Comparison of Spot Urine Protein/Creatinine Ratio, Spot Urine Protein/Osmolality Ratio with Measured 24-Hour Urine Protein in HIV Subjects in Nigeria

Abstract

Background and Objectives: Urine protein examination is a veritable tool in the management of renal diseases. Proteinuria evaluation from 24-hour urine collection is the gold standard. Prompt urine protein assessment from spot urine sample has become necessary to eliminate inaccuracies inherent in timed urine collection. This study aims at comparing spot urine protein/creatinine ratio (SUPCR) and measured 24-hour urine protein (24 HUP), and also spot urine protein/osmolality ratio (SUPOR) and 24 HUP against measured 24-hour urine protein (24 HUP) for assessment of proteinuria in human immunodeficiency virus (HIV) subjects. Methodology: Three hundred and ninety three HIV subjects from the HIV/AIDS clinic and 136 age- and sexmatched non-HIV subjects as Control. Investigations performed included 24-hour urine protein (24 HUP), spot urine protein (SUP), spot urine creatinine (SUCr), spot urine osmolality (SUOsm), fasting blood sugar (FBS), urinalysis, HIV screening and confirmatory test, electrolyte, urea and creatinine. SUPCR and SUPOR were calculated. Correlation statistics, 2 × 2 contingency table analysis, receiver operator characteristics (ROC) Curve analysis and Bland Altman plots were used to compare SUPCR and 24 HUP, and also SUPOR and 24 HUP in HIV subjects and control. SPSS version 17 and Medcal statistical software were used to analyze the data. P<0.050 was taken as statistically significant. Results: Using the 2 × 2 contingency table in the HIV subjects, the Sensitivity for SUPCR and SUPOR with 24 HUP was 43.4% and 11.5% respectively. Specificity for SUPCR and SUPOR with 24 HUP was 92.9% and 99.2% respectively. The SUPCR had a correlation (r) of 0.734 (p<0.001) with 24 HUP. In addition, SUPOR had a correlation coefficient of 0.417 (p<0.001) with 24 HUP. Using the Bland Altman plots, SUPCR compared with 24HUP the limits of agreement were +0.361 g/day to -0.248 g/day in HIV subjects. In addition for SUPOR the limits of agreements were +0.440 g/day to-0.180 g/day in HIV subjects. The bias was 0.060 g/day and 0.130 g/day for SUPCR and SUPOR respectively. The receiver operating characteristics (ROC) curve showed that SUPCR randomly chosen value of 0.042 mg/mg and SUPOR chosen value of 0.010 mg/dl/mOsm/kg H2O predicted 24 HUP at urinary excretion threshold of 0.150 g. Conclusion: The SUPCR and SUPOR are reliable tests, for quantifying proteinuria in HIV subjects, and should be used in assessment of proteinuria in HIV subjects in Sub Saharan African countries.