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More than just a skin condition

Distinctive nail changes occur in around 50% of all those affected and are more common in patients with psoriatic arthritis (PsA).5

Patients with psoriasis,

like those with other major medical disorders, have a decreased quality of life (QoL) as well as reduced levels of employment and income.6

The impact of

psoriasis encompasses functional, psychological and social dimensions.7

More than just a skin condition Several epidemiological studies have confirmed the association between chronic plaque psoriasis and comorbidities, which can be classified in three major groups, including: (1) PsA and inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis; (2) cardio-metabolic disorders such as myocardial infarction, hypertension, obesity, diabetes, dyslipidaemia, fatty liver disease and metabolic syndrome, and (3) psychological disorders including anxiety–depression syndrome (Table 1). The association between psoriasis and comorbidities could be explained through a common genetic background, the systemic effects of chronic inflammation, insulin resistance and unhealthy lifestyle such as smoking, over-eating and a sedentary lifestyle, all of which are common.8

Psoriasis and obesity-related

On the other hand, people with metabolic comorbidities might actively contribute to an increase in the inflammatory state of psoriasis, through the release of pathogenetic mediators from the liver and/or visceral adipose tissues, such as increased reactive oxygen species, elevated C-reactive protein, IL-6 and adipokines.10 The proportion of psoriatic patients developing PsA ranges from 6% to 42%, according to different studies.11

inflammatory states can act as reciprocally exacerbating factors. Indeed, it is likely that cytokines released from psoriatic keratinocytes could mediate metabolic effects such as insulin resistance, causing the development of type II diabetes mellitus.9

Table 1: Comorbidities of chronic plaque psoriasis

Immune-mediated diseases: Psoriatic arthritis Inflammatory bowel diseases: Crohn’s disease and ulcerative colitis

Cardio-metabolic diseases: Myocardial infarction Stroke Obesity

Diabetes mellitus Dyslipidaemia Fatty liver disease Metabolic syndrome

Psychological disorders: Anxiety–depression syndrome

significant increased mortality compared to the general population.

Psoriatic arthritis Nowadays, the early diagnosis of PsA has become a key concern, as an early treatment with biologics such as TNF-α blockers could prevent irreversible joint damage and deformities.12

PsA usually either coincides

with or follows the development of psoriasis, whereas it precedes psoriasis only in a minority of cases. Therefore, dermatologists are in a strategic position to make the diagnosis of PsA or refer the patient to a rheumatologist in case of suspicions. Validated questionnaires could be helpful in selecting patients with articular symptoms, who need to be carefully screened for PsA.13 Moreover, we believe that subclinical enthesopathy could be a useful marker for identifying those patients with higher risk of eventually developing PsA.14

Psoriasis and obesity PsA could

develop at any time, including childhood, but it appears between the ages of 30 and 50 years in most patients. PsA can affect peripheral joints, entheses, the synovial sheaths of tendons and the axial skeleton. Although PsA was formerly considered a mild disease, recent studies showed that PsA is erosive and deforming in 40–60% of patients, with bone damage arising in the first years after disease onset. Patients with PsA suffer from decreased quality of life, pain and functional impairment, and have a

Epidemiological studies indicate that there is a strong association between psoriasis and obesity; patients with psoriasis are more frequently overweight or obese than the general population. This association has been recently confirmed also in paediatric patients.15 Obesity generally precedes the development of psoriasis and PsA. The relationships between psoriasis and obesity are explained by the complex properties of the adipose tissue. Indeed, adipose tissue is an active endocrine organ, with many secretory products, such as adipocyte-derived hormones and pro-inflammatory adipokines, including chemerin, resistin, visfatin, IL-6 and TNF-α, which are released by macrophages and lymphocytes accumulating in the visceral fat. Visceral obesity is strongly associated

with metabolic syndrome. The metabolic syndrome is a set of metabolic changes, in particular insulin resistance, which confer a higher pro-inflammatory and pro- thrombotic risk. It includes at least three of the following conditions: abdominal obesity [waist circumference men >102 cm (40 in); women >88 cm (35 in)], elevated serum triglycerides [>150 mg/dl (1.7 mmol/l) or under treatment], low high-density lipoprotein cholesterol [men <40 mg/dl (1 mmol/l); women <50 mg/dl (1.3 mmol/l) or under treatment], elevated blood pressure (>130/85 mmHg or under treatment), and elevated fasting glucose (>110 mg/dL or under treatment).

Cardio-metabolic disorders In a cross-sectional study, we found that patients with psoriasis had a higher prevalence of metabolic syndrome compared to patients with other inflammatory skin diseases after controlling for sex and age (30.1% versus 20.6%, OR: 1.65, 95% CI 1.16–2.35).16


association between psoriasis and metabolic syndrome has been recently confirmed in a meta-analysis showing that psoriasis carries a pooled odds ratio for metabolic syndrome equal to 2.26 (95% CI 1.70–3.01).17

Fatty liver disease is the

hepatic manifestation of the metabolic syndrome and it is characterised by a wide range of liver diseases, including pure steatosis, steatohepatitis and cirrhosis. We found that prevalence of fatty liver – as diagnosed by patient history, blood sampling and ultrasonography – in patients with chronic plaque psoriasis was remarkably greater than that in non- psoriasis control subjects (47% versus 28%; p<0.0001) matched by age, sex and body mass index.18

Although the relationship between psoriasis and increased risk of cardiovascular disease (CVD) is still controversial, several studies have indicated that individuals with severe psoriasis are at increased risk of CVD mortality, stroke and myocardial infarction. Increased CVD risk appears to be limited to young individuals with severe psoriasis.19

Psychological disorders Chronic plaque psoriasis has a major impact on patients’ QoL, inducing physical discomfort, impaired emotional functioning, negative self-image, and limitations in daily activities, social contacts and work.20

For the majority of

patients with psoriasis, the most important negative impacts on QoL are 3

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