Use of Minimal Important Difference for Patient-Reported Outcome Measures in Plastic Surgery: A Systematic Review.

ABSTRACT

BACKGROUND: The minimal important difference (MID) is vital to consider when interpreting the clinical importance of observed changes from surgical interventions assessed by patient-reported outcome measures (PROMs). There is no gold-standard for how to calculate MIDs, and uptake in plastic surgery literature is currently unknown, leading to methodological and interpretation issues. METHODS: Medline and Embase were searched to identify all plastic surgery randomized controlled trials (RCTs) employing PROMs as outcomes, and MID estimation studies for PROMs used by RCTs. Included studies were assessed for uptake and application of MIDs, and MID estimation methodology and values were categorized. RESULTS: A total of 554 RCTs employing PROMs as outcomes were identified. Of these, 419 RCTs had the possibility of incorporating a previously published MID. Uptake rate of MIDs was 11.5% (n=48/419). The most common ways MIDs were applied was to calculate sample size (37.5%) or to determine whether results were clinically important (35.4%). A total of 99 studies estimating MID values for the most common PROMs in plastic surgery, based on our review, were analyzed. The most common estimation methodologies were receiver-operator curve analysis (49%), change difference (31%), and standard deviation (25%). CONCLUSIONS: Our review highlights limited uptake and application of MIDs in plastic surgery. We propose four major barriers 1) there existed no repository of published MIDs for PROMs used in plastic surgery; 2) available MIDs are not specific to plastic surgery populations; 3) high heterogeneity in MID estimation methodology; 4) wide ranges in MID values with no superior choice.