Assessment of the urinary uric acid-to-creatinine ratio as a diagnostic marker for perinatal asphyxia in a resource-poor setting: a case control study

Abstract

Background

The lack of simple but effective and affordable diagnostic tools presents a challenge for the management of perinatal asphyxia, especially in low- to middle-income countries. Current diagnostic tools, such as arterial blood gas estimation, are expensive and not readily available at primary and secondary levels of care, where most cases of perinatal asphyxia are identified. This causes a delay in diagnosis. Perinatal asphyxia may have improved outcomes if there are cheaper, reliable, and more convenient diagnostic biomarkers that can aid early diagnosis leading to early initiation of treatment. This study assessed the utility of the urinary uric acid-to-urinary creatinine (UUA/UC) ratio in the diagnosis of perinatal asphyxia.

Methods

This study was conducted among 90 term newborns aged less than 24-hours delivered at delivered at the Enugu State University Teaching Hospital (ESUTH). In the study population, there were an equal number of asphyxiated and apparently healthy babies. Relevant maternal and neonatal histories were obtained, and physical examination was carried out for all enrolled newborns. Umbilical arterial blood was collected for blood gas analysis, and spot urine samples were collected and sent for uric acid and creatinine estimation. Relevant statistical tests were applied in the data analysis.

Results

The mean UUA/UC ratio was significantly greater in the asphyxiated group (2.41 ± 0.73) than among the control group (0.87 ± 0.29) (t = 13.129, p < 0.001). The accuracy of the UUA/UC ratio in diagnosing perinatal asphyxia had an area under the curve (AUC) of 0.978, implying that the test is accurate. The cut-off point that gives the best diagnosis of perinatal asphyxia was 1.54, with a sensitivity of 95.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 96%. Additionally, the UUA/UC ratio has a very strong positive correlation with the severity of hypoxic–ischaemic encephalopathy (HIE) (r = 0.843, p < 0.001).

Conclusion

The UUA/UC ratio is a good diagnostic marker of asphyxia and varies with the severity of encephalopathy. Accordingly, the urinary uric acid-to-creatinine ratio is recommended as a surrogate biomarker for the diagnosis of perinatal asphyxia.