BackgroundContent validity is the most important measurement property of a patient-reported outcome measure (PROM) and the most challenging to assess. Our aims were to: (1) develop standards for evaluating the quality of PROM development; (2) update the original COSMIN standards for assessing the quality of content validity studies of PROMs; (3) develop criteria for what constitutes good content validity of PROMs, and (4) develop a rating system for summarizing the evidence on a PROM’s content validity and grading the quality of the evidence in systematic reviews of PROMs.MethodsAn online 4-round Delphi study was performed among 159 experts from 21 countries. Panelists rated the degree to which they (dis)agreed to proposed standards, criteria, and rating issues on 5-point rating scales (‘strongly disagree’ to ‘strongly agree’), and provided arguments for their ratings.ResultsDiscussion focused on sample size requirements, recording and field notes, transcribing cognitive interviews, and data coding. After four rounds, the required 67% consensus was reached on all standards, criteria, and rating issues. After pilot-testing, the steering committee made some final changes. Ten criteria for good content validity were defined regarding item relevance, appropriateness of response options and recall period, comprehensiveness, and comprehensibility of the PROM.DiscussionThe consensus-based COSMIN methodology for content validity is more detailed, standardized, and transparent than earlier published guidelines, including the previous COSMIN standards. This methodology can contribute to the selection and use of high-quality PROMs in research and clinical practice.Electronic supplementary materialThe online version of this article (10.1007/s11136-018-1829-0) contains supplementary material, which is available to authorized users.

Summary This article is a report of the fourth meeting of the Harmonising Outcome Measures for Eczema (HOME) initiative held in Malmö, Sweden on 23–24 April 2015 (HOME IV). The aim of the meeting was to achieve consensus over the preferred outcome instruments for measuring patient‐reported symptoms and quality of life for the HOME core outcome set for atopic eczema (AE). Following presentations, which included data from systematic reviews, consensus discussions were held in a mixture of whole group and small group discussions. Small groups were allocated a priori to ensure representation of different stakeholders and countries. Decisions were voted on using electronic keypads. For the patient‐reported symptoms, the group agreed by vote that itch, sleep loss, dryness, redness/inflamed skin and irritated skin were all considered essential aspects of AE symptoms. Many instruments for capturing patient‐reported symptoms were discussed [including the Patient‐Oriented SCOring Atopic Dermatitis index, Patient‐Oriented Eczema Measure (POEM), Self‐Administered Eczema Area and Severity Index, Itch Severity Scale, Atopic Dermatitis Quickscore and the Nottingham Eczema Severity Score] and, by consensus, POEM was selected as the preferred instrument to measure patient‐reported symptoms. Further work is needed to determine the reliability and measurement error of POEM. Further work is also required to establish the importance of pain/soreness and the importance of collecting information regarding the intensity of symptoms in addition to their frequency. Much of the discussion on quality of life concerned the Dermatology Life Quality Index and Quality of Life Index for Atopic Dermatitis; however, consensus on a preferred instrument for measuring this domain could not be reached. In summary, POEM is recommended as the HOME core outcome instrument for measuring AE symptoms.

ISS (paediatric version), POEM, PO-SCORAD, SA-EASI and adapted SA-EASI are currently the most appropriate instruments and therefore have the potential to be recommended as core symptom instrument in future clinical trials. These findings will be utilized for the development of a core outcome set for AE.

Level 1. Diagnostic study.

The negative impact of skin disease on quality of life (QoL) has been described in many studies. Patient education as an adjunct to treatment, with the aim of improving QoL and reducing disease severity, is a relatively new technique in dermatology. The objective of this article is to analyse and summarise evidence concerning the effects of patient education on QoL and disease severity in patients with chronic skin diseases. All source material was identified through searches in MEDLINE and Embase. The CONSORT statement was used to assess the quality of reported randomised controlled studies. Ten of 254 studies met the inclusion criteria. In five of them, statistically significant improvements in QoL were reported. The severity of skin disease significantly improved in three studies. In conclusion, patient education appears to be effective in improving QoL and in reducing the perceived severity of skin disease.