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Year : 2006  |  Volume : 51  |  Issue : 4  |  Page : 250-254
Patch testing in Iranian patients: A ten-year experience

1 Department of Dermatology, Baqiyatallah University of Medical Sciences, Tehran, Iran
2 Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran, Iran
3 Department of Epidemiology, Baqiyatallah University of Medical Sciences, Tehran, Iran

Correspondence Address:
Masoud Davoudi
Baqiyatallah University of Medical Sciences, Mollasadra Ave. Tehran
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0019-5154.30287

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Background: Allergic contact dermatitis is a common inflammatory skin disease, which may occur as a result of exposure to specific allergens. Genetic and allergen exposure variations are determinants of different frequency of sensitization in different countries. The objective of this study was to determine the frequency of sensitization to contact allergens in the Iranian patients with dermatitis. Materials and Methods: We analyzed our patch-test database in a referral skin clinic in Tehran, Iran, retrospectively. All patients patch-testing with a clinical diagnosis of contact dermatitis and/or atopic dermatitis over a 10-year period (1993 to 2002) were included. The 23-allergen European standard series (ESS) screening has been used for evaluation in all the patients. Results: Data were available from a total of 222 patients. Out of them, 145 patients (65.3%) showed at least one positive reaction and 34 patients (15.3%) had more than two positive reactions. The five most common allergens were: nickel sulfate 50 (22.6%), cobalt chloride chloride 32 (14.5%), fragrance mix 30 (13.6%), potassium dichromate 21 (9.5%) and neomycin sulfate 20 (9.0%). Contact allergy to nickel sulfate was significantly more common in females and in younger patients ( P <0.05). Fragrance mix was the most common allergen in male patients, but there was no significant difference in its frequency between males and females. Conclusion: The ESS seems to be suitable for patch testing patients in Iran. Nickel sulfate was found to be the most common contact allergen in Iran, mostly affecting women and younger patients probably due to more exposure.

Keywords: Allergic contact dermatitis, European standard series, patch test

How to cite this article:
Davoudi M, Firoozabadi MR, Gorouhi F, Zarchi AK, Kashani MN, Dowlati Y, Firooz A. Patch testing in Iranian patients: A ten-year experience. Indian J Dermatol 2006;51:250-4

How to cite this URL:
Davoudi M, Firoozabadi MR, Gorouhi F, Zarchi AK, Kashani MN, Dowlati Y, Firooz A. Patch testing in Iranian patients: A ten-year experience. Indian J Dermatol [serial online] 2006 [cited 2023 Mar 30];51:250-4. Available from:

   Introduction Top

Allergic contact dermatitis (ACD) is a very challenging problem in dermatology with considerable morbidity and economic impact. ACD, together with irritant contact dermatitis, comprises 6-10% of all dermatology clinic visits.[1] ACD is a delayed type hypersensitivity reaction, which develops in predisposed individual as a consequence of environmental exposures to allergens.[2],[3] The total number of sensitized persons in the population mainly depends on the degree of cutaneaous exposure, although it appears that some persons are more easily sensitized to common haptens than others, probably due to their genetic backgrounds.[4]

Exposure patterns change over time owing to fashion trends, technological developments, regional traditions and environmental specifications or as a result of official regulations.[5] There is also considerable variability from center to center and from country to country due to variation in exposure to the allergens.[6]

The patch-test has been established as a useful tool for the detection of allergic contact dermatitis and for exact identification of all the contact allergens, although 10-15% of healthy individuals may also show one or more positive reactions in the test.[7],[8] Patch-test studies in different countries and groups can provide information for direct preventive measures such as exposure reduction to prevent sensitization as well as elicitation of contact dermatitis. The purpose of this retrospective study was to summarize the results of patch-testing in a private dermatology clinic in Iran over a period of ten years.[9]

   Materials and Methods Top


We analyzed our patch-test database in a referral skin clinic in Tehran, Iran, retrospectively. All patients patch-testing with a clinical diagnosis of contact dermatitis and/or atopic dermatitis over a 10-year period (1993 to 2002) were included.

Patch testing

The patients were tested with the 23-allergen European standard series. Patch-tests were performed and read in accordance with the guidelines of the ICDRG[4] Finn-chamber-on-scanpor was used to apply allergens and patches were attached for 48h. First readings were performed between 20 to 40 minutes after removal of patches and then, 24h later.

Data analysis

Data were stored and assessed using SPSS for windows released 10.1 standard version. Chi-square and Fisher's exact tests were used wherever needed. Pearson's correlation coefficients were used to evaluate the strength of association between any two continuous variables and P values <0.05 were considered as significant.

   Results Top

Two hundred and twenty two patients consisting of 74 (33.3%) men and 148 (66.7%) women with an age range between three and 90 years (mean SD = 33.513.8 years) were patch-tested. The duration of eczema among these patients was between one month and 30 years. (mean SD = 53.6 61.7 months). The clinical diagnoses of patients before patch test were: ACD 59%, irritant contact dermatitis 24%, atopic dermatitis 10% and 17% other dermatitis. One hundred and forty five patients (65.3%) had at least one positive reaction and there were a total of 285 positive reactions in these patients. The five most common allergens were: nickel sulfate 50 (22.6%), cobalt chloride 32 (14.5%), fragrance mix 30 (13.6%), potassium dichromate 21 (9.5%) and neomycin sulfate 20 (9.0%). The distribution of sensitization to the allergens according to gender and age groups is shown in [Table - 1].

In total, 66 patients were positive to one substance, 45 to two substances, 17 to three substances, 11 to four substances, three to five and two to six substances. Only one patient showed positive reactions to seven substances - consisting of potassium dichromate, thiuram mix, cobalt chloride, epoxy resin, fragrance mix, quaternium-15 and nickel sulfate. In addition, none of the patients were sensitive to clioquinol.

Nickel sulfate (26.5%) was the most common allergen in women, followed by cobalt chloride (16.3%) and fragrance mix (12.2%). In men, fragrance mix (16.2%) was the most common sensitizer, followed by potassium dichromate and nickel sulfate (14.9% each). While the majority of females (70.1%) showed sensitivity to at least one allergen, this figure was only 56.7% in males ( P <0.05).

Females and younger patients had more sensitivity to nickel sulfate and methylchloroisothiazolinone than males and older patients ( P < 0.05). Besides, positive reactions to potassium dichromate and thiuram mix were more frequent in older patients ( P < 0.05).

Overall, similar percentage of men and women were sensitive to potassium dichromate, but the sensitivity was significantly more frequent among men than women in patients below the age of 40 years ( P <0.05). There were significant associations between positive reactions to cobalt chloride and positive reactions to nickel and potassium dichromate ( P <0.00001).

   Discussion Top

This study was performed to evaluate the results of patch-testing in a sample of Iranian patients over a 10-year period and to compare it with previous results from this region (Middle East) and worldwide [Table - 2],[Table - 3]. In this study, 145 out of 222 patients (65.3%) showed at least one positive reaction; this figure is comparable to most of other reports from Middle East.[10],[11]

The five most common allergens were: nickel sulfate (22.6%), cobalt chloride (14.5%), fragrance mix (13.6%), potassium dichromate (9.5%) and neomycin sulfate (9.0%).

While the majority of females (70.1%) showed sensitivity to at least one allergen, this figure was only 56.7% in males ( P <0.05). This is also in accordance with many other studies. It has been found that irritant and allergic contact dermatitides are more frequent in women as compared to men.[12],[13]

Nickel was the most common sensitizer in this study. Nickel is the leading allergen in the Middle East and its sensitivity rates vary from 15% to 39.5% in this region [Table - 2]; these rates are much higher than large studies done in the other parts of the world.[14]

There is no doubt that nickel is the most frequent allergen in majority of countries,[15],[16] but there are reports of some declination in frequency of nickel sensitivity in young German[17] and Danish[18] females that may be due to EU regulations that limited the nickel release threshold at 0.5 micrograms/cm 2sub per week from nickel containing alloy and coatings that are in prolonged contact with skin.[19] However, a German multi-center study showed a stable prevalence of nickel allergy from 16.7% in 1992 to 16.3% in 1996.[16] In this study, nickel sensitivity was significantly more common in females and younger patients. This finding is in agreement with that of most previous studies.[20],[21] Several studies have suggested that a prominent correlation between nickel allergy and sensitization lies with exposure and not sex.[22],[23] Therefore, the fact that ear-piercing as well as use of jewelry is so common in Iranian women but a very rare fashion trend in men, may explain this difference.

The significant associations between sensitivity to nickel and sensitivity to formaldehyde and epoxy resin ( P <0.05), which we observed in this study, has not been reported previously. We are unable to give an explanation for this observation and it might be a coincidental association.

In this study, sensitivity to cobalt chloride ranked second with a frequency of 14.5%. There were only three isolated positive cobalt chloride patch-tests, whereas strong associations between positive reactions to cobalt chloride and positive reactions to nickel and potassium dichromate were observed ( P <0.00001), which are in agreement with that of other studies.[4],[24],[25] These relationships are thought to be related to the fact that the metals are usually associated with one another.[26] However, enhanced individual susceptibility to sensitization has also been suggested.[27]

It is a considerable fact that fragrance mix is a relatively common allergen in Middle East, with sensitivity rates of 14.5%, 9.8% and 7.7% in Saudi Arabia, UAE and Pakistan, respectively. In our study, fragrance mix was the third most common allergen in total with frequency of 13.6%. The observation that fragrance mix was the most common allergen in males in our study (16.2%) is in accordance with a report from UAE (9.8%), but in contrast to some other studies.[10],[11],[12] The variations in the frequency of fragrance mix allergy between countries are related to differences in cosmetics and toiletries usage.[28] Fragrance mix is usually considered as one of the most frequent allergens in the elderly,[29] but surprisingly, we did not find even a single positive reaction to fragrance mix in the patients above the age of 60 years.

Potassium dichromate allergy has a relatively similar frequency rate among Middle East countries [Table - 2] except in Saudi Arabia with a high rate of 32.9%.[12] It is the second leading cause of contact allergy in Pakistan,[11] Turkey[30] and Saudi Arabia. It was the fourth common allergen in this study and the low rates of suspected occupational dermatitis in this sample of patients could be the cause. Despite some reports,[31] potassium dichromate sensitivity was found to be significantly more frequent in men than women in patients below the age of forty years ( P <0.05). However, this finding is consistent with report from Turkey and Saudi Arabia. The different geographical locations and associated ethnic and socio-economic considerations may be the real cause of these differences.

In the United States, a concentration of 0.25% of potassium dichromate is used for patch-testing but all other main patch test series contain 0.5% concentration; so sensitivity rate to this allergen is commonly lower in reports from USA than other parts of the world [Table - 3].[32],[33],[34]

The sensitivity rate of colophony in this study was similar to reports from other countries of the region, except Turkish study [Table - 2]. Major sources of colophony allergy are adhesives and cosmetics. There were significant associations between positive reactions to colophony and positive reactions to fragrance mix and balsam of Peru as well ( P <0.05). The fact that all these substances are used in cosmetic products may explain this finding.

Balsam of Peru is a common allergen in many countries,[20],[32] but the sensitivity to it was observed in only 2.7% of our patients. Preservatives used in various products may be responsible for allergy to it and preservatives containing products seems to be less commonly used in Iran.

We did not find even a single positive reaction to clioquinol. So it seems that this allergen may not be suitable for screening patients for allergic contact dermatitis in Iran.

   Conclusions Top

The European Standard Series seems to be suitable for patch-testing patients in our country; however we suggest exclusion of clioquinol. Women with positive sensitization significantly outnumbered men in our study. The five most common allergens were: nickel sulfate, cobalt chloride, fragrance mix, potassium dichromate and neomycin sulfate. Nickel sulfate found to be the most common contact allergen in Iran, mostly affecting women and younger patients probably due to more exposure.

   References Top

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  [Table - 1], [Table - 2], [Table - 3]

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