|LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 3 | Page : 477-479
A study of itch in psoriasis
Manju Meena1, Kriti Maheshwari2, Kapil Vyas2, Asit Kumar Mittal3
1 Government Doon Medical College, Dehradun, Uttarakhand, India
2 Geetanjali Medical College and Hospital, Udaipur, Rajasthan, India
3 RNT Medical College, Udaipur, Rajasthan, India
|Date of Submission||28-Jul-2020|
|Date of Decision||13-Sep-2020|
|Date of Acceptance||06-Oct-2020|
|Date of Web Publication||12-May-2021|
Asit Kumar Mittal
House No 62, Road Number 2, Ashok Nagar, Udaipur - 313 001, Rajasthan
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Meena M, Maheshwari K, Vyas K, Mittal AK. A study of itch in psoriasis. Indian Dermatol Online J 2021;12:477-9
Psoriasis is a complex, chronic, multifactorial, inflammatory disease characterized by well-demarcated scaly, red, coin-sized skin lesions commonly seen on elbows, knees, scalp, hands, and feet. In the past, itch was considered an uncommon symptom of psoriasis, however recent studies have documented that itch may be a frequent sensation in psoriasis., Chronic itch also negatively influences the quality of life in patients of psoriasis. The pathogenesis of itching in psoriasis remains unclear. Itch in psoriasis is non-histaminergic. The most often discussed theory mentions the importance of altered innervations and neuropeptide imbalance in psoriatic skin. Several studies have demonstrated changed expression and distribution within various layers of skin of several neuropeptides and their receptors including Substance P, Calcitonin gene-related peptide, vasoactive intestinal peptides in psoriasis. Increased numbers of IL-2 immunoreactive cells in pruritic versus nonpruritic lesions of Psoriasis have also been shown. There is also a marked increase in density of endothelial leucocyte adhesion molecule (ELAM-1) positive venules in patients of psoriasis with itching. Thus, vascular alterations found in psoriatic lesions may also contribute to itching. In spite of the perceived importance, studies on itch in psoriasis in India are sparse. This prompted us to carry out a study of itch in our psoriasis patients. The study was carried out over a period of one and half years on 200 patients of psoriasis attending outpatient department. Due approval from institutional review board was obtained before initiating the study.
Patients were classified on the basis of different clinical subtypes of psoriasis. Disease severity was defined as mild to severe based on PASI (Psoriasis Area Severity Index). Patients who were on any topical or systemic treatment for psoriasis in the last 4 weeks and had any other known dermatological, metabolic, or systemic cause of itch based on clinical history, examination or laboratory tests were excluded from the study. Clinico-demographic data of the recruited patients were recorded in a predesigned proforma [Table 1]. The global assessment of itch in all these patients was done with regards to extent, severity, diurnal or seasonal variation, aggravating or relieving factors, sensory qualities of itch, and time spent on itch. The onset of psoriasis and appearance of itch in our patients was concomitant. In addition to global assessment of itch, the severity and frequency of itch was also measured using a Four item itch questionare (FIIQ). The impact of itch on daily routine activities of patient was assessed using behavior rating scale (BRS). This was an indirect measurement of effect of itch on quality of life of patients. We did not use the usual monodimensional scales such as numerical rating scale (NRS) or verbal rating scale (VRS) to assess severity of itch because our patients found it difficult to point out a particular score which is a requirement for these scales. Qualitative data were expressed as percentage or proportion, whereas quantitative data were represented as mean with standard deviation. Mean FIIQ scores among psoriasis patients of different clinicodemographic profile were compared using ANOVA test and Student's t test. Mild psoriasis (PASI ≤3) was seen in 132 patients whereas 68 patients had moderate to severe psoriasis (PASI >3). Itch was reported in 172 (86%) out of 200 patients. Among these, 161 (93.60%) patients had itch restricted to psoriatic plaques, rest 11 (6.39%) patients experienced itch on both diseased and normal skin. The high prevalence of itch in our study is consistent with studies by Stinco et al. and Janowski et al. Global assessment of itch revealed diurnal variation of itch in 47 patients (27.32%) with worsening of symptoms at night. The cause of nocturnal worsening may be decreased threshold of itch due to increased patient's attention towards itch in the absence of other activities. One or more aggravating factors for itch were found in 84 of 172 (48.83%) patients. Most common aggravating factors in our study were skin dryness (71.4%), sun exposure (14.2%), ambient heat (7.14%), cold (7.14%) and stress (2.38%). The low percentage of stress-induced itch in our cohort is possibly due to inability of our patients to comprehend the correlation between stress as a trigger and aggravation of itch. Isolated itch was experienced by 158 patients (91.86%) whereas 14 (8.13%) patients reported itch of mixed sensory quality accompanied by burning and stinging [Table 1]. Mean FIIQ score amongst patients with moderate to severe psoriasis was statistically higher as compared to milder disease (P - 0.001). Patients with disease of more than 2-year duration had a higher mean FIIQ score (P-0.02). On comparing the mean FIIQ score among different morphological subtypes of psoriasis, no statistically meaningful difference was found (P - 0.168) [Table 2]. This finding is consistent with the observation of Szepietovski et al. and Chang et al. Mean FIIQ score among males (5.26) and females (6.08) was statistically similar (p - 0.149). Szepietovski et al. also reported that itch was independent of gender of the patients. BRS is a tool that measures both intensity of itch as well as the adverse impact of itch on daily physical activities of patients. A total of 37 patients recorded a score of 3 on BRS, whereas a majority of patients (132) had a score of 1 and 2. The low score on BRS suggests that the impact of psoriasis on daily activities of patients in this study was minimal. Prignano F et al. found a high prevalence of pruritus (85%) and observed that overweight or obese patients experienced more intense pruritus. This study reveals a high burden of itch in psoriasis patients, but itch was not severe enough to cause significant physical disability. It is important to conduct more studies on the quantitative and qualitative aspects of itch in psoriasis, as it can have a major impact on quality of life. The importance of itch in psoriasis can also be gauged from the fact that measurable and verifiable itch improvement is now included as a primary or secondary endpoint in many randomized controlled trials of systemic treatment of psoriasis.
|Table 2: Comparison of pruritus impact among subset of psoriasis patients with different clinico-epidemiological profiles|
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[Table 1], [Table 2]