Dermatology Online Journal

Epidemiologic characteristics of pityriasis rosea in Athens Greece
Kyriakos P. Kyriakis, Ioulios Palamaras, Sofia Terzoudi, Georgia Pagana, Smaro Emmanuelides, Charalambos Michailides
Dermatology Online Journal 12 (1): 24

Department of Dermatology and Venereology, West Attica General Hospital "St. Barbara" Athens, Greece. fountou@spark.net.gr

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Pityriasis rosea (PR) is a self-limited, acute, papulosquamous skin disease of unknown etiology, characterized by distinctive oval lesions, minimal or no constitutional symptoms and usually a herald patch. PR is worldwide in distribution without apparent racial or genetic predisposition [1]. There are few published studies regarding epidemiologic characteristics of PR in Western populations and in nontropical climates.

In a hospital-based cross-sectional study done between 1995 and 2002, we diagnosed 479 patients with PR based on clinical or laboratory criteria when appropriate, an incidence 0.95 percent. This compares with the 0.4-4.8 percent relative incidence reported from dermatologic centers world-wide [2]. The overall denominator and reference population comprised 50,237 patients (20,909 or 41.6 % men and 29,328 or 58.4 %). Greek dermatology outpatients, aged 35 days to 96 years, consecutively examined by experienced dermatologists (Table 1). All cases entered in the study were first time referrals. Information was tabulated in an Access data base. The number of dermatologic patients examined was used as denominator for all strata relative incidence comparisons to eliminate any confounding effects from demographic and health-seeking behavior characteristics of the catchment area population (Mantel-Haenszel χ² stratified analysis).

The median age was 26 years both for males (2-78) and females (3-90). There was no significant difference in incidence between childhood (0-10) and adolescence (11-20). Overall (Table 1), a protracted susceptibility trend in the Greek population was noted because frequencies of cases ≤35 years versus older were 70 percent (334/479) and 30 percent (145/479), significantly different from those shown in other studies (χ², p<0.0001, Turkey [3]: 92-8 %, odds ratio-OR 4.8; USA [4]: 86-14 %, OR 2.7).

A significant overall female preponderance was detected (p=0.001, MH-OR 1.4 (1.1-1.6)). MH-OR is not confounded by attendance fluctuations as might happen with female to male incidence ratio of some other studies on PR [2, 3]. In most of the 5-year age group strata (12/17), women had higher incidence rates than men but only in the group 16-20 years reached significance (p=0.01,OR 1.9 (1.1-3.4)) (Table 1).

Peak incidence was reached during different age periods. In males between 6-10 years (1.6 %) followed by a second peak between 36-40 (1.55 %), whereas in females this occurred in the age group of 21-25 (2.02 %) and 31-35 (1.94 %) respectively (Table 1). When judged on the basis of the average incidence (0.95 %) PR declined after the age of 40 years in males and 50 years in females indicating a protracted susceptibility in women (Table 1).These are in contrast with a previous study, where incidence for both sexes raised and declined in a parallel manner [4].

Yearly, female preponderance was observed in 7 of the 8 years of the study but only overall was significant (p=0.001, MH-OR 1.4 (1.1-1.6)). Yearly incidences fluctuated significantly (p=0.008, χ²) and an interchange of relatively high and low rates was noted (0.6-1.2 %, data not shown). This is reminiscent of the wide range of reported incidences and is probably due to clusters and erratic time fluctuations inherent both epidemiologically and pathogenically in this disease [2, 5].

Recurrences were not detected or reported. The diversity of described climate parameters in association with PR expression might also explain the lack of significance in the incidence seasonal variation [2, 3, 4].

References

1. Bjornberg A, Tegner E. Pityriasis rosea. In Freedberg IM, Eisen AZ, Wolff K et al. (eds) Fitzpatrick's Dermatology in General Medicine, 5th edition, Mc Graw Hill NY, 1999: 541-546.

2. Chuh AA, Lee A, Molinari N. Case clustering in pityriasis rosea. Arch Dermatol 2003; 139: 489-493.

3. Harman M, Aytekin S, Akdeniz S, Inaloz S. Epidemiological study of pityriasis rosea in the Eastern Anatolia. Eur J Epidemiol 1998; 14: 495-497

4. Chuang TY, Ilstrup DM, Perry HO, Kurland LT. Pityriasis rosea in Rochester, Minnesota, 1969 to 1978. J Am Acad Dermatol 1982; 7: 80-89.

5. Lechat MF. Epidemiometric modelling in leprosy based on Indian data. Lepr Rev 1992; 63: 31s-39s.

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