Background/Purpose:
To systematically
review literature on the utility of spot urinary protein-creatinine ratio (PCR)
as a screening test for proteinuria and its ability to accurately measure
proteinuria compared with 24 hour urine collection (24H-P) in patients with
Systemic Lupus Erythematosus (SLE).

Methods: Literature search
(1900 – 2015) for articles comparing PCR and 24H-P in SLE patients in the
databases Medline, Web of Science and Embase. Included studies and their
results were critically appraised and analyzed.

Results: 13 studies (1001
patients; 84.01% women) were included. 10 studies reported on Pearson
correlation (range: 0.67-0.94); 3 studies reported on Spearman correlation
(range: 0.78-1).  The meta-analysis of studies with Pearson correlation showed
a high overall correlation of 0.80 between 24H-P and PCR (Figure 1) however with
high heterogeneity (I²=97.2%). Correlation analysis is not
sufficient to evaluate the utility of a new test against the gold standard test
and analysis on agreement is required. Seven studies reported on agreement: 3
studies analyzed Concordance Correlation Coefficient (0.48-0.94); 3 Intraclass
Correlation Coefficient (0.66-0.95) and 1 kappa (0.58). These results confirmed
that the agreement between 24H-P and PCR was inappropriate. Three studies included
Bland-Altman plot and the results also demonstrated poor agreement between both
tests.

Conclusion: The PCR has a utility
as a screening test for proteinuria in SLE patients. The studies’ results of 24H-P
and PCR showed poor agreement between both tests signifying that PCR should not
substitute the gold standard test (24H-P) to accurately measure proteinuria.

Figure
1. Forest
plot of correlations for the 8 studies included in the meta-analysis for the
overall correlation of 24H-P and PCR