survey (Table 2). Physicians reported an average of 18 years in practice, and 98 % reported that their practice was office based. More than half of the dermatologists reported that their patients were diagnosed with psoriasis by another physician, while 41.1 % of rheumatologists reported that they had made the diagnosis of PsA themselves. Referrals of patients newly diagnosed with psoriasis or PsA came in large part from primary care physicians (&55 %). The majority of rheumatologists (73.2 %) reported being solely responsible for prescribing decisions for PsA patients, compared with 28.9 % of dermatologists (Table 2). Approximately one third of the dermatologists and rheumatologists indicated co-management of patients, most commonly with a rheumatologist primarily being responsible for prescribing decisions and a dermatologist also monitoring skin symptoms. 3.2 Factors Affecting Disease Severity Findings from the MAPP survey suggested that psoriasis patients and dermatologists may assess disease severity differently (Fig. 1a). More than one third of patients reported that itching was the most important factor contributing to their disease severity, followed by the location and size of lesions (21.8 %). In contrast, more than three times as many dermatologists (76.2 %) considered the location or size of the skin lesions to be the most important factor contributing to disease severity in their patients with psoriasis, while only one tenth of dermatologists cited itching (11.9 %). Although PsA patients’ and physicians’ assessments of factors affecting disease severity were more consistent than those of psoriasis patients and physicians, itching continued to be rated as less important by physicians than by PsA patients. Approximately half of the PsA patients reported joint pain and swelling as the most important factors in disease severity (Fig. 1b). This was followed by itching, the location and size of the skin lesions, and flaking. The majority of dermatologists and rheumatologists considered joint pain or swelling to be the most important factor contributing to severity in PsA patients; only 2 % of dermatologists and 2 % of rheumatologists rated itching as the most important factor contributing to disease severity. Table 2 Physician demographics and practice characteristics for the US portion of the Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) survey Characteristic Dermatologists, n = 101 Rheumatologists, n = 100 Number screened 1716 1235 Mean time in practice (years) 18.2 18.5 Practice setting (%) Urban 29.7 42.0 Suburban 60.4 55.0 Rural 9.9 3.0 Office based practice (%) 98.0 98.0 Hospital based practice (%) 2.0 2.0 Multispecialty practice (%) 12.9 41.0 Mean number of dermatologists in practice 3.8 1.8 Mean number of rheumatologists in practice 0.3 3.5 Mean weekly number of patients seen 161.1 114.1 Mean proportion of all visits related to medical dermatology (%) 82.0 – Mean proportion of all visits related to psoriasis (%) 12.9 – Mean proportion of all visits related to PsA (%) 3.4 15.5 Diagnosis of psoriasis (dermatologist) or skin symptoms in PsA patients (rheumatologist) made by Other physician 50.3 16.4 Self 33.2 41.1 Other dermatologist 6.5 39.5 Referrals of newly diagnosed psoriasis patients by Primary care physician 56.3 – Other dermatologist 5.3 – Other specialist 14.4 – Referrals of newly diagnosed PsA patients by: Primary care physician 49.4 54.7 Other dermatologist 4.0 27.6 Other specialist 14.1 13.0 Solely responsible for prescribing decisions for PsA patients 28.9 73.2 Rheumatologist responsible for prescribing decisions; dermatologist monitors skin symptoms 37.7 32.2 Dermatologist responsible for prescribing decisions; rheumatologist monitors joint symptoms 31.6 13.1 PsA psoriatic arthritis MAPP Survey Results from US Patients and Physicians 89 These observations are consistent with the global MAPP populations [14, 16] and highlight the differences between patients and physicians in the perception of disease severity and the factors that affect this perception. 3.3 Assessment of Joint Pain Of the psoriasis patients who did not have a diagnosis of PsA, 51.8 % reported joint pain; of these, 48.1 % reported having more than four affected joints. In contrast, dermatologists reported a substantially lower percentage (18.6 %) of their psoriasis patients complaining of joint symptoms. This discrepancy may be due to variations in assessing joint pain (which is also associated with many inflammatory conditions beyond PsA) among patients. However, while most dermatologists reported discussing the possibility of developing joint disease with all (57.4 %) or some (33.7 %) of their psoriasis patients, 87.1 % of dermatologists and 85.0 % of rheumatologists acknowledged that PsA is likely underdiagnosed because of failure to connect skin and