ORIGINAL REPORT

Validation of the Atopic Dermatitis Control Tool (ADCT) and a Comparison with the Recap of Atopic Eczema Questionnaire (RECAP)

Junfen ZHANG^1,2 , Leon MILTNER² , Laura LOMAN² , Aviël RAGAMIN³ , Jart A.F. OOSTERHAVEN² , and Marie L.A. SCHUTTELAAR²

¹Dermatology Hospital, Southern Medical University, Guangzhou, China, ²Department of Dermatology, University of Groningen, University Medical Center Groningen, the Netherlands, and ³Department of Dermatology, Leiden University Medical Center, Leiden, the Netherlands

Abstract

The Atopic Dermatitis Control Tool (ADCT) has not been validated in the Dutch population, and comparisons with the Recap of atopic eczema (RECAP) questionnaire are still lacking. This prospective study was conducted at a Dutch tertiary hospital between June 2021 and December 2022, to assess measurement properties of the Dutch ADCT in adults with atopic dermatitis (AD) and compare it with RECAP. Participants completed the ADCT, RECAP, and reference instruments including Patient’s Global Assessment (PtGA), Patient-Oriented Eczema Measure (POEM), Dermatology Life Quality Index (DLQI), quality-of-life questionnaire of the EuroQol Group (EQ-5D-5L), Numeric Rating Scale (NRS) peak itch/sleep disturbance, Skindex-29, and Global Rating of Change (GRC), at baseline, 1–3 days, and 4–12 weeks. Construct validity was assessed through a priori hypotheses, whilst reliability was evaluated with standard error of measurement (SEM_agreement) and intraclass correlation coefficient (ICC_agreement). Interpretability was examined using anchor-based approaches. In total, 196 adults with AD were included. Among a priori hypotheses, 82% (single-score validity) and 59% (responsiveness) were confirmed. The SEM_agreement was 1.15, and the ICC_agreement was 0.983. The final bandings for the ADCT were established, with a binary cutoff of ≥ 6 indicating uncontrolled AD. The smallest detectable change (SDC) was 3.2, and the minimally important change (MIC) value from predictive modelling was 2.9. Furthermore, the ADCT exhibited high correlations with RECAP at all levels (most correlations being above 0.80). These results demonstrated the Dutch ADCT as a valid, reliable, and responsive tool, and have important clinical implications.

SIGNIFICANCE

Atopic dermatitis is a chronic skin disease. To measure how well atopic dermatitis is controlled, the Atopic Dermatitis Control Tool was developed. Current research focused on testing its relevance, reliability, sensitivity to detect changes, the interpretation of total scores, and comparing it with another similar instrument, the Recap of atopic eczema questionnaire. Our results showed that the Atopic Dermatitis Control Tool was accurate and sensitive in measuring eczema control over time. A score of ≥ 6 on the Atopic Dermatitis Control Tool indicates poor disease control, with an improvement of ≥ 4 points indicating significant improvement. The Atopic Dermatitis Control Tool and Recap of atopic eczema were very similar and largely interchangeable.

Key words: atopic dermatitis; validation; comparison; eczema control; ADCT; RECAP.

 

 

INTRODUCTION

The Atopic Dermatitis Control Tool (ADCT) has been recommended by the Harmonising Outcome Measures for Eczema (HOME) initiative as a core outcome instrument for measuring eczema control in both clinical trials and clinical practice (1, 2). The ADCT consists of 6 items tailored to atopic dermatitis (AD)-specific symptoms (e.g., intense itch, sleep disturbances), and impact on patients’ daily functioning and emotional well-being (3). Each individual item is scored on a 4-point scale, leading to a total score of 0–24 points, with higher scores indicating poorer eczema control (3). The ADCT has demonstrated good-to-excellent content and construct validity, known group validity, and reliability in the original version, with a threshold of ≥ 7 being determined to identify patients whose AD remains inadequately controlled (3, 4). While the ADCT has been validated to some extent in the Chinese (5) and Japanese contexts (6) in addition to the original version in English, validation within the Dutch population is missing.

The Recap of atopic eczema questionnaire (RECAP), another instrument endorsed by the HOME initiative for assessing eczema control (1, 2), exhibits great similarity to the ADCT in terms of content domains (3, 4, 7–9). A Spanish study showed a high correlation between ADCT and RECAP total scores (Spearman’s rho = 0.91) (10). Nonetheless, further comparative studies are needed to better understand the distinctions and similarities between these 2 instruments, thereby aiding researchers and clinicians in making more informed choices in tool selection. Thus, in the present study, we aimed to assess measurement properties of the Dutch ADCT in adults with AD and compare it with RECAP.

MATERIALS AND METHODS

Study population and design

We conducted a prospective study following the guidelines by the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) group (11, 12). Adults (≥ 18 years) with AD, diagnosed by dermatologists according to the UK Working Party Criteria (13), were eligible to participate in this study, independent of disease severity and treatment. Participants were recruited from the outpatient clinic of the Department of Dermatology at the University Medical Center Groningen (UMCG), a tertiary referral centre for eczema in the Netherlands, between June 2021 and December 2022. Adults with AD were instructed to complete a series of questionnaires, including reference instruments, the ADCT and the RECAP, at 3 time points (T₀: baseline; T₁: after 1–3 days; T₂: after 4–12 weeks). Clinical severity was assessed by dermatologists at baseline using the Eczema Area and Severity Index (EASI) (14, 15) and the validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) (16). More details on the reference instruments and clinical assessments are summarized in Table I.

Table I. Reference instruments used in current study

Factor	Measure name	Time points	Content and construct measured	Interpretability
Completed by participants	RECAP(7)	T0, T1, T2	7 items related to eczema control in the past week	0–28: higher score indicating less control
	PtGA of AD control	T0, T1, T2	Single item on eczema control in the past week	Not at all/a little/moderately/mostly/completely controlled
	POEM(25)	T0, T2	7 items on AD-specific symptoms and signs in the past week	0–28: higher score indicating greater severity
	PtGA of AD severity(26)	T0, T2	Single item on eczema severity in the past week	Clear, mild, moderate, severe, very severe
	DLQI(27)	T0, T2	10 items related to impairment on quality of life due to skin conditions in the past week	0–30: higher score representing greater impairment on HRQoL
	Skindex-29(28)	T0, T2	29 items on impairment on quality of life caused by skin conditions in the past 4 weeks	0–100: higher score indicating greater impairment on HRQoL
	EQ-5D-5L(29)	T0, T2	6 items regarding impairment on generic HRQoL	Value score: –0.59 to 1, with 1 indicating the best possible health state VAS score: 0–100, with 100 representing the best
	NRS for itch(30)	T0, T2	Single item on the worst itch in the past 24 h	0–10, with 10 being the worst severity
	NRS for sleep disturbance	T0, T2	Single item on the eczema-related sleep disturbance during the last night	0–10, with 10 being the worst sleep disturbance
	GRC scale	T1, T2	The degree of changes in AD control between 2 time points, using 3 consecutive questions	No important change, important improvement (much/moderate/minor), important deterioration (much/moderate/minor)
Completed by physicians	EASI(14)	T0	Area and severity of clinical signs related to AD	0–72: higher score indicating more severe AD
	vIGA(16)	T0	A single scale assessing AD severity based on morphological descriptions	From 0 (clear) to 4 (severe)
RECAP: Recap of atopic eczema; PtGA: Patient’s Global Assessment; AD: atopic dermatitis; POEM: Patient-Oriented Eczema Measure; DLQI: Dermatology Life Quality Index; EQ-5D-5L: quality-of-life questionnaire of the EuroQol Group; VAS: visual analogue scale; NRS: numeric rating scale; GRC: Global Rating of Change; EASI: Eczema Area and Severity Index; vIGA: validated Investigator Global Assessment; HRQoL: health-related quality of life. The original publications of the reference instruments were cited.

This study was exempt from the Dutch Medical Research Involving Human Subjects Act according to the institutional review board of UMCG (reference: METc 202000915). All patients provided written informed consent.

Anchors

Patient Global Assessment (PtGA) of AD control. Patients were asked the following question in Dutch: “What is your overall impression of your atopic dermatitis control over the last week?” with response options: not at all, a little, moderately, mostly, and completely controlled (3).

Global Rating of Change (GRC) scale. This scale included 3 consecutive questions. First, patients were asked: “Overall, has there been any change in the level of disease control of your atopic dermatitis since the last time you completed the RECAP?” with response options: yes/no. Patients who answered “yes” were then asked 2 additional questions. The first question determined the direction and extent of change: “To what extent has the disease control of your atopic dermatitis changed?”, with response options: much improvement, moderate improvement, minor improvement, minor deterioration, moderate deterioration, and much deterioration. The second question assessed the importance of the change: “Was this change (improvement/deterioration) important to you?” Finally, these questions resulted in 7 categories: no important change, important improvement (much/moderate/minor), and important deterioration (minor/moderate/much).

Statistical analysis

For all analyses, cases with missing values were excluded. SPSS Statistics for Macbook (V29.0; IBM Corp, Armonk, NY, USA) was used for all analyses.

Construct validity: single-score validity and responsiveness

We used hypothesis testing to assess the construct validity of the ADCT, with a priori hypotheses formulated as indicated in Tables II and III. Correlations between the ADCT and reference instruments were assessed regarding single scores (T₀) and change scores (T₂) using Spearman’s rho (r). For change-score validity, a correlation difference of ≥ 0.1 was considered relevant (17). Additionally, we tested whether correlations on change-scores between the ADCT and reference instruments that measure similar constructs were ≥ 0.5, and those that measure related but dissimilar constructs were between 0.3 and 0.5 (17). Overall, high, moderate, and poor validity were identified if < 25%, 25–50%, and > 50% of hypotheses were rejected, respectively. A sample size of ≥ 70 (item/subject ratio of 1:10) was considered necessary for assessing construct validity (18).

Table II. Single-score validity (at T0) correlations between the Atopic Dermatitis Control Tool (ADCT) and reference instruments

Reference instruments	Correlation hypothesizeda	Correlation found	R2	Hypotheses confirmed?
EASI (n = 184)	++	0.64	0.34	Yes
vIGA (n = 175)	++	0.65	0.37	Yes
PtGA of AD severity (n = 195)	+++	0.83	0.69	Yes
PtGA of AD control (n = 195)	+++	–0.78b	0.57	Yes
POEM (n = 196)	+++	0.87	0.73	Yes
DLQI (n = 196)	+++	0.89	0.81	Yes
Skindex-29 (n = 195)	+++	0.88	0.78	Yes
EQ-5D-5L (Value score) (n = 194)	+	–0.64b	0.44	No
EQ-5D-5L (VAS score) (n = 194)	+	–0.51b	0.30	No
NRS peak itch (n = 188)	+++	0.86	0.71	Yes
NRS sleep disturbance (n = 195)	+++	0.77	0.67	Yes
Total amount of hypotheses that were confirmed	9/11 (82%)
ADCT: Atopic Dermatitis Control Tool; EASI: Eczema Area and Severity Index; vIGA: validated Investigator Global Assessment; PtGA: Patient’s Global Assessment; AD: atopic dermatitis; POEM: Patient-Oriented Eczema Measure; DLQI: Dermatology Life Quality Index; EQ-5D-5L: quality-of-life questionnaire of the EuroQol Group; VAS: visual analogue scale; NRS: numeric rating scale. aStrong correlation (+++) is defined as r>0.7; moderate correlation (++) as 0.4 < r < 0.7; and weak correlation (+) as 0.2 < r < 0.4, using Spearman’s rho (r). bNegative value owing to both the PtGA of AD control and EQ-5D-5L being scored inversely to the ADCT.

 

Table III. Responsiveness between T₀ and T₂

Factor	Correlations found	Hypotheses confirmed?
Hypothesis on correlationsa Change ADCT – Change PtGA of AD control vs the following: Change PtGA of AD severity – Change PtGA of AD control Change POEM – Change PtGA of AD control Change DLQI – Change PtGA of AD control Change Skindex-29 – Change PtGA of AD control Change EQ-5D value – Change PtGA of AD control Change EQ-5D VAS – Change PtGA of AD control Change NRS peak itch – Change PtGA of AD control Change NRS sleep disturbances – Change PtGA of AD control	–0.68b vs. –0.61b –0.68b vs. –0.64b –0.68b vs. –0.61b –0.68b vs. –0.61b –0.68b vs. 0.40 –0.68b vs. 0.43 –0.68b vs. –0.60b –0.68b vs. –0.53b	No No No No Yes Yes No Yes
Hypothesis according to COSMIN Instruments measuring similar constructs (≥ 0.50) Change ADCT – Change PtGA of AD control Change ADCT – Change PtGA of AD severity Change ADCT – Change POEM Change ADCT – Change NRS peak itch Change ADCT – Change NRS sleep disturbance Instruments measuring related, but dissimilar constructs (0.30–0.50) Change ADCT – Change Skindex-29 Change ADCT – Change EQ-5D value Change ADCT – Change EQ-5D VAS Change ADCT – Change DLQI	–0.68b 0.71 0.67 0.70 0.65 0.72 –0.50c –0.42c 0.75	Yes Yes Yes Yes Yes No Yes Yes No
Total number of hypotheses that were confirmed	10/17 (59%)
ADCT: Atopic Dermatitis Control Tool; PtGA: Patient’s Global Assessment; AD: atopic dermatitis; POEM: Patient-Oriented Eczema Measure; DLQI: Dermatology Life Quality Index; EQ-5D-5L: quality-of-life questionnaire of the EuroQol Group; VAS: visual analogue scale; NRS: numeric rating scale. aA correlation difference of ≥ 0.1 was deemed relevant and thus hypothesis confirmed. bNegative value owing to the PtGA of AD control being scored inversely to the ADCT and other reference instruments except EQ-5D-5L. cNegative value owing to the EQ-5D-5L being scored inversely to the ADCT.

Reliability

For assessing test–retest reliability, intra-class correlation coefficient (ICC_agreement) and measurement error were determined in unchanged patients between T₀ and T₁ based on the GRC scale (19). The ICC_agreement was calculated, using a two-way mixed effects model for absolute agreement, with an ICC_agreement value of > 0.70 indicating acceptable reliability. Measurement error was reported with standard error of measurement (SEM_agreement). A sample size of ≥ 50 unchanged patients was seen as adequate for reliability (11).

Interpretability

For single scores, an anchor-based method was used to determine cut-off values of the ADCT, based on the level of agreement (linear weighted kappa) between ADCT scores and the anchor PtGA of AD control at T₀. Additionally, sensitivity analyses were performed to examine whether the distribution of age and sex differed significantly between patients falling within and outside the proposed banding.

The smallest detectable change (SDC) was determined in unchanged patients at T₁ using the formula: SDC = 1.96 × √2 × SEM_agreement. The minimally important change (MIC) was determined in patients who reported important improvement at T₂ according to the GRC scale. MIC values were not assessed for deterioration due to a small size of 16 patients. Four methods were employed for assessing the MIC values, including the mean change method, 95% upper limit, receiver operating characteristics (ROC), and predictive modelling (20). Notably, considering that the prevalence of important improvement was 37.5% in this study, not equal to 50%, the MIC value based on predictive modelling was adjusted (21). More details on these 4 methods can be found in our previous studies (8, 9). A sample size of ≥ 100 patients with ≥ 50 reporting important improvement was deemed adequate for interpretability.

Floor and ceiling effects

Floor or ceiling effects were considered present if over 15% of patients had the highest or lowest ADCT scores (22).

Comparative analyses between RECAP and ADCT

This included 2 main parts: (i) Assessing correlations between these 2 instruments at the total score level, and the individual item level, using Spearman’s rho (r); (ii) Examining the overlap of patients who were categorized into the same group based on the proposed banding of both instruments.

RESULTS

Study population

A total of 196 adult patients were included in the T₀ analyses (Fig. 1). Of those, 57.1% were males, with a mean age of 38.6 years (Table SI). In total, 54.4% of patients had moderate-to-severe AD based on the EASI scores. In addition, the follow-up rates were 89.8% (n = 176) at T₁ and 92.9% (n = 182) at T₂, respectively.

Fig. 1. Study flow diagram. ^†n = 134 patients reported no change based on the Global Rating of Change Scale at T₁; of those, 110 patients filled out the T₁ questionnaire within 1–3 days. ^ⱡGRC scale was not included in the package of questionnaires at T₂ in the first 5 months of data collection.

Construct validity

Single-score and change-score validity. Regarding single-score validity, 82% of the a priori stated hypotheses were confirmed, indicating a high single-score validity of the Dutch ADCT (Table II). The observed correlations for the rejected hypotheses were higher than anticipated. With regard to responsiveness, 59% of the prior hypotheses were confirmed, suggesting a moderate responsiveness (Table III).

Known group validity. Known group analyses showed that patients with more severe disease had higher ADCT total scores, indicating poorer eczema control. Likewise, those who reported greater impairment in quality of life exhibited higher ADCT scores. The difference in ADCT total scores across groups was statistically significant (Fig. S1).

Reliability

Patients who completed the T₁ questionnaires within 3 days and reported no change on the GRC scale at T₁, were included in the test–retest reliability analyses (n = 110). The ICC_agreement was 0.983 (95% confidence interval [CI)] 0.975–988), indicating excellent reliability. The SEM_agreement was 1.15 points.

Interpretability

Single scores. A significant and high correlation was observed between ADCT total scores and the anchor PtGA of disease control (Spearman’s rho = –0.78, p < 0.001) (Fig. S2). For individual ADCT scores, a total of 54 banding options were tested (Tables SII and SIII). The banding: 0–1 (completely controlled), 2–3 (mostly controlled), 4–9 (moderately controlled), 10–14 (a little controlled), and 15–24 (not at all controlled), had the highest kappa coefficient of agreement of 0.616. Additionally, the second highest kappa coefficient of agreement was only 0.002 lower than the highest one, and the corresponding banding was: 0–1 (completely controlled), 2–5 (mostly controlled), 6–9 (moderately controlled), 10–14 (a little controlled), and 15–24 (not at all controlled). Taking previous validation studies into account (3, 4), a binary cutoff of ≥ 6 was determined to identify patients with inadequate AD control, according to the latter banding option reported above. “Not under control” included “not at all controlled”, “a little controlled”, and “moderately controlled”.

Overview of ADCT scores falling outside the proposed banding. Two patients (1.0%) had PtGA of AD control scores that were more than 2 groups less controlled than the proposed banding would have predicted. In total 8 patients (4.1%) and 11 patients (5.6%) had PtGA of AD control score that were 2 groups less or more controlled than the proposed banding would have predicted, respectively. Additionally, no significant differences in the distribution of age (p = 0.818) and sex (p = 0.112) were observed between the patients falling within and outside the proposed banding (Table SIV).

Change scores. The SDC was 3.2 points. For change scores, the correlation between ADCT change scores and the GRC scale at T₂ was –0.617, indicating the GRC scale as an appropriate anchor (23). The MIC values obtained by applying 4 different methods were 3.5 for the mean change (Table SV), 5.5 for the 95% upper limit cut-off point, 2.5 for the ROC (Table SVI, Fig. S3), and 2.9 for the predictive modelling after adjustment.

Floor and ceiling effect

No floor or ceiling effects were observed.

Comparative analysis between ADCT and RECAP

Correlation between ADCT and RECAP scores. ADCT total scores exhibited a strong correlation with RECAP total scores, with a Spearman’s rho exceeding 0.90 at all 3 time points. In addition, high correlations were observed between change scores on ADCT and RECAP between T₀ and T₂, as well as between T₁ and T₂, while the correlation strength between T₀ and T₁ was 0.50 (Table SVII, Figs S4, S5). Moreover, high correlations were noted between corresponding individual items from ADCT and RECAP, with a minimum strength of 0.74. Additionally, the extra item on itch from the RECAP showed moderate correlations with all items from ADCT at all time points (Spearman’s rho range: 0.47–0.69), except its high correlation with the first item of the ADCT on overall eczema-related symptoms at baseline (Spearman’s rho = 0.72) (Table SVIII).

Overview of ADCT scores falling outside the banding of RECAP scores. Upon comparison with the proposed RECAP bandings from our previous study (8), 70.9% of patients (n = 139/196) were classified into the same group based on the proposed ADCT bandings. In total, 41 patients (20.9%) and 14 patients (7.1%) who had an ADCT score 1 point lower and higher, respectively, than the RECAP banding would have been predicted. Additionally, 2 patients (1.0%) had an ADCT score 2 points lower or higher than anticipated by the RECAP banding. No patient exhibited a difference of > 2 points (Table SIX). Male patients were more likely to fall outside the proposed banding (p < 0.001), whereas no significant difference was noted among age groups between the patients falling within and outside the proposed banding.

DISCUSSION

Main finding

In the current study, the ADCT exhibited good single-score construct validity and known group validity, moderate responsiveness, and excellent test–retest reliability among Dutch adult patients. Proposed bands for ADCT scores were established: 0–1 (completely controlled), 2–5 (mostly controlled), 6–9 (moderately controlled), 10–14 (a little controlled), and 15–24 (not at all controlled), with a binary cut-off of ADCT ≥ 6 being set to identify patients with inadequately controlled AD. Additionally, an improvement of ≥ 4 points on the ADCT total scores was deemed clinically relevant. Moreover, comparative analyses revealed a high similarity between the ADCT and RECAP both at the total score level and individual item level. Also, 71% of patients were classified into the same groups regarding eczema control based on the proposed ADCT and RECAP bandings.

Validation of the ADCT in Dutch adults

Our findings of good single-score validity, known group validity, and reliability are in line with a previous validation report from the RELIEVE-AD study in a US population of AD patients (4). In addition to validity in single scores, it is crucial for an instrument to be able to capture changes over time in the construct to be assessed, namely responsiveness. In the present study we found moderate responsiveness for the Dutch ADCT, which was confirmed in the initial validation study, although assessed using a different methodology and set of reference instruments (4).

Regarding the interpretability of ADCT single scores, we proposed banding of scores alongside a binary cutoff point for poor control. However, it should be mentioned that the binary cut-off should preferably be used in conjunction with the category bandings and the MIC when drawing conclusions concerning (changes in) the disease state of a patient. The distinction between different states of disease control is crucial for the decision-making progress regarding treatment and monitoring of patients. Our proposed ADCT banding option could help assess self-perceived disease state of AD in clinical and research settings and assist in the communication between patient and healthcare professionals (6). The binary cut-off for disease control previously suggested by Pariser et al. (3) was ≥ 7 points. However, it was assessed using only the ROC method in patients treated with dupilumab and is thus only somewhat comparable to the methodology employed here (3). Important to note is that we found 3 banding options with relatively similar kappa coefficients of agreement on the upper end of the spectrum (highlight in Table S3) that solely differed in the cutoff value between “mostly controlled” and “moderately controlled”, which is simultaneously considered the threshold for the binary cutoff of overall disease control. Therefore, the proposed banding option was determined based on the kappa coefficient of agreement, in combination with this previous report (3) and the implications for clinical interpretability.

MIC values were determined using 4 different methods, which produced varying results, ranging from 2.5–5.5 points. Of the 4 MIC estimates, the predictive MIC (after adjustment) may be the most accurate (20). Previously, a MIC of ≥ 5 points had been proposed based on the anchor-based method, using a 1-level improvement of PtGA of disease control or DLQI as reference (4). However, this 1-level improvement does not necessarily reflect a meaningful change from the patient’s perspective. Ultimately, considering the SDC of 3.2, we concluded that an improvement of ≥ 4 points would be deemed clinically relevant.

Comparison between ADCT and RECAP

Because the ADCT and RECAP are measuring similar constructs regarding AD control (1, 2), we aimed to specifically elicit the similarities and discrepancies between these 2 PROMs. As expected, total scores of both instruments showed a strong correlation when compared cross-sectionally. Change scores of ADCT and RECAP showed high correlations between T₀ and T₂, as well as T₁ and T₂, but only moderate correlation between T₀ and T₁. This might be explained by the small variance in the ADCT change scores between T₀ and T₁, which mostly ranged between –3 and 3 points. When restricting the analysis to patients who had ADCT change scores between –3 and 3 points between T₀ and T₁, the Spearman rho was 0.72. Further, similarities between the items of both instruments allowed for the analysis of individual item correlations. Those items with comparable content observed high correlations with the respective item of the other instrument. One item of the RECAP, assessing itch, was not reflected directly by any of the items in the ADCT, suggesting it might add additional value by holistically capturing patient-perceived eczema control considering the importance of itch in a patient’s disease journey.

Overall, both instruments display great similarity in total scores, individual items, and their tested measurement properties among adults. In the study by Oosterhaven et al. (24), a stand-alone question was used to ask patients about their preference between the ADCT and RECAP, in which 80% indicated no preference, while 11% preferred the ADCT and 9% RECAP. These findings make it challenging to recommend 1 instrument over the other for measuring eczema control in adults. However, recommending a single, standardized instrument would improve the comparability of future research, as multiple instruments can decrease comparability. Future studies, including qualitative research focusing on patient and clinician preferences, could be beneficial to help HOME select a single instrument to measure eczema control for the core outcome set for AD. Regarding the child population, the lack of validation studies for the ADCT in children suggests that RECAP may currently be the more appropriate for this group.

Strengths and limitations

We employed rigorous methods to assess various measurement properties of the ADCT, following the COSMIN guidelines (11, 12). This is the first validation study on the Dutch ADCT and we additionally provide comprehensive comparative analyses between the ADCT and RECAP across various aspects. However, the generalizability of our results might be a concern, considering that only Dutch adult patients were included in this study. Future studies conducted in children and other language settings are needed. In addition, MIC values were assessed only for improvement, but not deterioration, due to the small sample size of the deteriorated group (n = 16). Lastly, the anchors used, including PtGA of AD control and GRC scale, are not validated.

Conclusion

The Dutch ADCT demonstrates good single-score validity, moderate responsiveness, good known group validity, and excellent reliability, with a threshold of ≥ 6 indicating uncontrolled AD. An improvement of ≥ 4 points is considered clinically important. These findings support the use of ADCT as a valid and reliable tool for assessing eczema control. Moreover, our comprehensive comparative analyses highlight a high similarity between ADCT and RECAP across various aspects. Future qualitative research on patient and clinician preferences would be beneficial for HOME to recommend 1 instrument over the other for standardized use.

ACKNOWLEDGEMENTS

The authors would like to thank all the patients who participated and all others who voluntarily helped with running the study.

Data availability: The data underlying this article will be shared on reasonable request to the corresponding authors.

Ethics statement: This research was reviewed and approved by the Medical Ethical Review Board of the University Medical Center Groningen (reference: METc 202000915).

Patient consent on file: All patients provided written informed consent.

REFERENCES

1. Thomas KS, Apfelbacher CA, Chalmers JR, Simpson E, Spuls PI, Gerbens LAA, et al. Recommended core outcome instruments for health-related quality of life, long-term control and itch intensity in atopic eczema trials: results of the HOME VII consensus meeting. Br J Dermatol 2021; 185: 139–146. https://doi.org/10.1111/bjd.19751
2. Leshem YA, Chalmers JR, Apfelbacher C, Katoh N, Gerbens LAA, Schmitt J, et al. Measuring atopic eczema control and itch intensity in clinical practice: a consensus statement from the Harmonising Outcome Measures for Eczema in Clinical Practice (HOME-CP) Initiative. JAMA Dermatol 2022; 158: 1429–1435. https://doi.org/10.1001/jamadermatol.2022.4211
3. Pariser DM, Simpson EL, Gadkari A, Bieber T, Margolis DJ, Brown M, et al. Evaluating patient-perceived control of atopic dermatitis: design, validation, and scoring of the Atopic Dermatitis Control Tool (ADCT). Curr Med Res Opin 2020; 36: 367–376. https://doi.org/10.1080/03007995.2019.1699516
4. Simpson E, Eckert L, Gadkari A, Mallya UG, Yang M, Nelson L, et al. Validation of the Atopic Dermatitis Control Tool (ADCT©) using a longitudinal survey of biologic-treated patients with atopic dermatitis. BMC Dermatol 2019; 19: 15. https://doi.org/10.1186/s12895-019-0095-3
5. Luan TT, Peng CY, Song XT, Liao SL, Zhao ZT. [Validation study of the Chinese version of atopic dermatitis control tool]. Zhonghua Yu Fang Yi Xue Za Zhi 2023; 57: 422–426.
6. Kido-Nakahara M, Yokote G, Yoshida M, Furue M, Nakahara T. Atopic Dermatitis Control Tool (ADCT): a useful tool for self-evaluation in patients with atopic dermatitis. J Dermatol 2021; 48: 1951–1952. https://doi.org/10.1111/1346-8138.16176
7. Howells LM, Chalmers JR, Gran S, Ahmed A, Apfelbacher C, Burton T, et al. Development and initial testing of a new instrument to measure the experience of eczema control in adults and children: Recap of atopic eczema (RECAP). Br J Dermatol 2020; 183: 524–536. https://doi.org/10.1111/bjd.18780
8. Zhang J, Ragamin A, Romeijn GLE, Loman L, Oosterhaven JAF, Schuttelaar MLA. Validity, reliability, responsiveness and interpretability of the Recap of atopic eczema (RECAP) questionnaire. Br J Dermatol 2023; 189: 578–587. https://doi.org/10.1093/bjd/ljad247
9. Ragamin A, Zhang J, Pasmans SGMA, Schappin R, Romeijn GLE, van Reusel MA, et al. The construct validity, responsiveness, reliability and interpretability of the Recap of atopic eczema questionnaire (RECAP) in children. Br J Dermatol 2024; 190: 867–875. https://doi.org/10.1093/bjd/ljae017
10. Onteniente-Gomis MM, Ortiz-Romero PL, Tous Romero F, Salamanca Castro AB, Ortiz de Frutos FJ. Spanish version of the RECAP Questionnaire to Assess Control of Atopic Eczema: translation, cultural adaptation, validation, and correlations with other patient-reported outcome measures. Actas Dermosifiliogr 2023; 114: 488–493. https://doi.org/10.1016/j.ad.2023.02.018
11. Mokkink LB, Prinsen CA, Patrick DL, Alonso J, Bouter LM, de Vet HC, et al. COSMIN study design checklist for patient-reported outcome measurement instruments. 2019.
12. de Vet HC, Terwee CB, Mokkink LB, Knol DL. Measurement in medicine: a practical guide. Cambridge: Cambridge University Press, 2011. https://doi.org/10.1017/CBO9780511996214
13. Williams HC, Burney PG, Pembroke AC, Hay RJ. The U.K. Working Party’s Diagnostic Criteria for Atopic Dermatitis. III. Independent hospital validation. Br J Dermatol 1994; 131: 406–416. https://doi.org/10.1111/j.1365-2133.1994.tb08532.x
14. Hanifin JM, Thurston M, Omoto M, Cherill R, Tofte SJ, Graeber M. The eczema area and severity index (EASI): assessment of reliability in atopic dermatitis. EASI Evaluator Group. Exp Dermatol 2001; 10: 11–18. https://doi.org/10.1034/j.1600-0625.2001.100102.x
15. Chopra R, Vakharia PP, Sacotte R, Patel N, Immaneni S, White T, et al. Severity strata for Eczema Area and Severity Index (EASI), modified EASI, Scoring Atopic Dermatitis (SCORAD), objective SCORAD, Atopic Dermatitis Severity Index and body surface area in adolescents and adults with atopic dermatitis. Br J Dermatol 2017; 177: 1316–1321. https://doi.org/10.1111/bjd.15641
16. Simpson E, Bissonnette R, Eichenfield LF, Guttman-Yassky E, King B, Silverberg JI, et al. The Validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD): The development and reliability testing of a novel clinical outcome measurement instrument for the severity of atopic dermatitis. J Am Acad Dermatol 2020; 83: 839–846. https://doi.org/10.1016/j.jaad.2020.04.104
17. Prinsen CAC, Mokkink LB, Bouter LM, Alonso J, Patrick DL, de Vet HCW, et al. COSMIN guideline for systematic reviews of patient-reported outcome measures. Qual Life Res 2018; 27: 1147–1157. https://doi.org/10.1007/s11136-018-1798-3
18. Anthoine E, Moret L, Regnault A, Sébille V, Hardouin JB. Sample size used to validate a scale: a review of publications on newly-developed patient reported outcomes measures. Health Qual Life Outcomes 2014; 12: 176. https://doi.org/10.1186/s12955-014-0176-2
19. de Vet HCW, Terwee CB, Knol DL, Bouter LM. When to use agreement versus reliability measures. J Clin Epidemiol 2006; 59: 1033–1039. https://doi.org/10.1016/j.jclinepi.2005.10.015
20. Terluin B, Eekhout I, Terwee CB, de Vet HCW. Minimal important change (MIC) based on a predictive modeling approach was more precise than MIC based on ROC analysis. J Clin Epidemiol 2015; 68: 1388–1396. https://doi.org/10.1016/j.jclinepi.2015.03.015
21. Terluin B, Eekhout I, Terwee CB. The anchor-based minimal important change, based on receiver operating characteristic analysis or predictive modeling, may need to be adjusted for the proportion of improved patients. J Clin Epidemiol 2017; 83: 90–100. https://doi.org/10.1016/j.jclinepi.2016.12.015
22. McHorney CA, Tarlov AR. Individual-patient monitoring in clinical practice: are available health status surveys adequate? Qual Life Res 1995; 4: 293–307. https://doi.org/10.1007/BF01593882
23. Revicki D, Hays RD, Cella D, Sloan J. Recommended methods for determining responsiveness and minimally important differences for patient-reported outcomes. J Clin Epidemiol 2008; 61: 102–109. https://doi.org/10.1016/j.jclinepi.2007.03.012
24. Oosterhaven JAF, Spekhorst LS, Zhang J, Voorberg AN, Romeijn GLE, Boesjes CM, et al. Eczema control and treatment satisfaction in atopic dermatitis patients treated with dupilumab: a cross-sectional study from the BioDay registry. J Dermatol Treat 2022; 33: 1986–1989. https://doi.org/10.1080/09546634.2021.1937485
25. Charman CR, Venn AJ, Ravenscroft JC, Williams HC. Translating Patient-Oriented Eczema Measure (POEM) scores into clinical practice by suggesting severity strata derived using anchor-based methods. Br J Dermatol 2013; 169: 1326–1332. https://doi.org/10.1111/bjd.12590
26. Vakharia PP, Chopra R, Sacotte R, Patel N, Immaneni S, White T, et al. Validation of patient-reported global severity of atopic dermatitis in adults. Allergy 2018; 73: 451–458. https://doi.org/10.1111/all.13309
27. Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI) – a simple practical measure for routine clinical use. Clin Exp Dermatol 1994; 19: 210–216. https://doi.org/10.1111/j.1365-2230.1994.tb01167.x
28. Chren MM, Lasek RJ, Quinn LM, Mostow EN, Zyzanski SJ. Skindex, a quality-of-life measure for patients with skin disease: reliability, validity, and responsiveness. J Invest Dermatol 1996; 107: 707–713. https://doi.org/10.1111/1523-1747.ep12365600
29. Rabin R, de Charro F. EQ-5D: a measure of health status from the EuroQol Group. Ann Med 2001; 33: 337–343. https://doi.org/10.3109/07853890109002087
30. Yosipovitch G, Reaney M, Mastey V, Eckert L, Abbé A, Nelson L, et al. Peak Pruritus Numerical Rating Scale: psychometric validation and responder definition for assessing itch in moderate-to-severe atopic dermatitis. Br J Dermatol 2019; 181: 761–769. https://doi.org/10.1111/bjd.17744