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Background: The 2017 American College of Cardiology/American Heart Association guidelines defined hypertension at ≥130/80 mm Hg. Studies on patients with connective tissue diseases were not considered. Our aim was to assess the impact of this definition on atherosclerotic vascular events (AVEs) in systemic lupus erythematosus.Patients Methods: Individuals from the Toronto Lupus Clinic with at least 2 years of follow-up and no prior AVE were divided in three groups according to their mean blood pressure (BP) over that period (≥140/90 mm Hg, 130-139/80-89 mm Hg and <130/80 mm Hg). They were followed until the first occurrence of an AVE (fatal or non-fatal coronary artery disease, cerebrovascular event and peripheral vascular disease) or last visit. Groups were compared as per the baseline atherosclerotic risk factors. A multivariable time-dependent analysis was performed to adjust for the presence of other risk factors.Results: Of 1532 patients satisfying the inclusion criteria, 155 (10.1%) had a BP ≥140/90 mm Hg, 316 (20.6%) 130-139/80-89 mm Hg and 1061 (69.3%) were normotensives. After a mean follow-up of 10.8 years, 124 AVEs were documented. The incidence rates were 18.9, 11.5 and 4.5 per 1000 patient-years for the three groups, respectively (p=0.0007 between the 130-139/80-89 mm Hg group and the normotensives). A mean BP of 130-139/80-89 mm Hg over the first 2 years was independently associated with the occurrence of AVEs (HR 1.73, 95% CI 1.13 to 2.65, p=0.011).Conclusion: Patients with lupus with a sustained mean BP of 130-139/80-89 mm Hg over 2 years had a significantly higher incidence of AVEs compared with normotensive individuals. This BP level should be the target for antihypertensive therapy to minimise their cardiovascular risk. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the properties of a frailty index (FI), constructed using data from the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort, as a novel health measure in systemic lupus erythematosus (SLE). Methods: For this secondary analysis, the baseline visit was defined as the first study visit at which both organ damage (SLICC/American College of Rheumatology Damage Index [SDI]) and health‐related quality of life (Short‐Form 36 [SF‐36] scores) were assessed. The SLICC‐FI was constructed using baseline data. The SLICC‐FI comprises 48 health deficits, including items related to organ damage, disease activity, comorbidities, and functional status. Content, construct, and criterion validity of the SLICC‐FI were assessed. Multivariable Cox regression was used to estimate the association between baseline SLICC‐FI values and mortality risk, adjusting for demographic and clinical factors. Results: In the baseline data set of 1,683 patients with SLE, 89% were female, the mean ± SD age was 35.7 ± 13.4 years, and the mean ± SD disease duration was 18.8 ± 15.7 months. At baseline, the mean ± SD SLICC‐FI score was 0.17 ± 0.08 (range 0–0.51). Baseline SLICC‐FI values exhibited the expected measurement properties and were weakly correlated with baseline SDI scores (r = 0.26, P < 0.0001). Higher baseline SLICC‐FI values (per 0.05 increment) were associated with increased mortality risk (hazard ratio 1.59, 95% confidence interval 1.35–1.87), after adjusting for age, sex, steroid use, ethnicity/region, and baseline SDI scores. Conclusion: The SLICC‐FI demonstrates internal validity as a health measure in SLE and might be used to predict future mortality risk. The SLICC‐FI is potentially valuable for quantifying vulnerability among patients with SLE, and adds to existing prognostic scores. [ABSTRACT FROM AUTHOR]

Objective: To develop an evidence‐based guideline for the pharmacologic and nonpharmacologic treatment of psoriatic arthritis (PsA), as a collaboration between the American College of Rheumatology (ACR) and the National Psoriasis Foundation (NPF). Methods: We identified critical outcomes in PsA and clinically relevant PICO (population/intervention/comparator/outcomes) questions. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available pharmacologic and nonpharmacologic therapies for PsA. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to rate the quality of the evidence. A voting panel, including rheumatologists, dermatologists, other health professionals, and patients, achieved consensus on the direction and the strength of the recommendations. Results: The guideline covers the management of active PsA in patients who are treatment‐naive and those who continue to have active PsA despite treatment, and addresses the use of oral small molecules, tumor necrosis factor inhibitors, interleukin‐12/23 inhibitors (IL‐12/23i), IL‐17 inhibitors, CTLA4‐Ig (abatacept), and a JAK inhibitor (tofacitinib). We also developed recommendations for psoriatic spondylitis, predominant enthesitis, and treatment in the presence of concomitant inflammatory bowel disease, diabetes, or serious infections. We formulated recommendations for a treat‐to‐target strategy, vaccinations, and nonpharmacologic therapies. Six percent of the recommendations were strong and 94% conditional, indicating the importance of active discussion between the health care provider and the patient to choose the optimal treatment. Conclusion: The 2018 ACR/NPF PsA guideline serves as a tool for health care providers and patients in the selection of appropriate therapy in common clinical scenarios. Best treatment decisions consider each individual patient situation. The guideline is not meant to be proscriptive and should not be used to limit treatment options for patients with PsA. [ABSTRACT FROM AUTHOR]

Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease affecting up to 30% of psoriasis vulgaris (PsV) cases and approximately 0.25 to 1% of the general population. To identify common susceptibility loci, we performed a meta-analysis of three imputed genome-wide association studies (GWAS) on psoriasis, stratified for PsA. A total of 1,160,703 single-nucleotide polymorphisms (SNPs) were analyzed in the discovery set consisting of 535 PsA cases and 3,432 controls from Germany, the United States, and Canada. We followed up two SNPs in 1,931 PsA cases and 6,785 controls comprising six independent replication panels from Germany, Estonia, the United States, and Canada. In the combined analysis, a genome-wide significant association was detected at 2p16 near the REL locus encoding c-Rel (rs13017599, P=1.18 × 10−8, odds ratio (OR)=1.27, 95% confidence interval (CI)=1.18-1.35). The rs13017599 polymorphism is known to associate with rheumatoid arthritis (RA), and another SNP near REL (rs702873) was recently implicated in PsV susceptibility. However, conditional analysis indicated that rs13017599, rather than rs702873, accounts for the PsA association at REL. We hypothesize that c-Rel, as a member of the Rel/NF-κB family, is associated with PsA in the context of disease pathways that involve other identified PsA and PsV susceptibility genes including TNIP1, TNFAIP3, and NFκBIA. [ABSTRACT FROM AUTHOR]

Objectives: To assess 52-week safety and efficacy of bimekizumab in patients with active psoriatic arthritis (PsA) and prior inadequate response/intolerance to tumour necrosis factor inhibitors., Methods: Patients completing the 16-week phase III double-blind, placebo-controlled BE COMPLETE (NCT03896581) study entered the open-label extension, BE VITAL (NCT04009499). All patients in BE VITAL received 160 mg bimekizumab every 4 weeks. Safety and efficacy are reported to week 52., Results: A total of 347/400 (86.8%) patients completed week 52. To week 52, the exposure-adjusted incidence rate/100 patient-years for ≥1 treatment-emergent adverse event (TEAE) was 126.0, and was 7.0 for serious TEAEs. The most frequent TEAEs were SARS-CoV-2 (COVID-19), oral candidiasis, nasopharyngitis and urinary tract infection. All fungal infections were mild or moderate in severity and localised; two patients discontinued the study due to oral candidiasis. No cases of active tuberculosis, uveitis or inflammatory bowel disease were reported. One sudden death occurred. Sustained efficacy was observed with bimekizumab from week 16 to ‍52 across clinical and patient-reported outcomes. At week 52, 51.7% bimekizumab-randomised and 40.6% placebo/bimekizumab patients (receiving bimekizumab from week 16 to 52) had ≥50% improvement in the American College of Rheumatology criteria. Complete skin clearance (Psoriasis Area and Severity Index 100) was achieved by 65.9% bimekizumab and 60.2% placebo/bimekizumab patients at week 52. Minimal disease activity was achieved by 47.2% bimekizumab and 33.1% placebo/bimekizumab patients at week 52., Conclusions: Bimekizumab demonstrated a safety profile consistent with previous reports; no new safety signals were identified. Sustained efficacy was observed from week 16 to 52., Competing Interests: Competing interests: LCC: Grants/research support from AbbVie, Amgen, Celgene, Eli Lilly, Gilead, Janssen, Novartis, Pfizer and UCB Pharma; consultant for AbbVie, Amgen, BMS, Boehringer Ingelheim, Celgene, Domain, Eli Lilly, Galapagos, Gilead, Janssen, Moonlake Pharma, Novartis, Pfizer and UCB Pharma; speaking fees from AbbVie, Amgen, Biogen, Celgene, Eli Lilly, Galapagos, Gilead, GSK, Janssen, medac, Novartis, Pfizer and UCB Pharma. Associate Editor of RMD Open. RL: Consultancy fees from AbbVie, AstraZeneca, BMS, Eli Lilly, Novartis, Pfizer and UCB Pharma; research grants from AbbVie, Pfizer, Novartis, and UCB Pharma; owner of Rheumatology Consultancy BV, an AMS company under Dutch law. On the Editorial Board of RMD Open. IBM: Consulting fees and honoraria from AbbVie, AstraZeneca, BMS, Boehringer Ingelheim, Cabaletta, Causeway Therapeutics, Celgene, Eli Lilly, Evelo, Janssen, Moonlake Pharma, Novartis and UCB Pharma; research support from BMS, Boehringer Ingelheim, Celgene, Janssen, Novartis and UCB Pharma. On the Editorial Board of RMD Open. PJM: Research grants from AbbVie, Amgen, BMS, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, Sun Pharma and UCB Pharma; consultancy fees from AbbVie, Acelyrin, Aclaris, Amgen, BMS, Boehringer Ingelheim, Eli Lilly, Galapagos, Gilead, GSK, Janssen, Moonlake Pharma, Novartis, Pfizer, Sun Pharma and UCB Pharma; speakers’ bureau for AbbVie, Amgen, Eli Lilly, Janssen, Novartis, Pfizer and UCB Pharma. CTR: Research for AbbVie; consultant for AbbVie, Amgen, Eli Lilly, Gilead, Janssen, Novartis, Pfizer and UCB Pharma. YT: Speaking fees and/or honoraria from AbbVie, AstraZeneca, BMS, Boehringer Ingelheim, Chugai, Eisai, Eli Lilly, Gilead, GSK, Pfizer, Taiho and Taisho; received grants from Chugai, Eisai, Mitsubishi-Tanabe and Taisho. On the Editorial Board of RMD Open. AA: Honoraria and/or research grants from AbbVie, Amgen, BMS, Boehringer Ingelheim, Eisai, Eli Lilly, Janssen, Kyowa Kirin, LEO Pharma, Maruho, Mitsubishi Tanabe Pharma, Novartis, Pfizer, Sun Pharma, Taiho Pharma, Torii Pharmaceutical Co. and UCB Pharma. FB: Consultant and/or speaker and/or investigator for AbbVie, Affibody, Amgen, BMS, Boehringer Ingelheim, Celgene, Chugai, Eli Lilly, Genzyme, GSK, Janssen, MoonLake Pharma, MSD, Novartis, Pfizer, Roche, Sandoz and Sanofi. DDG: Consultant and/or received grant support from AbbVie, Amgen, BMS, Eli Lilly, Galapagos, Gilead, Janssen, Novartis, Pfizer and UCB Pharma. LG: Grants from AbbVie, Biogen, Eli Lilly, Novartis, Sandoz and UCB Pharma; personal fees from AbbVie, Amgen, BMS, Celltrion, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Sandoz and UCB Pharma. AMO: Research grants to Johns Hopkins University from AbbVie, Amgen, and Janssen; consulting fees from BMS, Janssen, Sanofi and UCB Pharma. ABG: Received research/educational grants from AnaptypsBio, BMS, Highlights Therapeutics, Janssen, Moonlake Immunotherapeutics AG, Novartis and UCB Pharma, (all paid to Mount Sinai School of Medicine); Received honoraria as an advisory board member and consultant for Amgen, AnaptypsBio, Avotres Therapeutics, BMS, Boehringer Ingelheim, Dice Therapeutics, Eli Lilly, Highlights Therapeutics, Janssen, Novartis, Sanofi, UCB and Xbiotech. RBW: Consulting fees from AbbVie, Almirall, Amgen, Arena, Astellas, Avillion, Biogen, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, GSK, Janssen, LEO Pharma, Novartis, Pfizer, Sanofi and UCB Pharma; research grants to his institution from AbbVie, Almirall, Janssen, LEO Pharma, Novartis and UCB Pharma; honoraria from Astellas, DICE Therapeutics, GSK and Union Therapeutics. BI: Shareholder of AbbVie, GSK and UCB Pharma; employee of UCB Pharma. RB and JC: Employees and shareholders of UCB Pharma. VS: Employee of UCB Pharma. JFM: Consultant and/or investigator for AbbVie, Amgen, Biogen, BMS, Dermavant, Eli Lilly, Janssen, LEO Pharma, Pfizer, Novartis, Regeneron, Sanofi, Sun Pharma and UCB Pharma., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background/objectives: The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 classification criteria for systemic lupus erythematosus system showed high specificity, while attaining also high sensitivity. We hereby analysed the performance of the individual criteria items and their contribution to the overall performance of the criteria., Methods: We combined the EULAR/ACR derivation and validation cohorts for a total of 1197 systemic lupus erythematosus (SLE) and n=1074 non-SLE patients with a variety of conditions mimicking SLE, such as other autoimmune diseases, and calculated the sensitivity and specificity for antinuclear antibodies (ANA) and the 23 specific criteria items. We also tested performance omitting the EULAR/ACR criteria attribution rule, which defines that items are only counted if not more likely explained by a cause other than SLE., Results: Positive ANA, the new entry criterion, was 99.5% sensitive, but only 19.4% specific, against a non-SLE population that included other inflammatory rheumatic, infectious, malignant and metabolic diseases. The specific criteria items were highly variable in sensitivity (from 0.42% for delirium and 1.84% for psychosis to 75.6% for antibodies to double-stranded DNA), but their specificity was uniformly high, with low C3 or C4 (83.0%) and leucopenia <4.000/mm³ (83.8%) at the lowest end. Unexplained fever was 95.3% specific in this cohort. Applying the attribution rule improved specificity, particularly for joint involvement., Conclusions: Changing the position of the highly sensitive, non-specific ANA to an entry criterion and the attribution rule resulted in a specificity of >80% for all items, explaining the higher overall specificity of the criteria set., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To develop new classification criteria for systemic lupus erythematosus (SLE) jointly supported by the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR)., Methods: This international initiative had four phases. 1) Evaluation of antinuclear antibody (ANA) as an entry criterion through systematic review and meta-regression of the literature and criteria generation through an international Delphi exercise, an early patient cohort, and a patient survey. 2) Criteria reduction by Delphi and nominal group technique exercises. 3) Criteria definition and weighting based on criterion performance and on results of a multi-criteria decision analysis. 4) Refinement of weights and threshold scores in a new derivation cohort of 1,001 subjects and validation compared with previous criteria in a new validation cohort of 1,270 subjects., Results: The 2019 EULAR/ACR classification criteria for SLE include positive ANA at least once as obligatory entry criterion; followed by additive weighted criteria grouped in 7 clinical (constitutional, hematologic, neuropsychiatric, mucocutaneous, serosal, musculoskeletal, renal) and 3 immunologic (antiphospholipid antibodies, complement proteins, SLE-specific antibodies) domains, and weighted from 2 to 10. Patients accumulating ≥10 points are classified. In the validation cohort, the new criteria had a sensitivity of 96.1% and specificity of 93.4%, compared with 82.8% sensitivity and 93.4% specificity of the ACR 1997 and 96.7% sensitivity and 83.7% specificity of the Systemic Lupus International Collaborating Clinics 2012 criteria., Conclusion: These new classification criteria were developed using rigorous methodology with multidisciplinary and international input, and have excellent sensitivity and specificity. Use of ANA entry criterion, hierarchically clustered, and weighted criteria reflects current thinking about SLE and provides an improved foundation for SLE research., (© 2019, American College of Rheumatology.)

Objective: To develop an evidence-based guideline for the pharmacologic and nonpharmacologic treatment of psoriatic arthritis (PsA), as a collaboration between the American College of Rheumatology (ACR) and the National Psoriasis Foundation (NPF)., Methods: We identified critical outcomes in PsA and clinically relevant PICO (population/intervention/comparator/outcomes) questions. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available pharmacologic and nonpharmacologic therapies for PsA. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to rate the quality of the evidence. A voting panel, including rheumatologists, dermatologists, other health professionals, and patients, achieved consensus on the direction and the strength of the recommendations., Results: The guideline covers the management of active PsA in patients who are treatment-naive and those who continue to have active PsA despite treatment, and addresses the use of oral small molecules, tumor necrosis factor inhibitors, interleukin-12/23 inhibitors (IL-12/23i), IL-17 inhibitors, CTLA4-Ig (abatacept), and a JAK inhibitor (tofacitinib). We also developed recommendations for psoriatic spondylitis, predominant enthesitis, and treatment in the presence of concomitant inflammatory bowel disease, diabetes, or serious infections. We formulated recommendations for a treat-to-target strategy, vaccinations, and nonpharmacologic therapies. Six percent of the recommendations were strong and 94% conditional, indicating the importance of active discussion between the health care provider and the patient to choose the optimal treatment., Conclusion: The 2018 ACR/NPF PsA guideline serves as a tool for health care providers and patients in the selection of appropriate therapy in common clinical scenarios. Best treatment decisions consider each individual patient situation. The guideline is not meant to be proscriptive and should not be used to limit treatment options for patients with PsA., (© 2018, American College of Rheumatology.)

Objective: We aimed to estimate the proportion of underdiagnosis and undertreatment of cardiovascular risk factors (CVRF) in an international multicenter cohort of patients with psoriasis and psoriatic arthritis (PsA)., Methods: A cross-sectional analysis was conducted of patients with psoriatic disease from the International Psoriasis and Arthritis Research Team cohort. The presence of modifiable CVRF [diabetes, hypertension (HTN), dyslipidemia, smoking, elevated body mass index, and central obesity] and the use of appropriate therapies for HTN and dyslipidemia were determined. The 10-year CV risk was calculated according to the Framingham Risk Score. Physician adherence with guidelines for the treatment of dyslipidemia and HTN was assessed. Regression analysis was used to assess predictors of undertreatment of HTN and dyslipidemia., Results: A total of 2254 patients (58.9% PsA, 41.1% psoriasis) from 8 centers in Canada, the United States, and Israel were included. Their mean age was 52 ± 13.8 years and 53% were men. Of the patients, 87.6% had at least 1 modifiable CVRF, 45.1% had HTN, 49.4% dyslipidemia, 13.3% diabetes, 75.3% were overweight or obese, 54.3% central obesity, and 17.3% were current smokers. We found 59.2% of patients with HTN and 65.6% of patients with dyslipidemia were undertreated. Undertreatment was associated with younger age (≤ 50 yrs), having psoriasis, and male sex., Conclusion: In real-world settings, a large proportion of patients with psoriasis and PsA were underdiagnosed and undertreated for HTN and dyslipidemia. Strategies to improve the management of CVRF in psoriatic patients are warranted.

A biosimilar is intended to be highly similar to a reference biologic such that any differences in quality attributes (i.e., molecular characteristics) do not affect safety or efficacy. Achieving this benchmark for biologics, especially large glycoproteins such as monoclonal antibodies, is challenging given their complex structure and manufacturing. Regulatory guidance on biosimilars issued by the U.S. Food and Drug Administration, Health Canada and European Medicines Agency indicates that, in addition to a demonstration of a high degree of similarity in quality attributes, a reduced number of nonclinical and clinical comparative studies can be sufficient for approval. Following a tiered approach, clinical studies are required to address concerns about possible clinically significant differences that remain after laboratory and nonclinical evaluations. Consequently, a critical question arises: can clinical studies that satisfy concerns regarding safety and efficacy in one condition support "indication extrapolation" to other conditions? This question will be addressed by reviewing the case of a biosimilar to infliximab that was approved recently in South Korea, Europe, and Canada for multiple indications through extrapolation. The principles discussed should also apply to biosimilars of other monoclonal antibodies that are approved to treat multiple distinct conditions., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In the United States, access to care is the number one issue facing our patients with dermatological conditions. In part, this is because we do not have outcome measures that are useful in clinical practice and available in databases where payers and governmental agencies can compare the performance of physicians and treatments. There is a growing recognition that insufficient attention has been paid to the outcomes measured in clinical trials and subsequently in clinical practice. The International Dermatology Outcome Measures group includes all willing stakeholders: patients, physicians, payers, and pharmaceutical scientists. As reported herein, the group's goal is to develop outcome measures in dermatology that address the needs of all involved.

Background: Prompt identification and treatment of psoriatic arthritis (PsA) in patients with psoriasis is critical to reducing the risk of joint damage, disability, and comorbidities., Objective: We sought to estimate PsA prevalence in patients with plaque psoriasis in 34 dermatology centers in 7 European and North American countries., Methods: Consecutive patients were evaluated by dermatologists for plaque psoriasis and subsequently by rheumatologists for PsA. PsA prevalence was estimated primarily based on rheumatologists' assessment of medical history, physical examination, and laboratory tests., Results: Of 949 patients evaluated, 285 (30%) had PsA (95% confidence interval 27-33) based on rheumatologists' assessment. PsA diagnosis changed in 1.2% of patients when diagnostic laboratory tests were added to medical history and physical examination. Of 285 patients given the diagnosis of PsA, 117 (41%) had not been previously given the diagnosis., Limitations: Bias may have been introduced by lack of standardized diagnostic criteria and unbalanced recruitment based on country populations., Conclusions: In this study, almost a third of patients with psoriasis seen in dermatology centers had PsA as determined by rheumatologists. More than a third of patients with PsA had not been previously given the diagnosis. Clinical evaluation alone is often sufficient basis for PsA diagnosis, but laboratory test results may be helpful in some patients., (Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

Introduction: In the last decade, the development of a number of potential drugs for lupus that target the pathogenesis of the disease at different levels has been witnessed. Despite a number of negative trials during this period, belimumab was recently approved for the treatment of adult seropositive lupus patients with mild-to-moderate disease activity., Areas Covered: This review summarizes the results of the most recent drug trials in lupus and highlights the aspects that require further refinement and modification in order to facilitate positive results in new drug trials for lupus., Expert Opinion: The success of a clinical trial depends on the efficacy of the study drug and its appropriate dosing. Several other factors play a major role in the success of trials, including the patient inclusion criteria, the choice of evidence-based study outcomes and endpoints and other aspects of study design that are described in this review.

Patients with systemic lupus erythematosus (SLE) have a significantly increased risk of atherosclerotic coronary events. Traditional risk factors, such as hypertension and hypercholesterolemia, only partly account for the increased risk of coronary disease in SLE. Other important risk factors include disease and treatment-related factors. Novel markers of coronary risk in SLE are being investigated. Several methods have been used to detect subclinical atherosclerosis in patients with SLE. Among these, scintigraphic myocardial perfusion defects have been shown to be predictive of subsequent coronary events, independent of traditional Framingham risk factors. Although the aggressive treatment of reversible risk factors, such as lipids and blood pressure, is advocated by many, no published studies have yet demonstrated a clear reduction in risk of coronary events with this approach. Elucidation of risk factors and preventive strategies for accelerated atherosclerosis in SLE is the subject of ongoing research.

Background: Estimates of the prevalence of psoriatic arthritis vary widely and are usually not determined by population-based studies., Objectives: We sought to determine the prevalence of psoriatic arthritis and the impact of the disease on quality of life in the US population., Methods: Patients were selected randomly from the US population and were interviewed by telephone. Cases were defined as patients who reported a physician diagnosis of psoriasis and psoriatic arthritis., Results: Interviews of 27,220 persons were conducted; 601 of the interviewees had psoriasis and 71 had psoriasis and psoriatic arthritis. The prevalence of psoriatic arthritis was 0.25% (95% confidence interval [CI]: 0.18%, 0.31%). The prevalence of psoriatic arthritis among patients with psoriasis was 11% (95% CI: 9%, 14%) and varied substantially based on self-reporting of the extent of skin involvement with psoriasis. Thirty-nine percent of patients with psoriatic arthritis indicated that it was a large problem in everyday life., Limitations: Psoriatic arthritis was classified on the basis of the patient's self-report., Conclusion: Psoriatic arthritis affects an estimated 520,000 patients in the US population, and many rate it as a large problem in everyday life. The prevalence varies widely based on the extent of skin involvement, which demonstrates the importance of performing broadly representative studies to measure the prevalence of psoriatic arthritis.