A Primer on Selected Aspects of Evidence-Based Practice Relating to Questions of Treatment, Part 2: Interpreting Results, Application to Clinical Practice, and Self-Evaluation

Abstract

SYNOPSIS:The process of evidence-based practice (EBP) guides clinicians in the integration of individual clinical expertise, patient values and expectations, and the best available evidence. Becoming proficient with this process takes time and consistent practice, but should ultimately lead to improved patient outcomes. The EBP process entails 5 steps: (1) formulating an appropriate question, (2) performing an efficient literature search, (3) critically appraising the best available evidence, (4) applying the best evidence to clinical practice, and (5) assessing outcomes of care. This second commentary in a 2-part series will review principles relating to steps 3 through 5 of this 5-step model. The purpose of this commentary is to provide a perspective to assist clinicians in interpreting results, applying the evidence to patient care, and evaluating proficiency with EBP skills in studies of interventions for orthopaedic and sports physical therapy. J Orthop Sports Phys Ther 2008;38(8):485-501. doi:10.2519/jospt.2008 describe a number of statistical concepts and procedures commonly used in physical therapy literature. Bandy 6 conducted a 2-year review of the literature published in the journal Physical Therapy and identified 10 statistical procedures that were used in 80% of the articles reviewed. These were descriptive statistics, 1-way analysis of variance (ANOVA), t tests, factorial ANOVA, intraclass correlation, post hoc analyses, Pearson correlation, regression, chi-square, and nonparametric tests analogous to t tests. 6 In this commentary we will review some basic statistical concepts that we feel are important for readers performing critical appraisals. We will also discuss statistical methods used to identify between-group differences in clinical trials that use both continuous scale outcomes and dichotomous scale outcomes, with illustrations from orthopaedic and sports physical therapy literature. Reporting of Results in Treatment StudiesResults published in studies of physical therapy interventions typically include a summary of the findings from a wide variety of tests and measures that quantify the outcome variables selected by the authors to determine the effects of the intervention being studied. In some instances, such as with case reports or case series, raw data from each subject in the study may be presented. However, this approach is not realistic or warranted in studies with larger samples. More commonly, data are analyzed and reported as aggregated group results. Numerical indices are then used to describe attributes of the aggregated data. The mean or average is a measure that describes central tendency in a distribution of scores, and is most useful for variables that are on an interval or ratio scale. 69 If data exhibit outliers such that the value of the mean would be distorted, the median is often reported as the measure of central tendency. The median might also be preferred over the mean when sample sizes are so small that they may not represent the target population. For example, in...

Mechanosensitivity of the Lower Extremity Nervous System During Straight-Leg Raise Neurodynamic Testing in Healthy Individuals

“…The lower bound of the CI exceeded the minimal detectable change, indicating that this difference was a real difference in range. 28 Our results are consistent with a previous study that identified a significant 9° reduction in hip range of motion by the addition of ankle dorsiflexion. 5 We hypothesize that the SLR with ankle plantar flexion does not preload the sciatic, tibial, and plantar nerves, thus allowing the hip greater range of flexion before the nerve complex undergoes sufficient mechanical stress to trigger a symptomatic or motor response.…”

Thoracic Spine Manipulation for the Management of Patients With Neck Pain: A Randomized Clinical Trial

“…25 Again, the relatively narrow confidence intervals indicate the precision of the results. 32 While no MCID has been reported for cervical range of motion, we feel that the magnitude of these changes is clinically important, as the point estimates, and the lower bound estimate of the 95% CI exceeded the previously reported standard error of measure in a population with neck pain. 12 Although statistically significant, the differences in cervical range of motion between groups were smaller when measured at the 2-week follow-up.…”

“…assurance when making clinical decisions regarding the treatment effect identified in this study. 32 It should also be noted that even the lower bound estimates for the 95% CIs fall above the previously reported MCID of 9 to 11 3,22 and provide further certainty about the value of thoracic manipulation in the management of patients with neck pain. These results also suggest that the difference between groups for pain scores remains beyond the 1-and 2-week follow-up periods.…”

Manual Physical Therapy for Injection-Confirmed Nonacute Acromioclavicular Joint Pain

“…We can be reasonably confident in this observation because the lower boundaries of the 95% CIs exclude the MCID for both outcome measures at both time points. 47 Additionally, the raw SPADI scores at 4 weeks and 6 months approached those of an asymptomatic population. 15 The GROC values indicated moderate to large overall improvement.…”