Diagnostic performance of anti-RA33 antibody as a serological marker for rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis is diagnosed based on the 2010 Rheumatoid Arthritis Classification Criteria whereby rheumatoid factor and anti-citrullinated protein antibody are the serological markers included in these criteria. Anti-RA33 antibody has the potential to provide additional diagnostic value in rheumatoid arthritis. The aim of this study is to determine the diagnostic performance of anti-RA33 antibody as a serological marker for rheumatoid arthritis.

MATERIAL AND METHODS

Thirtyfour patients with rheumatoid arthritis and 34 non-rheumatoid arthritis individuals were included in this cross-sectional study. Anti-RA33 antibody and rheumatoid factor were performed on all samples.

RESULTS

The sensitivity, specificity, positive and negative predictive value for anti-RA33 antibody and rheumatoid factor were 41.1%, 97.1%, 93.3%, 62.3% and 64.7%, 79.4%, 75.9%, 69.2% respectively. The overall sensitivity and specificity if either anti-RA33 antibody or rheumatoid factor are positive were 79.4% and 76.47% respectively.

CONCLUSION

Anti-RA33 antibody showed good specificity and positive predictive value and could be considered as a potential serological marker for rheumatoid arthritis diagnosis.

The association between serum prolactin levels and interleukin-6 and systemic lupus erythematosus activity

Based on the recent evidence of association between hyperprolactinemia and systemic lupus erythematosus disease activity (SLEDAI), a study was conducted to analyze the association of hyperprolactinemia with lupus nephritis disease activity. In this cross-sectional study, the analysis was conducted on SLE patients who visited the University Kebangsaan Malaysia Medical Centre (UKMMC) Nephrology Clinic from August 2015 till February 2016. The disease activity was measured using the SLEDAI score, with more than 4 indicating active lupus nephritis. Basal resting prolactin level was analyzed in 43 patients with lupus nephritis, in 27.9% of them had raised serum prolactin. The median of serum prolactin level at 0 minutes was 19.91 ng/mL (IQR: 15.95-22.65 ng/ mL) for active lupus nephritis, which was significantly higher compared to the median of serum prolactin level of 14.34 ng/mL (IQR: 11.09-18.70 ng/mL) for patients in remission (p=0.014). The serum prolactin level positively correlated with SLEDAI (rhos: 0.449, p=0.003) and the UPCI level in lupus nephritis patients (rhos: 0.241, p=0.032). The results were reproduced when the serum prolactin was repeated after 30 minutes. However, the serum prolactin levels at 0 minutes were higher than those taken after 30 minutes (p=0.001). An assessment of serum IL-6 levels found that the active lupus nephritis patients had a higher median level of 65.91 pg/ mL (IQR: 21.96-146.14 pg/mL) compared to the in-remission level of 15.84 pg/mL (IQR: 8.38-92.84 pg/mL), (p=0.039). Further correlation analysis revealed that there was no statistical correlation between the interleukin (IL)-6 levels with serum prolactin, SLEDAI and other lupus nephritis parameters. An ROC curve analysis of serum prolactin at 0 minutes and serum prolactin after 30 minutes and IL-6 levels for prediction of SLE disease activity provided the cutoff value of serum prolactin at 0 minutes, which was 14.63 ng/mL with a sensitivity of 91.7% and specificity of 58.1% and AUC of 0.74 (p=0.015). This study concurred with the previous findings that stated that hyperprolactinemia is prevalent in SLE patients and correlated with clinical disease activity and UPCI level. The baseline of the fasting serum prolactin level was found to be a sensitive biomarker for the evaluation of lupus nephritis disease activity.

Suicidal ideation in systemic lupus erythematosus: NR2A gene polymorphism, clinical and psychosocial factors

Background Systemic lupus erythematosus (SLE) patients are a high-risk population for suicide. Glutamatergic neurosystem genes have been implicated in the neurobiology of depression in SLE and suicidal behaviour in general. However, the role of glutamate receptor gene polymorphisms in suicidal behaviour among SLE patients remains unclear in the context of established clinical and psychosocial factors. We aimed to investigate the association of NR2A gene polymorphism with suicidal ideation in SLE while accounting for the interaction between clinical and psychosocial factors. Methods A total of 130 SLE patients were assessed for mood disorders (MINI International Neuropsychiatric Interview), severity of depression (Patient Health Questionnaire-9), suicidal behaviour (Columbia-Suicide Severity Rating Scale), socio-occupational functioning (Work and Social Adjustment Scale), recent life events (Social Readjustment Rating Scale) and lupus disease activity (SELENA-SLE Disease Activity Index). Eighty-six out of the 130 study participants consented for NR2A genotyping. Results Multivariable logistic regression showed nominal significance for the interaction effect between the NR2A rs2072450 AC genotype and higher severity of socio-occupational impairment with lifetime suicidal ideation in SLE patients ( p = 0.038, odds ratio = 1.364, 95% confidence interval = 1.018-1.827). However, only the association between lifetime mood disorder and lifetime suicidal ideation remained significant after Bonferroni correction ( p < 0.001, odds ratio = 33.834, 95% confidence interval = 7.624-150.138). Conclusions Lifetime mood disorder emerged as a more significant factor for suicidal ideation in SLE compared with NR2A gene polymorphism main and interaction effects. Clinical implications include identification and treatment of mood disorders as an early intervention for suicidal behaviour in SLE. More adequately-powered gene-environment interaction studies are required in the future to clarify the role of glutamate receptor gene polymorphisms in the risk stratification of suicidal behaviour among SLE patients.