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 , 0.01). 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.

Comparison of therapies in lumbar degenerative disc disease: a network meta-analysis of randomized controlled trials

“…Several different thresholds have been used to interpret the importance of ODI changes, however, meaningful score changes are likely different for each patient and a single cut-off value may not appropriately capture change for all [35]. One study defined a 10-point minimum clinically important difference between treatment groups, which was not achieved despite results being statistically significant [12].…”

“…Currently, there is no consensus on what constitutes a meaningful improvement [35]. Several different thresholds have been used to interpret the importance of ODI changes, however, meaningful score changes are likely different for each patient and a single cut-off value may not appropriately capture change for all [35].…”

Invited commentary on ‘different minimal clinically important difference (MCID) scores lead to different clinical prediction rules for the Oswestry disability index when using the same sample of patients’

“…There is debate regarding appropriate interpretation and application of MCID's because multiple values exist for commonly used outcome measures. 1,2 Schwind et al 3 add to the MCID literature with an interesting secondary analysis from a randomized clinical trial of patients with low back pain receiving thrust or non thrust manipulation in combination with other physical therapist directed approaches. In this analysis, Schwind et al 3 identify baseline predictors for 6 previously established MCID's for a commonly used outcome measure, the Oswestry Disability Index (ODI).…”

“…1,2 Schwind et al 3 add to the MCID literature with an interesting secondary analysis from a randomized clinical trial of patients with low back pain receiving thrust or non thrust manipulation in combination with other physical therapist directed approaches. In this analysis, Schwind et al 3 identify baseline predictors for 6 previously established MCID's for a commonly used outcome measure, the Oswestry Disability Index (ODI). Previous studies have mostly focused on development of a particular ODI MCID, so this analysis is a change in direction that may have relevance for clinicians and researchers.…”

The value of patient global assessment in lumbar spine surgery: an evaluation based on more than 90,000 patients

“…Many studies testify to the difficulty associated with determining how large a change in a certain score needs to be before it can be considered relevant for the patient and/or the caregiver [5,6]. Sometimes it is even difficult to tell whether the score change reflects a true change or if the change simply reflects a measurement error [7].…”