Development and Validation of the Visual Medical Scale to Evaluate Nail Psoriasis Severity (ViSENPsO^®)

Abstract

Introduction

A reliable, well-defined measure of fingernail psoriasis severity for clinical trials is an unmet need. The objective of this study was to develop and validate the Visual Medical Scale to Evaluate Nail Psoriasis Severity (ViSENPsO), an illustrated 5-point tool for assessing nail psoriasis severity.

Methods

A global panel of dermatologists participated in concept elicitation (CE) interviews exploring experiences with nail psoriasis, severity markers, and biologic treatment. Participants sorted and ranked histopathology-verified photographs to refine severity categories. Follow-up cognitive interviews assessed the scale's usability and content validity, alongside a preliminary test of interrater reliability (IRR). Dermatologists' assessments were analyzed using thematic analysis to generate qualitative insights.

Results

Sixteen dermatologists participated in CE and five in cognitive interviews. Consensus analysis showed strong alignment among high task competence (expertise ratings [r_its] of 5.08 and 16.85 for sorts and full ranking) and high-average competence scores $(\overline{x}$ r_its, 0.60 and 0.81). Cognitive interviews validated category definitions and visual layout. Preliminary IRR for photo rating was 0.74 (95% confidence interval, 0.34–0.84).

Conclusion

ViSENPsO is a validated, visually guided tool for assessing standardized nail psoriasis severity. Preliminary interrater agreement was observed; comprehensive psychometric validation, including full IRR and sensitivity to change, is ongoing.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-026-01762-6.

Key Summary Points

Why carry out this study?

Nail psoriasis affects up to 90% of patients with psoriasis and significantly impairs quality of life, but existing assessment tools, such as the Nail Psoriasis Severity Index, are time-consuming, lack precision, and have inconsistent interrater reliability.

A simplified, standardized, validated tool for evaluating fingernail psoriasis severity in clinical trials remains an unmet need.

What was learned from this study?

The ViSENPsO offers a standardized, user-friendly alternative to improve consistency and reliability in nail psoriasis assessment, supporting its adoption in clinical trials.

Further psychometric validation in larger, diverse populations will confirm its applicability and reliability in clinical trials.

Introduction

Nail psoriasis impacts the nail matrix and bed, causing pain, reduced hand function, and impaired quality of life (QoL). It affects 40%–50% of patients with plaque psoriasis, with a lifetime prevalence of 80%–90% [1–3].

The standard clinical evaluation tool for nail psoriasis, the Nail Psoriasis Severity Index (NAPSI) [4], is cumbersome and time-consuming, lacks precision in assessing specific nail features, and omits QoL assessment [5]. NAPSI also underperforms at capturing treatment benefits because of inconsistent interobserver reliability and a focus on feature identification rather than severity evaluation [6]. Published data demonstrate variable interobserver reliability for NAPSI, with reported intraclass correlation coefficients (ICCs) of 0.78 for total NAPSI scores and 0.65 for individual nail scores. Reliability also varies across domains, with lower agreement observed for nail matrix features (ICC, 0.58) compared with nail bed features (ICC, 0.87) [7]. Simplified tools, such as the modified NAPSI (mNAPSI) and N-NAIL, focus on whole-nail assessment rather than defined quadrants and specific features but risk missing disease nuances and QoL impacts, thereby underrepresenting severity [1, 6].

To address these limitations, we developed the Visual Medical Scale to Evaluate Nail Psoriasis Severity (ViSENPsO), an illustrated clinician-reported outcome (ClinRO), for consistent severity scoring in clinical trials. Here, we describe the development and content validation of the ViSENPsO [8, 9].

Methods

Study Design

The study comprised concept elicitation interviews with board-certified dermatologists to evaluate content validity, followed by cognitive interviews to refine category descriptors, illustrations, and usability of the draft scale. Patient interviews and subsequent clinician cognitive interviews were also performed to refine scale descriptors, illustrations, and usability prior to finalization of the instrument.

Clinician participants were informed of the study objectives before and at the start of the interviews; they were included as members of the ViSENPsO Study Group. Patient consent for the qualitative interviews was obtained before the start of the interviews; patients reviewed the study information sheet, which included the study objectives and informed them that the results could be published, before providing consent. The studies were performed in accordance with the Helsinki Declaration of 1964 and its later amendments, the US Food and Drug Administration (21 CFR Parts 50 and 56), the Department of Health and Human Services (45 CFR Part 46), the ICH Guideline for Good Clinical Practice E6(R2), and the ethical principles outlined in the Belmont Report. Institutional review board approval was obtained for the patient pile sort and interviews from the Salus Institutional Review Board (protocol no. 3783–0026).

Concept Elicitation

A global panel of 16 practicing dermatologists participated in 1-h semi-structured teleconference or videoconference interviews led by experienced qualitative researchers. The first half focused on clinicians' experiences with nail psoriasis, key pathologic features, and responses to biologic treatments. The second half involved a 5-level pile-sort rating and ranking exercise, categorizing 27 histopathology-verified photographs representing the nail psoriasis pathology spectrum into 5 severity levels and then ordering them by severity.

Qualitative Analysis

Interviews were audio-recorded, transcribed verbatim, and analyzed using grounded theory and thematic analysis (MAXQDA, VERBI GmbH). Conceptual saturation was achieved for nail pathologic features, with further analysis of dermatologists' descriptions of meaningful clinical change. Category definitions and severity level boundary conditions were refined using triangulation of qualitative responses with rating and ranking data.

Quantitative Analysis

Pile-sort and ranking data were analyzed using UCINET (Analytic Technologies) [10]. Each photograph was uniquely coded, and ratings were recorded by pile to generate a proximity matrix, while rankings were coded in a person-by-rank profile matrix. Consensus analysis employed a shared "cultural" knowledge framework using eigenvalue ratios and individual competence coefficients to generate consensus-based photograph placement. The eigenvalue ratio was used to determine the presence of a single shared consensus among participants, where a ratio of the first to second eigenvalue > 3.0 indicates a high level of agreement within a single "cultural" perspective. Individual competence scores were calculated to represent the degree to which an individual’s responses aligned with the group’s shared consensus, with scores closer to 1 indicating higher task expertise and agreement [11].

Multidimensional Scaling Analyses

A multidimensional scaling (MDS) graphic was generated from the aggregate proximity matrix of high-competence respondents (ANTHROPAC, Analytic Technologies), providing a two-dimensional representation of severity patterns to refine category organization and clarify boundary definitions for the final ViSENPsO. In the MDS graphic, the distance between points reflects the degree of similarity in how participants categorized the photographs; closer clusters indicate high clinician agreement on specific severity levels, and the spread of points helps identify "boundary cases" where pathologic features overlap between categories. This allows for the visualization of clustering density to ensure the five severity levels are distinct and well-defined.

Cognitive Interviews

After the draft ViSENPsO development, a subset of five Latin American dermatologists participated in cognitive interviews to further refine category definitions and illustrations.

Patient Pile Sort and Interviews

Twelve patients participated in structured sessions—guided by experienced qualitative researchers and conducted with local institutional review board approval—using a 5-level pile-sort task and focused interviews exploring experiences with fingernail psoriasis, perceptions of severity, and expectations for symptom resolution. Although not used in scale development, patient input was analyzed to enhance severity appraisal and inform potential product labeling.

Results

The 16 clinicians interviewed for concept elicitation were highly experienced. Thirteen had ≥ 20 years of experience; 3 specialized in nail disease, immunology, and rheumatology; 8 managed > 500 patients with nail psoriasis annually; 7 had prior clinical research experience.

The 27 histopathology-verified photographs used for clinician consensus development represented adult patients 25 to 60 years of age; all photographed patients were White (representative patient photographs are shown in Supplementary Fig. 1). Clinicians agreed on a continuum of nail psoriasis severity, identifying fingernail involvement and specific features (e.g., pitting, hyperkeratosis, crumbling, onycholysis, oil drop or salmon patches, and splinter hemorrhages) as key severity markers; no hierarchy was established. Pitting indicated milder severity, while severe crumbling, hyperkeratosis, and onycholysis indicated the highest severity. Pain, impairment, and appearance influenced perceptions of severity but were not uniformly prioritized. Photographic assessments improved clarity; percentage involvement estimation and quadrant-based assessments were less definitive.

Consensus analysis showed strong alignment. The full sample (n = 16) had rating and ranking task eigenvalue ratios of 5.06 and 3.33, with competence scores ($\overline{x}$ r_its) of 0.53 (95% confidence interval [CI], 0.47–0.59) and 0.77 (95% CI, 0.71–0.84), respectively. High-competence participants in rating (n = 11) and ranking tasks (n = 14) showed even stronger agreement, with eigenvalue ratios of 5.08 and 16.85 and competence scores of 0.60 (95% CI, 0.57–0.63) and 0.81 (95% CI, 0.78–0.85; Table 1).

Table 1.

Consensus analysis results for full concept elicitation sample and consensus drivers in rating and ranking tasks for clinicians and patients

Rating task (5-level constrained photo pile sort)
Clinicians	Eigenvalue ratio	Average competence ($\overline{x}$ rits)	95% CI	Range
Full sample (n = 16)	5.06	0.53	0.47–0.59	0.26–0.71
High “competence” (rits > 5; n = 11)	5.08	0.60	0.57–0.63	0.53–0.73
Patients
Full sample (n = 12)	5.94	0.55	0.50–0.61	0.41–0.78
Combined group
All patients and clinicians (n = 28)	6.10	0.54	0.49–0.58	0.21–0.69
All patients and high-competence clinicians (n = 23)	6.41	0.56	0.53–0.59	0.47–0.71

Ranking task (full-sample array ranking severity)
Sample	Eigenvalue ratio	Average competence ($\overline{x}$ rits)	95% CI	Range
Full sample (n = 16)	3.33	0.77	0.71–0.84	0.46–0.89
High “competence” (rits > 5; n = 14)	16.85	0.81	0.78–0.85	0.62–0.92

CI confidence interval

The MDS diagram (Supplementary Fig. 2) showed clear clustering of severity ratings "0" and "1" and severe cases, although intermediate ratings lacked clear boundaries between categories "2" and "3" and between categories "3" and "4." Based on qualitative feedback, a draft ViSENPsO with images and descriptions to guide evaluations was prepared. Severity levels ranged from normal ("0"), described as no discoloration or nail disease, to severe ("4"), described as > 75% destruction and significant pain.

Cognitive interviews confirmed the format, clarified category boundaries, validated layout, illustrations, and pathologic features, and refined adjectives, particularly for mid-to-high severity, for translation. Participants found the instruction to focus on the patient's worst nail based on nail impairment severity (extension and/or ungual dystrophic signs; "worst fingernail" approach) acceptable. Preliminary reliability testing with 10 photographs showed strong intraclass correlation (0.74; 95% CI, 0.34–0.84). Comprehensive psychometric evaluation, including full interrater reliability and sensitivity to change, is ongoing using the data from the Phase 3 trial.

Based on feedback, category 1 pitting severity was reduced, and category 2 onycholysis coloration was adjusted. Pain and functional impairment statements were added to support severity categorization, and "at least 75%" nail destruction was noted for category 4, resulting in the final ViSENPsO (Table 2).

Table 2.

The final ViSENPsO measure

Severity level	Description	Visual representation
0	Normal nail (i.e., clear, with no discoloration, and no nail disease)
1	Minimal nail psoriasis features (most typically nail plate pitting; possibly oil drop/salmon patches, or onycholysis present). No pain or functional impairment likely to be reported
2	< 50% nail involvement. May have ≥ 2 nail psoriasis features (e.g., nail plate oil drop/salmon patches, onycholysis, and possibly splinter hemorrhages, hyperkeratosis, or crumbling). Pain and/or functional impairment may be reported
3	50%–75% nail destruction. May have ≥ 3 nail psoriasis features (e.g., nail plate crumbling, hyperkeratosis, oil drop/salmon patches, onycholysis, or splinter hemorrhages). Pain and/or functional impairment likely to be reported
4	At least 75% nail destruction. Multiple nail psoriasis features (e.g., nail plate crumbling, hyperkeratosis, oil drop/salmon patches, onycholysis, or splinter hemorrhages). Pain and/or functional impairment likely to be reported

ViSENPsO Visual Medical Scale to Evaluate Nail Psoriasis Severity

ViSENPsO^® is a registered trademark applied to a copyrighted scale owned by Sun Pharmaceutical Industries Ltd. (SPIL). All rights reserved. Provided that appropriate acknowledgment is given by stating “ViSENPsO^{® ©}2021 Sun Pharmaceutical Industries Ltd.,” use of this scale solely for noncommercial publication purposes is permitted without the express written permission of SPIL. Any other duplication, modification, derivation, copying, or reuse of any portion of the scale, or visual elements or concepts contained therein, is strictly prohibited without the prior, express written permission of SPIL

Patients' photo ratings aligned with the consensus model, meeting the "single culture" criterion (Table 2). Patients’ ratings were less influenced by detailed clinical knowledge than clinicians' ratings, were less consistent at a score of "0," and generally rated moderate cases as more severe.

Discussion

The ViSENPsO for assessing nail psoriasis severity was developed using global clinical expertise and structured methodologies to create a streamlined, user-friendly tool. Integrating qualitative and quantitative data achieved high consensus on severity classification, enabling consistent, reproducible outcomes in clinical trials. The consensus-driven descriptors reflect shared clinical judgment by experienced dermatologists, ensuring usability and adaptability in real-world settings.

The ViSENPsO addresses limitations of tools like NAPSI and N-NAIL, which provide detailed analyses of nail pathology [1, 4] but are complex, time-intensive, and prone to interrater variability [1, 6, 12, 13]. The mNAPSI, while simplified, retains a multidimensional structure that limits usability and consistency [1, 6]. ViSENPsO overcomes these challenges with a simplified 5-point scale that uses clear, consensus-based descriptors and visual examples to minimize variability. Categorical descriptions addressing pain and functional impairment enhance accessibility for nonspecialists and suitability for large-scale trials. Although not used in scale development, patient input aligned with the clinician consensus model, fulfilling US Food and Drug Administration recommendations and ensuring clinical relevance. The single-item, visually guided structure of the ViSENPsO may also facilitate integration into electronic health record systems and digital platforms, enabling consistent, scalable implementation in clinical research settings.

The structured, mixed-methods approach used to develop the ViSENPsO, including clinician concept elicitation, formal consensus analysis, cognitive interviewing, and preliminary agreement assessment, aligns with established regulatory guidance for ClinRO instrument development [14, 15]. By classifying severity categories with clearly defined descriptors and standardized visual examples, the ViSENPsO is designed to promote interpretability and consistency among raters. Upon completion of comprehensive psychometric validation, the ViSENPsO has the potential to serve as a standardized, clinically meaningful endpoint for assessing nail psoriasis severity in pivotal trials, thereby supporting clearer evaluation of treatment effects.

Limitations of the validation include the small cognitive interview sample, resulting in variable ratings and rankings. Patient input was obtained from a small, localized sample, limiting generalizability; because patient data were not used to derive severity categories, these findings should be interpreted as a supportive qualitative context rather than evidence of population-level validity. In addition, the clinician panel consisted predominantly of highly experienced dermatologists with extensive exposure to nail psoriasis and clinical research. Although this was intentional to support accurate determination of nail psoriasis severity, this level of expertise may not fully reflect the average dermatology practice or global variation. Broader international validation across clinicians with varying experience levels and larger, geographically diverse patient populations is needed to confirm global applicability across populations and treatments. The "worst-affected" nail approach was used to enhance the sensitivity of the ViSENPsO to clinically meaningful changes in the nail, which usually drive patient burden and treatment response; however, this approach may overlook subtle changes in other nails, thereby impacting accuracy. The ViSENPsO is therefore intended to complement, rather than replace, whole-hand instruments when a comprehensive assessment of total nail involvement is required. Finally, applicability to diverse skin types, especially for persons of color, requires further investigation.

Using a new instrument in pivotal trials introduces risks due to ambiguities arising from measure development based solely on qualitative data. However, the mixed methods approach used in ViSENPsO development captured clinical consensus and reduced ambiguity by focusing on clear descriptors and images, ensuring reliability and robustness as a clinical trial tool. Future research should formally evaluate construct validity using hypothesis-driven correlations with established clinician- and patient-reported outcomes, assess responsiveness using longitudinal clinical trial data to quantify sensitivity to change, and estimate thresholds for clinically meaningful improvement. Structured cross-cultural adaptation and linguistic validation will also be important to support multinational use and regulatory acceptance in global clinical development programs.

Conclusions

The ViSENPsO is a well-defined, illustrated ClinRO tool for assessing nail psoriasis severity using consensus-driven descriptors to overcome limitations of existing tools. Initial findings demonstrate feasibility and clinician alignment; validation using clinical trial results is ongoing to determine its utility for reliable severity assessment across diverse settings.

Supplementary Information

Below is the link to the electronic supplementary material.

Author Contributions

All named authors meet the International Committee of Medical Journal Editors criteria for authorship for this article, take responsibility for the integrity of the work, and have given their approval for this version to be published. All authors contributed substantially to this manuscript. Adilson DaCosta, James P. Stansbury, Olga Moshkovich, and Siu-Long Yao contributed to the study concept or design. Cláudio de Lélis Filgueiras de Souza and Renan Minotto were involved in the concept elicitation and cognitive interviews. James P. Stansbury, Olga Moshkovich, and Selam Shah contributed to data acquisition and analysis. James P. Stansbury and Olga Moshkovich contributed to biostatistical analysis. All authors contributed to the data interpretation, reviewed each draft of the manuscript for important intellectual content, and approved the final version.

Funding

The study, analyses, medical writing, and editorial support were funded by Sun Pharma. Sun Pharma funded the journal’s Rapid Service Fees.

Data Availability

Data and other documents will be made available after publication, with no end date, to anyone who submits a reasonable request to the study sponsor.

Declarations

Conflict of interest

Adilson DaCosta is a former employee of Sun Pharma Advanced Research Company Limited. Cláudio de Lélis Filgueiras de Souza and Renan Minotto report no conflicts of interest. Selam Shah and James P. Stansbury are former employees of ICON plc. Olga Moshkovich is a current employee of ICON plc. Siu-Long Yao is a former employee of Sun Pharma Advanced Research Company Limited.

Ethical Approval

Clinician participants were informed of the study objectives before the interviews and at the start of the interviews; they are included as members of the ViSENPsO Study Group. Patient consent for the qualitative interviews was obtained before the start of the interviews; patients reviewed the study information sheet, which included the study objectives and informed them that the results could be published, before providing consent. The studies were performed in accordance with the Helsinki Declaration of 1964 and its later amendments, the US Food and Drug Administration (21 CFR Parts 50 and 56), the Department of Health and Human Services (45 CFR Part 46), the ICH Guideline for Good Clinical Practice E6(R2), and the ethical principles outlined in the Belmont Report. Institutional review board approval was obtained for the patient pile sort and interviews from the Salus Institutional Review Board (Protocol number: 3783–0026).