Christopher Showalter

Different minimally important clinical difference (MCID) scores lead to different clinical prediction rules for the Oswestry disability index for the same sample of patients

Abstract Background: Minimal clinically important difference (MCID) scores for outcome measures are frequently used evidence-based guides to gage meaningful changes. There are numerous outcome instruments used for analyzing pain, disability, and dysfunction of the low back; perhaps the most common of these is the Oswestry disability index (ODI). A single agreed-upon MCID score for the ODI has yet to be established. What is also unknown is whether selected baseline variables will be universal predictors regardless of the MCID used for a particular outcome measure. Objective: To explore the relationship between predictive models and the MCID cutpoint on the ODI. Setting: Data were collected from 16 outpatient physical therapy clinics in 10 states. Design: Secondary database analysis using backward stepwise deletion logistic regression of data from a randomized controlled trial (RCT) to create prognostic clinical prediction rules (CPR). Participants and Interventions: One hundred and forty-nine patients with low back pain (LBP) were enrolled in the RCT. All were treated with manual therapy, with a majority also receiving spine-strengthening exercises. Results: The resultant predictive models were dependent upon the MCID used and baseline sample characteristics. All CPR were statistically significant (P < 001). All six MCID cutpoints used resulted in completely different significant predictor variables with no predictor significant across all models. Limitations: The primary limitations include sub-optimal sample size and study design. Conclusions: There is extreme variability among predictive models created using different MCIDs on the ODI within the same patient population. Our findings highlight the instability of predictive modeling, as these models are significantly affected by population baseline characteristics along with the MCID used. Clinicians must be aware of the fragility of CPR prior to applying each in clinical practice.

Which Prognostic Factors for Low Back Pain Are Generic Predictors of Outcome Across a Range of Recovery Domains

Background Recovery from low back pain (LBP) is multidimensional and requires the use of multiple-response (outcome) measures to fully reflect these many dimensions. Predictive prognostic variables that are present or stable in all or most predictive models that use different outcome measures could be considered “universal” prognostic variables. Objective The aim of this study was to explore the potential of universal prognostic variables in predictive models for 4 different outcome measures in patients with mechanical LBP. Design Predictive modeling was performed using data extracted from a randomized controlled trial. Four prognostic models were created using backward stepwise deletion logistic, Poisson, and linear regression. Methods Data were collected from 16 outpatient physical therapy facilities in 10 states. All 149 patients with LBP were treated with manual therapy and spine strengthening exercises until discharge. Four different measures of response were used: Oswestry Disability Index and Numeric Pain Rating Scale change scores, total visits, and report of rate of recovery. Results The set of statistically significant predictors was dependent on the definition of response. All regression models were significant. Within both forms of the 4 models, meeting the clinical prediction rule for manipulation at baseline was present in all 4 models, whereas no irritability at baseline and diagnosis of sprains and strains were present in 2 of 4 of the predictive models. Limitations The primary limitation is that this study evaluated only 4 of the multiple outcome measures that are pertinent for patients with LBP. Conclusions Meeting the clinical prediction rule was prognostic for all outcome measures and should be considered a universal prognostic predictor. Other predictive variables were dependent on the outcomes measure used in the predictive model.

Thrust and Nonthrust Manipulation for Older Adults With Low Back Pain: An Evaluation of Pain and Disability

OBJECTIVE The purpose of the study was to compare the effects of thrust manipulation (TM) and non-TM (NTM) on a sample of older subjects with low back pain. METHODS This is a secondary data analysis of a randomized control trial. Forty-nine subjects aged 55 to 88 years participated in the trial, who received either a TM or NTM on at least 2 occasions during the course of care, and were extracted from the larger data set. The treatment program included a standardized home exercise program for the first 2 sessions, which could be modified by the therapist after those 2 sessions. Numeric pain rating scale and Oswestry Disability Index (ODI) were the outcomes for this study. RESULTS Multivariate analysis revealed no significant between-group differences for treatment group (P=.99) without group×time interaction (P=.90). Significant within-group changes were observed for both groups for ODI and numeric pain rating scale (P<.001); the average self-report of recovery was 78.0% (SD, 19.8%). Age stratification of the older subset revealed between-group differences in ODI change scores for the oldest subjects (>70 years) compared with 60 to 69 years (P=.02). CONCLUSIONS This study showed that outcomes for both TM and NTM improved in older adults with low back pain.

Does the use of a prescriptive clinical prediction rule increase the likelihood of applying inappropriate treatments? A survey using clinical vignettes

Clinical prediction rules (CPR) have been promoted as a natural progression in treatment decision-making. Methodological limitations of derivation and validation studies have resulted in some researchers questioning the indiscriminate use of CPRs. The purpose of this study was to explore the influence of the lumbar spine manipulation CPR (LCPR) use on clinical decision making through a survey of practicing clinicians. A sample of 535 physiotherapists from the United States, who routinely use thrust manipulation (TM), agreed to participate in this study. Those who use and those who do not use the LCPR determined group designation. A 9-step clinical vignette progressed a fictitious patient meeting the LCPR from no medical concern to significant concern for general health. A 2 × 9 chi-square was used to analyze the progression of decision-making. APTA board certification (P = 0.04), gender (P < 0.01), and manual therapy course attendance (P = 0.04) may increase and following the McKenzie philosophy (P < 0.01) may decrease the use of the LCPR. Subjects using the LCPR were more likely to choose to manipulate the patient (P < 0.01 and P = 0.02) during the first 2 scenarios of the vignette but both groups avoided TM equally as the medical concerns progressed. The results would suggest that subjects who routinely use TM would modify their decision-making to accommodate medical complications that preclude the indication for TM, and hence a potentially harmful intervention. This propensity to modify behaviour, was seen in both groups, regardless of their initial tendency to use the LCPR.

No Differences in Outcomes in People with Low Back Pain Who Met the Clinical Prediction Rule for Lumbar Spine Manipulation When a Pragmatic Non-thrust Manipulation Was Used as the Comparator

PURPOSE To investigate differences in pain and disability between patients treated with thrust manipulation (TM) and those treated with non-thrust manipulation (NTM) in a group of patients with mechanical low back pain (LBP) who had a within-session response to an initial assessment and met the clinical prediction rule (CPR). METHODS Data from 71 patients who met the CPR were extracted from a database of patients in a larger randomized controlled trial comparing TM and NTM. Treatment of the first two visits involved either TM or NTM (depending on allocation) and a standardized home exercise programme. Data analysis included descriptive statistics and a two-way ANOVA examining within- and between-groups effects for pain and disability, as well as total visits, total days in care, and rate of recovery. RESULTS No between-group differences in pain or disability were found for NTM versus TM groups (p=0.55), but within-subjects effects were noted for both groups (p<0.001). CONCLUSIONS This secondary analysis suggests that patients who satisfy the CPR benefit as much from NTM as from TM.