title: Annual Incidence of Nephrolithiasis among Children and Adults in South Carolina from 1997 to 2012.
abstract: OBJECTIVE
  The prevalence of nephrolithiasis in the United States has increased substantially, but recent changes in incidence with respect to age, sex, and race are not well characterized. This study examined temporal trends in the annual incidence and cumulative risk of nephrolithiasis among children and adults living in South Carolina over a 16-year period.
  
  
  METHODS
  We performed a population-based, repeated cross-sectional study using the US Census and South Carolina Medical Encounter data, which capture all emergency department visits, surgeries, and admissions in the state. The annual incidence of nephrolithiasis in South Carolina from 1997 to 2012 was estimated, and linear mixed models were used to estimate incidence rate ratios for age, sex, and racial groups. The cumulative risk of nephrolithiasis during childhood and over the lifetime was estimated for males and females in 1997 and 2012.
  
  
  RESULTS
  Among an at-risk population of 4,625,364 people, 152,925 unique patients received emergency, inpatient, or surgical care for nephrolithiasis. Between 1997 and 2012, the mean annual incidence of nephrolithiasis increased 1% annually from 206 to 239 per 100,000 persons. Among age groups, the greatest increase was observed among 15-19 year olds, in whom incidence increased 26% per 5 years (incidence rate ratio, 1.26; 95% confidence interval, 1.22 to 1.29). Adjusting for age and race, incidence increased 15% per 5 years among females (incidence rate ratio, 1.15; 95% confidence interval, 1.14 to 1.16) but remained stable for males. The incidence among blacks increased 15% more per 5 years compared with whites (incidence rate ratio, 1.15; 95% confidence interval, 1.14 to 1.17). These changes in incidence resulted in doubling of the risk of nephrolithiasis during childhood and a 45% increase in the lifetime risk of nephrolithiasis for women over the study period.
  
  
  CONCLUSIONS
  The incidence of kidney stones has increased among young patients, particularly women, and blacks.
authors.affiliation: Department of Surgery, Division of Pediatric Urology, Department of Surgery, Division of Urology, Center for Pediatric Clinical Effectiveness, Center for Clinical Epidemiology and Biostatistics, and tasiang@chop.edu.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Tasian
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, and Departments of Biostatistics and Epidemiology and.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Ross
authors.affiliation: Center for Pediatric Clinical Effectiveness.
authors.forename: Lihai
authors.initials: L
authors.lastname: Song
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Division of Nephrology, Mayo Clinic, Rochester, Minnesota;
authors.forename: David J
authors.initials: DJ
authors.lastname: Sas
authors.affiliation: Center for Pediatric Clinical Effectiveness, Center for Clinical Epidemiology and Biostatistics, and Department of Pediatrics, Division of General Pediatrics, and Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania;
authors.forename: Ron
authors.initials: R
authors.lastname: Keren
authors.affiliation: Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; Department of Pediatrics, Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Denburg
authors.affiliation: Department of Surgery, Division of Pediatric Urology.
authors.forename: David I
authors.initials: DI
authors.lastname: Chu
authors.affiliation: Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; Department of Pediatrics, Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
authors.forename: Lawrence
authors.initials: L
authors.lastname: Copelovitch
authors.affiliation: Department of Urology, University of California, Los Angeles, California; and RAND Corporation, Santa Monica, California.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Saigal
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, and Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; Department of Pediatrics, Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
authors.forename: Susan L
authors.initials: SL
authors.lastname: Furth
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000175:diagnosis / Q000453:epidemiology* / Q000208:ethnology; D018570:Risk Assessment; D012307:Risk Factors; D017678:Sex Distribution; D013022:South Carolina / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult
keywords: adults; children; epidemiology; humans; incidence; kidney stones; nephrolithiasis; prevalence; temporal trends