Gold nanoparticle-based lateral flow immunoassay for detection of urinary 8-hydroxy-2ʹ-deoxyguanosine in preterm infants: A promising tool for pain-free, low-cost, and bedside screening of retinopathy of prematurity

Purpose: The clinical gold standard for screening of retinopathy of prematurity (ROP) in preterm infants involves binocular indirect ophthalmoscopy (BIO), an expensive, stressful, and not easily accessible procedure. In this study, we present the development of gold nanoparticle-based lateral flow immunoassay (LFIA) as an alternative screening procedure for ROP to reduce the burden of BIO. Design: Prospective clinical study. Methods: 23 pre-terms were enrolled for the study. Infants with the expected length of stay of <7 days were excluded from the study. LFIA was used to evaluate the levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in 130 urine samples collected at multiple time points during their stay in the neonatal intensive care unit (NICU). The 8-OHdG levels were correlated with different ROP stages determined by BIO performed closest to the day of urine collection. An 8-OHdG cut-off concentration that predicts the ROP status with high sensitivity was established based on Receiver Operating Characteristic (ROC) analysis. The accuracy of the LFIA to identify high risk ROP infants based on the urinary 8-OHdG cut-off value was evaluated. Results: The average urinary 8-OHdG levels increased concomitantly with the progression of ROP from stages 0–3. 8-OHdG levels in the high-risk ROP group (stages 1–3) (50.36 ± 12.85 ng/mL) were 1.8-fold higher than the low-risk group (stage 0) (27.18 ± 8.20 ng/mL). The 95 % confidence interval (95 % CI) for the difference in 8-OHdG medians between the two groups was 14.4–30.0 ng/mL. An 8-OHdG cut-off concentration of 30 ng/mL was established to predict the low- or high-risk ROP status using LFIA. The LFIA was able to predict the ROP status with a sensitivity of 83 % (95 % CI: 71.03 %–91.56 %), specificity of 58 % (95 % CI: 45.44 %–69.39 %), positive predictive value (PPV) of 62 % (95 % CI: 54.87 %–68.70 %), and a negative predictive value (NPV) of 80 % (95 % CI: 69.26 %–88.18 %). With 8-OHdG as the only biomarker, the LFIA was found to reduce the BIO screening burden by at least 38.3 %. Conclusions: This study presents the results of a prospective trial of using LFIA to predict ROP status based on urinary 8-OHdG levels. Urinary 8-OHdG was established as a biomarker for ROP progression. Urinary 8-OHdG levels were determined by LFIA and correlated with standard BIO procedure. A cut-off 8-OHdG concentration to predict the high-risk ROP with high sensitivity was established.