title: Update of the NIOSH life table analysis system: a person-years analysis program for the windows computing environment.
abstract: BACKGROUND
  Person-years analysis is a fundamental tool of occupational epidemiology. A life table analysis system (LTAS), previously developed by the National Institute for Occupational Safety and Health, was limited by its platform and analysis and reporting capabilities. We describe the updating of LTAS for the Windows operating system (LTAS.NET) with improved properties.
  A group of epidemiologists, programmers, and statisticians developed software, platform, and computing requirements. Statistical methods include the use of (indirectly) standardized mortality ratios, (directly) standardized rate ratios, confidence intervals, and P values based on the normal approximation and exact Poisson methods, and a trend estimator for linear exposure-response associations.
  We show examples using LTAS.NET to stratify and analyze multiple fixed and time-dependent variables. Data import, stratification, and reporting options are highly flexible. Users may export stratified data for Poisson regression modeling.
  
  
  CONCLUSIONS
  LTAS.NET incorporates improvements that will facilitate more complex person-years analysis of occupational cohort data.
authors: Division of Surveillance, Hazard Evaluations, and Field Studies, Industrywide Studies Branch, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, USA. zcg3@cdc.gov
authors: Mary K
authors: MK
authors: Schubauer-Berigan
authors: Misty J
authors: MJ
authors: Hein
authors: William M
authors: WM
authors: Raudabaugh
authors: Avima M
authors: AM
authors: Ruder
authors: Sharon R
authors: SR
authors: Silver
authors: Steven
authors: S
authors: Spaeth
authors: Kyle
authors: K
authors: Steenland
authors: Martin R
authors: MR
authors: Petersen
authors: Kathleen M
authors: KM
authors: Waters
mesh_terms: D015331:Cohort Studies; D016001:Confidence Intervals; D004812:Epidemiologic Methods; D006801:Humans; D015993:Life Tables; D008175:Lung Neoplasms / Q000453:epidemiology; D015233:Models, Statistical; D009314:National Institute for Occupational Safety and Health, U.S. / Q000706:statistics & numerical data*; D016272:Occupational Health / Q000706:statistics & numerical data*; D012984:Software / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology