State-level adjusted ESRD incident rates: Use of observed vs model-predicted category-specific rates

J. Liu, T. A. Louis, W. Pan, J. Z. Ma, A. J. Collins

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Because of differences in case-mix across states, state-level case-mix-adjusted end-stage renal disease (ESRD) incident rates are reported in each United States Renal Data System Annual Data Report to make the across-state comparisons valid. The adjusted rates were estimated by the direct adjustment method, a widely used method for adjusted event rate calculation, based on observed category-specific ESRD incident rates in each state (called the observation-based method). However, when some adjusting categories in a state are small, the adjusted rate and the standard error for this state as estimated by this method may be inaccurate. This report proposes a model-based method that can overcome the disadvantages of the observation-based method and can be extended to continuous adjusting variables. National ESRD incident data and national population data from 1990 to 1999 were used. State-level adjusted ESRD incident rates were estimated by both the observation- and the model-based methods. For the model-based method, a Poisson regression model was used to estimate category-specific ESRD incident rates. For large-population states, both observation- and model-based methods produced similar estimates for adjusted ESRD incident rates. For small-population states, however, the observation-based method produced year-to-year estimates of adjusted ESRD incident rates that varied considerably and also had very large standard errors. In contrast, the model-based method produced stable estimates. The model-based method can overcome the disadvantages of the observation-based method for estimating state-level adjusted ESRD incident rates, especially for small states.

Original languageEnglish (US)
Pages (from-to)1459-1463
Number of pages5
JournalKidney international
Volume69
Issue number8
DOIs
StatePublished - Apr 2006

Bibliographical note

Funding Information:
The data reported here have been supplied by the United States Renal Data System. This study was performed as a deliverable under Contract No. N01-DK-9-2343 (National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA). We thank the Centers for Medicare & Medicaid Services for providing the Medicare data for this study. Within the United States Renal Data System Coordinating Center, Eric Frazier provided data-handling and data-processing support, and Dana Knopic, Beth Forrest, and Nan Booth, MSW, MPH, provided regulatory, manuscript-preparation, and editing assistance. Dr Robert N Foley read the manuscript carefully and offered valuable suggestions.

Keywords

  • Adjusted rate
  • Direct adjustment method
  • End-stage renal disease
  • Incident rate
  • Model-based method
  • Observation-based method

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