title: Epidemiology of idiopathic nephrotic syndrome in children: endemic or epidemic?
abstract: The etiology of idiopathic nephrotic syndrome (INS) remains partially unknown. Viral infections have been reported to be associated with INS onset and relapse. The aim of this study was to describe the epidemiology of a population-based cohort of children with INS and propose a spatiotemporal analysis.
  
  
  
  All children aged 6 months to 15 years with INS onset between December 2007 and May 2010 and living in the Paris area were included in a prospective multicenter study. Demographic and clinical features at diagnosis and 2 years were collected.
  
  
  
  INS was diagnosed in 188 children, 93 % of whom were steroid sensitive. Annual incidence was 3.35/100,000 children. Standardized incidence ratio (SIR) was higher in one of the eight counties: Seine-Saint-Denis, with SIR 1.43 [95 % confidence interval (CI) 1.02-1.95]. A spatial cluster was further identified with higher SIR 1.36 (95 % CI 1.09-1.67). Temporal analysis within this overincidence area showed seasonal variation, with a peak during the winter period (p <0.01). In addition, partition of the Paris area into quintiles of the population showed that the average delay of occurrence, with regard to the first study case, followed a longitudinal progression (p <0.0001).
  
  
  
  The clustering of cases, the seasonal variation within this particular area, and the progression over the Paris area altogether suggest that INS may occur on an epidemic mode.
authors: Service de Néphrologie Pédiatrique, Hôpital Robert-Debré, APHP, Paris, France. claire.dossier@aphp.fr.
authors: Claire
authors: 0000-0001-7918-2879
authors: C
authors: Dossier
authors: Sorbonne Universités, UPMC Univ Paris 06, INSERM, Institut Pierre Louis d'Epidémiologie et de Santé Publique (IPLESP UMRS 1136), F75012, Paris, France.|Department of Public Health, Hôpital Saint-Antoine, AP-HP, Paris, France.
authors: Nathanael
authors: N
authors: Lapidus
authors: Agence de la Biomédecine, Saint-Denis La Plaine, Paris, France.
authors: Florian
authors: F
authors: Bayer
authors: Service de Néphrologie Pédiatrique, Hospices Civiles de Lyon, Lyon, France.
authors: Anne-Laure
authors: AL
authors: Sellier-Leclerc
authors: Service de Néphrologie Pédiatrique, Necker-Enfants-Malades, APHP, Paris, France.
authors: Olivia
authors: O
authors: Boyer
authors: Service de Pédiatrie, Hôpital Jean-Verdier, APHP, Bondy, France.
authors: Loic
authors: L
authors: de Pontual
authors: Service de Pédiatrie, Centre Hospitalier Sud Francilien, Corbeil-Essonne, France.
authors: Adrien
authors: A
authors: May
authors: Service de Pédiatrie, Centre Hospitalier de Versailles, Le Chesnay, France.
authors: Sylvie
authors: S
authors: Nathanson
authors: Service de Pédiatrie, Hôpital Saint-Camille Bry-sur-Marne, Le Chesnay, France.
authors: Christine
authors: C
authors: Orzechowski
authors: Unité de Recherche Clinique URC-Est, Université Paris 6, Paris, France.
authors: Tabassome
authors: T
authors: Simon
authors: Sorbonne Universités, UPMC Univ Paris 06, INSERM, Institut Pierre Louis d'Epidémiologie et de Santé Publique (IPLESP UMRS 1136), F75012, Paris, France.|Department of Public Health, Hôpital Saint-Antoine, AP-HP, Paris, France.
authors: Fabrice
authors: F
authors: Carrat
authors: Service de Néphrologie Pédiatrique, Hôpital Robert-Debré, APHP, Paris, France.
authors: Georges
authors: G
authors: Deschênes
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D015331:Cohort Studies; D019353:Endemic Diseases; D058872:Epidemics; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy / Q000453:epidemiology* / Q000821:virology; D010297:Paris / Q000453:epidemiology; D011446:Prospective Studies; D012621:Seasons; D012959:Socioeconomic Factors; D013256:Steroids / Q000627:therapeutic use
chemical_list: D013256:Steroids
keywords: Childhood; Cluster; Epidemiology; Nephrotic syndrome; Seasonal periodicity