Laura Ferris, MD, PhD
Several recent studies have evaluated that association between psoriasis and known comorbidities including cardiovascular disease, non-alcoholic fatty liver disease (NAFLD), and malignancy. Several recent studies have added to our understanding of the relationship between these conditions.
Using the largest database of hospitalized patients in the United States, Edgen et al found that hospitalization rates for patients with psoriasis are increasing. While the proportion of patients with psoriasis hospitalized with psoriasis as a primary diagnosis decreased about four-fold over a 20-year period (1999-2018), incidence of hospitalizations with any diagnosis of psoriasis has increased. Hospitalized psoriasis patients are increasingly more likely to have other comorbid conditions as during the study period the proportion of hospitalized psoriasis patients with a Charlson Comorbidity Index score of 3 or higher increased from 13.9% to 30.9%. Psoriasis severity, medication use, and reasons for hospitalization were not reported. The authors suggest that screening and management of comorbidities in the outpatient setting may help reduce preventable psoriasis hospitalizations.
Both NAFLD and cardiovascular disease are well-known psoriasis comorbidities, Gonzalez-Cantaro et al studied two cohorts of patients to better define the relationship between these two conditions. In a European cohort of 76 psoriasis patients and 76 control patients, psoriasis patients with NAFLD had a higher prevalence of subclinical atherosclerosis than both psoriasis patients without NAFLD (61% vs 23%) and age, sex, and BMI-matched controls with NAFLD (61% vs 32%). Psoriasis patients were also more likely that control patients to have insulin resistance, higher weight circumference, and dysplipidemia. Among 162 psoriasis patients who underwent PET and coronary CT angiography, higher hepatic FDG uptake (indicating NAFLD) was associated higher atherosclerotic disease burden. Importantly, both the NAFLD and CAD were subclinical in these patients. While the cross-sectional study design precludes any conclusions about causality, physicians should be aware that these two comorbidities are related. Lower waist circumference and greater physical activity were both associated with lower rates of NAFLD among patients with psoriasis, providing some guidance for counseling patients.
Several recent studies have found that cancer rates among patients with psoriasis are higher than what is observed in the general population. The association of psoriasis with lymphohematologic malignancies (LHM) has been controversial. A systematic review and meta-analysis of 25 observational studies including over 2.5 million subjects (Bellinato et al.) found a 1.55-fold increased risk of LHM in patients with moderate to severe psoriasis. Strikingly, the risk of cutaneous T cell lymphoma (CTCL) was increased 6.22-fold, with more severe psoriasis being associated with the highest risk of CTCL. A causal relationship cannot be established from this type of studies, but the authors hypothesize that drugs used to treat psoriasis or the chronic T cell activation caused by active disease may contribute to the risk of LMH. Additionally, psoriasis and CTCL can share clinical features and some cases may be due to misdiagnosis. Interestingly, two psoriasis comorbities, diabetes and obesity, are also associated with an increased risk of LHM.
Early identification and management of comorbidities can help in reducing morbidity and mortality. With so many psoriasis treatments available, understanding how different therapies may impact comorbid conditions is important in helping dermatologists to choose the best therapy for each individual patient.