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. 2017 Nov 2;12(11):e0187607.
doi: 10.1371/journal.pone.0187607. eCollection 2017.

Seasonal Proteinuria Changes in IgA Nephropathy Patients After Proteinuria Remission

Free PMC article

Seasonal Proteinuria Changes in IgA Nephropathy Patients After Proteinuria Remission

Koji Inagaki et al. PLoS One. .
Free PMC article


Background: Proteinuria is a powerful prognostic factor for end-stage renal disease in IgA nephropathy (IgAN) patients. However, it is not known whether proteinuria exacerbations are related to seasonal changes.

Methods: We retrospectively enrolled consecutive patients diagnosed with IgAN by kidney biopsy at our hospital between 2002 and 2014. Proteinuria remission was defined as urinary protein <0.3 g/gCr in two consecutive outpatient urinalyses and exacerbation as urinary protein ≥0.75 g/gCr. Four seasons were defined: spring (March-May), summer (June-August), autumn (September-November), and winter (December-February). We performed a multivariate analysis to identify factors associated with the second remission following a proteinuria exacerbation.

Results: We analyzed 116 patients. Proteinuria remission and exacerbation occurred in 77, and 43 patients, respectively. The incidence of proteinuria exacerbation was significantly higher in autumn and winter than in spring and summer (p = 0.040). The cumulative second remission rate was significantly higher in patients with autumn and winter proteinuria exacerbation than in patients with spring and summer exacerbations (p = 0.0091). In multivariate analyses, exacerbation onset in autumn and winter (hazard ratio [HR], 3.51; 95% confidence interval [CI], 1.41-8.74) and intensive therapy (HR, 2.26; 95% CI, 1.05-4.88) were significantly associated with a second proteinuria remission.

Conclusion: In IgAN patients in proteinuria remission, proteinuria exacerbation frequently occurred in autumn and winter. Exacerbations occurring in autumn and winter tended to remit early.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.


Fig 1
Fig 1. Kaplan–Meier analyses of the second remission after proteinuria exacerbation in two combined seasonal periods.

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Grant support

Nagoya university nephrology is supported by the following funders; Astellas Pharma, Alexion Pharmaceuticals, Otsuka Pharmaceutical, Kyowa Hakko Kirin, Daiichi-Sankyo, Takeda Pharmaceutical Company, Chugai Pharmaceutical, Dainippon Sumitomo Pharma, Pfizer Japan, Merck Sharp and Dohme, Mochida Pharmaceutical Company, Torii Pharmaceutical, Kissei Pharmaceutical, Novartis Pharma, Kowa Pharmaceutical, Nippon Boehringer Ingelheim, Bristol-Myers Squibb, Mitsubishi Tanabe Pharma Corporation, and Teijin Pharma Limited. However, the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.