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INVESTIGATIVE REPORT ActaDV ActaDV Advances in dermatology and venereology Acta Dermato-Venereologica
Incidence and Prevalence of Psoriasis in Denmark
Alexander EGEBERG 1 , Lone SKOV 1 , Gunnar H . GISLASON 2 – 4 , Jacob P . THYSSEN 1 and Lotus MALLBRIS 5
1
Department of Dermatology and Allergy , 2 Department of Cardiology , Herlev and Gentofte Hospital , University of Copenhagen , Hellerup ,
3
The Danish Heart Foundation , 4 The National Institute of Public Health , University of Southern Denmark , Copenhagen , Denmark , and 5 Eli Lilly and Co , Indianapolis , Indiana , USA
The incidence and temporal trends of psoriasis in Denmark between 2003 and 2012 were examined . There was a female predominance ranging between 50.0 % ( 2007 ) and 55.4 % ( 2009 ), and the mean age at time of diagnosis was 47.7 – 58.7 years . A total of 126,055 patients with psoriasis ( prevalence 2.2 %) were identified . Incidence rates of psoriasis ( per 100,000 person years ) ranged from 107.5 in 2005 to a peak incidence of 199.5 in 2010 . Incidence rates were higher for women , and patients aged 60 – 69 years , respectively . Use of systemic non-biologic agents , i . e . methotrexate , cyclosporine , retinoids , or psoralen plus ultraviolet A ( PUVA ) increased over the study course , and were used in 15.0 % of all patients . Biologic agents ( efalizumab , etanercept , infliximab , adalimumab , or ustekinumab ) were utilized in 2.7 % of patients . On a national level , incidence of psoriasis fluctuated during the 10- year study course . The relationship between psoriasis incidence and age appeared to be relatively linear , and disease prevalence was comparable to that in other European countries .
Key words : psoriasis ; incidence ; prevalence ; epidemiology . Accepted Apr 6 , 2017 ; Epub ahead of print Apr 17 , 2017 Acta Derm Venereol 2017 ; 97 : 808 – 812 .
Corr : Alexander Egeberg , Department of Dermatology and Allergy , Herlev and Gentofte Hospital , Kildegårdsvej 28 , DK-2900 Hellerup , Denmark . E- mail : alexander . egeberg @ gmail . com
Psoriasis is a prevalent chronic inflammatory disease characterized by localized or widespread , thick , silvery-white , scaly , pruritic plaques . The exact aetiology of psoriasis is not fully understood , but both genetic and environmental factors are involved in the onset and progression of the disease ( 1 ). Approximately 70 – 80 % of all patients with psoriasis are considered to have mild disease that can be managed with topical treatment alone ( 2 , 3 ). Studies have shown that psoriasis negatively affects patients ’ quality of life , and that depression occurs more often than in controls ( 2 , 4 , 5 ). Along this line , studies have also shown that psoriasis is a systemic disease , which also affects the joints , vasculature and other tissues . Indeed , approximately one-third of patients with psoriasis develop psoriatic arthritis , and patients with severe psoriasis have a shortened life expectancy as well as several major comorbidities ( 6 , 7 ).
While most recent epidemiological studies have examined comorbidities in psoriasis , potential changes in disease prevalence and incidence are less common . Based on past studies , psoriasis is estimated to affect approximately 2 – 4 % of the population in western countries ( 8 ); however , the prevalence varies with age , sex , geography and ethnicity . For example , while some studies have suggested that the onset of psoriasis is bimodal , with peaks at ages between 15 and 20 years and , later , at between 55 and 60 years ( 2 ), others have described that the prevalence increases are roughly linear over the life-course ( 3 ). Since few studies on psoriasis prevalence in Denmark have been published ( 9 – 11 ), we examined the time trend in incidence , as well as the prevalence of psoriasis in a Danish nationwide cohort .
MATERIALS AND METHODS Data sources and study population
Study approval was obtained from the Danish Data Protection Agency ( ref . 2007-58-0015 , int . ref . GEH-2014-018 , I-Suite 02736 ). Approval from an ethics committee is not required for registry studies in Denmark . The study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology ( STROBE ) recommendations ( 12 ).
Using the unique personal identification number assigned to all Danish citizens , individual-level information from nationwide administrative registers was linked . The Civil Registration System ( 13 ) contains information on sex , date of birth , and updated information on vital status and emigration , thus minimizing loss to follow-up . All inpatient and outpatient ( ambulatory ) hospital consultations are recorded in the Danish National Patient Register ( DNPR ) ( 14 ) including one primary and up to 19 secondary diagnoses coded by discharging physicians according to the International Classification of Diseases , 8 th revision ( ICD-8 ) ( prior to 1994 ), and according to the 10 th revision ( ICD-10 ) thereafter . The primary diagnosis is the main reason for the hospital consultation or hospitalization , and secondary diagnoses are additional conditions , including complications . The DNPR was established in 1977 , and outpatient data has been available from 1995 onwards . Since 1994 , detailed and accurate information on all pharmacydispensed medications has been registered in the Danish Registry of Medicinal Products Statistics according to the Anatomical Therapeutic Chemical ( ATC ) classification ( 15 ). Hospital administered pharmacotherapy is coded in the DNPR as treatment procedure ( SKS ) codes . We defined patients with incident psoriasis as those recorded with a corresponding first-time ICD-10 code ( L40 ) or an ATC code for pharmacotherapy for use exclusively in psoriasis ( D05AX ), and thus excluded all patients with a history of psoriasis based on the above criteria before 1 January 2003 in analyses of incident psoriasis . When examining the prevalence of psoriasis , these patients were not excluded . The study period was divided into 1-year groups from 2003 to 2012 . We identified use of systemic therapy , i . e . methotrexate , cyclosporine , PUVA , retinoids , efalizumab , etanercept , infliximab , adalimumab , and ustekinumab . doi : 10.2340 / 00015555-2672 Acta Derm Venereol 2017 ; 97 : 808 – 812
This is an open access article under the CC BY-NC license . www . medicaljournals . se / acta Journal Compilation © 2017 Acta Dermato-Venereologica .