Latitude and psoriasis prevalence
2011; Elsevier BV; Volume: 65; Issue: 4 Linguagem: Inglês
10.1016/j.jaad.2009.05.047
ISSN1097-6787
AutoresChristine C. Jacobson, Sandeep Kumar, Alexa B. Kimball,
Tópico(s)Dermatology and Skin Diseases
ResumoTo the Editor: Two important factors influencing psoriasis prevalence rates include climate and ethnicity, although these relationships are complicated. The ultraviolet index is of interest given the popular and effective treatment modality of light therapy, and known effects of weather patterns on psoriasis.1Okada S. Weatherhead E. Targoff I.N. Wesley R. Miller F.W. Global surface ultraviolet radiation intensity may modulate the clinical and immunologic expression of autoimmune muscle disease.Arthritis Rheum. 2003; 48: 2285-2293Crossref PubMed Scopus (131) Google Scholar We collected psoriasis prevalence rates from regions around the globe by locating journal articles through the search engine PubMed using search terms “psoriasis epidemiology” and “prevalence” or “incidence.” We identified 22 population-based surveys, case-control studies, and reviews. Average, absolute latitudes for the study populations identified were based on the Central Intelligence Agency’s World Factbook 2008.2Central Intelligence Agency. The world factbook 2008. Available from: URL:https://www.cia.gov/library/publications/the-world-factbook/index.html. Accessed August 8, 2008.Google Scholar US and Chinese data were not included because of the multiple latitudes and the diverse climates present in each country. Where the study population comprised adults only, an approximate psoriasis prevalence of 0.6% in those younger than 20 years was assumed based on several studies.3Leder R.O. Farber E.M. The variable incidence of psoriasis in sub-Saharan Africa.Int J Dermatol. 1997; 36: 911-919Crossref PubMed Scopus (39) Google Scholar Results are listed in Table I and Fig 1. Prevalence rates ranged from 0% (Samoa, average absolute latitude 13.35) to 3.3% (Tanzania, average absolute latitude 6), with the exception of the Arctic Kasach’ye (average absolute latitude 66.03), an outlier with 11.8% psoriasis prevalence. The median prevalence rate was 1.43%. The mean of the prevalence values was 1.90%. No meaningful correlation between absolute latitude and psoriasis prevalence was demonstrated (r2 = 0.1201, P < .05).Table ICountry of study, absolute latitude, and psoriasis prevalenceCountryAbsolute latitudePsoriasis prevalence, %Data sourceTanzania63.3Masawe AEJ. Psoriasis in Tanzania. Int Psor Bull 1973;I:I.Sri Lanka70.4Gunawardena DA, Gunawardena KA, Vasanthanathan NS, Gunawardena JA. Psoriasis in Sri Lanka–a computer analysis of 1366 cases. Br J Dermatol 1978;98:85-96.Nigeria10<0.1Shrank AB. A field survey in Nigeria. Trans St Johns Hosp Dermatol Soc 1965;51:85-94.Samoa13.350Nall ML, Farber EM. World epidemiology in psoriasis. In: Farber EM, Cox AJ (editors). Psoriasis: proceedings of the second international symposium. New York: Yorke Medical Books; 1977. p. 331-3.South Africa29<0.1Ross CM. Skin disease in the Venda. S Afr Med J 1966;40:302-8.Busselton, Australia33.382.16Quirk CJ. Skin disease in the Busselton population survey. Med J Aust 1979;1:569-70.Spain401.43Ferrandiz C, Bordas X, Garcia Patos V, Puig S, Pujol R, Smandía A. Prevalence of psoriasis in Spain (Epiderma Project: phase I). J Eur Acad Dermatol 2001;15:20-3.Croatia45.11.55Barisic-Drusko V, Paljan D, Kansky A, Vujasinovic S. Prevalence of psoriasis in Croatia. Acta Derm Venereol Suppl (Stockh) 1989;146:178-9.Billesdon, United Kingdom52.361.5Nevitt GJ, Hutchinson PE. Psoriasis in the community: prevalence, severity and patients’ beliefs and attitudes towards the disease. Br J Dermatol 1996;135:533-7.England531.5Rea JN, Newhouse ML, Halil T. Skin disease in Lambeth: a community study of prevalence and use of medical care. Br J Prev Soc Med 1976;30:107-14.United Kingdom541.5Gelfand JM, Weinstein R, Porter SB, Neimann AL, Berlin JA, Margolis DJ. Prevalence and treatment of psoriasis in the United Kingdom. Arch Dermatol 2005;141:1537-41.Denmark562.85 (3.2% M, 2.5% F)Brandrup E, Green A. The prevalence of psoriasis in Denmark. Acta Derm Venereol 1981;61:344-6.Faroe Islands622.8Lomholt G. Psoriasis: prevalence, spontaneous course and genetics: a census study on the prevalence of skin diseases in the Faroe Islands. Copenhagen: GEC Gad; 1963.Norway621.4Braathen LR, Botten G, Bjerkedal T. Psoriatics in Norway: a questionnaire study on health status, contact with paramedical professions, and alcohol and tobacco consumption. Acta Derm Venereol Suppl (Stockh) 1989;142:9-12.Sweden622.3Lindegard B. Diseases associated with psoriasis in a general population of 159,200 middle-aged, urban, native Swedes. Dermatologica 1986;172:298-304.Sweden622Hellgren L. Psoriasis: a statistical, clinical and laboratory investigation of 255 psoriatics and matched controls. Acta Derm Venereol 1964;44:191-207.Sweden621.4Hellgren L. Psoriasis: the prevalence in sex, age, and occupational groups in total populations in Sweden; morphology, inheritance and association with other skin and rheumatic diseases. Stockholm: Almqvist & Wiskell; 1967.Arctic Kasach’ye66.0311.8Eckes L, Ananthakrishnan R, Walter H. The geographic distribution of psoriasis [in German]. Hautarzt 1975;26:563-7.Norway (Lapps)701.4Falk ES, Vandbakk Y. Prevalence of psoriasis in a Norwegian Lapp population. Acta Derm Venereol 1993;182:6-9.Norway (Lapps)700.6Kavli G, Stenvold SE, Vandbakk O. Low prevalence of psoriasis in Norwegian Lapps. Acta Derm Venereol 1985;65:262-3.Italy422.9Saraceno R, Mannheimer R, Chimenti S. Regional distribution of psoriasis in Italy. J Eur Acad Dermatol Venereol 2008;22:324-9.F, Female; M, male. Open table in a new tab F, Female; M, male. A very weak relationship was found between latitude and psoriasis prevalence in this study, which suggests that susceptibility to psoriasis is not mitigated by ambient ultraviolet exposure, and that other factors, or combinations of factors may play a role. Humidity also does not appear play a dominant role, although the data are more limited. Coastal Angola and Dakar, Senegal, for example–areas of high aridity–are regions of low psoriasis incidence, whereas two studies from Kampala, Uganda–an area of high annual rainfall–showed a relatively high psoriasis incidence. Conversely, the tropical rainforest areas of Nigeria and Sierra Leone have quite low psoriasis rates.3Leder R.O. Farber E.M. The variable incidence of psoriasis in sub-Saharan Africa.Int J Dermatol. 1997; 36: 911-919Crossref PubMed Scopus (39) Google Scholar Limitations of this study include data heterogeneity: this is a compilation of individually performed studies with nonstandardized methods, moreover, many studies relied on self-reports of a psoriasis diagnosis. Other drawbacks of the study include the variability of prevalence rates caused by other factors including the possibility of different psoriasis rates in different genetic pools, altitude (ultraviolet directly proportional to altitude), and days of actual sunshine per year, which may vary in different regions regardless of latitude. However, although no substantial correlation between latitude and psoriasis prevalence has been shown here, one interesting aspect of this study is the demonstration of the relative consistency of psoriasis prevalence rates across the globe. Although an outlier existed in areas with limited genetic variability (ie, the Arctic Kasach’ye), in general the prevalence rates were quite consistent and tended to be in the 1.5 to 2.0 range, suggesting conserved genetic and environmental susceptibilities worldwide. Psoriasis: Latitude does make a differenceJournal of the American Academy of DermatologyVol. 77Issue 2PreviewTo the Editor: In their review of the epidemiology literature on psoriasis, Jacobson et al1 concluded that: “No meaningful correlation between absolute latitude and psoriasis prevalence was demonstrated (r2 = 0.1201, P < .05).” The conclusion of “no meaningful association” is a quotation that pervades the literature.2-4 Full-Text PDF
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