The 5-D itch scale

The 5-D itch scale: a new measure of pruritus

 Source: U.S. National Library of Medicine

Background

Itching is a subjective and multidimensional experience which is difficult to quantify. Most methodologies to assess itching suffer from being unidimensional, for example only measuring intensity without impact on quality of life, or only measuring scratching activity. None has actually been demonstrated to be able to detect change over time, which is essential to using them as an outcome measure of response to an intervention. The 5-D itch scale was developed as a brief but multidimensional questionnaire designed to be useful as an outcome measure in clinical trials. The five dimensions are degree, duration, direction, disability and distribution.

The 5-D, therefore, is a reliable, multidimensional measure of itching that has been validated in patients with chronic pruritus to able to detect changes over time. The 5-D should be useful as an outcome measure in clinical trials.

Pruritus is a primary symptom of many dermatological diseases, including atopic dermatitis, psoriasis, urticaria and postburn healing. It is also a common feature of several systemic diseases, including chronic kidney failure, hepatobiliary disease, human immunodeficiency virus (HIV) and haematopoietic disorders. More than just an annoyance, chronic pruritus significantly reduces quality of life and can ultimately lead to severe disability. Its sequelae may include sleep disturbance, embarrassment, prolonged wound healing and secondary skin changes. Current treatments provide inconsistent and partial relief. Therefore, novel treatments are necessary. However, well-designed clinical trials require appropriate outcome measures to evaluate the response of pruritus to treatment.

VISUAL ANALOG SCALE

Currently, only a few resources are available to measure pruritus. A visual analogue scale (VAS; Fig. 1) has been used most often to quantify pruritus. ritus in subjects with psoriasis. None of these scales, however, has been demonstrated to be sensitive to change over time: a critical feature that determines whether they are useful as an outcome measure in clinical trials.

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5-D ITCH QUESTIONNAIRE

Time sensitivity, as well as ease of administration and scoring, are all important qualities of a desirable outcome measure to be used in clinical trials. The 5-D itch questionnaire was specifically developed to be a measure of itch that is brief (one page), easy to complete, easy to score (either manually at the bedside or electronically as part of a large clinical trial), sensitive to the multidimensional nature of pruritus and its effect on quality of life, applicable to multiple diseases, and capable of detecting change over time.

Preliminary items for the 5-D itch scale were derived from (i)
(1)  modification of the Total Neuropathy Scale to be relevant to pruritus rather than neuropathy,
(2)  clinical experience by the authors and expert consultants with chronic pruritus under conditions of patient care and clinical trials and|
(3) review of the pruritus literature.
The preliminary version included both open-ended questions and specific response questions regarding the patient’s perception of pruritus. This preliminary version was administered to 21 patients participating in a trial of sertraline for a treatment of cholestatic pruritus. Ambiguous items or response choices were revised and response choices selected less than 5% of the time were removed. The remaining items were grouped into five domains: duration, degree, direction, disability and distribution.
Accordingly, the scale was titled the ‘5-D itch scale’ (Fig. 2). The duration, degree and direction domains each included one item, while the disability domain had four items. All items of the first four domains were measured on a five-point Likert scale.
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Scoring of the 5-D itch scale

The scores of each of the five domains are achieved separately and then summed together to obtain a total 5-D score.


Let’s say your dermatologist doesn’t quite understand how painful and debilitating your itching is. What would he or she say — and do — if you walked into your net clinic visit and handed over a copy of your 5-D Itch Scale?

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