psoriasis per 100 000, rates for all ages and both sexes Source: Adapted from IHME GBD 2010 (1). The DALYs for both sexes increased linearly with increasing age up to 60 years. The study showed the greatest burden of disease occurred in the 50–69 years of age group and that psoriasis caused slightly higher DALYs burden in adult males than in adult women up to 75 years of age (Figure 4). In the Global Burden of Disease Study, the specific patient burden of chronic skin diseases such as psoriasis may have been underestimated since the underlying disease weights were not derived from the affected patients. Several studies have shown that chronic skin diseases with high stigmatization are perceived in a significantly more negative manner by the patients than by the public. Thus, the limitations of the Global Burden of Disease Study reflect a major psychosocial problem for patients with psoriasis in general: the lack of awareness of their specific burden by others. Recent publications on the global burden of disease of psoriasis and skin diseases have outlined this discrepancy accordingly (101,102). For this, any comparative analysis of disease burden between conditions needs to better balance between objective and subjective burden. DALYs per 100 000 12 109 19 428 Global report on psoriasis 12 Figure 4. Distribution of DALYs for psoriasis per 100 000, by gender and age group Source: Adapted from IHME GBD 2010 (1). Gaps in data Good epidemiological data are essential for disease control and appropriate health-care planning. This chapter illustrates the many gaps in psoriasis data, and dermatology remains one of the most neglected fields of epidemiological study. There is a need for better quality data on incidence and prevalence of psoriasis to understand better the size and distribution of the problem. The available prevalence data come from only 20 countries, meaning there are huge geographic gaps in knowledge, especially from low- and middle-income settings. In order to compare the incidence and prevalence of psoriasis between regions and to track their trends over time, data must be obtained in the same way in different places, reproducibly. Standardized measurements are needed, including uniform diagnostic assessment, definition of adulthood and case-finding methods, in order to provide further insight into dermatological problems such as psoriasis. The estimation of disease burden from psoriasis such as the 2010 Global Burden of Disease Study should be based on improved, more patient-centred methods. This includes the consideration of disease-specific rather than generic measures. Global report on psoriasis 13 Chapter 3. How does psoriasis affect peoples’ lives? Introduction Psoriasis is a chronic, noncommunicable, painful, disfiguring and disabling disease for which there is no cure, presenting without a single, typical clinical picture. It can manifest in many different forms. In addition to the involvement of skin and nails, inflammatory arthritis (psoriatic arthritis) may develop. Patients suffering from psoriasis are at higher risk of developing cardiovascular and other NCDs (103). Moreover, psoriasis affects mental health and people suffering from the disease experience significant social stigma. In assessing the severity of psoriasis, more than 40 different tools are being used (104). Commonly used measures for scoring the severity of psoriasis include the Psoriasis Area and Severity Index (PASI), and the Physician Global Assessment. Clinicians assess the severity of the disease, taking into account the degree of scaling, redness, thickness of the skin lesions or the size of the BSA occupied by psoriasis. QoL measures are also important. Skin and nails Based on the type of skin lesions, location, the age of onset and course of disease, several clinical classifications of psoriasis are used (Table 2). The most frequently reported symptoms connected to psoriasis are (105): n scaling of the skin in 92% n itching in 72% n erythema in 69% n fatigue in 27% n swelling in 23% n burning in 20% n bleeding in 20% of individuals. According to another study, flaking or scaling in the non-scalp area occurred in 89% and flaking or scaling of scalp areas in 62% of patients. Itching or scratching were observed in 87%, rash in