Measurement properties and interpretability of the Patient-Reported Impact of Dermatological Diseases (PRIDD) measure.

BACKGROUND: Patient-reported outcome measures (PROMs) are crucial for assessing the impact of dermatological conditions on patients' lives, but the existing dermatology-specific PROMs are not recommended for use according to the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN). We developed the Patient-Reported Impact of Dermatological Diseases (PRIDD) measure in partnership with patients. It has strong evidence of content validity, structural validity, internal consistency, acceptability, and feasibility. OBJECTIVES: To test PRIDD's remaining measurement properties and establish the interpretability of scores against the COSMIN criteria using classic and modern psychometric methods. METHODS: A global longitudinal study consisting of two online surveys administered two to four weeks apart. Adults (≥ 18 years) living with a dermatological condition were recruited through the International Alliance of Dermatology Patient Organizations' (GlobalSkin) membership network. Participants completed PRIDD, a demographics questionnaire, and other related measures including the Dermatology Life Quality Index (DLQI). We tested PRIDD's criterion validity, construct validity and responsiveness (Spearman's ρ, independent-samples t-tests and ANOVA), test-retest reliability (interclass correlation coefficient [ICC]), measurement error (Smallest Detectable Change or Limits of Agreement [LoA], distribution-based Minimally Important Change [MIC]), floor and ceiling effects (number of minimum and maximum scores and Person-Item Location Distribution Maps), score bandings (κ coefficient of agreement) and anchor-based MIC. RESULTS: 504 patients with 35 dermatological conditions from 38 countries participated. Criterion validity (ρ = 0.79), construct validity (76% hypotheses met), test-retest validity (ICC = 0.93), and measurement error (LoA = 1.3 < MIC = 4.14) were sufficient. Floor and ceiling effects were in the acceptable range (< 15%). Score bandings were determined (κ = 0.47), however, the anchor-based MIC could not be calculated due to an insufficient anchor. CONCLUSIONS: PRIDD is a valid and reliable tool to evaluate the impact of dermatological disease on patients' lives in research and clinical practice. It is the first dermatology-specific PROM to meet the COSMIN criteria. These results support the value of developing and validating PROMs with a patient-centred approach and using classic and modern psychometric methods. Further testing of responsiveness and MIC, cross-cultural translation, linguistic validation, and global data collection are planned.

Patient prioritisation of items to develop the Patient-Reported Impact of Dermatological Diseases measure: A global Delphi study.

BACKGROUND: The Global Research on the Impact of Dermatological Diseases (GRIDD) project is developing the new Patient-Reported Impact of Dermatological Diseases (PRIDD) measure. PRIDD measures the impact of dermatological conditions on the patient's life. OBJECTIVES: This study aimed to seek consensus from patients on which items to prioritize for inclusion in PRIDD. METHODS: A modified, two-round Delphi study was conducted. Adults (≥18 years) with dermatological conditions were recruited. The survey consisted of a demographic's questionnaire and 263 potential impact items in six languages. Quantitative data used Likert-type ranking scales and analysed against consensus criteria. Qualitative data collected free text responses for additional feedback and a framework analysis was conducted. RESULTS: 1154 people representing 90 dermatological conditions from 66 countries participated. Items were either removed (n = 79), edited (n = 179) or added (n = 2), based on consensus thresholds and qualitative feedback. Results generated the first draft of PRIDD with 27 items across five impact domains. CONCLUSION: This Delphi study resulted in the draft version of PRIDD, ready for psychometric testing. The triangulated data helped refine the existing conceptual framework of impact. PRIDD has since been pilot tested with patients and is currently undergoing psychometric testing.

Further refinement of the Patient-Reported Impact of Dermatological Diseases (PRIDD) measure using classical test theory and item response theory.

BACKGROUND: Existing dermatology-specific Patient-Reported Outcome Measures (PROMs) do not fully capture the substantial physical, psychological and social impact of dermatological conditions on patients' lives and are not recommended for use according to the COSMIN criteria. Most were developed with insufficient patient involvement and relied on classical psychometric methods. We are developing the new Patient-Reported Impact of Dermatological Diseases (PRIDD) measure for use in research and clinical practice in partnership with patients. OBJECTIVES: To examine the factor structure of PRIDD, determine the definitive selection of items for each subscale, and establish structural validity and internal consistency through classical and modern psychometric methods. METHODS: Two cross-sectional online surveys were conducted. Adults (≥ 18 years) worldwide living with a dermatological condition were recruited through the membership network of the International Alliance of Dermatology Patient Organizations (GlobalSkin). They completed the PRIDD questionnaire and a demographics questionnaire via an online survey. We examined missing data and distribution of scores for each item. The factor structure was assessed using confirmatory and exploratory factor analysis (Survey 1). Internal consistency was examined using Cronbach's α. Rasch measurement theory analyses were conducted, including iterative assessment of rating scale function, fit to the Rasch model, unidimensionality, reliability, local dependence, targeting and differential item functioning (DIF) (Surveys 1 and 2). RESULTS: Participants in Surveys 1 and 2 numbered 483 and 504 people, respectively. All items had ≤ 3% missing scores and all five response options were used. A four-factor model showed the best fit. PRIDD and all four subscales were internally consistent but showed some misfit to the Rasch measurement model. Adjustments were made to rectify disordered thresholds, remove misfitting items, local dependency and DIF, and improve targeting. The resulting 16-item version and subscales fit the Rasch model, showed no local dependency or DIF at the test level, and were well targeted. CONCLUSIONS: This field test study produced the final PRIDD measure, consisting of 16 items across four domains. The data triangulated and refined the conceptual framework of impact and provide evidence of PRIDD's structural validity and internal consistency. The final step in the development and validation of the PRIDD measure is to test the remaining measurement properties.

Evidence of the content validity, acceptability, and feasibility of a new Patient-Reported Impact of Dermatological Diseases measure.

Background: The Global Research on the Impact of Dermatological Diseases (GRIDD) team is developing the new Patient-Reported Impact of Dermatological Diseases (PRIDD) measure of the impact of dermatological conditions on the patient's life, in partnership with patients. To develop PRIDD, we conducted a systematic review, followed by a qualitative interview study with 68 patients worldwide and subsequently a global Delphi survey of 1,154 patients to ensure PRIDD items were meaningful and important to patients. Objective: To pilot test PRIDD with patients with dermatological conditions, focusing on its content validity (comprehensiveness, comprehensibility, and relevance), acceptability, and feasibility. Methods: We conducted a theory-led qualitative study using the Three-Step Test-Interview method of cognitive interviewing. Three rounds of semi-structured interviews were conducted online. Adults (≥ 18 years) living with a dermatological condition and who spoke English sufficiently to take part in the interview were recruited through the International Alliance of Dermatology Patient Organizations' (GlobalSkin) global membership network. The topic guide met the gold-standard COSMIN (Consensus-based Standards for the Selection of Health Measurement Instruments) standards for cognitive interviewing. Analysis followed the thematic analytical model of cognitive interviewing. Results: Twelve people (58% male) representing six dermatological conditions from four countries participated. Overall, patients found PRIDD to be comprehensible, comprehensive, relevant, acceptable, and feasible. Participants were able to discern the conceptual framework domains from the items. Feedback resulted in: the recall period being extended from 1 week to 1 month; removal of the 'not relevant' response option; and changes to the instructions and item ordering and wording to improve clarity and increase respondents' confidence in their ability to respond. These evidence-based adjustments resulted in a 26-item version of PRIDD. Conclusion: This study met the gold-standard COSMIN criteria for the pilot testing of health measurement instruments. The data triangulated our previous findings, in particular the conceptual framework of impact. Our findings illuminate how patients understand and respond to PRIDD and other patient-reported measurement instruments. The results of comprehensibility, comprehensiveness, relevance, acceptability, and feasibility of PRIDD provide evidence of content validity from the target population. The next step in the development and validation of PRIDD is psychometric testing.

Development of a Conceptual Framework for a Patient-Reported Impact of Dermatological Diseases (PRIDD) Measure: A Qualitative Concept Elicitation Study.

Existing patient-reported outcome measures cannot comprehensively capture the full impact of living with a dermatological condition. The aim of this study was to develop a conceptual framework on which to build a new Patient-Reported Impact of Dermatological Diseases (PRIDD) measure. Adults (≥ 18 years of age) living with a dermatological condition, worldwide and/or representatives from a patient organization recruited via a global patient organization network, were invited to an individual or group interview. Data were analyzed thematically. Sixty-five people from 29 countries, representing 29 dermatological conditions, participated. Key themes were: (i) impacts at the individual, organizational and societal levels; (ii) impacts were point-in-time and cumulative; and (iii) impact is a multifaceted construct, with two subthemes (iiia) common impacts and (iiib) psychological and social impacts are most significant. The conceptual framework shows that impact is a multifaceted concept presenting across physical, psychological, social, financial, daily functioning and healthcare, and provides the basis for co-constructing the PRIDD with patients.

Patient-Reported Outcome Measures in Dermatology: A Systematic Review.

By relying on data from existing patient-reported outcome measures of quality of life, the true impact of skin conditions on patients' lives may be underestimated. This study systematically reviewed all dermatology-specific (used across skin conditions) patient-reported outcome measures and makes evidence-based recommendations for their use. The study protocol is registered on PROSPERO (CRD42018108829). PubMed, PsycInfo and CINAHL were searched from inception to 25 June 2018. The Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) criteria were used to assess the measurement properties and methodological quality of studies. A total of 12,925 abstracts were identified. Zero patient-reported outcome measures were assigned to category A (ready for use without further validation), 31 to category B (recommended for use, but only with further validation) and 5 to category C (not recommended for use). There is no gold-standard dermatology-specific patient-reported outcome measure that can be recommended or used without caution. A new measure that can comprehensively capture the impact of dermatological conditions on the patient's life is needed.