Maki Shinzawa

Self-reported Sleep Duration and Prediction of Proteinuria: A Retrospective Cohort Study

BACKGROUND Although multiple studies have shown that sleep duration is a predictor of cardiovascular diseases and mortality, few studies have reported an association between sleep duration and chronic kidney disease. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS 6,834 employees of Osaka University aged 20-65 years who visited Osaka University Healthcare Center for their mandatory annual health examinations between April 2006 and March 2010 and did not have estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), proteinuria, or treatment for self-reported kidney disease. PREDICTOR Self-reported questionnaires about life style, including sleep duration, and blood and urine testing at the first examinations during the study period. An association between sleep duration and outcome was assessed using multivariate Poisson regression models adjusting for clinically relevant factors. OUTCOME Time to the development of proteinuria defined as 1+ or higher by dipstick test. RESULTS Self-reported baseline sleep duration was 6.0 ± 0.9 hours, which reflected the mean sleep duration during a median of 2.5 (25th-75th percentile, 1.4-3.9) years of the observational period. Development of proteinuria was observed in 550 employees (8.0%). A multivariate Poisson regression model clarified that shorter sleep duration, especially 5 or fewer hours, was associated with the development of proteinuria in a stepwise fashion (vs 7 hours; incidence rate ratios of 1.07 [95% CI, 0.87-1.33; P = 0.5], 1.28 [95% CI, 1.00-1.62; P = 0.05], and 1.72 [95% CI, 1.16-2.53; P = 0.007] for 6, 5, and ≤4 hours, respectively), along with younger age, heavier current smoking, trace urinary protein by dipstick test, higher eGFR, higher serum hemoglobin A(1c) level, and current treatment for heart disease. A stepwise association between shorter sleep duration and the development of proteinuria also was verified in 4,061 employees who did not work the night shift. LIMITATIONS Self-reported sleep duration might be biased. Results in a single center should be confirmed in the larger cohort including different occupations. CONCLUSION Short sleep duration, especially 5 or fewer hours, was a predictor of proteinuria.

Comparison of Methylprednisolone Plus Prednisolone with Prednisolone Alone as Initial Treatment in Adult-Onset Minimal Change Disease: A Retrospective Cohort Study

BACKGROUND AND OBJECTIVES Previous studies suggested that intravenous methylprednisolone possibly accelerates remission of proteinuria in adult-onset minimal change disease; its impact on relapse of proteinuria is unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This multicenter retrospective cohort study included 125 adult-onset minimal change disease patients diagnosed by kidney biopsy between 2000 and 2009 and treated initially with corticosteroid in five nephrology centers in Japan participating in the Study of Outcomes and Practice Patterns of Minimal Change Disease. Times to first remission and first relapse of proteinuria after initiating the first immunosuppressive therapy were compared between 65 patients with initial use of intravenous methylprednisolone followed by prednisolone and 60 patients with initial use of prednisolone alone using multivariate Cox proportional hazards models. After calculating the probability of receiving methylprednisolone and prednisolone using a logistic regression model (propensity score), the results were ascertained using propensity score-matched and -stratified models. RESULTS During the median 3.6 years of observation (interquartile range=2.0-6.9), all 65 patients in the methylprednisolone and prednisolone group achieved remission within 11 (8-20) days of the corticosteroid initiation, whereas in the prednisolone group, 58 of 60 patients (96.7%) achieved remission within 19 (12-37) days (P<0.001). After achieving first remission, 32 (49.2%) patients in the methylprednisolone and prednisolone group and 43 (74.1%) patients in the prednisolone group developed at least one relapse. Multivariate Cox proportional hazards models revealed that methylprednisolone and prednisolone use was significantly associated with early remission (multivariate-adjusted hazard ratio, 1.56; 95% confidence interval, 1.06 to 2.30) and lower incidence of relapse (0.50; 95% confidence interval, 0.29 to 0.85) compared with prednisolone use alone. These results were ascertained in propensity score-based models. No significant difference was observed in incidence of adverse events, including infection, aseptic osteonecrosis, cataract, diabetes, and gastrointestinal bleeding. CONCLUSIONS Initial use of methylprednisolone was associated with earlier remission and lower incidence of relapse in adult-onset minimal change disease patients. Efficacy of methylprednisolone should be evaluated in randomized controlled trials.

Body Mass Index Modifies an Association between Self-Reported Regular Exercise and Proteinuria.

AIM Regular exercise habits are well-known to exert a favorable effect on the metabolic syndrome, which may cause proteinuria and chronic kidney disease (CKD). However, it remains unknown if exercise exerts a favorable effect on proteinuria and kidney dysfunction. The aim of this study was to reveal the association between exercise and the prevalence of proteinuria and kidney dysfunction and the attenuation by obesity. METHODS This study was a cross-sectional cohort study that included 292,013 participants who underwent the Specific Health Check and Guidance in Japan. The exercise score (range 0-3) was based on the number of positive answers to three questions regarding exercise habits. The outcome was defined as urinary protein detected by a dipstick test and kidney dysfunction [estimated glomerular filtration rate (GFR) less than 45 ml/min/1.73 m(2)]. RESULTS The exercise score was significantly associated with the prevalence of proteinuria in both males [vs. exercise score 0; exercise score 1, multivariate-adjusted odds ratio 0.86 (95% confidence interval 0.81-0.92), P<0.001; exercise score 2, 0.84 (0.79-0.90), P<0.001; exercise score 3, 0.77 (0.72-0.82), P<0.001] and females (same as in males). After the male subjects were divided into quintiles according to body mass index (BMI) in more than three groups (22.9<BMI<24.1), there was no significant association between the exercise score and the prevalence of proteinuria. In females, a higher exercise score was associated with a lower prevalence of proteinuria, regardless of BMI. The association between the exercise score and kidney dysfunction was as similar as that between the exercise score and proteinuria, except the attenuation of BMI. CONCLUSION Exercise may associate with a lower prevalence of proteinuria and kidney dysfunction, and a high BMI may attenuate this association between exercise and proteinuria in male subjects.

The association of alcohol and smoking with CKD in a Japanese nationwide cross-sectional survey

Chronic kidney disease (CKD) is characterized by a reduced glomerular filtration rate (GFR) and proteinuria. Modifiable lifestyle factors such as smoking and alcohol contribute to CKD. Recent cohort studies have shown that moderate alcohol consumption attenuates the decline of the GFR and smoking has been previously shown to be associated with CKD. However, the association of smoking and alcohol consumption on CKD is not entirely clear. To examine whether there is evidence to assume that smoking is an effective modifier of the association between CKD and alcohol consumption, we conducted a cross-sectional study of a population of people who presented for a health checkup under a program that targets the insured population aged ≧40 years using data from the Specific Health Check and Guidance in Japan between April 2008 and March 2009. Of the 506 807 participants aged ⩾40 years, 292 013 (57.6%) were included in the present analysis. Outcomes were kidney dysfunction, as an eGFR of <60 ml/min/1.73 m2, and proteinuria. In nonsmokers, drinking a small amount was associated with a lower prevalence of proteinuria, but in smokers, the association between alcohol and proteinuria was not observed. The analysis regarding eGFR <60 ml/min/1.73 m2 revealed that in both smokers and nonsmokers, alcohol consumption was inversely associated with the risk of CKD. Mild to moderate alcohol consumption might be associated with a lower risk of CKD (proteinuria and eGFR), especially among nonsmokers, because smoking might have modified the potential benefits of alcohol to prevent CKD.

IFI27 Is a Useful Genetic Marker for Diagnosis of Immunoglobulin A Nephropathy and Membranous Nephropathy Using Peripheral Blood

Diagnosis of chronic glomerulonephritis (CGN) depends primarily on renal biopsy, which is expensive and requires hospitalization, creating a demand for noninvasive diagnostic method for this disease. We used DNA microarray analysis to search for genes whose expression levels in peripheral blood mononuclear cells (PBMCs) could distinguish between patients with CGN and healthy volunteers (HVs). We selected immunoglobulin A nephropathy (IgAN) and membranous nephropathy (MN) as typical forms of CGN. The mRNA level of the gene encoding interferon (IFN)-alpha-inducible protein 27, IFI27, which is preferentially expressed in podocytes of glomeruli, was lower in PBMCs of IgAN and MN patients than in those of HVs. This result was confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Moreover, qRT-PCR analysis revealed that the IFI27 mRNA level was reduced in PBMCs of patients with other types of chronic glomerulonephritis. IFI27 immunohistochemical staining of biopsied specimens also confirmed reduced expression of IFI27 protein in IgAN and MN patients. Based on these results, we propose that IFI27 could serve as a noninvasive diagnostic marker for CGNs using peripheral blood.