days unfit for work (108). These patients were also more likely to be admitted to the hospital and more often suffered from psoriatic arthritis. Psoriatic arthritis In addition to the skin, psoriasis can be associated with an inflammatory arthritis known as psoriatic arthritis, which involves the joints of the spine and other joints. This occurs without presence of specific antibodies in the blood (seronegative spondyloarthropathy). The rheumatoid factor (antibody occurring in rheumatoid arthritis) is also negative. A review of the literature showed that psoriatic arthritis affects between 1.3% (6) and 34.7% (7) of patients diagnosed with psoriasis. There are no data on sex predilection. In a United States population, it was observed that psoriatic arthritis occurred more frequently in Caucasian patients than in other ethnic groups (109). Two large consecutive German studies from dermatological practices that assessed the prevalence of arthritis from examinations by rheumatologists in 2005 and 2007 was 20.6% (10) and 19.6% (110), respectively. The clinical symptoms are variable, however, peripheral arthritis, spondylitis, enthesitis (inflammation of the sites where tendons insert into the bone), arthritis in the fingers and dactylitis (profuse swelling of the fingers or toes) are considered to be most common (Figure 6). Psoriatic arthritis can lead to chronic pain and change in physical appearance. Patients suffering from psoriatic arthritis have reduced physical fitness, compared to psoriasis patients without it (22). Typically, psoriatic arthritis occurs in conjunction with longstanding skin lesions, although rarely it occurs alone, in the absence of psoriasis. Global report on psoriasis 16 Figure 6. Psoriasis arthritis ©Matthias Augustin, University Medical Center Hamburg. Associated diseases Numerous studies have reported the coexistence of psoriasis and other serious systemic diseases, most often mentioned are cardiovascular diseases, metabolic syndrome, including hypertension, dyslipidemia and diabetes mellitus, and Crohn’s disease. Even children show increased rates of comorbidity compared to unaffected infants, or those with atopic eczema (11,49). Most publications discuss the association between cardiovascular disease and psoriasis. Patients diagnosed with psoriasis have an increased burden of subclinical atherosclerosis and vascular inflammation (111). They also have significantly higher levels of serum lipids, including triglycerides and total cholesterol, compared to healthy individuals (112). Moreover, psoriasis is associated with atrial fibrillation and stroke, which may be aggravated in young patients (113). However, it should be noted that at present it is not known whether psoriasis is an independent risk factor for the development of cardiovascular disease. Obesity or weight gain has been shown to be an independent risk factor for psoriasis. Tobacco smoking is another risk factor (114). Frequency of metabolic syndrome, depression and erectile dysfunction has also been found to be significantly higher in patients diagnosed with psoriasis (115). In some diseases and subgroups of patients, psoriasis has been shown to be an independent risk factor for non-alcoholic fatty liver disease (116). In spite of a high number of studies on the association of psoriasis with comorbidity, the causality and independence on some associated diseases remain unclear and need further research (117,118). Psychological and mental health Psoriasis is not only a disease that causes painful, debilitating, highly visible physical symptoms. It is also associated with a multitude of psychological impairments. For many reasons, psoriasis can be psychologically devastating. Patients’ lives become especially difficult when psoriasis is present in highly visible areas of the skin such as the face and hands. Related psychological problems can affect every day social activities and work. It causes embarrassment, lack of self-esteem, anxiety and increased prevalence of depression (24,25). Patients with psoriasis report experiencing anger or helplessness, and they disclose a higher rate of suicidal ideations than other patients. In a study of 127 patients with psoriasis, 9.7% reported a wish to be dead and 5.5% reported active suicidal ideation at the time of