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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.