SYSTEMIC INFECTIONS IN ATOPIC DERMATITIS

Droitcourt et al. evaluated the risk of developing systemic infections leading to hospital-based management, in patients with atopic dermatitis (AD). 10,602 adults with AD and 106,020 reference individuals were included in the study. The study was conducted in Denmark, 1995-2017. The median age of the participants was 29.8 years and there was a slight predominance of women (63%). Approximately 20% of patients received at least one immunosuppressive drug for AD treatment at any time.

The patients were monitored from the time they were diagnosed with AD until they developed a systemic infection. The authors determined increased incidence rates of all systemic infections among patients with AD. The overall incidence rate per 10,000 person years of systemic infections was 180.6 (95% CI 172.6-189.0) in patients with AD compared to reference subjects 120.4 (95% CI 118.3-122.5). The identified infections involved the following systems: respiratory tract, gastrointestinal tract, nervous system, musculoskeletal system, heart, skin, urinary system. Therefore, they showed that AD is associated with an increased risk of developing systemic infections. The highest risk has been identified for musculoskeletal, cardiac, and respiratory tract infections. Of note, the high risk for musculoskeletal infections has not been notified before from a population-based study. No association was found between gastrointestinal, urinary tract, or nervous system infections. Furthermore, AD patients had a higher risk of developing sepsis and skin infections compared to non-AD individuals. Patients with AD have several characteristics that make them more susceptible to infection. They had a high pH of the skin, a low synthesis of antimicrobial peptides, an altered skin microbiota, and frequent colonization by Staphylococcus aureus (S. aureus). A high density of S. aureus is associated with an increased risk of skin infections, sepsis, and endocarditis.

The results of the study are valuable because the authors included a large number of patients, who have been monitored for a long time, over 20 years, and many types of systemic infections have been analyzed. The patients included in the study had moderate / severe forms of AD that required hospital-based treatment; therefore patients with mild forms of AD were not included. Therefore, as the authors stated, these findings cannot be extended to patients with mild forms of AD. In this study, over 90% of subjects had active AD lesions. However, the study does not provide data on the etiological agents, referring only to S. aureus and herpes simplex virus, pathogens well known to be involved in AD.

It is very important that the clinician treating a patient with AD be aware that the patient has a risk of developing systemic infections. These results may explain why other studies have shown that death due to cardiovascular or infectious diseases is more common in people with AD than in patients without AD. Certainly, additional studies to provide data on the types of pathogens involved and the severity of the infections are needed. AD is a chronic condition that tends to flare periodically and has a significant impact on quality of life. These results are also important in signaling the need to implement screening and prevention programs to reduce the morbidity / mortality associated with AD. In addition, knowledge of the risk of developing infectious diseases in AD patients is essential for the introduction of biological therapies in the treatment of the disease.

In conclusion, the immunological abnormalities that characterize AD seem to have a significant impact on the defense against pathogens allowing the development of systemic infections. Therefore, these data are important not only for the management of the disease but also for the understanding of the pathogenesis of AD.

* Droitcourt C, Vittrup I, Kerbrat S, Egeberg A, Thyssen JP. Risk of systemic infections in adults with atopic dermatitis: A nationwide cohort study. J Am Acad Dermatol. 2021;84(2):290-99.