ORIGINAL ARTICLE

Comparison of Perceptions of Skin Condition, Product Use and Allergen Reactivity Between People with Psoriasis and Controls in the European Dermato-Epidemiology Network (EDEN) Fragrance Study

Fortunato CASSALIA^1,2, Simone CAZZANIGA^1,3, Robert OFENLOCH⁴, Peter ELSNER⁵, Margarida GONÇALO⁶, Marie-Louise SCHUTTELAAR⁷, Åke SVENSSON⁸, Elena PEZZOLO^1,9, Magnus BRUZE¹⁰ and Luigi NALDI^1,9

¹Centro Studi GISED, Bergamo, ²Dermatology Unit, Department of Medicine, University of Padova, Padua, Italy, ³Inselspital University Hospital of Bern, University of Bern, Bern, Switzerland, ⁴Section of Occupational Dermatology, Department of Dermatology, University Hospital Heidelberg, Heidelberg, Germany, ⁵Dermatology, Allergology, Dermatopathology, SRH- Klinikum Gera, Germany, ⁶Department of Dermatology, Faculty of Medicine, University Hospital, University of Coimbra, Portugal, ⁷Department of Dermatology, University Medical Center Groningen, Groningen, The Netherlands, ⁸Department of Dermatology, University Hospital, Lund University, Malmö, Sweden, ⁹Department of Dermatology, Ospedale San Bortolo, Vicenza, Italy and ¹⁰Department of Occupational and Environmental Dermatology, Skåne University Hospital, Malmö, Sweden

Psoriasis, a chronic inflammatory skin disease, goes beyond visible symptoms and affects the general well-being of patients. The aim of this study is to understand how patients with psoriasis perceive their skin characteristics and reactivity to allergens. The study population includes 11,283 participants within the European Dermato-Epidemiology Network (EDEN) Fragrance study, covering several European regions. The study compared perceptions of skin dryness, sensitivity, product avoidance and reactivity to allergens between patients with psoriasis and controls, evaluating the potential influence of psoriasis severity. The results showed that subjects with psoriasis reported dry skin (71.1%) and sensitive skin (49.4%) more often than did controls (51.6% and 38.5%, respectively). Psoriasis patients were more likely to avoid specific products. Interestingly, there were no significant differences in patch-test results between the 2 groups and the severity of psoriasis did not have a consistent impact on these perceptions. In conclusion, people with psoriasis tend to perceive their skin as drier and more sensitive. Notably, the severity of psoriasis did not consistently influence these perceptions and objective reactivity to allergens did not align with subjective perception. Understanding these aspects is crucial for tailoring treatments to improve the well-being of patients with psoriasis, which warrants further research to explore subjective perceptions of skin well-being in patients with psoriasis.

Key words: psoriasis; skin dryness; skin sensitivity; allergen reactivity; patch-test; topical treatment; neuro-immune inflammation.

SIGNIFICANCE

This study examines the question as to whether the perception of skin dryness and sensitivity differs between patients with psoriasis and controls. In this population-based survey (cross-sectional study) of 11,283 participants, subjects with psoriasis reported a higher prevalence of dry (71.1%) and sensitive (49.4%) skin than those without psoriasis (51.6% and 38.5%, respectively). However, no significant differences in patch-test results were observed between the 2 groups. Finally, the study found that people with psoriasis perceived their skin as drier and more sensitive than controls, regardless of psoriasis severity, highlighting the importance of addressing subjective perceptions in treatment strategies.

 

 

INTRODUCTION

Psoriasis is a chronic, inflammatory skin disease characterized by the presence of red, scaly plaques accompanied by symptoms such as itching, burning and pain (1). Notably, psoriasis is not limited to dermatological implications, as it has been associated with arthritis (2, 3) and other comorbidities, e.g. cardiovascular disease (4–7). The association between psoriasis and mental health should not be overlooked (8). Numerous studies have reported the social, relational, work, and quality of life (QoL) implications of living with psoriasis (9–12). In this scenario, an area of interest focuses on the subjective perception of overall skin well-being reported by people with psoriasis. Most studies have considered itching, and pain associated with skin lesions (13–15). To our knowledge, there is no work to date that has investigated the association of the subjective perception of overall skin dryness or sensitivity, and reactivity to specific allergens in patients with psoriasis. This population-based survey, performed in the context of the European Dermato-Epidemiology Network (EDEN) Fragrance study (16) aimed to comprehensively explore the subjective perception of dry and/or sensitive skin, and avoidance of products of common use in subjects with psoriasis and in people without psoriasis, by using a validated questionnaire, and to assess allergen reactivity using standardized patch-test procedures.

MATERIALS AND METHODS

Study design

The study was approved by the ethics committee of each participating centre. All participants gave written informed consent before starting the interview. The European Dermato-Epidemiology Network (EDEN) Fragrance Study comprised a large descriptive epidemiological survey of the general population conducted in 6 European regions. These included the metropolitan areas of Malmö (Sweden), Thüringen (Germany), and Heidelberg (Germany), as well as the provinces of Groningen (The Netherlands), Bergamo (Italy), and Coimbra (Portugal). The study methods were previously published (17). Briefly, a random sample (age range 18–74 years) was selected from the general population, based on electoral precincts. The study followed a stratified, proportional, random sampling-with-replacement design. The participants were interviewed using a standardized questionnaire and were offered patch-testing to investigate sensitization to various fragrances. We present here the interview data and patch-test results. The full phase of the study was from 20 August 2008 to 10 October 2011. Each potential participant was contacted by letter. Non-responses were followed up with a second and third letter and a telephone call. If no contact was achieved, another individual was randomly selected in the same age and sex strata. The initial contact participation rates ranged from 20.3% to 50.7% depending on the region considered. Psoriasis was defined as a medical diagnosis of the disease ever received in the past. Severe psoriasis was considered as a disease diagnosed by a dermatologist and undergoing systemic therapy. Controls were all the people in the samples not reporting psoriasis. People reporting other skin diseases, such as atopic dermatitis or contact dermatitis, were maintained in the control group.

Data collection

Trained interviewers conducted face-to-face interviews, either at the home of the sampled person or at hospital, based on participant preference. The interview comprised 3 parts, recording demographic data, skin problem history, and exposure to consumer products. Participants were asked about sensitive and dry skin, previous dermatological diagnoses and their treatment, previous allergy tests, and product usage frequency. Questionnaire reliability was assessed on a subsample of 96 individuals, with strong agreement for demographic data and skin-related questions. For exposure frequencies to products, κ statistics ranged from 0.54 to 0.91, mostly exceeding 0.70. A web-based electronic form minimized errors and inconsistencies during data collection. In addition, a random sample (n = 3,119) of subjects were patch-tested with TRUE-test panel 1, 2 and 3 plus fragrance mix II, hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC), and sesquiterpene lactone mix. A positive patch-test reaction was considered as contact allergy.

Since information on psoriasis severity was not collected in the study, an algorithmic classification of disease severity was used. More specifically, the study considered subjects with moderate-to-severe psoriasis to be those diagnosed and treated by a dermatologist with the use of non-topical (systemic) medications in the previous 12 months (Table SI).

Sample size and data analyses

The study aimed to obtain confidence estimates of rates exceeding 0.5%. Using the Clopper-Pearson confidence interval (CI) method (18), we estimated that a sample size of 12,000 individuals would produce a 95% CI, with a width equal to 0.003 and a relative standard error (SE) of 13% when the sample prevalence was 0.5%. Therefore, we interviewed approximately 2,000 individuals per centre; a total of 12,377 participants. To assess the representativeness of the sample, selected demographic variables of the sample were compared with those of Eurostat 2010 data (19). For the purpose of this analysis, continuous data were categorized using clinically relevant or pre-defined cut-offs and presented as absolute numbers with percentages. Univariate differences of investigated variables between groups of patients were assessed using Pearson’s χ² test or Fisher’s exact test in places where required. In addition, multivariable logistic regression analysis was performed to control for potential confounding factors, such as sex, age, occupation, marital status, smoking habits, body mass index (BMI), and country of residence (20). The strength of association was expressed in terms of odds ratio (OR) along with its 95% CI and p-value. Patients with missing data were excluded from the analyses. All tests were considered statistically significant at p < 0.05. Analyses were performed using SPSS software v.26.0 (IBM Corp, Armonk, NY, USA).

RESULTS

Demographics and characteristics of the study population

The demographics and general characteristics of the study population is presented in Table I. A larger proportion of individuals in the age group 30–44 was observed among those with psoriasis (27.0%) than controls (24.4%) (p-value 0.02), and the prevalence of psoriasis tended to increase in older age groups. A significant increased prevalence of smokers and ex-smokers in the psoriasis group compared with controls (p < 0.001), and a significant association between psoriasis and higher BMI categories (p < 0.001) were also documented.

Table I. Demographics and characteristics of the study population, in total and in subjects with and without a lifetime diagnosis of psoriasis

		Total		Univariate analysis					Multivariable analysis
				No psoriasis		With psoriasis		p**	OR (95% CI)	p***
		N*	%	N*	%	N*	%
Sex	Total	11,283	100	10,693	94.8	590	5.2
	Male	5,274	46.7	4,993	46.7	281	47.6	0.66	1
	Female	6,009	53.3	5,700	53.3	309	52.4		1.00 (0.84–1.20)	0.96
Age	18–29 years	2,906	25.8	2,796	26.1	110	18.6	< 0.001	1
	30–44 years	3,035	26.9	2,891	27.0	144	24.4		1.49 (1.07–2.08)	0.02
	45–59 years	2,881	25.5	2,708	25.3	173	29.3		1.98 (1.39–2.82)	< 0.001
	60–74 years	2,461	21.8	2,298	21.5	163	27.6		2.09 (1.33–3.27)	0.001
Occupation	Working	6,386	56.7	6,060	56.7	326	55.3	< 0.001	1
	Student	1,677	14.9	1,606	15.0	71	12.1		1.08 (0.76–1.55)	0.67
	Unemployed	482	4.3	450	4.2	32	5.4		1.21 (0.82–1.79)	0.33
	Retired	1,824	16.2	1,698	15.9	126	21.4		1.00 (0.70–1.42)	0.98
	Homemaker	479	4.3	468	4.4	11	1.9		0.54 (0.28–1.04)	0.07
	Other	420	3.7	397	3.7	23	3.9		0.90 (0.57–1.41)	0.64
Marital status	Married/common law	6,224	55.4	5,919	55.6	305	51.8	0.07	1
	Divorced/widowed	1,110	9.9	1,038	9.8	72	12.2		1.03 (0.78–1.35)	0.85
	Single	3,899	34.7	3,687	34.6	212	36.0		1.25 (1.00–1.57)	0.06
Smoking habits	Non-smoker	6,299	55.9	6,036	56.5	263	44.7	< 0.001	1
	Ex-smoker	2,439	21.6	2,267	21.2	172	29.2		1.36 (1.10–1.68)	0.004
	Smoker	2,529	22.4	2,375	22.2	154	26.1		1.50 (1.22–1.86)	< 0.001
Body mass index (kg/m2)	< 20	998	8.9	960	9.0	38	6.5	< 0.001	0.88 (0.62–1.26)	0.48
	20–24.9	5,399	48.1	5,128	48.2	271	46.1		1
	25–29.9	3,554	31.7	3,374	31.7	180	30.6		0.96 (0.78–1.18)	0.72
	≥30	1,269	11.3	1,170	11.0	99	16.8		1.44 (1.12–1.85)	0.005
95% CI: 95% confidence interval; OR: odds ratio.
*Numbers may not add up to the total due to missing data. **Pearson’s χ2 test. ***Multivariable logistic regression analysis including terms for sex, age, occupation, marital status, smoking habits, body mass index and country of residence.

Subjective perceptions related to skin conditions and avoidance experience of subjects with and without a lifetime diagnosis of psoriasis

Table II presents the findings regarding perception related to the skin and avoidance experience in subjects with and without a lifetime diagnosis of psoriasis. An association between psoriasis and dry skin, with an OR 1.99 (95% CI 1.64–2.41) was observed, indicating that individuals with psoriasis were nearly twice as likely to experience dry skin compared with controls. Similarly, the perception of sensitive skin was more prevalent in the psoriasis group (49.4%) than in the non-psoriasis group (38.5%), OR 1.65 (95% CI 1.38–1.97), indicating that individuals with psoriasis had a 65% higher likelihood of reporting sensitive skin. Regarding avoidance behaviour, individuals with psoriasis showed higher rates of avoiding leave-on products (49.8%), rinse-off products (30.3%), household products (26.9%), and other products (33.7%) compared with individuals without psoriasis. All these avoidance behaviours exhibited statistically significant associations with psoriasis (p < 0.001) with ORs ranging from 1.47 to 1.62. Also, avoidance of topical medications at any time was significantly more common in individuals with psoriasis (9.2%) than in those without psoriasis (5.0%). Fig. 1 depicts the avoidance of products among subjects with and without a lifetime diagnosis of psoriasis. No consistent association between psoriasis severity and the factors investigated was documented, the only variables showing an association with severity being avoidance of household products (Table SII).

Table II. Perceptions related to the skin and avoidance experience of subjects with and without a lifetime diagnosis of psoriasis

	Univariate analysis					Multivariable analysis
	No psoriasis		With psoriasis		p**	OR (95% CI)^	p***
	N*	%	N*	%
Dry skin	5,435	51.6	414	71.1	< 0.001	1.99 (1.64–2.41)	< 0.001
Sensitive skin	4,054	38.5	288	49.4	< 0.001	1.65 (1.38–1.97)	< 0.001
Avoidance of metals	3,107	29.0	208	35.3	0.001	1.20 (0.99–1.46)	0.06
Avoidance of rubbers	688	6.4	52	8.8	0.02	1.29 (0.95–1.75)	0.10
Avoidance of leave-on products	3,780	35.3	294	49.8	< 0.001	1.47 (1.23–1.77)	< 0.001
Avoidance of rinse-off products	2,156	20.1	179	30.3	< 0.001	1.48 (1.22–1.79)	< 0.001
Avoidance of household products	1,812	16.9	159	26.9	< 0.001	1.62 (1.33–1.98)	< 0.001
Avoidance of other products°	2,360	22.1	199	33.7	< 0.001	1.43 (1.19–1.73)	< 0.001
Avoidance of topical medications	537	5.0	54	9.2	< 0.001	1.62 (1.19–2.19)	< 0.001
95% CI: 95% confidence interval; OR: odds ratio.
*Numbers may not add up to the total due to missing data. **Pearson’s χ2 test. ***Multivariable logistic regression analysis including terms for sex, age, occupation, marital status, smoking habits, body mass index (BMI) and country of residence.
^Odds ratio (OR) comparing yes vs no. °Including bandages or tape, leather products, henna or permanent tattoos, hair colourants.

Fig. 1. Avoidance of products among subjects with and without a lifetime diagnosis of psoriasis.

Use of medications, history of allergy tests and results of patch-testing

As shown in Table III, the use of anti-inflammatories, antibiotics and analgesics showed no significant difference between subjects with and without a lifetime diagnosis of psoriasis. The use of topical steroids in the past year was significantly more prevalent in the psoriasis group (40.3%) compared with the non-psoriasis group (14.9%) (p < 0.001), with a substantial OR of 3.13.

Table III. Use of selected drugs and performance of allergy tests in subjects with and without a lifetime diagnosis of psoriasis

	Univariate analysis					Multivariable analysis
	No psoriasis		With psoriasis		p**	OR (95% CI)^	p***
	N*	%	N*	%
Anti-inflammatory drugs used in past year?	3,294	31.2	195	33.5	0.24	1.07 (0.89–1.28)	0.48
Analgesics used in past year?	3,713	35.1	233	40.0	0.02	1.02 (0.85–1.23)	0.81
Antibiotics used in past year?	958	9.1	49	8.6	0.65	1.06 (0.77–1.45)	0.73
Topical steroids used in past year?	1,568	14.9	231	40.3	< 0.001	3.13 (2.60–3.76)	< 0.001
Topical anaesthetics used in past year?	734	7.7	33	6.7	0.39	0.93 (0.63–1.35)	0.69
Prick tests performed in lifetime?	2,879	27.4	211	37.2	< 0.001	1.14 (0.94–1.38)	0.17
Patch tests performed in lifetime?	1,088	10.5	121	21.1	< 0.001	1.60 (1.28–2.00)	< 0.001
Allergy testing performed in lifetime?	730	7.2	65	12.0	< 0.001	1.56 (1.18–2.06)	0.002
95% CI: 95% confidence interval; OR: odds ratio.
*Numbers may not add up to the total due to missing data. **Pearson’s χ2 test. ***Multivariable logistic regression analysis including terms for sex, age, occupation, marital status, smoking habits, body mass index (BMI) and country of residence.
^OR comparing yes vs no.

Individuals with psoriasis were more likely to have undergone patch-tests (21.1%) and other allergy tests (12.0%) in their lifetime compared with those without psoriasis (10.5% and 7.2%, respectively). Both patch-tests and other allergy tests showed statistically significant associations with psoriasis (p < 0.001), with ORs of 1.60 and 1.56, respectively.

Table IV presents the results of patch-testing in the random sample of subjects selected for performing such a procedure. There was no significant difference in the rates of positive reactions between individuals with psoriasis and those without psoriasis for the tested allergens. No consistent correlation of any of the above-mentioned variables with the severity of psoriasis was shown; the only significant association being antibiotics used in the last year (Table SIII).

Table IV. Positive reactions in the random sample of subjects undergoing patch-test

At least 1 positive reaction to:	Univariate analysis					Multivariable analysis
	No psoriasis		With psoriasis		p**	OR (95% CI)^	p***
	N = 2,743*	%	N = 163*	%
True Test Panel 1	507	18.5	32	19.6	0.71	1.15 (0.75–1.76)	0.52
True Test Panel 2	246	9.0	19	11.7	0.25	1.26 (0.74–2.12)	0.39
True Test Panel 3	23	0.8	1	0.6	1	0.62 (0.08–4.72)	0.65
Single substances of FM I	73	2.7	7	4.3	0.21	1.35 (0.56–3.24)	0.50
Single substances of FM II	62	2.3	5	3.1	0.42	1.02 (0.36–2.91)	0.97
EU–Standard series1	103	4.2	6	4.1	0.98	1.04 (0.44–2.46)	0.94
Metals2	422	15.4	25	15.3	0.99	1.07 (0.67–1.72)	0.77
Preservatives3	179	6.5	9	5.5	0.61	0.69 (0.33–1.46)	0.34
Rubbers4	37	1.3	5	3.1	0.08	2.35 (0.87–6.35)	0.09
Topical steroids5	17	0.6	1	0.6	1	0.77 (0.10–5.97)	0.80
Any tested allergen	772	28.1	43	26.4	0.63	0.90 (0.62–1.32)	0.60
1Including new fragrance mix (b+), fragrance mix ii 14% pet, balsam of Peru, sesquiterpenelactone mix 0.1% pet and lyral 5% pet. 2Including nickel sulphate, potassium dichromate and cobalt chloride. 3Including thiomersal, cl+me-isothiazolinone, quaternium 15-, formaldehyde, parabens mix, diazolidinyl urea and imidazolidinyl urea. 4Including carba mix 250, black rubber mix, mercaptobenzothiazole, mercapto mix and thiuram mix. 5Including budesonide, tixocortol-21-pivalate and hydrocortisone-17-butyrate.
95% CI: 95% confidence interval; FM: fragrance mix; OR: odds ratio.
*Numbers may not add up to the total due to missing data. **Pearson’s χ2 test or Fisher’s exact test where required. ***Multivariable logistic regression analysis including terms for sex, age, occupation, marital status, smoking habits, body mass index (BMI) and country of residence.
^OR comparing yes vs no.

DISCUSSION

Psoriasis, a complex and chronic inflammatory skin disease, has a significant impact on the physical, emotional, and social well-being of people with the condition (1). This study, using data from the EDEN Fragrance Study, conducted in 6 European regions sheds light on various aspects of psoriasis, revealing valuable information about the subjective experiences, coping behaviours, and allergen reactivity of those living with the condition. One of the most significant and intriguing finding was the higher prevalence of perceived dry and sensitive skin reported by those with psoriasis compared with those without the condition. Remarkably, this perception was independent of the severity of psoriasis, suggesting that factors other than the visible extent of skin lesions may contribute to these feelings (21). The study also revealed the cautious approach taken by people with psoriasis in exposing themselves to products of common use. Patients showed greater vigilance in avoiding specific products and substances than those without psoriasis. Specifically, patients with psoriasis showed a significantly higher tendency to avoid leave-on products, rinse-off products, and household products. Despite a significant association between psoriasis and the use of topical steroids in the past year, a greater percentage of patients with psoriasis (9.2%) compared with those without psoriasis (5.0%) reported having avoided some topical medications in their past history. This behaviour of avoiding topical medications may suggest a degree of non-adherence to topical medications. Psoriasis is a chronic condition that requires consistent and regular use of topical medications. Such a regular use may be difficult to follow on a long-term basis (22–26). In general, the avoidance behaviour might be a consequence of the perceived heightened sensitivity and dryness of the skin experienced by individuals with psoriasis. The higher frequency of allergy tests performed in their lifetime history may be an additional reflection of the concern of people with psoriasis about contact with products of common use (27). Despite these subjective experiences and behaviours, the study found no significant difference in positive reactions to patch-tests between individuals with and without psoriasis. It is possible that the psycho-emotional impact of psoriasis, widely documented in the literature, may influence the perception of skin reaction and sensitivity (28). Also, the release of cytokines and chemokines linked with psoriasis may influence neuro-inflammation and/or an increased excitability of peripheral nerve fibres, resulting in nerve hypersensitivity and alloesthesia not proportional to objective disease severity (29–39). Notably, vulvar pruritus and burning sensation is highly prevalent in women with psoriasis. In most of the cases these symptoms are not correlated with psoriasis severity or with location of the disease in the vulvar area (40).

It should be noted that the current study did not exclude from the control group people with dermatological conditions, such as atopic dermatitis or contact dermatitis. Hence, our estimates may be conservative and the association of psoriasis with skin sensitivity or product avoidance may be even more relevant than documented in this study.

To the best of our knowledge there is a paucity of studies investigating the subjective skin perception and skin reactivity of patients with psoriasis. Therefore, the current study will be a basis for future research and further investigation. In fact, delving into these aspects could be of importance in developing effective treatment strategies tailored to the specific needs of individuals with psoriasis. Considering the multifaceted nature of the condition, a better understanding of the complex interplay of factors contributing to subjective experiences in psoriasis may pave the way for more personalized and effective management approaches, ultimately improving the quality of life of people with the condition.

ACKNOWLEDGEMENTS

This study was partly funded by the Research Institute for Fragrance Materials (RIFM) and L’Oreal.

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