Saturday, June 22, 2024

Diagnostic Accuracy of Flow Cytometry and PCR in Brazilian Axial Spondyloarthritis Patients

Similar articles

Brazilian researchers embarked on a study to evaluate the effectiveness of Flow Cytometry (FC) and Polymerase Chain Reaction (PCR) in detecting Human Leukocyte Antigen B-27 (HLA-B27) among Axial Spondyloarthritis (AxSpA) patients. This study is particularly significant as it addresses the unique characteristics of the Brazilian demographic, offering insights into the relative accuracy and practicality of these diagnostic methods.

The relevance of HLA-B27 in diagnosing and predicting AxSpA is well-documented, with a significant proportion of Ankylosing Spondylitis (AS) patients testing positive for the gene. FC and PCR are the primary methods used for routine HLA-B27 typing, yet their efficacy in a Brazilian context had not been thoroughly assessed until now.

Study Methods and Participants

An analytical cross-sectional study was conducted involving 62 outpatients diagnosed with AxSpA from a Brazilian University Hospital. Both FC and PCR-SSP assays were employed to determine HLA-B27 status. The results were meticulously analyzed, and the agreement between the two methods was evaluated using the kappa statistic, with a statistically significant p-value set at less than 0.05.

Findings and Statistical Analysis

The study revealed that 90.3% of participants were HLA-B27 positive according to FC, while PCR identified 79% as positive. FC demonstrated a sensitivity of 98% but a lower specificity of 38.5%. The Positive Predictive Value (PPV) for FC was 85.7%, and the Negative Predictive Value (NPV) was 83.5%, resulting in an overall accuracy of 85.5%. The kappa coefficient was calculated to be κ = 0.454, indicating moderate agreement between the two methods.

Implications for Clinical Practice

The findings suggest that FC, with its high sensitivity and satisfactory accuracy, is a viable and cost-effective method for preliminary HLA-B27 screening, especially in regions with limited resources. However, its lower specificity compared to PCR suggests that a negative FC result should be followed by PCR if clinical suspicion remains high.

To enhance diagnostic accuracy while maintaining cost-effectiveness, the researchers recommend an optimized algorithm. This would start with evaluating the necessity of HLA-B27 typing based on Choosing Wisely guidelines, using FC for initial screening, and resorting to PCR for confirming negative FC results when clinical suspicion persists.

Key Takeaways for Practitioners

– FC is highly sensitive but less specific compared to PCR for HLA-B27 detection.
– FC is more cost-effective and easier to implement in resource-limited settings.
– A stepwise diagnostic algorithm involving both FC and PCR can optimize resource use and diagnostic accuracy.
– Evaluating the need for HLA-B27 typing using Choosing Wisely recommendations can prevent unnecessary testing and reduce costs.

In conclusion, while PCR remains the gold standard for HLA-B27 typing due to its higher specificity, FC offers a pragmatic alternative for initial screening in clinical practice. Adopting a tailored diagnostic approach can ensure accurate diagnosis while considering financial constraints, particularly in low-income regions.

Original Article: Adv Rheumatol. 2024 May 23;64(1):42. doi: 10.1186/s42358-024-00383-x.

You can follow our news on our Telegram and LinkedIn accounts.

Subscribe to our newsletter

To be updated with all the latest news, offers and special announcements.

Latest article