Measuring Psoriasis Severity at Home

Summary

This paper details the creation of a Psoriasis Thickness Reference Card, enabling psoriasis patients to self-assess their psoriasis plaque thickness without the need for physician assistance. Additionally, the precision of self-assessment for psoriasis redness and scaliness by employing reference images depicting various skin tones is assessed.

Abstract

Psoriasis plaque severity metrics, such as induration (thickness), erythema (redness), and desquamation (scaliness), are associated with the subsequent development of psoriatic arthritis (PsA) among cutaneous-only psoriasis patients (patients with skin or nail psoriasis but no psoriatic arthritis). These metrics can be used for PsA screening. However, a key challenge in PsA screening is to optimize accessibility and minimize costs for patients, while also reducing the burden on healthcare systems. Therefore, an ideal screening tool consists of questions that patients can answer without a physician's assistance. Although reference images can be used to help a patient self-assess erythema and desquamation severity, a patient would need a tactile induration reference card to self-assess induration severity. This protocol describes how to create an induration reference card, the Psoriasis Thickness Reference Card, as well as how to use it to assess lesion induration severity. Administration of reference images for erythema and desquamation and a Psoriasis Thickness Reference Card for induration to 27 psoriasis patients showed that patients were moderately successful at self-assessing the severity of these three metrics. These findings support the feasibility of a future PsA screening test that patients can complete without the need for physician assistance.

Introduction

Psoriatic arthritis (PsA) is an inflammatory arthritis that develops in approximately 2.9% of patients with psoriasis each year^1,2. Early prediction of which patients will develop PsA is crucial for a patient's quality of life as a diagnostic delay of as little as six months may cause irreversible damage to the joints³. A previous study had identified features associated with early-stage PsA. The three components of the Investigator's Global Assessment (IGA)-induration (thickness), erythema (redness), and desquamation (scaliness)-were highly correlated with each other and were nominally associated with subsequent PsA development. Multivariate analysis showed that a history of fingernail psoriasis and untreated induration of psoriasis lesions were independent PsA predictors⁴. Other studies have also identified psoriasis severity as associated with psoriatic arthritis^2,5,6. The collection of these clinical factors is likely to be important in future PsA screening.

Several PsA screening tests exist^7,8,9,10, but they require physicians to conduct them. A questionnaire-based screening test that can be completed by patients without physician assistance is an ideal format because it will not burden the dermatology and primary care clinics. Previously, the authors described a questionnaire with images that depict different severities of erythema and desquamation in multiple skin tones¹¹. However, the measurement of induration requires a reference card corresponding to various plaque severities, such as that developed by the National Psoriasis Foundation¹². The reference card is characterized by multiple raised areas of varying elevations, each corresponding to a number representing induration severity. To assess a patient's psoriasis severity in terms of induration, the card user compares the thickest psoriasis patch on a patient's body to the elevated areas on the card.

However, distributing a reference card to psoriasis patients may not be the most efficient approach for reaching a broad audience, especially for patients located outside the USA and for online survey studies. For researchers and clinicians gathering induration self-assessments from numerous patients, an alternative option could involve creating a homemade induration card using inexpensive office supplies. For patients, creating a homemade device from inexpensive office supplies can be more cost-effective than purchasing commercially available alternatives. This protocol describes how to create the Psoriasis Thickness Reference Card, an induration reference card that psoriasis patients can feel to assess the severity of their psoriasis induration. The Card can be made with standard office supplies and is inexpensive to make.

Protocol

This study was approved by the University of Utah Institutional Review Board (IRB_00137694). Twenty-seven psoriasis patients at the University of Utah dermatology clinic were enlisted to complete a questionnaire about psoriasis severity at the time of the questionnaire's administration. All patients provided informed consent and completed the questionnaire without instructions from research or medical personnel, either before or immediately after the dermatologist's assessment.

1. Procedure for making a Psoriasis Thickness Reference Card

1. Print the Psoriasis Thickness Reference Card template (Supplemental Figure S1) on a standard piece of printer paper. If a printer is not accessible, manually write down the numbers as in the template on any paper and follow the subsequent steps.
2. Place sticky notes.
   1. Purchase a package of sticky notes. The smallest-sized sticky notes (5.08 cm height x 5.08 cm width or 5.08 cm height x 3.81 cm width) will work. The thickness of each sticky note should be between 0.09 and 0.1 mm.
      NOTE: The authors have tested multiple brands of sticky notes (see Table of Materials) in the market and found that they all fulfill this requirement. If in doubt, one can calculate the thickness of each page by dividing the total thickness of a stack of sticky notes by the number of pages in the stack.
   2. Place a stack of three sticky notes on the box labeled "3."
   3. Place a stack of 5 sticky notes on the box labeled "5."
   4. Place a stack of 8 sticky notes on the box labeled "8."
   5. Place a stack of 10 sticky notes on the box labeled "10."
   6. Place a stack of 13 sticky notes on the box labeled "13."
3. Align the adhesive side of the sticky notes on the left side of each corresponding box and press them down to adhere each stack firmly to the sheet of paper.
4. Apply a strip of tape along the right side of each stack of sticky notes (Figure 1). Ensure the tape adheres smoothly, creating a gentle slope between the top of the stack and the paper.
   NOTE: If the left side of each stack is not adhered securely to the paper via the sticky note adhesive, tape the left side in the same way as the right side.

2. Usage of the Psoriasis Thickness Reference Card

1. Slide a finger across the taped side of each stack of sticky notes to get a sense of its thickness or elevation from the paper it is adhered to.
2. In a similar manner, slide a finger across the edge of one's thickest psoriasis patch, feeling its elevation from the surrounding, unaffected skin.
3. Identify the stack that is most similar in elevation to one's thickest psoriasis patch and record the corresponding score of 0 to 13.

Results

To validate whether patient assessments of desquamation, erythema, and induration are comparable to those of a dermatologist, 27 psoriasis patients at the University of Utah dermatology clinic were enlisted to complete a questionnaire about psoriasis severity at the time of the questionnaire's administration. Each participant was provided with a Psoriasis Thickness Reference Card along with the questionnaire. The dermatologist provided their independent assessment of the current status of each patient using the same meas...

Discussion

Protocol step 1.4 is a crucial aspect of the proper construction of the Psoriasis Thickness Reference Card. To achieve an accurate representation of plaque thickness, it is imperative to avoid placing the tape vertically or flush against the vertical edge of the stack of sticky notes. If the tape is positioned in such a manner, the sharp edge of each stack will not mimic the feel of a psoriasis plaque. The tape should be applied in a way that creates a smooth slope connecting the stack to the paper.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Post-it Notes, 1 3/8 in x 1 7/8 in, Canary Yellow, 6 Pads/Pack	3M	00021200569029	The smallest sized sticky notes (5.08 cm height x 5.08 cm width or 5.08 cm height x 3.81 cm width) work best with the printed template. The thickness of each sticky note should be between 0.09 and 0.1 mm; sticky notes from the brands Post-it, Pen+Gear, and Office Works meet these requirements.
Printworks Printer and Copy Paper - 500 Pack - White	Paris Corporation	0009014600006	Any brand of printer paper is acceptable; if recreating the template manually rather than printing, any brand of paper is acceptable.
R	http://www.r-project.org		The R programming language version 4.3.1 was used to analyze the data in this study.
Scotch Magic Tape Dispensered Rolls	3M	00021200000041	Any brand of smooth adhesive tape is acceptable; do not use tape with a coarse texture.