Characteristic and Outcome of Psoriatic Arthritis Patients with Hyperuricemia

Hematological indices in psoriatic enthesopathy: relation to clinical and ultrasound evaluation

BACKGROUND

Enthesopathy is considered a crucial aspect of assessment and outcome in psoriatic arthritis (PsA). Musculoskeletal ultrasound (MSUS) is a critical tool for accurately detecting enthesitis. Recent research focuses on identifying simple biomarkers for detecting and monitoring psoriatic enthesopathy. Red cell distribution width (RDW), mean platelet volume (MPV), and neutrophil/lymphocyte ratio (NLR) are components of a complete blood count (CBC) and are reliable bio-inflammatory markers in various rheumatic diseases.

AIM OF WORK

To measure MPV, RDW, and NLR in psoriatic enthesopathy and determine their relationship to disease activity and MSUS findings.

PATIENTS AND METHODS

This study focused on 30 people with psoriatic arthritis (PsA) as per CASPAR criteria, along with 20 control subjects. Enthesopathy was evaluated clinically using the Leeds Enthesitis Index (LEI). The modified Disease Activity Index of Psoriatic Arthritis (DAPSA28) was calculated, and RDW, MPV, NLR, CRP, and ESR were measured. Each enthesis in LEI was radiologically assessed using plain radiography and MSUS according to OMERACT definitions.

RESULTS

There was a significant relationship between clinical tenderness, the presence of enthesophytes on plain radiography, and MSUS findings at entheses sites (p < 0.001 for each). Psoriatic patients had higher levels of RDW and MPV (p < 0.001 and 0.01, respectively) than controls, with no significant differences in NLR (p = 0.189) between the two groups. RDW and MPV levels were positively correlated with the DAPSA28 score.

CONCLUSION

Monitoring PsA disease activity can be improved by considering RDW and MPV as reliable indicators and using them to screen for psoriatic enthesopathy with MSUS indices. Key points • Clinically identifying enthesitis in patients with PsA can be challenging. Imaging MSUS indices hold promise for objective analysis, but there is no consensus on which indices to use in clinical trials and daily practice. • Patients with psoriatic enthesopathy have higher RDW and MPV levels, which are positively correlated with DAPSA28 score. • RDW and MPV can be considered in the turn of improved screening of psoriatic enthesopathy with MSUS scores.

Interest in daily clinical practice of screening for gouty disease in patients with psoriatic arthritis

Objectives

PsA and gout are two prevalent rheumatic diseases, that can be associated as part of a rheumatism known as 'Psout'. Both conditions are associated with cardiovascular (CV) risk, thus their co-occurrence could have significant implications for the management of CV risks and patient care. This study aimed to determine the prevalence of gout within a PsA patient cohort and, consequently, to identify factors associated with this pathological association.

Methods

This is an observational, descriptive, cross-sectional, single-center study, including patients diagnosed with PsA. Demographic, clinical, biological and imaging data were collected. We identified the proportion of patients simultaneously affected by PsA and gout and compared characteristics between those with and without gout.

Results

The prevalence of gout among PSA patients was 9.8% (12/122), with a prevalence of 23% for asymptomatic hyperuricemia and 7.4% presenting with specific US signs of gout. Significant associated factors in the univariate analysis included weight, hypertension, diabetes, certain medications (diuretics, aspirin, lipid-lowering agents), impaired renal function, elevated fasting blood glucose, lipid abnormalities and specific US signs of gout.

Conclusion

Our study has described the existence of patients simultaneously affected by PsA and gout ('Psout'). Performing joint US along with uric acid level measurements in PsA patients can enable personalized therapeutic care.

Impact of hyperuricaemia on patients with psoriatic arthritis treated with secukinumab in the FUTURE 2-5 and MAXIMISE studies

OBJECTIVES

Patients with psoriatic arthritis (PsA) are at a significantly increased risk of hyperuricaemia and development of gout, and those with hyperuricaemia have been found to respond poorly to PsA treatment and have more peripheral and destructive joint damage. We present a comprehensive post hoc analysis using pooled data from the FUTURE 2-5 studies and the MAXIMISE study to further evaluate the impact of hyperuricaemia on clinical presentation/disease severity and response to secukinumab in patients with PsA.

METHODS

Patients were stratified into two groups based on baseline serum uric acid (SUA) level (threshold of 360 µmol/L). A sensitivity analysis was also performed based on SUA thresholds of 300 µmol/L and 420 µmol/L. Demographics, clinical, radiological characteristics and comorbidities data were collected.

RESULTS

At baseline, patients with hyperuricaemia were mostly male, reported a higher prevalence of hypertension, with more clinical dactylitis, more psoriasis and more severe skin disease compared with patients with normouricaemia. A similar proportion of patients in the normouricaemic and hyperuricaemic cohorts achieved American College of Rheumatology responses, resolution of enthesitis and dactylitis, inhibition of structural damage progression and improvement in health-related quality of life across all secukinumab doses at week 52.

CONCLUSION

Patients with PsA and hyperuricaemia have different clinical characteristics from patients with PsA and normouricaemia. Identification of these patients at an early stage may facilitate a personalised treatment approach and improved management of comorbidities. Furthermore, secukinumab provided a rapid and sustained response across all manifestations of PsA up to week 52, irrespective of baseline uricaemia status.

Consensus statements for pharmacological management, monitoring of therapies, and comorbidity management of psoriatic arthritis in the United Arab Emirates

OBJECTIVE

Psoriatic arthritis (PsA), a chronic inflammatory disease characterized by heterogeneous clinical manifestations, substantially impacts the quality of life of affected individuals. This article aims at developing consensus recommendations for the management of PsA and associated comorbidities and screening and monitoring requirements of PsA therapies in the United Arab Emirates (UAE) population.

METHODS

An extensive review of present international and regional guidelines and publications on the pharmacological management, monitoring of therapies in the context of PsA was performed. Key findings from guidelines and literature were reviewed by a panel of experts from the UAE at several meetings to align with current clinical practices. Consensus statements were formulated based on collective agreement of the experts and members of Emirates Society for Rheumatology.

RESULTS

The consensus recommendations were developed to aid practitioners in clinical decision-making with respect to dosage recommendations for pharmacological therapies for PsA, including conventional drugs, non-biologic, and biologic therapies. Consensus recommendations for therapeutic options for the treatment of PsA domains, including peripheral arthritis, axial disease, enthesitis, dactylitis, psoriasis, and nail disease, were developed. The panel emphasized the importance of monitoring PsA therapies and arrived at a consensus on monitoring requirements for PsA therapies. The expert panel proposed recommendations for the management of common comorbidities associated with PsA.

CONCLUSION

These consensus recommendations can guide physicians and healthcare professionals in the UAE in making proper treatment decisions, as well as efficiently managing comorbidities and monitoring therapies in patients with PsA.

Acute joint swelling in psoriatic arthritis: Flare or "psout"-A 10-year-monocentric study on synovial fluid

Psoriatic arthritis (PsA) is a multifaceted inflammatory disease associated with psoriasis that can affect peripheral joints, entheses, and the axial skeleton with a variable clinical course. Acute episodes of joint swelling in PsA patients can have different causes and require specific treatments. We aimed to describe the acute joint swelling in PsA patients via synovial fluid (SF) analyses, assessing in particular the presence of pathogenic crystals, to determine whether it is a flare or an acute episode of gout ("psout") during the course of the disease. This retrospective study was based on the results of SF analysis of samples collected from unselected adult PsA patients referred to our clinic for acute joint swelling. Demographic characteristics, disease involvement, laboratory findings on SF, and treatment options were recorded and reviewed. Among 5,478 SF samples analyzed in a 10-year time span, 213 complete SF records from PsA patients were evaluated. Overall, after adjustment for the degree of synovial inflammation, significant differences were observed in term of sex (p = 0.0017) and ongoing therapy (p = 0.0246). Non-inflammatory SFs, indeed, were mainly described for female PsA patients under therapy. Regarding serum uric acid levels, there were 19/213 (8.9%) PsA with hyperuricemia (HU), who were older, mostly male, patients with mild articular involvement and rare pathogenic crystals in their SF. Although it is known that the risk of gout is higher among patients with PsA ("psout"), monosodium urate crystals were reported only in 5/213 SFs (2.4%) of our cohort and in 2/19 SFs (10.5%) of HU PsA patients. Moreover, hyperuricemia seems not to modify the SF features in PsA patients. This study results seem to suggest that the convergence of gout and PsA, involving the role of urate crystals, is a more intricate relationship, which needs further insights to be unraveled.

The risk of organ-based comorbidities in psoriasis: a systematic review and meta-analysis

Background

The close relationship between psoriasis and concomitant diseases is widely accepted. However, a comprehensive analysis of organ-based comorbidities in psoriasis is still lacking.

Objective

The authors aimed to present the risk of organ-based comorbidities in psoriasis by comparing the general population.

Methods

The authors retrieved a search of Pubmed, EMBASE, and Cochrane databases for studies reporting organ-based comorbidities in psoriasis versus the general population. Observational studies that met the following criteria were assessed: 1) Psoriasis diagnosis; 2) Cardiovascular or kidney or liver or respiratory or cerebrovascular outcomes; 3) Comparison group of individuals without psoriasis. Pooled Relative Risks (pRRs) and 95% Confidence Intervals (CIs) were calculated by using the random-effect model.

Results

Fifteen observational studies with 216,348 psoriatic patients and 9,896,962 individuals from the general population were included. Psoriasis showed a greater risk of organ-based comorbidities. Compared to the general population, pRR for all organ-based comorbidities was 1.20 (95% CI 1.11‒1.31) in psoriasis, and pRR was lower in mild 0.61 (95% CI 0.46‒0.81) than in moderate/severe patients. pRR was 1.20 (95% CI 1.11‒1.30) for cardiovascular, 1.56 (95% CI 1.20‒2.04), and 1.75 (95% CI 1.33‒2.29) for cerebrovascular and liver diseases, respectively. pRR for coexisting renal and cardiovascular events was 1.09 (95% CI 1.01‒1.18). pRR for coexisting renal and cerebrovascular events was 1.28 (95% CI 0.99‒1.66). pRR for coexisting renal and liver diseases was 1.46 (95% CI 1.10‒1.94). pRR for coexisting cardiovascular and liver diseases was 1.41 (95% CI 1.11‒1.80).

Study limitations

There is heterogeneity.

Conclusion

Psoriasis has a higher risk of single and multiple organ-based comorbidities than the general population. The present study will further improve attention to psoriasis as a systemic inflammatory disease.

Related Risk Factors and Treatment Management of Psoriatic Arthritis Complicated With Cardiovascular Disease

Psoriatic arthritis (PsA) is a chronic autoimmune inflammatory joint disease related to psoriasis (PsO). The risk of PsA patients with cardiovascular disease (CVD) is significantly higher than that of the general population. At present, the relevant mechanism is not clear, chronic inflammation and traditional cardiovascular risk factors are the most important factors for the increased risk of CVD in PsA patients. Early assessment of the risk of PsA patients with CVD, and active control of the disease activity of PsA patients and intervention of traditional cardiovascular risk factors can delay the progression of CVD risk. This article reviews the epidemiology and pathogenesis between PsA and CVD, and reviews the latest developments in the risk assessment and management of CVD in PsA patients.

Cardiovascular Diseases in the Patients with Psoriatic Arthritis

There are limited data regarding the burden and trend of cardiovascular diseases (CVD) in psoriatic arthritis (PsA). We analyzed the National Inpatient Sample database from January 2005 to December 2018 to examine the hospitalization trends amongst adults with PsA primarily for heart failure (HF), acute myocardial infarction (AMI), and stroke. The primary outcomes of interest included in-hospital mortality, length of stay (LOS), and inflation-adjusted cost. The age-adjusted percentage of HF hospitalizations among PsA patients decreased from 2.5% (2005/06) to 1.4% (2011/12; P-trend 0.013) and subsequently increased to 2.0% (2017/18; P-trend 0.044). The age-adjusted percentage of AMI hospitalizations among PsA patients showed a non-statistically significant decreasing trend from 2.1% (2005/06) to 1.7% (2011/12; P-trend 0.248) and showed a non-statistically significant increase to 2.3% (2017/18; P-trend 0.056). The age-adjusted stroke hospitalizations increased from 1.1% (2005/06) to 1.3% (2017/18; P-trend 0.036). Apart from a decrease in adjusted inflation-adjusted cost among heart failure hospitalizations, there was no significant change in inpatient mortality, length of stay or hospital cost, during the study period. We found an increasing trend of cardiovascular hospitalizations in patients with PsA. These findings will raise awareness and inform further research and clinical practice for PSA patients with CVD.

Psoriatic arthritis with hyperuricemia: more peripheral, destructive, and challenging to treat

Objective

To study the impact of hyperuricemia on clinical presentation, severity, and associated comorbidities of psoriatic arthritis (PsA).

Methods

Retrospective bicentric case–control study performed in Strasbourg and Colmar, France, from 2009 to 2019. Patients with PsA (according to ICD-10 coding) and at least one available serum urate (SU) measurement were included. Demographic, comorbidities, clinical, and radiographic data were collected. Hyperuricemia was defined as SU level ≥ 360 µmol/L.

Results

We included 242 patients: 73 (30.2%) had hyperuricemia and 15 (6.2%) met 2015 ACR/EULAR criteria for gout. On univariate analysis, as compared with normo-uricemic patients, hyperuricemic patients were more frequently male (72.6% vs 39.1%, p = 1.6 × 10⁻⁶) with higher body mass index (30.9 vs 28.7 kg/m², p = 0.015) and more comorbidities (Charlson comorbidity index: 2.6 vs 1.8, p = 0.005). PsA started at an older age (47.5 vs 43 years, p = 0.016) was more polyarticular (56.2% vs 41.9%, p = 0.049) than axial (9.6% vs 22.8%, p = 0.019) and more destructive (52.8% vs 37.4%, p = 0.032). PsA patients with joint destruction more frequently had hyperuricemia than did others (37.6% vs 25.8%, p = 0.047). Multivariable analysis confirmed the association of hyperuricemic PsA with peripheral joint involvement (odds ratio 2.98; 95% confidence interval 1.15–7.75; p = 0.025) and less good response to treatment (0.35; 0.15–0.87; p = 0.024).

Conclusion

Patients with hyperuricemic PsA show poorer response to PsA treatment and have more peripheral and destructive joint damage than normo-uricemic patients.

Key Points • Gout and psoriatic arthritis (PsA) can co-exist in the same patient. • Monosodium urate crystals might have a deleterious impact on PsA. • Hyperuricemic PsA is more polyarticular, less frequently axial, and more destructive than normo-uricemic PsA. • PsA with hyperuricemia should lead to more personalized medicine.

Hyperuricemia in Psoriatic Arthritis: Epidemiology, Pathophysiology, and Clinical Implications

Psoriatic arthritis (PsA) represents the articular component of the systemic psoriatic disease and the extra-cutaneous disorder most frequently found in patients with psoriasis. Besides the articular involvement, PsA is associated with several metabolic abnormalities such as insulin resistance, hypertension, diabetes and hyperuricemia. Uric acid is the final product of purine metabolism and the etiological substrate of gout. Accumulating evidence highlights the emerging role of hyperuricemia as a major cardiovascular risk factor. Moreover, different studies evaluated the interplay between hyperuricemia and psoriatic disease, suggesting that individuals affected by psoriasis or PsA might present higher serum levels of uric acid and that hyperuricemia might affect severity of clinical manifestations and degree of inflammation in PsA patients. In this review, we focus on the bidirectional relationship between uric acid and PsA, analyzing how uric acid may be involved in the pathogenesis of psoriasis/PsA and how clinical manifestations of PsA and inflammatory mediators are affected by uric acid concentrations. Finally, the effects of anti-rheumatic drugs on uric acid levels and the potential benefit of urate-lowering therapies on psoriasis and PsA were summarized.

Does Disease Activity Influence the Levels of Uric Acid in Psoriatic Arthritis?

Background:

Hyperuricemia is not only associated with the development of gout but also with renal and vascular dysfunction. The prevalence of this condition has already been studied in psoriasis, but there are a few studies that have been carried out in psoriatic arthritis (PsA). Some studies have shown an association with metabolic syndrome, while others with the extent of cutaneous involvement, but there are no studies that have evaluated the disease activity with compound indexes.

Objective:

The aim of the study was to determine if disease activity, measured by different composite scores, influences the levels of uric acid.

Method:

This was a cross-sectional, observational study, which included 52 PsA patients. Clinical assessments included dactylitis, tender and swollen joint counts, Psoriasis Area and Severity Index, Leeds Enthesis Index, Minimal Disease Activity and Disease Activity for Psoriatic Arthritis. Hyperuricemia was defined as serum uric acid levels ≥ 6mg/dL in females and ≥ 7mg/dL in males.

Results:

Among the 52 included patients, 55.76% were female. The mean age was 54.9 ± 11.6 years. Hyperuricemia occurred in 26.92%. Demographic data, diet, comorbidities and medication were similar between patients with and without hyperuricemia. Patients with hyperuricemia had higher waist circumference (p <0.0046). There was no difference in disease activity between groups, either in the isolated items or in the composite indexes. There was a significant difference in uric acid levels according to the classification of chronic kidney disease by estimated glomerular filtration rate (p=0.0016). Individuals using leflunomide had significantly lower levels of uric acid than those who were not using (p=0.0071).

Conclusion:

This study supports the notion that, in PsA, hyperuricemia is more related to metabolic factors than to disease activity.

The Impact of Comorbidity on Patient-Reported Outcomes in Psoriatic Arthritis: A Systematic Literature Review

INTRODUCTION

A systematic literature review was conducted with the aim to analyse the impact of comorbidity on patient-reported outcomes (PROs) in patients with psoriatic arthritis (PsA).

METHODS

A sensitive search strategy of the Medline, Embase and the Cochrane Library (up to March 2019) was applied to retrieve studies for inclusion in this systematic literature review. Abstracts of the ACR and EULAR scientific meetings were also searched. The selection criteria were: (1) patients with PsA (population) with a comorbidity (intervention) and (2) report of any impact of the comorbidity on PROs. Systematic literature reviews, randomized controlled trials and observational were included in this systematic literature review. Two of the authors selected the articles and collected the data.

RESULTS

Eighteen articles were included in this systematic literature review, with most being cross-sectional studies that included more than 9000 patients with PsA. Some studies analysed the impact of an individual comorbidity, such as fibromyalgia (FM), and in others the analysis was according to the number of comorbidities. The most frequently analysed PROs were function, quality of life and fatigue. Analysis of the studies included in the review showed that patients with a higher number of comorbidities and/or more severe comorbidities reported worse impacts of their disease on function, patient's global assessment (PGA), pain, fatigue, work disability and quality of life. Specifically, FM had a negative impact on the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), function, quality of sleep and quality of life; anxiety and depression had a negative impact on function and fatigue; metabolic syndrome had a negative impact on BASDAI, function, PGA and quality of life; obesity had a negative impact on function and pain; smoking (current and ex-smokers) had a negative impact on pain, function, fatigue, quality of life and overall health; alcohol intake had a negative impact on pain, function, fatigue, quality of life and overall health.

CONCLUSIONS

The prevalence and impact of medical comorbidity on PROs are very high in patients with PsA.

Bone microstructure and volumetric bone mineral density in patients with hyperuricemia with and without psoriasis

We analyzed volumetric bone mineral density (vBMD) and bone microstructure using HR-pQCT in subjects with normouricemia (NU) and subjects with hyperuricemia (HU) with and without psoriasis (PSO). HU was associated with higher cortical vBMD and thickness. Differences in average and trabecular vBMD were found between patients with PSO + HU and NU.

INTRODUCTION

Hyperuricemia (HU) and gout are co-conditions of psoriasis and psoriatic arthritis. Current data suggest a positive association between HU and areal bone mineral density (BMD) and a negative influence of psoriasis on local bone, even in the absence of arthritis. However, the influence of the combination of HU and psoriasis on bone is still unclear. The aim of this study was to assess the impact of HU with and without psoriasis on bone microstructure and volumetric BMD (vBMD).

METHODS

Healthy individuals with uric acid levels within the normal range (NU), with hyperuricemia (HU), patients with hyperuricemia and psoriasis (PSO + HU), and patients with uric acid within the normal range and psoriasis (PSO + NU) were included in our study. Psoriasis patients had no current or past symptoms of arthritis. Average, trabecular, and cortical vBMD (mgHA/cm³); trabecular number (Tb.N, 1/mm) and thickness (Tb.Th, mm); inhomogeneity of the network (1/N.SD, mm); and cortical thickness (Ct.Th., mm) were carried out at the ultradistal radius using high-resolution peripheral quantitative computed tomography. In addition, bone turnover markers such as DKK-1, sclerostin, and P1NP were analyzed.

RESULTS

In total, 130 individuals were included (44 NU participants (34% female), 50 HU (24%), 16 PSO + HU (6%), 20 PSO + NU (60%)). Subjects were aged: NU 54.5 (42.8, 62.1), HU 57.5 (18.6, 65.1), PSO + HU 52.0 (42.3, 57.8), and PSO + NU 42.5 (34.8, 56.8), respectively. After adjusting for age, sex, BMI, and diabetes, patients in the HU group revealed significantly higher values of cortical vBMD (p < 0.001) as well as cortical thickness (p = 0.04) compared to the NU group. PSO + NU showed no differences to NU, but PSO + HU demonstrated both lower average (p = 0.03) and trabecular vBMD (p = 0.02). P1NP was associated with average, cortical, and trabecular vBMD as well as cortical thickness while sclerostin levels were related to trabecular vBMD.

CONCLUSION

Hyperuricemia in otherwise healthy subjects was associated with a better cortical vBMD and higher cortical thickness. However, patients with both psoriasis and hyperuricemia revealed a lower vBMD.

At the crossroads of gout and psoriatic arthritis: "psout"

Psoriatic arthritis and gout are frequently encountered conditions sharing a number of common risk factors, which render their independent study difficult. Epidemiological studies have demonstrated a strong link between these diseases, suggesting the presence of underlying, intertwined pathophysiological mechanisms that currently remain unknown. Indeed, sodium urate crystals could play a pathogenic role in psoriasis and psoriatic arthritis. In daily practice, the distinction between psoriatic arthritis associated with hyperuricemia and a gouty arthropathy with psoriasis is complex. Several common pathogenic features suggest a more intricate relationship than their mere coexistence in the same patient. Thus, the concurrence of these two diseases should be seen as a novel overlap syndrome, at the boundary between inflammatory and metabolic rheumatism. The present update aims to clarify the determinants of the link and to define this new nosological entity. Its recognition could have therapeutic implications that appear essential for treatment optimization in a personalized setting.Key Points• What is already known about this subject? Psoriatic arthritis (PsA) and gout have strong interconnections, including comorbidities and pathophysiology. One must note that confounding clinical symptoms and radiological signs of PsA and gout are similar and difficult to differentiate in patients whose radiological lesions become too advanced to be differentiated or with less clearly defined phenotypes.• What does this study add? The pathogenic role of chronic hyperuricemia in the development and maintenance of PsA is based on epidemiological, clinical, and fundamental arguments and hence does not appear fortuitous. These two pathological processes can influence each other.• How might this impact on clinical practice? This new line of thinking regarding the convergence of gout and PsA, involving the role of urate crystals, could prompt a potential new approach to treatment (urate-lowering therapy) among patients with active/refractory PsA.

The association of serum uric acid levels in psoriasis patients: A systematic review and network meta-analysis

BACKGROUND

Current research has proved that psoriasis is associated with serum uric acid (SUAC) levels. Our purpose is to clarify SUAC levels and the incidence of hyperuricemia in psoriasis patients, and to compare SUCA levels in different groups' psoriasis patients.

METHODS

We plan to search 7 electronic bibliographic databases (PubMed, Embase, Cochrane, and 4 Chinese databases) from inception to August 2019. Literatures selection and data collection will be performed independently by 2 authors. The Newcastle-Ottawa scale will be used to assess the methodologic quality and bias of included studies. Firstly, standard pairwise meta-analysis will be used to examine the considered data synthesis. Secondly, if the identified studies appear sufficiently similar within and across the different comparisons between different groups of psoriasis patients, we will estimate SUAC levels using network meta-analysis in different age and ethnicity psoriasis patients. Mean difference, risk ratio, and 95% confidence intervals will be used to assess the SUAC levels and the incidence of hyperuricemia in psoriasis patients. The software of Stata and WinBUGS will be used to calculations.

RESULTS

The results will be published in a peer-reviewed journal.

CONCLUSION

Our study will compare SUCA levels in different groups' psoriasis patients through network meta-analysis, and we believe our job is very meaningful.

ETHICS AND DISSEMINATION

Our study is a secondary study of the existing literature. So, ethical and dissemination approval is not required.

Undiluted human whole blood uric acid detection using a graphitized mesoporous carbon modified electrode: a potential tool for clinical point-of-care uric acid diagnosis

Direct sensing of uric acid (UA) in an undiluted whole blood sample is reported here taking human whole blood as an analyte and a self-supporting electrolyte. Among various solid electrodes (Pt, Au, GCE, and GCE/Nafion) and carbon nanomaterials (carbon nanofibers, graphene oxide, graphite nanopowder, graphitized mesoporous carbon (GMC), single-walled carbon nanotubes, and multiwalled carbon nanotubes) tested, a GMC-modified glassy carbon electrode, designated as GCE/GMC, showed a remarkable response towards direct electrochemical oxidation of blood uric acid at ∼0.25 V vs. Ag/AgCl, unlike the poor and/or feeble current signals with the other unmodified and modified electrodes. It is plausible that the mesoporous nature of the GMC favours the formation of a blood-GMC bio-corona through internalization and provides straight access to blood-matrixed uric acid. Furthermore, the effects of the scan rate and interference with various biochemicals on the GCE/GMC were analysed. The electrochemical oxidation reaction is found to be diffusion controlled in nature and there is no interference from common biochemicals like ascorbic acid, glucose, tryptophan, H2O2, xanthine, hypoxanthine, cysteine, nitrate, nitrite, and sulfide in blood. Real blood UA sample analysis was demonstrated with comparable UA analysis results from the clinical measurement.