Magnetic Resonance Imaging in Psoriatic Arthritis: A Descriptive Study of Indications, Features and Effect on Treatment Change.

OBJECTIVE: The aims of this study were to describe the indications for, and features of, axial/peripheral joint magnetic resonance imaging (MRI) in psoriatic arthritis (PsA) and to examine the influence of MRI findings on clinical practice. METHODS: All axial and peripheral (hand and/or foot) MRI scans on patients attending the Toronto PsA clinic l between 2003 and 2014 were included. Scan details were garnered from the radiologist's official report. A chart review was performed to determine if MRI findings contributed to a change of treatment. RESULTS: One hundred sixty-eight scans were performed on 125 patients (135 axial and 33 peripheral). The mean age was 50.5 (SD, 11.5) years, with 51.2% being female. Mean duration of PsA was 11.2 (SD, 10.9) years. Of the axial scans, the majority were performed on the whole spine (excluding the sacrum) (27.4%) or the sacroiliac joints and spine together (45.2%). The predominant indications were for suspected inflammatory (51.1%) or degenerative (24.4%) disease. Magnetic resonance imaging revealed inflammatory and/or structural change in 34.1% versus 54.8% with degenerative changes. In MRI axial inflammation (n = 25), the majority (48%) had sacroiliac joint involvement, whereas 28% had inflammation at 2 or more sites.Of the periphery, 60.6% of scans were on hands and 21.2% were on feet alone. The main indications were for suspected subclinical synovitis (78.8%). Inflammatory arthritis was the MRI diagnosis in 72.7%. Magnetic resonance imaging findings influenced treatment change (n = 32) in 56.3%, but were insufficient to effect treatment change without clinical findings (100%). CONCLUSIONS: Magnetic resonance imaging is useful in evaluating patients with active PsA, particularly when suspecting inflammation and radiographic findings are unhelpful. In some cases, it can be used as an adjunct to clinical examination in determining treatment change.

Obesity is associated with a lower probability of achieving sustained minimal disease activity state among patients with psoriatic arthritis.

AIM: To assess whether overweight and obese patients with psoriatic arthritis (PsA) are less likely to achieve sustained minimal disease activity (MDA) state compared to patients with normal weight. METHODS: A cohort of patients was assessed at the University of Toronto PsA clinic at 6-12-month intervals according to a standard protocol from 2003 to 2012. Patients were categorised into the following groups according to their body mass index (BMI): normal (<25), overweight (25-30), and obese (>30). Sustained MDA was defined as achieving low disease activity state in five or more of the following domains for at least 1 year: skin, enthesitis, tender and swollen joint counts, pain, patient global assessment and function. Proportional odds discrete time to event analysis was used to investigate the association between BMI category and the achievement of sustained MDA. RESULTS: Of the 557 patients included in the study, 36.2% were classified as overweight and 35.4% were obese. Overall, 66.1% of the patients achieved sustained MDA during the follow-up period. A dose-response association was found between obesity and the probability of achieving sustained MDA in the multivariate regression analysis. Patients in the higher BMI categories were less likely to achieve sustained MDA compared those in the lowest BMI category (overweight: OR 0.66 p=0.003; obese: OR 0.53 p<0.0001) after adjusting for potential confounding variables. CONCLUSIONS: Overweight and obese patients with PsA are less likely to achieve sustained MDA compared to those of normal weight.

Increased burden of inflammation over time is associated with the extent of atherosclerotic plaques in patients with psoriatic arthritis.

AIM: To investigate whether a higher burden of inflammation is associated with more severe atherosclerosis in patients with psoriatic arthritis (PsA). METHODS: Patients from a large PsA cohort were analysed. The cumulative effect of inflammation was measured by a time-adjusted arithmetic mean of all measurements from the first visit to the clinic. The following variables were considered as predictors: Psoriasis Activity and Severity Index (PASI), erythrocyte sedimentation rate (ESR), white blood cell (WBC) count, tender and swollen joint counts, C-reactive protein, Psoriatic Arthritis Disease Activity Score (PASDAS) and Disease Activity for PsA (DAPSA). Vascular ultrasound of the carotid arteries was performed, and total plaque area was measured. This measure represented the extent of atherosclerosis and was considered the outcome of interest. The association between inflammation over time and atherosclerosis was assessed by regression models adjusted for age, sex and cardiovascular risk factors. RESULTS: A total of 235 patients with PsA were analysed. Patients with more severe atherosclerosis were older (p<0.001), more likely to be obese (p=0.01), smokers (p=0.008) and have hypertension (p=0.001), diabetes (p<0.0001) and dyslipidaemia (p<0.0001). In a multivariate regression model adjusted for age and sex, higher ESR (p=0.009), WBC count (p=0.015) and DAPSA (p=0.04) were associated with more severe atherosclerosis. These associations were not significant after adjustment for traditional cardiovascular risk factors. No association was found between disease duration and atherosclerosis. CONCLUSIONS: Exposure to an increased burden of inflammation is associated with more severe atherosclerosis in patients with PsA. This association may be mediated by traditional cardiovascular risk factors.

Tumour necrosis factor inhibitor therapy and infection risk in axial spondyloarthritis: results from a longitudinal observational cohort.

OBJECTIVES: Long-term data on infection risk in axial SpA (axSpA) are sparse. TNF inhibitors (TNFis) are increasingly being used in axSpA, with infection being the most important adverse event. We aimed to investigate the frequency of infections in axSpA and to identify factors predisposing to infection. METHODS: Data were extracted from a longitudinal observational cohort of patients with axSpA. Infection rates were calculated and multivariate analysis was performed to investigate the association of independent variables with infection. RESULTS: Data were analysed for 440 patients followed for a total of 1712 patient-years (pys). A total of 259 infections, of which 23 were serious, were recorded in 185 patients. The overall rate of any infection was 15 (95% CI 13, 17)/100 pys and the serious infection rate was 1.3 (95% CI 0.9, 2.0)/100 pys. There was no significant difference in the rate of any infection or serious infection in patients on TNFis compared with patients never on biologic agents. In the multivariate analysis, DMARD treatment, but not TNFi treatment, was associated with risk of infection. Age, disease duration, smoking status, BASFI, BASDAI, co-morbidity score and hospitalization were not associated with an increased risk of infection. CONCLUSION: The serious infection rate in axSpA in this observational cohort is low when compared with rates reported in other rheumatic diseases. Biologic use was not a significant risk factor for serious infection.

Tumour necrosis factor α blockers are more effective than methotrexate in the inhibition of radiographic joint damage progression among patients with psoriatic arthritis.

AIM: To determine whether tumour necrosis factor α (TNFα) blockers are more effective than methotrexate in inhibiting the progression of radiographic joint damage in patients with psoriatic arthritis (PsA). METHODS: A cohort analysis of patients followed prospectively in a large PsA clinic was conducted. Patients who received a TNFα blocker were compared to those treated with methotrexate. Patients who had records of at least 12 months of treatment with either medication for active peripheral PsA and had radiographic bone erosions were analysed. Radiographs of the hands and feet were performed at baseline, 1-2 years (time 1) and 3-4 years (time 2). Radiographic joint damage was scored according to the modified Steinbrocker score. The outcome of interest was the occurrence of radiographic progression. Multivariate logistic regression analysis using generalised estimating equations for repeated measures was used to compare progression in radiographic joint damage between the two treatment groups. RESULTS: 65 patients treated with TNFα blockers and 70 patients treated with methotrexate were analysed. The proportion of patients who demonstrated progression of radiographic damage score at time 1 and time 2 was higher in the methotrexate group compared to the TNFα blockers group (at time 1: 80% vs 58.9% p=0.005; at time 2: 88% vs 61% p=0.005). In the multivariate regression analysis methotrexate treatment was associated with an increase in radiographic damage compared to TNFα blockers (p=0.001). CONCLUSIONS: In a clinic setting, patients with erosive PsA receiving TNFα blockers had a better radiographic outcome compared to those treated with methotrexate.

The effectiveness of leflunomide in psoriatic arthritis.

OBJECTIVES: This study aimed to evaluate the effectiveness and safety of leflunomide alone and in combination with methotrexate in the treatment of psoriatic arthritis (PsA). METHODS: Patients were followed at the University of Toronto PsA Clinic. PsA patients who received leflunomide alone or in combination with methotrexate were identified from the PsA clinic database. Effectiveness was defined by drug persistence, a ≥40% reduction in actively inflamed joints, a ≥40% reduction in swollen joint count, and PASI50 and PASI75 response following treatment with leflunomide. Descriptive statistics and logistic regression analyses with stepwise selection were used for data analysis. RESULTS: 85 patients were identified. 43 patients (50.6%) were on leflunomide alone and 42 (49.4%) patients were on combined leflunomide and methotrexate therapy. 30 patients discontinued leflunomide mainly due to toxicity. Of the 55 patients who continued the drug, 38%, 48% and 56% achieved a ≥40% reduction of actively inflamed joint count at 3, 6 and 12 months, respectively. PASI50 was achieved by 27%, 28% and 38% at 3, 6 and 12 months, whereas PASI75 was achieved by 19% at 3 and 6 months and 32% at 12 months. Longer duration of PsA and higher swollen joint count at baseline were predictive for improvement of the swollen joint count at 3 months. The use of concomitant MTX was predictive of achieving PASI50 at 12 months. CONCLUSIONS: Leflunomide led to improvement in almost 50% of the patients by 1 year. Those also taking methotrexate were more likely to achieve a PASI50 response.

Gender difference in disease expression, radiographic damage and disability among patients with psoriatic arthritis.

OBJECTIVE: The authors aimed to assess gender-related differences in severity of psoriatic arthritis (PsA) as reflected by measures of disease activity, joint damage, quality of life and disability. METHODS: A cross-sectional analysis was performed among patients who have been followed in a large PsA clinic. Demographic, clinical and radiographic data as well as information about quality of life and function were retrieved from the clinic database. Radiographic damage was assessed according to modified Steinbrocker score (mSS). The association between gender and the following outcome variables, radiographic joint damage, axial involvement and measures of quality of life and function, was assessed by multivariate regression analysis after adjustment for potential confounders. RESULTS: Three hundred and forty-five men and 245 women were included in the study. Axial involvement was more frequent in men (42.9% vs 31%, p=0.003). In multivariate analysis, adjusting for potential confounders, men were more likely to develop axial involvement (OR 1.8, p=0.003). Men were also more likely to develop more severe radiographic damage in the peripheral joints as evident by mSS. Men were more likely to be in a higher mSS damage category compared with women after adjusting for potential confounders in multivariate analysis (OR 1.6, p=0.007). Women suffered from more severe limitations in function and worse quality of life compared with men based on several patients' reported outcomes. CONCLUSIONS: Men with PsA are more likely to develop axial involvement and radiographic joint damage, while women are more likely to report about limitation in function and impaired quality of life.

The burden of carotid artery plaques is higher in patients with psoriatic arthritis compared with those with psoriasis alone.

AIM: To compare the extent of atherosclerosis in patients with psoriatic arthritis (PsA) and patients with cutaneous psoriasis without arthritis (PsC). METHODS: In this cross-sectional study the authors compared patients with PsA with PsC patients. Psoriasis patients underwent a rheumatological assessment to exclude inflammatory arthritis. Ultrasonographic measurements of carotid total plaque area (TPA) and carotid intima-media thickness (cIMT) were performed. t Test was used to compare the imaging findings between the two groups. Multivariate linear regression analysis was used to assess the association between disease status and imaging findings after adjusting for potential confounders. RESULTS: Overall, 125 PsA and 114 PsC patients were compared. There were no significant differences in age, gender or cardiovascular risk factors between the two groups. Patients with PsA exhibited greater TPA than did PsC patients (TPA (square root of area in mm(2)) 3.33±3.34 vs 2.43±2.72, p=0.03). This difference remained statistically significant in the multivariate regression analysis after adjusting for potential confounders (p=0.03). The difference in cIMT between the groups did not achieve statistical significance (p=0.09). The following disease-related variables were associated with increase in TPA in multivariate regression analysis among PsA patients: duration of PsA (p=0.04), highest Psoriasis Area and Severity Index recorded in the first 3 years of follow-up (p=0.02) and erythrocyte sedimentation rate (p=0.005). CONCLUSIONS: PsA patients suffer from more severe subclinical atherosclerosis compared with patients with PsC. This difference is independent of traditional cardiovascular risk factors and correlates with PsA disease duration, more severe skin disease and increased inflammatory markers.

Serum adipokines in patients with psoriatic arthritis and psoriasis alone and their correlation with disease activity.

OBJECTIVE: To compare the prevalence of metabolic syndrome (MetS) and the levels of related biomarkers in patients with psoriatic arthritis (PsA) and psoriasis without arthritis (PsC). METHODS: This study compared patients with PsA and patients with PsC. The presence of MetS was determined. Serum levels of insulin, adiponectin and leptin were measured. The homeostasis model assessment for insulin resistance (HOMA-IR) was calculated. HOMA-IR, adiponectin and leptin were log-transformed. Continuous variables were compared using the t test and the χ(2) test was used for discrete variables. Multivariate regression models were used to investigate the association of MetS and adiponectin with PsA compared to PsC after adjusting for potential confounding variables. RESULTS: 203 PsA and 155 PsC patients were analysed. The prevalence of MetS was higher in PsA patients compared to those with PsC. However, this did not reach statistical significance (36.5% vs 27.1%, p=0.056). The levels of adipokines were significantly higher in PsA compared to PsC: adiponectin (8.8±5.2 vs 7.4±4.5 log (µg/ml), p=0.009) and leptin in women (3.1±0.8 vs 2.8±0.8, log (ng/ml), p=0.04). HOMA-IR was also higher in PsA (0.97±0.63 vs 0.68±0.81, p<0.001). No difference was observed in leptin levels in men. In multivariate regression analysis, PsA (p=0.04) and the psoriasis area and severity index score (p=0.02) were associated with MetS. Adiponectin was significantly associated with PsA (p=0.005), the use of anti-tumour necrosis factor α therapy (p=0.03) and active joint count (p=0.001). CONCLUSIONS: MetS and related adipokines correlated with an increased burden of skin and joint inflammation.

Physician scores vs patient self-report of joint and skin manifestations in psoriatic arthritis.

OBJECTIVE: We aimed to determine the degree of agreement between patient self-report and physician assessment of joint disease activity and damage and degree of skin disease. METHODS: Patients were followed up in the PsA clinic for homunculus for tender joints, swollen joints, deformed joints and problematic joints, as well as the severity of their psoriasis. A rheumatologist documented tender joints, swollen joints and damaged joints as well as psoriasis area and severity index score. The scores were compared using the concordance correlation coefficient and Bland-Altman plots were constructed. RESULTS: One hundred and forty outpatients participated in the study (60 females and 80 males) with a mean age of 52.8 years. Their mean age at onset of psoriasis was 27.4 years and at PsA onset was 36.9 years. The average duration of psoriasis at the time of the study was 25.3 years and of PsA was 16.2 years. The correlation between patient and physician scores was poor for tender and swollen joints, although it was better for deformed joints and psoriasis area and severity index score but still did not reach a level of good agreement. CONCLUSION: PsA patient's self-report has a poor correlation with physician assessment. Thus patient self-reported data are insufficient to accurately monitor PsA disease activity when compared with a physician's joint examination and skin score. Expert physical examination should remain the gold standard for the assessment of actively inflamed joint and skin disease in patients with PsA in both clinical trials and observational cohort studies.

Serum kallikrein-8 correlates with skin activity, but not psoriatic arthritis, in patients with psoriatic disease.

BACKGROUND: About 30% of cutaneous psoriasis (PsC) patients develop psoriatic arthritis (PsA) in the joint, which is under-recognized by dermatologists. Biomarkers for PsA are needed so that early referral to a rheumatologist is made. Kallikreins (KLKs) are secreted serine proteases implicated in skin desquamation and inflammation. This study examined KLK potential as serum biomarkers of PsA in cutaneous psoriasis patients. METHODS: KLKs were measured by ELISAs in synovial fluids of three PsA patients and three control early osteoarthritis (OA) patients, as well as in a cohort of 152 serum samples collected from age- and sex-matched PsC patients, with (n=76) or without PsA (n=76). KLK expression in psoriatic plaques was examined by immunohistochemistry. Univariate and multivariate logistic regression analyses were conducted to analyze the association between serum KLK levels and disease class (PsC, PsA). Serum KLKs that associated with PsA were correlated with clinical parameters of skin and joint activity. RESULTS: Among the seven KLKs tested, KLK6 and KLK8 were elevated in both PsA synovial fluids and psoriatic plaques, but only serum KLK8 levels were associated with psoriatic disease (odds ratio=2.56, p=0.03). Although significantly elevated in PsC and PsA sera compared to healthy controls, KLK8 did not discriminate PsA from PsC patients. KLK8 correlated positively with the psoriasis area and severity index (PASI) (r=0.43, p=0.001) independent of age, sex and psoriasis duration ( ß=1.153, p=0.0003) and exhibited no correlations with tender or swollen joint counts. CONCLUSIONS: Increased KLK8 serum level in PsA patients reflects disease activity in the skin but not in the joints. Serum KLK levels are not useful for screening psoriasis patients for PsA.

Does the change in season affect disease activity in patients with psoriatic arthritis?

OBJECTIVES: To determine whether there is seasonal variation in disease activity of patients with psoriatic arthritis (PsA). METHODS: The authors identified the first available set of consecutive summer and winter visits for every patient from the prospective cohort of PsA. Comparison between summer and winter visits, and comparison of the repeated summer/winter visits, from 1978 until 2011 for the same identified patients was conducted for demographics, disease activity outcomes, laboratory results and treatment. The authors categorised disease activity into high, moderate and low states, and improvement versus flare/worsening. Descriptive statistics were computed and multivariate analyses using logistic regression and generalised estimating equations were conducted. RESULTS: The first available summer and winter visit were identified for 253 patients, and 1789 observations were analysed. There was no statistically significant difference in patients' demographics, disease activity outcomes, laboratory results and treatment between summer and winter visits. Bath Ankylosing Spondylitis Disease Activity Index scores were greater for summer visits and patients graded their disease as being worse in winter as compared with summer in the univariate analysis, but this difference did not hold in the multivariate analysis. CONCLUSIONS: The change in season does not affect PsA patients' characteristics and disease activity outcomes as determined by the physicians and patients.

The association between smoking and the development of psoriatic arthritis among psoriasis patients.

AIM: To investigate the association between smoking and psoriatic arthritis (PsA) among patients with psoriasis and its interaction with the HLA-C*06 allele. METHODS: In this exploratory case-control study, smoking status was determined at the time of the diagnosis of arthritis for PsA patients and at their first study visit for psoriasis patients, when they were confirmed not to have PsA. The proportions of patients exposed to smoking were compared in patients with PsA to those with psoriasis alone. A logistic regression model was constructed to test the independent association of smoking and PsA after adjusting for potential confounders. The statistical interaction between HLA-C*06 and smoking was tested through a regression model. RESULTS: The proportions of current and past smokers were higher in the psoriasis group compared with the PsA group (30.2% vs 23.4% and 26.7% vs 22.3%, p=0.001, respectively). On multivariate analysis being a current smoker versus a lifetime non-smoker remained inversely associated with PsA (OR 0.57, p=0.002), while past smoker versus lifetime non-smoker status was no longer significant. In a subgroup analysis, smoking remained inversely associated with PsA only among patients who were HLA-C*06 negative. Regression analysis revealed that the interaction between smoking status (ever smoked vs lifetime non-smoker) and HLA-C*06 was statistically significant (p=0.01). CONCLUSION: Smoking may be inversely associated with PsA among psoriasis patients. This association is not present among HLA-C*06-positive individuals.

Patients with psoriatic arthritis have worse quality of life than those with psoriasis alone.

OBJECTIVE: PsA is an inflammatory arthritis present in ∼30% of people with psoriasis (PsC). Both conditions have a significant impact on quality of life (QoL). Our objective was to test the hypothesis that people with PsA have poorer QoL than patients with PsC because of the added burden of arthritis, age and comorbidities. METHODS: Consecutive patients with PsA (CASPAR criteria) and PsC were approached to participate in this study. Patients with PsC were examined by a rheumatologist using a standardized protocol to exclude PsA. Patients completed the HAQ, Medical Outcome Study 36-item Short Form Health Survey, Dermatology Life Quality Index (DLQI), EuroQoL 5 domains (EQ-5D) and Fatigue Severity Scale (FSS). Mean scores were compared and multivariate analyses were conducted to compare the QoL measures between the two patient groups. RESULTS: Two hundred and one patients with PsC and 201 patients with PsA were studied. A significant decrease in QoL for patients with PsA compared with those with PsC was identified by all questionnaires except for the DLQI. This skin-specific questionnaire revealed a lower QoL in patients with PsC. Multivariate analyses for each QoL measure confirmed the results of these analyses. After adjusting for age, sex, duration of PsC, comorbidities, DMARDs and biologic therapy, HAQ and DLQI were independently associated with PsA in a logistic regression. CONCLUSION: Patients with PsA have a poorer QoL compared with those with PsC as measured by all questionnaires except the DLQI.

Do patients with psoriatic arthritis who present early fare better than those presenting later in the disease?

BACKGROUND: This investigation aimed to determine whether patients presenting to a psoriatic arthritis (PsA) clinic early in the course of the disease had less severe disease at presentation, and whether disease duration at presentation predicts progression of joint damage. METHODS: Patients followed prospectively in a specialised clinic were divided into those first seen within 2 years of diagnosis (group 1) and those seen with more than 2 years of disease (group 2). The groups were compared with regard to demographics and disease characteristics at presentation. A multivariate analysis using a negative binomial model was conducted to determine whether patients with early disease had less progression of joint damage. RESULTS: 436 patients were identified in group 1 and 641 patients in group 2. Patients in group 2 were older, had longer duration of psoriasis and PsA, more joint damage and were less likely to be treated with disease-modifying antirheumatic drugs, but had similar level of education and degree of psoriasis severity. After adjusting for age, sex, education level, clinical joint damage at first visit and treatment, group 2 had significantly greater rate of clinical damage progression compared with group 1. CONCLUSIONS: Disease progression is more marked in patients presenting with established disease of more than 2 years' duration. These results suggest that patients with PsA should be treated earlier in the course of their disease.

Sensitivity and Specificity of Radiographic Scoring Instruments for Detecting Change in Axial Psoriatic Arthritis.

OBJECTIVE: There is no widely recognized method used to assess axial disease in psoriatic arthritis (PsA). We aimed to determine the sensitivity to change of the Bath Ankylosing Spondylitis Radiology Index for the spine (BASRI-s), the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), the Radiographic Ankylosing Spondylitis Spine Score (RASSS), and the PsA Spondylitis Radiology Index (PASRI) in axial PsA. METHODS: Radiographs of 105 patients with axial PsA were retrieved for 2 time points at least 2 years apart and subsequently anonymized. All radiographs were scored by 3 rheumatologists blinded to name and order of examination using an electronic application that allowed recording of disease manifestations specific to axial PsA and automatically calculated the BASRI-s, mSASSS, RASSS, and PASRI scores. An independent expert determined whether there was true radiographic progression from an overall impression after viewing the radiographs with knowledge of chronologic order. The sensitivity, specificity, and odds ratios for every 1-unit increase in the scores were determined to identify true change. RESULTS: Of the patients studied, 25 (24%) showed progression, as determined by the independent expert. The respective sensitivity and specificity values for an increase in score to detect true change were as follows: 0.48 and 0.78 (BASRI-s), 0.52 and 0.84 (mSASSS), 0.44 and 0.84 (RASSS), and 0.52 and 0.74 (PASRI). Logistic regression analyses showed that an increase of 1 point in the respective scores was associated with the following odds ratios for identifying true progression: BASRI-s 3.0, mSASSS 5.27, RASSS 3.70, and PASRI 3.06. CONCLUSION: Available scoring systems for quantifying radiographic axial PsA have moderate sensitivity but high specificity for detecting true change.

Association of variably expressed KIR3dl1 alleles with psoriatic disease.

The purpose of this study is to examine the genetic interaction of variably expressed killer cell immunoglobulin-like receptor (KIR) 3DL1 alleles with their cognate ligand, human leukocyte antigen (HLA)-Bw4, in susceptibility to psoriatic disease (PsD). A novel allelic typing system was developed to differentiate KIR3DL1 alleles (*High, *Low, *Null expression, and 3DS1), in PsD patients, including those with psoriatic arthritis (PsA) and cutaneous psoriasis without arthritis (PsC) and healthy controls. Frequencies of each KIR3DL1 allele, Bw4-80I and Bw4-80T, as well as the genetic interaction between the KIR3DL1 alleles and the Bw4 epitope were analyzed. KIR3DL1 alleles were successfully genotyped in 392 PsA, 260 PsC, and 371 control subjects. Only the KIR3DL1*Null allele was associated with PsD (OR = 0.69, p = 0.008), both in the PsA (OR = 0.69, p = 0.02) and PsC patients (OR = 0.70, p = 0.04) compared to control subjects. No difference in the frequency of KIR3DL1*Null was found between the PsA and PsC patients. The presence of the HLA-Bw4 epitope was significantly associated with PsD, particularly in the PsA patients compared to controls. Bw4-80I was increased in PsD and PsA subjects, but not in PsC patients compared to controls. Bw4-80T was increased in PsA compared to both PsC patients or to controls. No interaction was detected between any of the KIR3DL1 alleles and HLA-Bw4, Bw4-80I, or Bw4-80T. The novel qPCR technique successfully identified the four variably expressed KIR3DL1 alleles. The HLA-Bw4 epitope was associated with psoriatic disease, particularly with PsA, but no genetic interactions with KIR3DL1 alleles were detected.

Attainment of Minimal Disease Activity Using Methotrexate in Psoriatic Arthritis.

OBJECTIVE: An international task force has recommended that disease remission or minimal disease activity (MDA) be the target of treatment for psoriatic arthritis (PsA) and that remission or MDA should be attained within 6 months of initiating medication. The aim of this study was to establish the proportion of patients with PsA who achieve MDA after 6 months of methotrexate (MTX) treatment. METHODS: Patients who initiated MTX and were naive to biologics between 2004 and 2014 were included. The primary outcome was the achievement of MDA after 6 months of MTX, defined as the presence of at least 5 out of the following 7: tender joint count ≤ 1, swollen joint count (SJC) ≤ 1, Psoriasis Area Severity Index (PASI) ≤ 1 or body surface area ≤ 3%, tender entheseal points ≤ 1, Health Assessment Questionnaire score ≤ 0.5, patient global disease activity visual analog scale (VAS) score ≤ 20, and patient pain VAS ≤ 15. Of 204 patients identified, 167 were treated with MTX for at least 3 months and had sufficient data for analysis at 6 months. RESULTS: At 6 months, 29 patients (17.4%) achieved MDA; 97 patients (58.1%) achieved an SJC ≤ 1 and 138 (82.6%) a PASI ≤ 1. Only 22 (13.2%) achieved the patient global disease activity criterion. Lower back pain and dactylitis were associated with a lower probability of achieving MDA. CONCLUSION: MTX use achieves MDA by 6 months in < 20% of patients. This compares unfavorably with data for tumor necrosis factor inhibitor use.

Clinical and Demographic Characteristics of Erosion-free and Erosion-present Status in Psoriatic Arthritis in a Cohort Study.

OBJECTIVE: Psoriatic arthritis (PsA) has been recognized as a severe erosive disease. However, some patients do not develop erosions. We aimed to determine the prevalence, characteristics, and predictors of erosion-free patients (EFP) as compared with erosion-present patients (EPP) among patients with PsA followed prospectively. METHODS: This is a retrospective analysis conducted on patients from the Toronto PsA cohort. Patients with at least 10 years of followup and radiographs were analyzed. Radiographs were scored with the modified Steinbrocker method. Baseline (first visit to clinic) characteristics were used to predict the development of erosions with logistic regression models. To examine the effect of time-varying covariates, Cox regression models were fit for the time to development of erosions from baseline. RESULTS: Among 290 patients, 12.4% were EFP and 87.6% were EPP over the study period. The mean time to development of erosion in the EPP over the course of followup was 6.8 ± 6.1 years. EFP were diagnosed with psoriasis at a younger age compared with EPP. In both models, actively inflamed joints and clinically damaged joints were predictive of the development of erosion, whereas a longer duration of psoriasis at baseline decreased the odds of developing erosion. EPP had a higher percentage of unemployment as compared with EFP at baseline and followup visits. CONCLUSION: Among patients with PsA followed for at least 10 years, 12.4% never develop erosions. The clinical and radiographic findings can ultimately assist in the stratification of a patient's prognosis regarding the development of erosions.

The Incidence and Predictors of Infection in Psoriasis and Psoriatic Arthritis: Results from Longitudinal Observational Cohorts.

OBJECTIVE: To investigate the rate, type, characteristics, and predictors of infection in a cohort of patients with psoriatic arthritis (PsA) and a cohort of patients with psoriasis without arthritis (PsC). METHODS: A cohort of patients with PsA and a cohort of patients with PsC were followed according to a standard protocol and information on the occurrence of infections was recorded. The rate of infection was estimated by fitting an exponential model. A Weibull regression model was fitted to estimate the relative risk of first infection associated with a number of covariates. Risk factors for recurrent infections were investigated using generalized estimating equations. RESULTS: There were 498 and 74 infections reported among 695 and 509 patients with PsA and PsC, respectively, with an incidence rate of 19.6 per 100 person-years in the PsA cohort compared with 12.2 in the PsC cohort. The HR of the time to the first infection in PsA versus PsC was 1.6 (p = 0.002), and higher in patients treated with biologics versus nonbiologics at 1.56 (95% CI 1.22-2.00) in PsA and 1.50 (95% CI 0.64-3.54) in the PsC cohorts. Female sex and treatment with biologics were associated with infection in the PsA cohort, whereas a lower Psoriasis Area and Severity Index score and a higher Functional Comorbidity Index were associated with infection in the PsC cohort. Ultraviolet treatment was protective against infection in both cohorts. No difference in rates of hospitalization was found (p = 0.66). There were no infection-related deaths in either cohort. CONCLUSION: The incidence rate of infection was higher in the PsA than the PsC cohort and higher among patients treated with biologics. The data confirm the association between infection and biologic treatment in psoriatic disease.