Anti-HCV Pozitif Hastalarda HCV RNA Düzeylerinin Retrospektif Analizi

Abstract

Hepatit C, kronik karaciğer hastalığı, siroz ve hepatoselüler karsinoma ile sonuçlanabilen önemli bir hastalıktır. Türkiye’de prevalansı %0,5 ile %1,9 arasında değişmektedir. Tanıda hem HCV antikorları hem de HCV RNA kullanılır ve yanlış pozitif sonuçlardan kaçınmak için birlikte değerlendirilmesi önemlidir. Bu çalışma, anti-HCV pozitif vakalarda HCV RNA pozitifliğini belirlemeyi ve anti-HCV düzeyleri ile HCV RNA arasındaki ilişkiyi incelemeyi amaçlamıştır. Çalışmaya, HCV RNA testi yapılan toplam 312 anti-HCV pozitif hasta dahil edilmiştir. Anti-HCV testi, kemilüminesan enzim immünoassayı kullanılarak yapılmış ve Cut-Off Index (COI) ≥1,0 pozitif kabul edilmiştir. HCV RNA, PCR yöntemiyle saptanmış ve IU/mL olarak raporlanmıştır. Anti-HCV’nin HCV RNA pozitifliğini öngörmedeki tanısal performansını değerlendirmek için Receiver Operating Characteristic (ROC) analizi kullanılmıştır. 312 hastanın 42’si (%13,5) HCV RNA pozitif bulunmuştur. Anti-HCV <5 COI olan 54 hastanın hiçbirinde HCV RNA pozitif bulunmamıştır. Hastaların yaş ortalaması 46,3 yıl olup, %45,5’i erkek ve %54,5’i kadındır. Düşük anti-HCV düzeyine sahip vakalarda HCV RNA’nın bulunmaması, potansiyel yanlış pozitif sonuçları veya çapraz reaksiyonları düşündürmektedir. Bu bulgular, özellikle sınırda değerlerde, serolojik sonuçların klinik ve laboratuvar verileri ile birlikte yorumlanmasının önemini vurgulamaktadır. Bu gözlemleri netleştirmek için daha büyük hasta gruplarıyla yapılacak çalışmalara ihtiyaç vardır.

Keywords

• Hepatit C
• Yanlış Pozitif Reaksiyonlar
• Polimeraz Zincir Reaksiyonu

Retrospective analysis of HCV RNA levels in Anti-HCV positive patients

Abstract

Although anti-HCV screening is widely used, the value of the antibody signal level (Cut-off Index, COI) in predicting the presence of active viremia remains controversial. This study aimed to evaluate the relationship between anti-HCV COI levels and HCV RNA positivity, and to investigate the potential value of low COI values in excluding viremia. A total of 312 patients with anti-HCV reactivity (COI ≥1.0) and an available HCV RNA test result between January 2023 and June 2025 were evaluated retrospectively. When repeated results were recorded for the same patient, the first anti-HCV result and the first valid HCV RNA result were included in the analysis. Anti-HCV testing was performed by chemiluminescent immunoassay, and HCV RNA testing by PCR. The diagnostic performance of the anti-HCV COI value in predicting HCV RNA positivity was assessed using ROC analysis, the Youden index, sensitivity, specificity, positive predictive value, negative predictive value, and 95% confidence intervals. The association between COI groups and HCV RNA positivity was evaluated using the chi-square test and Fisher’s exact test. HCV RNA positivity was detected in 42 (13.5%) of the 312 patients included. The discriminative power of the anti-HCV COI value as a continuous marker for HCV RNA positivity was poor (AUC: 0.438; 95% CI: 0.278–0.606). The relationship between HCV RNA positivity and COI level was not linear; positivity was highest in the 10.01–50.00 COI range (32.5%), with lower rates in the low and very high COI groups (p<0.001). The statistically derived threshold based on the Youden index was 16.46. At this threshold, sensitivity was 97.6% (95% CI: 87.7–99.6), specificity 28.5% (95% CI: 23.5–34.2), positive predictive value 17.5%, and negative predictive value 98.7%. No HCV RNA positivity was detected in the 54 patients with COI <5 (0%; 95% CI: 0–6.6). Whereas no HCV RNA positivity was observed in the COI <5 group, the HCV RNA positivity rate in the COI ≥5 group was 16.3% (42/258); the difference between the two groups was statistically significant (Fisher’s exact test, p<0.001). The anti-HCV COI level does not predict HCV RNA positivity in a linear manner, and its overall discriminative performance remains limited. The absence of HCV RNA positivity in the 54 patients with COI <5 (0%; 95% CI: 0–6.6) suggests that very low COI values may define a low-risk group for active viremia. However, the low AUC, low specificity, and low positive predictive value indicate that the COI level alone is insufficient to confirm active infection. Therefore, a COI <5 threshold may assist in prioritizing reflex molecular testing; however, it cannot replace HCV RNA testing, and HCV RNA testing is required to confirm active infection.

Keywords

• Hepatitis C
• False Positive Reactions
• Polymerase Chain Reaction

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