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Advances in dermatology and venereology Acta Dermato-Venereologica
Two Minimal Clinically Important Difference( 2MCID): A New Twist on an Old Concept
Faraz M. ALI 1, M. Sam SALEK 2, 3 and Andrew Y. FINLAY 1
1
Department of Dermatology and Wound Healing, Division of Infection and Immunity, School of Medicine, College of Biomedical and Life Sciences, Cardiff University, Cardiff, 2 School of Life and Medical Sciences, University of Hertfordshire, Hatfield, and 3 Institute for Medicines Development, Cardiff, UK. Accepted Jan 23, 2018; Epub ahead of print Jan 24, 2018
The minimal clinically important difference( MCID) is a widely used concept to interpret the meaning of health-related quality of life( HRQoL) score changes. However, to give a greater sense of the meaning of score change across a wider spectrum of score changes, we propose a new concept of‘ 2MCID’. This represents a score change of twice the MCID. This approach, novel in dermatology, has been used in other areas( 1, 2) and highlights therapies that reach this higher change threshold. We hypothesise that this method would better discriminate between the efficacy of interventions to help guide clinical judgement and patient progress.
HRQoL outcome measures capture several aspects of a patient’ s overall well-being( 3). Such measures are increasingly being implemented in interventional studies alongside clinical objective parameters as important contributors towards morbidity and mortality data( 4). Reports of studies often include HRQoL data citing statistical differences pre- and post-intervention, though statistically significant changes may not be reflective of meaningful change in HRQoL, particularly within large sample sizes which may produce statistically significant change despite the change being small( 5).
The MCID is the minimum difference needed for a patient to perceive the change as beneficial( 6) and may be used to determine whether a medical intervention improves patient perceived outcomes. Factors to consider when calculating the MCID for a particular outcome include: patient baseline severity, particular disease or condition, patient demographics and treatment. There is no consensus on the best methodology for calculating the MCID( 7), and values may therefore differ. Despite these limitations, it is still more useful for clinicians to assess intervention effectiveness based on the patient’ s perspective, rather than solely on statistical significance.
The most commonly utilized quality of life( QoL) tool in psoriasis trials is the Dermatology Life Quality Index( DLQI), with an MCID of 4 points( 8, 9). During this systematic review we noted that multiple MCID could provide a further aid to the results’ interpretation: we felt this novel concept deserved further exploration. We have therefore applied the 2MCID concept to data from that review( 8).
METHODS
A systematic review was presented by Ali et al.( 8). We have introduced the concept of 2MCID to that dataset( i. e. DLQI score change of at least 8) to demonstrate comparative efficacy between interventions.
RESULTS
A total of 100 trials were identified by the systematic review, covering diverse interventions. As the DLQI was the most commonly used QoL measure( 83 % of studies), the 2MCID concept was tested on interventions with documented DLQI scores. Fig. 1 summarises all the interventions that met the different MCID thresholds.
For topical treatments, clobetasol 0.05 % spray showed the greatest improvement at 4 weeks( 2MCID, 8 point improvement), followed by calcipotriol plus betamethasone at 8 weeks( 6.4 points). These changes are comparable to ustekinumab 90 mg at 12 weeks( mean 2MCID( 8 point) improvement) and ciclosporin 3 – 5 mg / kg at 12 weeks( 6.6 point improvement). No other topical therapy reached 2MCID. However, it is important to consider the context of baseline psoriasis severity, treatment duration and long-term QoL maintenance.
Methotrexate 15 mg at 16 weeks was the only systemic intervention over the 2MCID threshold( 8.7 points). This was comparable to several biologics, including etanercept 50 mg at 24 weeks and ustekinumab 90 mg at 12 weeks( 8.7 points).
Infliximab 5 mg / kg at 16 weeks and secukinumab 300 mg at 12 weeks demonstrated the largest improvement in DLQI score of a mean of 11.4(> 2MCID), just short of 3MCID. Amongst other interventions, an energy-restricted diet with immunosuppressive therapy at 24 weeks recorded DLQI improvement of 14.4( 3MCID). DLQI at 12 weeks improved by 11.2(> 2MCID) with PUVAsol 0.6 mg / kg + isotretinoin 0.5 mg / kg: for PUVAsol alone, DLQI improvement was 6.8.
For studies with treatment endpoint and assessment at 12 weeks, the interventions with the greatest mean DLQI impact in each category were secukinumab 300 mg( 2MCID, 11.4 points), ciclosporin 3 – 5 mg / kg( 1MCID, 6.6 points), PUVAsol 0.6 mg / kg + isotretinoin 0.5 mg / kg( 2MCID, 11.2 points), Liquor Carbonis Distillate solution 15 %( 1MCID, 5.8 points) and educational programme( 1MCID, 4 points).
DISCUSSION
Previously, Leaf & Goldfarb( 1) described the impact of erythropoiesis stimulating agents on HRQoL using Short-
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2018 Acta Dermato-Venereologica. doi: 10.2340 / 00015555-2894 Acta Derm Venereol 2018; 98: 715 – 717