title: Progression from beryllium exposure to chronic beryllium disease: an analytic model.
abstract: BACKGROUND
  Understanding the progression from beryllium exposure (BeE) to chronic beryllium disease (CBD) is essential for optimizing screening and early intervention to prevent CBD.
  
  
  METHODS
  We developed an analytic markov model of progression to cbd that assigns annual probabilities for progression through three states: from BeE to beryllium sensitization and then to CBD. We used calculations of the number in each state over time to assess which of several alternative progression models are most consistent with the limited available empirical data on prevalence and incidence. We estimated cost-effectiveness of screening considering both incremental (cost/case) and cumulative program costs.
  
  
  RESULTS
  No combination of parameters for a simple model in which risk of progression remains constant over time can meet the empirical constraints of relatively frequent early cases and continuing development of new cases with long latencies. Modeling shows that the risk of progression is initially high and then declines over time. Also, it is likely that there are at least two populations that differ significantly in risk. The cost-effectiveness of repetitive screening declines over time, although new cases will still be found with long latencies. However, screening will be particularly cost-effective when applied to persons with long latencies who have not been previously screened.
  
  
  CONCLUSIONS
  To optimize use of resources, the intensity of screening should decrease over time. Estimation of lifetime cumulative CBD risk should consider the declining risk of progression over time.
authors: Division of Occupational and Environmental Medicine, Department of Family Medicine, University of California at Los Angeles, Los Angeles, California 90024, USA. pharber@mednet.ucla.edu
authors: Philip
authors: P
authors: Harber
authors: Siddharth
authors: S
authors: Bansal
authors: John
authors: J
authors: Balmes
mesh_terms: D001607:Berylliosis / Q000175:diagnosis* / Q000517:prevention & control*; D001608:Beryllium; D003362:Cost-Benefit Analysis; D004781:Environmental Exposure; D006801:Humans; D008403:Mass Screening / Q000191:economics; D008962:Models, Theoretical; D013997:Time Factors
chemical_list: D001608:Beryllium