Treating patients with comorbidities is a common practice that makes dermatologists consider the best options in the management of patients. Ronald Prussick, an assistant clinical professor of dermatology at George Washington University, Washington DC, USA reminded dermatologists of an eloquent and succinct definition for comorbidities as “a disease or condition that coexists with a primary disease but also stands alone as a specific disease.” He also reminded dermatologists to focus not only on the safety and efficacy of the drug, but to also consider the comorbidities that can easily derail a traditional therapy for a primary condition.
Often, the main focus for comorbidities is placed on patients with moderate-to-severe conditions. However, it is important to note, that even patients with mild skin conditions have elevated risks for comorbidities. For example, 27.9% of patient with mild psoriatic arthritis had comorbidity associations. When reviewing overall risk, patients with mild psoriasis had comorbidities including diabetes (1.14), diabetes with complications (1.17), and atherosclerotic outcomes (1.14). Diabetic complications were defined as nephropathy, retinopathy, neuropathy, and vasculopathy.
Risk of cancer, such as lymphoproliferative diseases, nonmelanoma skin cancer, and lung cancer is also inherently higher in patients with psoriasis, with higher rate in patients with more severe psoriasis. A study reviewing almost 200,000 patients in the UK with mild, moderate, and severe psoriasis noted increases in lymphoma, lung cancer, and nonmelanoma skin cancer but found no significant association with an increase in cancers of the breast, colon, prostate, or leukemia.
A review of the nurses’ health survey also found trends for increased risk for melanoma (HR 1.95) and kidney cancer (HR 2.5) in patients with mild and severe psoriasis with increased risk in patients with high body surface area (BSA) involvement. A separate review of the nurses’ health survey I and II over a 16 year period noted that psoriasis was an independent risk for squamous cell carcinoma but not basal cell carcinoma with the relative risk increasing with the severity of the disease; mild (BSA <3%) RR 1.43, severe (BSA >10%) RR 1.99.
Obesity is considered a national issue and is a common comorbidity in patients suffering from psoriasis. According to a study presented by Prussick, patients with both mild and severe psoriasis often suffer from obesity as a comorbidity (mild psoriasis OR 1.46 [CI 1.17-1.82] and severe psoriasis OR 2.23 [CI 1.63-3.05]).
Risk for the development of psoriasis has also been uncovered via the nurses’ health study. Many of the findings show that nurses with a high body mass index were more likely to develop psoriasis, including other risk factors such as family history, alcohol, and smoking. Vigorous physical activity such as running or aerobic exercise was associated with a 25-30% lower risk of developing psoriasis, a key pearl that can be given to patients to help avoid the onset of psoriasis.
Nonalcoholic fatty liver disease (NAFLD) is an independent risk for cardiovascular disease but its cousin, nonalcoholic steatohepatitis (NASH) can lead to severe scarring, fibrosis, and cirrhosis. Ultrasound sensitivity can vary depending on the degree of steatosis (60-94%), but only a liver biopsy can diagnose the degree of fibrosis.
The Rotterdam study conducted by Van der Voort et al. demonstrated that psoriasis, in and of itself, was actually a risk factor for developing fatty liver disease. While it was previously known that psoriasis patients could have fatty livers, because of their many risks, the correlation was not solidified. Many of the factors for NAFLD include obesity, insulin resistance, metabolic syndrome, chronic inflammation, sedentary lifestyle, smoking, high fat/sugar diet, and a mutation in the PNPLA3 gene. The study showed that psoriasis was independently associated with a 70% increase in NAFLD, and that 60% of psoriasis patients were more likely to have the severe forms of NASH.
In an Italian study conducted by Miele et al., 59% out of 142 psoriasis patients had NAFLD which correlated with metabolic syndrome, obesity, and psoriatic arthritis. In addition, when psoriasis and NAFLD patients were compared to nonpsoriatic controls, psoriatic patients were more likely to have severe fibrosis by NAFLD fibrosis scores.
Prussick provided some recommendations for NAFLD in psoriasis which included correction of vitamin D deficiency, use of vitamin E, possible use of omega-3-fatty acids, and the avoidance of alcohol and systemic agents that may affect the liver.
Patients with psoriasis have also been found to have increased rates of depression, anxiety, and suicide rate, with higher levels of depression corresponding to the severity of the disease.
Autoimmunity also appears to be a comorbidity in psoriatic patients with the overall risk of one autoimmune at OR 1.6 while the risk of 2 autoimmune diseases was OR 1.6 in patients suffering from psoriasis.
Crohn’s disease and ulcerative colitis are significantly higher in patients with psoriasis as an active comorbidity. The incident rate ratio of patients with any form of psoriasis having Crohn’s disease was IRR 1.04 and ulcerative colitis was IRR 1.72. Patients with psoriasis and psoriatic arthritis had a substantially higher ratio of having Crohn’s disease or ulcerative colitis with IRR 4.42 and IRR 2.43 for Crohn’s and ulcerative colitis respectively.