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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