title: Spot urine protein/creatinine ratio is unreliable estimate of 24 h proteinuria in lupus nephritis when the histological scores of activity index are higher.
abstract: OBJECTIVE
  The aim of this study was to evaluate the correlation and agreement of spot urine protein/creatinine (P/C) ratio with 24 h proteinuria in patients with lupus nephritis (LN) under different scores of activity index (AI).
  
  
  METHODS
  In total, 90 pairs of 24 h urine and spot urine samples from 90 patients with biopsy-proven LN were analyzed. The correlation and agreement between the two sample types were assessed by Pearson correlation and intra-class correlation coefficient (ICC) using mixed model for repeated measurements, respectively.
  
  
  CONCLUSIONS
  Overall, 24 h proteinuria correlated strongly with the spot urine P/C ratio (r = 0.671, p < 0.001) with a good agreement (ICC = 0.656, 95% confidence interval (CI): 0.52-0.76). Subgroup analyses revealed that the correlation remained high in all groups (r = 0.825, p < 0.001; r = 0.567, p = 0.001; r = 0.686, p = 0.020), the agreement in group A (low AI) was good (ICC = 0.824, 95% CI: 0.70-0.89), but in group B (middle AI) and group C (high AI), the agreements were weak (ICC = 0.503, 95% CI: 0.19-0.72; ICC = 0.532, 95% CI: 0.06-0.84). Our work suggests that over the range of a higher AI, however, correlation was present but agreement was poor.
authors: Department of Nephrology, Lishui Center Hospital, Lishui, China.
authors: Q
authors: Q
authors: Zhang
authors: Department of Nephrology, Lishui Center Hospital, Lishui, China.
authors: L
authors: L
authors: Sun
authors: Department of Nephrology, Lishui Center Hospital, Lishui, China 296765973@qq.com.
authors: L
authors: L
authors: Jin
mesh_terms: D000328:Adult; D001706:Biopsy; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008181:Lupus Nephritis / Q000473:pathology / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011507:Proteinuria / Q000473:pathology / Q000652:urine*; D015203:Reproducibility of Results; D012107:Research Design; D012720:Severity of Illness Index; D013048:Specimen Handling / Q000379:methods; D016482:Urinalysis / Q000379:methods
chemical_list: D003404:Creatinine
keywords: Lupus nephritis; activity index; creatinine ratio; proteinuria; spot urine protein