Credibility and Generalization of the Minimally Important Difference Concept in Dermatology: A Scoping Review

Importance

The minimally important difference (MID) represents the point at which a difference in an outcome measure (eg, Dermatology Life Quality Index) is important enough that it warrants a change in treatment, and, to the authors' knowledge, the robustness and limitations of MIDs have not been thoroughly evaluated in skin diseases. The MID is increasingly used in clinical trials to demonstrate that an intervention is worthwhile for patients; furthermore, MIDs also contribute to sample size calculations in clinical trials, influence treatment guidelines, and can guide clinicians to modify treatment.

Objective

To evaluate the credibility and generalization of MIDs for patient-reported outcome measures (PROMs) in skin disorders.

Evidence Review

A systematic search was conducted in PubMed and Embase for all original articles using the MID concept for skin disorders from inception to December 29, 2021. The credibility of MIDs obtained via an anchor-based approach (eg, global rating of change scale) was assessed with a previously developed credibility instrument. The validity of generalizing established MIDs to other patient groups was evaluated based on the diagnosis and the patient characteristics.

Findings

A total of 126 articles were selected, and 84 different MIDs were identified for PROMs. A total of 13 of 84 MIDs (15.5%) for PROMs displayed acceptable credibility. The anchors used had varying capacity to assess minimal important changes from a patient's perspective and were deemed inappropriate for this purpose in 52 of 84 cases (61.9%). Correlations between the anchors and PROMs were frequently not determined (39 of 84; 46.4%). The time interval for anchor questions assessing a change in the experienced disease burden was not optimal for 10 of 32 transition anchors (>3 months), introducing potential recall bias. Previously reported MIDs were widely used to examine relevant changes in other study populations. However, the diagnosis and disease severity were different from the original MID population in 39 of 70 (55.7%) and 45 of 70 (64.3%) cases, respectively.

Conclusions and Relevance

In this scoping review, only a minority of MIDs for PROMs demonstrated sufficient credibility in dermatology. Inappropriate generalization of previously reported MIDs to patient populations with different disease characteristics was found to be a major concern. Furthermore, the study supported the use of multiple anchors and encouraged consistent reporting of the correlation between changes in the anchor and changes in the outcome measures.

Quality of life measurement in skin cancer patients: literature review and position paper of the European Academy of Dermatology and Venereology Task Forces on Quality of Life and Patient Oriented Outcomes, Melanoma and Non-Melanoma Skin Cancer

The European Academy of Dermatology and Venereology (EADV) Task Forces (TFs) on Quality of Life (QoL) and Patient Oriented Outcomes, Melanoma and Non-Melanoma Skin Cancer (NMSC) present a review of the literature and position statement on health-related (HR) QoL assessment in skin cancer patients. A literature search was carried out to identify publications since 1980 that included information about the impact of SC on QoL. Generic, dermatology-specific, cancer-specific, SC-specific, facial SC-specific, NMSC-specific, basal cell carcinoma-specific and melanoma-specific QoL questionnaires have been used to assess HRQoL in SC patients. HRQoL was assessed in the context of creation and validation of the HRQoL instruments, clinical trials, comparison of QoL in SC and other cancers, other diseases or controls, HRQoL assessment after treatment, comorbidities, behaviour modification, predictors of QoL and survival, supportive care needs, coping strategies and fear of cancer recurrence. The most widely used instruments for HRQoL assessment in SC patients are the European Organisation for Research and Treatment of Cancer Core Questionnaire (EORTC QLQ-C30), the Functional Assessment of Cancer Therapy-Melanoma (FACT-M), Skin Cancer Index (SCI), Short Form 36 Item Health Survey (SF-36) and the Dermatology Life Quality Index (DLQI). The TFs recommend the use of the cancer-specific EORTC QLQ-C30, especially in late stages of disease, and the melanoma-specific FACT-M and SC-specific SCI questionnaires. These instruments have been well validated and used in several studies. Other HRQoL instruments, also with good basic validation, are not currently recommended because the experience of their use is too limited. Dermatology-specific HRQoL instruments can be used to assess the impact of skin-related problems in SC. The TFs encourage further studies to validate HRQoL instruments for use in different stages of SC, in order to allow more detailed practical recommendations on HRQoL assessment in SC.

Patient-reported outcome measures for facial skin cancer: a systematic review and evaluation of the quality of their measurement properties

BACKGROUND

Skin cancer is the commonest malignancy worldwide, often occurring on the face. Both the condition and treatment can lead to scarring and facial disfigurement, affecting a patient's health-related quality of life (HRQoL), which can be measured using patient-reported outcome measures (PROMs).

OBJECTIVES

This systematic review identifies PROMs for facial skin cancer and appraises their methodological quality and psychometric properties using up-to-date methods.

METHODS

MEDLINE, Embase, PsycINFO, Cochrane and CINAHL were searched systematically in accordance with PRISMA guidelines, identifying all PROMs designed for or validated in facial skin cancer. Methodological quality and evidence of psychometric properties were assessed using the COnsensus-based Standards for the Selection of Health Measurement INstruments (COSMIN) checklist and criteria proposed by Terwee and colleagues. A best-evidence synthesis and assessment of instrument focus on post-resection reconstruction was also performed.

RESULTS

We included 24 studies on 11 PROMs. Methodological quality and psychometric evidence was variable, with the Patient Outcome of Surgery - Head/Neck (POS-H/N), Skin Cancer Index (SCI), Skin Cancer Quality of Life Impact Tool (SCQOLIT) and Essers and colleagues demonstrating the greatest level of validation. None scored well in their relevance to post-skin cancer reconstruction of the face.

CONCLUSIONS

This systematic review critically appraises PROMs for facial skin cancer using internationally accepted criteria. The identified PROMs demonstrate a variation in the quality of validation performed, with a need to improve this across all PROMs in the field. Only through improving the quality of available PROMs and their focus on the post-treatment aesthetic and functional outcome will we be able to truly appreciate the concerns of our patients and improve the management of facial skin cancer.