manual therapy trials: A methodological review

OBJECTIVES

The aim of this study was to quantify and analyze the presence and type of self-acknowledged limitations (SALs) in a sample of manual therapy (MT) randomized controlled trials.

STUDY DESIGN AND SETTING

We randomly selected 120 MT trials. We extracted data related to SALs from the original reports and classified them into 12 categories. After data extraction, specific limitations within each category were identified. A descriptive analysis was performed using frequencies and percentages for qualitative variables.

RESULTS

The number of SALs per trial article ranged from 0 to 8, and more than two-thirds of trials acknowledged at least two different limitations. Despite its small proportion, 9% of trials did not report SALs. The most common limitation declared, in almost half of our sample, related to sample size (47.5%) followed by limitations related to study length and follow-up (33.3%) and inadequate controls (32.5%).

CONCLUSION

Our results indicate that at least two different limitations are consistently acknowledged in MT trial reports, the most common being those related to sample size, study length, follow-up, and inadequate controls. Analysis of the reasons behind the SALs gives some insights about the main difficulties in conducting research in this field and may help develop strategies to improve future research.

Benefits and harms of spinal manipulative therapy for the treatment of chronic low back pain: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To assess the benefits and harms of spinal manipulative therapy (SMT) for the treatment of chronic low back pain.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

DATA SOURCES

Medline, PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, Physiotherapy Evidence Database (PEDro), Index to Chiropractic Literature, and trial registries up to 4 May 2018, including reference lists of eligible trials and related reviews.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials examining the effect of spinal manipulation or mobilisation in adults (≥18 years) with chronic low back pain with or without referred pain. Studies that exclusively examined sciatica were excluded, as was grey literature. No restrictions were applied to language or setting.

REVIEW METHODS

Two reviewers independently selected studies, extracted data, and assessed risk of bias and quality of the evidence. The effect of SMT was compared with recommended therapies, non-recommended therapies, sham (placebo) SMT, and SMT as an adjuvant therapy. Main outcomes were pain and back specific functional status, examined as mean differences and standardised mean differences (SMD), respectively. Outcomes were examined at 1, 6, and 12 months. Quality of evidence was assessed using GRADE. A random effects model was used and statistical heterogeneity explored.

RESULTS

47 randomised controlled trials including a total of 9211 participants were identified, who were on average middle aged (35-60 years). Most trials compared SMT with recommended therapies. Moderate quality evidence suggested that SMT has similar effects to other recommended therapies for short term pain relief (mean difference -3.17, 95% confidence interval -7.85 to 1.51) and a small, clinically better improvement in function (SMD -0.25, 95% confidence interval -0.41 to -0.09). High quality evidence suggested that compared with non-recommended therapies SMT results in small, not clinically better effects for short term pain relief (mean difference -7.48, -11.50 to -3.47) and small to moderate clinically better improvement in function (SMD -0.41, -0.67 to -0.15). In general, these results were similar for the intermediate and long term outcomes as were the effects of SMT as an adjuvant therapy. Evidence for sham SMT was low to very low quality; therefore these effects should be considered uncertain. Statistical heterogeneity could not be explained. About half of the studies examined adverse and serious adverse events, but in most of these it was unclear how and whether these events were registered systematically. Most of the observed adverse events were musculoskeletal related, transient in nature, and of mild to moderate severity. One study with a low risk of selection bias and powered to examine risk (n=183) found no increased risk of an adverse event (relative risk 1.24, 95% confidence interval 0.85 to 1.81) or duration of the event (1.13, 0.59 to 2.18) compared with sham SMT. In one study, the Data Safety Monitoring Board judged one serious adverse event to be possibly related to SMT.

CONCLUSION

SMT produces similar effects to recommended therapies for chronic low back pain, whereas SMT seems to be better than non-recommended interventions for improvement in function in the short term. Clinicians should inform their patients of the potential risks of adverse events associated with SMT.

Immediate effects of cervical mobilisations on global perceived effect, movement associated pain and neck kinematics in patients with non-specific neck pain. A double blind placebo randomised controlled trial

BACKGROUND

Neck pain is prevalent, costly and disabling. Cervical mobilisations are frequently used to treat it but their effectiveness has been questioned by several systematic reviews. Evidence suggests that better outcomes are achieved with mobilisations when they are applied to specific patient subgroups. A criteria for patients suitable for neck mobilisations has been proposed, but the effectiveness on this patient subgroup has not been tested.

OBJECTIVE

To assess the effectiveness of cervical mobilisations applied to a subgroup of patients with neck pain who fulfil specific criteria.

DESIGN

Randomised controlled trial.

METHOD

40 patients with neck pain attending a Physiotherapy clinic were recruited and randomised to a single session of either cervical mobilisations or motionless manual contact placebo. The immediate effects on global perceived effect, range of movement (ROM), movement velocity and movement associated pain were assessed.

RESULTS

mobilisation participants reported significantly better global perceived effect (p˂0.001) and improvements in movement associated pain (p = 0.041). Mobilisations produced a significant increase in ROM in side flexion (p = 0.006) and rotation (p = 0.044) when compared with placebo, but only in patients with pre-intervention ROM restriction. 29-47% of all movement associated pains were resolved following mobilisations and 11-27% following placebo. Patients in both groups showed a significant (p < 0.05) increase in movement velocity, but only in those who had a velocity restriction pre-intervention.

CONCLUSIONS

Cervical mobilisations are effective in improving movement-associated pain, increasing ROM and velocity, and patient perceived improvement when applied to patients with neck pain that fulfil a criteria. Their use should be advocated.

Immediate and short-term effects of mulligan concept positional sustained natural apophyseal glides on an athletic young-adult population classified with mechanical neck pain: an exploratory investigation

Objectives: Mechanical neck pain (MNP) is common in the athletic population. While symptoms may present at the cervical spine for patients complaining of MNP, thoracic spinal alignment or dysfunction may influence cervical positioning and overall cervical function. Clinicians often employ cervical high-velocity low-amplitude (HVLA) thrust manipulations to treat MNP, albeit with a small level of inherent risk. Mulligan Concept positional sustained natural apophyseal glides (SNAGs) directed at the cervicothoracic region are emerging to treat patients with cervical pain and dysfunction, as evidence supporting an interdependent relationship between the thoracic and cervical spine grows. The purpose of this a priori study was to evaluate outcome measures of patients classified with MNP treated with the Mulligan Concept Positional SNAGs. Methods: Ten consecutive young-adult patients, ages ranging from 15 to 18 years (mean = 16.5 ± 1.78), classified with MNP were treated utilizing Mulligan Concept Positional SNAGs. The Numeric Rating Scale (NRS), Patient-Specific Functional Scale (PSFS), Neck Disability Index (NDI), Disablement in the Physically Active (DPAS), and Fear-Avoidance Based Questionnaire-Physical Activity (FABQPA) were collected for inclusion criteria and to identify patient-reported pain and dysfunction. Results: Patients reported decreases in pain on the NRS [5.4 to .16, p = .001], increases in function on the PSFS [5.2 to 10, p = .001], and increases in cervical range of motion (CROM) [ext p = .003, flex p = .009, left rot p = .001, right rot p = .002] immediately post-treatment and between treatments. Discussion: Positional SNAGs directed at the cervicothoracic region may address a variety of patient reported symptoms for MNP, and the number of treatment sessions needed for symptom resolution may be closer to a single session rather than multiple treatments. Level of Evidence: 4.

How frequent are non-evidence-based health care beliefs in chiropractic students and do they vary across the pre-professional educational years

Background

Evidence suggests that a students’ beliefs already prior to entering a program may be important as a determinant in sustaining unsuitable health care beliefs. Our objectives were to investigate the proportion of Australian chiropractic students who hold non-evidence-based beliefs in the first year of study and the extent to which they may be involved in non-musculoskeletal health conditions. Finally, to see if this proportion varies over the course of the chiropractic program.

Method

In 2016, students from two Australian chiropractic programs answered a questionnaire on how often they would give advice on five common health conditions in their future practices as well as their opinion on whether chiropractic spinal adjustments could prevent or help seven health-related conditions.

Results

From a possible 831 students, 444 responded (53%). Students were highly likely to offer advice (often/quite often) on a range of non-musculoskeletal conditions. The proportions were lowest in first year and highest the final year. Also, high numbers of students held non-evidence-based beliefs about ‘chiropractic spinal adjustments’ which tended to occur in gradually decreasing in numbers in sequential years, except for fifth year when a reversal of the pattern occurred.

Conclusions

New strategies are required for chiropractic educators if they are to produce graduates who understand and deliver evidence-based health care and able to be part of the mainstream health care system.

Electronic supplementary material

The online version of this article (10.1186/s12998-018-0178-y) contains supplementary material, which is available to authorized users.

The quality of placebos used in randomized, controlled trials of lumbar and pelvic joint thrust manipulation-a systematic review

BACKGROUND CONTEXT

Spinal manipulative therapy (SMT) has been attributed with substantial non-specific effects. Accurate assessment of the non-specific effects of SMT relies on high-quality studies with low risk of bias that compare with appropriate placebos.

PURPOSE

This review aims to characterize the types and qualities of placebo control procedures used in controlled trials of manually applied, lumbar and pelvic (LP)-SMT, and to evaluate the assessment of subject blinding and expectations.

STUDY DESIGN

This is a systematic review of randomized, placebo-controlled trials.

METHODS

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Index to Chiropractic Literature, and relevant bibliographies. We included randomized, placebo or sham-controlled trials where the index treatment was manually applied LP-SMT. There were no restrictions on the type of condition being investigated. Two independent reviewers selected the studies, assessed study quality, and extracted the data. Relevant data were the type and quality of placebo control(s) used, the assessment of blinding and expectations, and the results of those assessments.

RESULTS

Twenty-five randomized, placebo-controlled trials were included in this review. There were 18 trials that used a sham manual SMT procedure for their placebo control intervention; the most common approach was with an SMT setup but without the application of any thrust. One small pilot study used an unequivocally indistinguishable placebo, two trials used placebos that had been validated as inert a priori, and eight trials reported on the success of subject blinding. Risk of bias was high or unclear, for all included studies.

CONCLUSIONS

Imperfect placebos are ubiquitous in clinical trials of LP-SMT, and few trials have assessed for successful subject blinding or balanced expectations of treatment success between active and control group subjects. There is thus a strong potential for unmasking of control subjects, unequal non-specific effects between active and control groups, and non-inert placebos in existing trials. Future trials should consider assessing the success of subject blinding and ensuring inertness of their placebo a priori, as a minimum standard for quality.

Effect of a single session of ear acupuncture on pain intensity and postural control in individuals with chronic low back pain: a randomized controlled trial

Background

Ear Acupuncture (EA) is a form of acupuncture in which needles are applied to the external ear and has been used in multiple painful conditions. Low back pain (LBP) is highly prevalent in active individuals and causes high economic burden to health systems worldwide. LBP affects the person’s ability to keep balance, especially in challenging conditions.

Objective

The aim of the study was to examine the effects of a single session of EA on pain intensity and body sway during postural tasks.

Method

Eighty adults with LBP and pain intensity equal to or greater than 4 (0-10 scale) were randomly allocated (1:1) to EA group (EAG) or placebo group (PG). Initially, the level of pain intensity was assessed. Next, participants stood still on a force plate either with feet in parallel or in semi-tandem and with eyes open or closed. Then, the EAG was treated with EA for 20 min and the PG was treated with detuned ultrasound. After the treatment, pain intensity was assessed again and the postural test was repeated. Pain intensity was the primary outcome and center of pressure sway area and speed were the secondary outcomes measured.

Results

Results revealed that pain intensity decreased in both groups after treatment, but decreased more in the EAG. For postural control, no effect of treatment and no interaction between treatment and postural condition on body sway were found.

Conclusion

Those findings indicate that EA is better than placebo to reduce pain, but neither treatment has any effect on postural control.

Quality of reporting of randomised controlled trials in chiropractic using the CONSORT checklist

BACKGROUND

Reviews indicate that the quality of reporting of randomised controlled trials (RCTs) in the medical literature is less than optimal, poor to moderate, and require improving. However, the reporting quality of chiropractic RCTs is unknown. As a result, the aim of this study was to assess the reporting quality of chiropractic RCTs and identify factors associated with better reporting quality. We hypothesized that quality of reporting of RCTs was influenced by industry funding, positive findings, larger sample sizes, latter year of publication and publication in non-chiropractic journals.

METHODS

RCTs published between 2005 and 2014 were sourced from clinical trial registers, PubMed and the Cochrane Reviews. RCTs were included if they involved high-velocity, low-amplitude (HVLA) spinal and/or extremity manipulation and were conducted by a chiropractor or within a chiropractic department. Data extraction, and reviews were conducted by all authors independently. Disagreements were resolved by consensus.

OUTCOMES

a 39-point overall quality of reporting score checklist was developed based on the CONSORT 2010 and CONSORT for Non-Pharmacological Treatments statements. Four key methodological items, based on allocation concealment, blinding of participants and assessors, and use of intention-to-treat analysis (ITT) were also investigated.

RESULTS

Thirty-five RCTs were included. The overall quality of reporting score ranged between 10 and 33 (median score 26.0; IQR = 8.00). Allocation concealment, blinding of participants and assessors and ITT analysis were reported in 31 (87 %), 16 (46 %), 25 (71 %) and 21 (60 %) of the 35 RCTs respectively. Items most underreported were from the CONSORT for Non-Pharmacological Treatments statement. Multivariate regression analysis, revealed that year of publication (t32 = 5.17, p = 0.000, 95 % CI: 0.76, 1.76), and sample size (t32 = 3.01, p = 0.005, 95 % CI: 1.36, 7.02), were the only two factors associated with reporting quality.

CONCLUSION

The overall quality of reporting RCTs in chiropractic ranged from poor to excellent, improving between 2005 and 2014. This study suggests that quality of reporting, was influenced by year of publication and sample size but not journal type, funding source or outcome positivity. Reporting of some key methodological items and uptake of items from the CONSORT Extension for Non-Pharmacological Treatments items was suboptimal. Future recommendations were made.

Manual and Instrument Applied Cervical Manipulation for Mechanical Neck Pain: A Randomized Controlled Trial

OBJECTIVE

The purpose of this study was to compare the effects of 2 different cervical manipulation techniques for mechanical neck pain (MNP).

METHODS

Participants with MNP of at least 1 month's duration (n = 65) were randomly allocated to 3 groups: (1) stretching (control), (2) stretching plus manually applied manipulation (MAM), and (3) stretching plus instrument-applied manipulation (IAM). MAM consisted of a single high-velocity, low-amplitude cervical chiropractic manipulation, whereas IAM involved the application of a single cervical manipulation using an (Activator IV) adjusting instrument. Preintervention and postintervention measurements were taken of all outcomes measures. Pain was the primary outcome and was measured using visual analogue scale and pressure pain thresholds. Secondary outcomes included cervical range of motion, hand grip-strength, and wrist blood pressure. Follow-up subjective pain scores were obtained via telephone text message 7 days postintervention.

RESULTS

Subjective pain scores decreased at 7-day follow-up in the MAM group compared with control (P = .015). Cervical rotation bilaterally (ipsilateral: P = .002; contralateral: P = .015) and lateral flexion on the contralateral side to manipulation (P = .001) increased following MAM. Hand grip-strength on the contralateral side to manipulation (P = .013) increased following IAM. No moderate or severe adverse events were reported. Mild adverse events were reported on 6 occasions (control, 4; MAM, 1; IAM, 1).

CONCLUSION

This study demonstrates that a single cervical manipulation is capable of producing immediate and short-term benefits for MNP. The study also demonstrates that not all manipulative techniques have the same effect and that the differences may be mediated by neurological or biomechanical factors inherent to each technique.

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.