Indian Journal of Dermatology
E-IJD SHORT COMMUNICATION
Year
: 2015  |  Volume : 60  |  Issue : 5  |  Page : 525-

Biopsychosocial factors associated with prurigo nodularis in endogenous eczema


Choon Chiat Oh1, Huihua Li2, Wellington Lee1, Hong Liang Tey1,  
1 Department of Dermatology, National Skin Centre, Singapore General Hospital, Singapore
2 Department Health Service Research, Singapore General Hospital, Singapore

Correspondence Address:
Hong Liang Tey
National Skin Centre Singapore, 1Mandalay Road, Singapore - 308205
Singapore

Abstract

Background: Prurigo nodularis is a dermatological manifestation secondary to chronic scratching or picking on focal areas of the skin. Its pathogenesis remains poorly understood, and limited data has indicated its association with psychological factors. Aim: To determine the biological, psychological and social factors associated with the occurrence of prurigo nodularis in patients with underlying endogenous eczema. Methods: A prospective case-control questionnaire -based study on patients with endogenous eczema, with and without prurigo nodules, was performed. The Impact of Skin Disease on Daily Life questionnaire was used to assess dimensions of physical functioning, including extent and severity of skin disease, itch, pain, fatigue and scratching, as well as dimensions of psychological and social functioning, including mood, illness cognition, disease-related impact, stigmatization and social support. Results: Thirty-six cases and 47 controls were recruited. Patients with endogenous eczema and prurigo nodules indicated a higher itch score on the visual analog scale over the previous 4 weeks compared to those without prurigo nodules (p=0.0292). There were no significant differences between the 2 groups in the scores reflecting the other parameters of physical, psychological and social functioning. Conclusion: In patients with endogenous eczema, those with prurigo nodules experience a greater itch intensity compared to those without prurigo nodules. There were no other physical, psychological and social factors that were found to be associated with the occurrence of prurigo nodules in endogenous eczema.



How to cite this article:
Oh CC, Li H, Lee W, Tey HL. Biopsychosocial factors associated with prurigo nodularis in endogenous eczema.Indian J Dermatol 2015;60:525-525


How to cite this URL:
Oh CC, Li H, Lee W, Tey HL. Biopsychosocial factors associated with prurigo nodularis in endogenous eczema. Indian J Dermatol [serial online] 2015 [cited 2021 Jan 15 ];60:525-525
Available from: https://www.e-ijd.org/text.asp?2015/60/5/525/164451


Full Text

Prurigo nodularis is a dermatological manifestation secondary to chronic scratching or picking on focal areas of the skin. Its pathogenesis is poorly understood with few studies describing the incidence and strength of association of co-morbidities. [1],[2] The most common dermatological disorder associated with prurigo nodularis was found to be atopic dermatitis in a study. [1] Psychological factors have been associated with the occurrence of prurigo nodularis in two previous studies. [3.],[4] However, it is not clear if the psychological association was with the underlying diseases causing itch or directly with prurigo nodularis, and if the psychological morbidities were a cause or effect of prurigo nodularis.

In this case-control study, we aim to determine if biological, psychological and social factors are associated with the occurrence of prurigo nodularis in patients with underlying endogenous eczema.

Patients with endogenous eczema visiting a general dermatology clinic and the itch clinic in the National Skin Centre in Singapore were invited to complete a comprehensive questionnaire. Patients with co-existing prurigo nodularis were identified and those without prurigo nodularis were recruited as controls. The study was conducted over a 6-month period from April 2011 to September 2013. The Impact of Skin Disease on Daily Life (ISDL) questionnaire, [5] a tool validated for use as a multidimensional health status inventory for chronic skin diseases, was used. The dermatology-specific component of the questionnaire assesses dimensions of physical functioning, including extent and severity of skin disease, physical symptoms of itch, pain and fatigue, and scratching, as well as disease-related stressors like stigmatization. It includes a 10-cm visual analog scale to access patients' itch intensity over the previous 4 weeks. The generic part of the questionnaire assesses psychological functioning, disease-related impact, illness cognition and social support.

In the statistical analysis, Fisher's exact test was carried out to compare categorical data between two groups of patients, while the Kruskal-Wallis test was performed to compare continuous data between these two groups as the data di follow normal distribution.

Thirty-six endogenous eczema patients with prurigo nodularis and 47 endogenous eczema patients without prurigo nodularis were recruited. The characteristics of the two groups are listed in [Table 1]; there were no significant differences between their gender, education, employment and marital statuses.{Table 1}

Comparison of ISDL scores between the two groups is shown in [Table 2]. The extent of skin disease was determined by accessing the involvement of 9 different regions of the body and the severity of skin lesions in each region was graded with a score ranging from 1 to 4. The composite scores of both these parameters between the two groups were comparable.{Table 2}

The subjects with endogenous eczema and prurigo nodules indicated a higher itch score on the visual analog scale over the previous 4 weeks compared to those endogenous eczema patients without prurigo nodules (P = 0.0292). There was no significant difference between the two groups in the scores reflecting impact on daily life, stigmatization, psychological functioning, social support and illness cognition.

In our study, endogenous eczema patients with prurigo nodularis experienced higher itch intensities. We did not find psychological and social factors to be associated factors with the occurrence of prurigo nodularis in endogenous eczema. This is in contrast to two previous studies indicating that prurigo nodularis is associated with psychological factors.

In a study comparing patients with prurigo nodules with patients with psoriasis, Schneider et al. showed that the former has a higher prevalence of alexithymia, somatization symptoms, hypochondriasis, anxiety and depression and proposed that clinical management of prurigo nodularis should include psychosomatic assessment. [3] Carla et al. performed a questionnaire-based psychometric study on 20 patients with prurigo nodularis and found that symptoms of anxiety and depression were more severe in patients compared to controls. [4] In both the above studies, however, conditions causing itch in the patients with prurigo nodularis were not identified; it is therefore unclear if the associations of these psychological traits are directly linked to prurigo nodules or the underlying pruritic conditions, such as endogenous eczema.

A recent study has suggested that subclinical neuropathy is present in prurigo nodularis. [6] Compared to healthy controls, both lesional and uninvolved skin in patients with prurigo nodules were found to have a significantly lower density of intra-epidermal nerve fibers (these fibers are known to transmit the itch sensation). Hypersensitivity of the cutaneous nerves transmitting itch signals may be an explanation for the increased itch intensity observed in patients with prurigo nodularis in this study, and it may explain why some patients are more prone to the development of prurigo nodules compared to others with the same underlying condition.

Treatment of prurigo nodules is a challenge, and it is frustrating for both patients and dermatologists as the response is often limited and recurrences are frequent. It is important to continue trying to identify the etiological factors in the disease in order to develop more effective therapeutic and preventive strategies.

In summary, in patients with endogenous eczema, those with prurigo nodules experience a greater itch intensity compared to those without prurigo nodules. There were no other physical, psychological and social factors that were found to be associated with the occurrence of prurigo nodules in endogenous eczema.

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