Medina–Rosas J, et al. – The accuracy of spot urine protein–to–creatinine ratio (PCR) was compared with 24–hour proteinuria (24H–P) to determine the change in proteinuria. Outcomes confirmed that protein–to–creatinine ratio did not have sufficient accuracy compared with 24H–P to analyze changes in proteinuria in lupus.

Methods

• This was a retrospective analysis on patients’ paired visits and paired urine samples for PCR and 24H–P.
• At baseline visit, patients with both abnormal 24H–P (>0.5 g/d) and PCR (>0.05 g/mmol) or both normal 24H–P (≤0.5 g/d) and PCR ( ≤0.05 g/mmol) were identified.
• The first follow–up visit with partial recovery (50% decrease in proteinuria) or complete recovery (≤0.5 g/d) was identified for those with abnormal baseline 24H–P, and new proteinuria (>0.5 g/d) was identified for those with normal 24H–P.
• 24 hour urine collection and PCR end–point frequencies were compared.
• Twenty–four–hour urine collection results were converted to 24H–PCR.
• To measure the magnitude of change (by standardized response mean [SRM]) in patients who achieved the end points, 24–hour PCR and PCR were utilized.

Results

• Out of 230 patients, at baseline, 95 patients had abnormal and 109 had normal 24H–P and PCR.
• 57 achieved partial recovery, and 53 achieved complete recovery by 24H–P, on follow–up.
• Standardized response mean was –1.03 and –1.10 for 24H–PCR and PCR, respectively.
• By PCR, 53 patients had partial recovery, and 27 had complete recovery.
• Standardized response mean was –1.25 and –0.86 by 24H–PCR and PCR, respectively.