Original article
Increased risk of infectious disease requiring hospitalization among patients with psoriasis: A population-based cohort

https://doi.org/10.1016/j.jaad.2010.08.036Get rights and content

Background

Immunologic alterations caused by psoriasis and/or its therapies may affect the risk of serious infections.

Objective

For patients with psoriasis, we explored the overall and therapy-related risk of contracting an infectious disease (ID) requiring hospitalization in a large population-based cohort.

Methods

The incidence of ID was compared between patients with psoriasis and a randomly selected cohort (ratio 1:5) using hospital and pharmacy databases covering 2.5 million Dutch residents between 1997 and 2008. First and multiple IDs were defined and categorized into 20 groups based on primary International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnoses. Multivariate Cox regression and Poisson event-count models were used to test the risk difference of IDs between patients with psoriasis and reference cohort.

Results

A total of 25,742 patients with psoriasis and 128,710 reference subjects were followed up for approximately 6 years. The likelihood of IDs in patients with psoriasis was twice as high as the reference population (908 vs 438 events/100,000 person-years, crude hazard ratio 2.08, 95% confidence interval 1.96-2.22). In a multivariate model the hazard ratio decreased to 1.54 (95% confidence interval 1.44-1.65). This risk was highest for patients with more severe psoriasis (adjusted hazard ratio 1.81, 95% confidence interval 1.57-2.08), but was not associated with recent systemic antipsoriatic drug dispensing. Respiratory tract, abdominal, and skin infections occurred most frequently in patients with psoriasis. Multiple event analysis that counted the total number of infectious discharge diagnoses gave similar results.

Limitations

No data were available on lifestyle factors.

Conclusion

The risk of severe infections was significantly higher for patients with psoriasis compared with control subjects and could not be explained by exposure to systemic antipsoriatic drugs.

Section snippets

Data source

For this study we used data from the PHARMO Record Linkage System, which links various medical databases, including the National Medical Register of hospital discharge information and outpatient drug dispensing records (by general practitioners and medical specialists) concerning 2.5 million individuals who were ever residents in defined areas in The Netherlands.8, 9, 10, 11, 12 The hospital records included detailed information on primary and secondary diagnoses (coded according to the

Study population

A total of 154,452 people, 25,742 (16.7%) of whom had psoriasis, were followed up for an average of 6 years (Table I). Patients with psoriasis were older than the reference cohort (mean age 44.3 vs 38.2 years, P < .001), but the distribution between male and female gender was comparable. The proportion of subjects with a hospitalization of any kind in the 6 months before cohort entry was almost twice as high in the psoriasis cohort. During the available follow-up, 8.4% of the patients with

Discussion

The results of this large population-based cohort study indicate that the risk of serious infections requiring hospitalization is about two times higher in patients with psoriasis than in the general Dutch population. The ID risk was positively related to the psoriasis severity. It was highest in subjects with more severe psoriasis (ie, those who had used PUVA, a systemic therapy, or an inpatient treatment) showing one additional ID per 82 severe psoriasis cases, whereas there was one extra ID

References (35)

  • A.L. Neimann et al.

    Prevalence of cardiovascular risk factors in patients with psoriasis

    J Am Acad Dermatol

    (2006)
  • R.S. Stern et al.

    Psoriasis is common, carries a substantial burden even when not extensive, and is associated with widespread treatment dissatisfaction

    J Investig Dermatol Symp Proc

    (2004)
  • S.K. Kurd et al.

    The prevalence of previously diagnosed and undiagnosed psoriasis in US adults: results from NHANES 2003-2004

    J Am Acad Dermatol

    (2009)
  • E.J. Hollox et al.

    Psoriasis is associated with increased beta-defensin genomic copy number

    Nat Genet

    (2008)
  • R. Lande et al.

    Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide

    Nature

    (2007)
  • P.L. Zeeuwen et al.

    Genetically programmed differences in epidermal host defense between psoriasis and atopic dermatitis patients

    PLoS One

    (2008)
  • B. Lindegard

    Diseases associated with psoriasis in a general population of 159,200 middle-aged, urban, native Swedes

    Dermatologica

    (1986)
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    Supported by an unrestricted grant provided by Wyeth.

    Disclosure: PHARMO is a research institute that performs financially supported studies for several pharmaceutical companies, including Wyeth and Novartis. Mr van den Haak has no financial or other relationship with any commercial companies related to this study or article. Drs Wakkee, de Vries, and Nijsten have no conflicts of interest to declare.

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