title: Testing the Feasibility of a Passive and Active Case Ascertainment System for Multiple Rare Conditions Simultaneously: The Experience in Three US States.
abstract: BACKGROUND
  Owing to their low prevalence, single rare conditions are difficult to monitor through current state passive and active case ascertainment systems. However, such monitoring is important because, as a group, rare conditions have great impact on the health of affected individuals and the well-being of their caregivers. A viable approach could be to conduct passive and active case ascertainment of several rare conditions simultaneously. This is a report about the feasibility of such an approach.
  
  
  OBJECTIVE
  To test the feasibility of a case ascertainment system with passive and active components aimed at monitoring 3 rare conditions simultaneously in 3 states of the United States (Colorado, Kansas, and South Carolina). The 3 conditions are spina bifida, muscular dystrophy, and fragile X syndrome.
  
  
  METHODS
  Teams from each state evaluated the possibility of using current or modified versions of their local passive and active case ascertainment systems and datasets to monitor the 3 conditions. Together, these teams established the case definitions and selected the variables and the abstraction tools for the active case ascertainment approach. After testing the ability of their local passive and active case ascertainment system to capture all 3 conditions, the next steps were to report the number of cases detected actively and passively for each condition, to list the local barriers against the combined passive and active case ascertainment system, and to describe the experiences in trying to overcome these barriers.
  
  
  RESULTS
  During the test period, the team from South Carolina was able to collect data on all 3 conditions simultaneously for all ages. The Colorado team was also able to collect data on all 3 conditions but, because of age restrictions in its passive and active case ascertainment system, it was able to report few cases of fragile X syndrome. The team from Kansas was able to collect data only on spina bifida. For all states, the implementation of an active component of the ascertainment system was problematic. The passive component appears viable with minor modifications.
  
  
  CONCLUSIONS
  Despite evident barriers, the joint passive and active case ascertainment of rare disorders using modified existing surveillance systems and datasets seems feasible, especially for systems that rely on passive case ascertainment.
authors: Institute on DisabilityUniversity of New HampshireDurham, NHUnited States.
authors: Amanda
authors: 0000-0002-7431-1333
authors: A
authors: Reichard
authors: Department of Epidemiology and BiostatisticsUniversity of South CarolinaColumbia, SCUnited States.
authors: Suzanne
authors: 0000-0003-1517-5033
authors: S
authors: McDermott
authors: Special Health Care NeedsColorado Department of Public Health and EnvironmentDenver, COUnited States.
authors: Margaret
authors: 0000-0002-1378-3724
authors: M
authors: Ruttenber
authors: Department of Preventive MedicineUniversity of Mississippi Medical CenterJackson, MSUnited States.
authors: Joshua
authors: 0000-0002-3716-3642
authors: J
authors: Mann
authors: South Carolina Department of Health and Environmental ControlColumbia, SCUnited States.
authors: Michael G
authors: 0000-0002-8297-2203
authors: MG
authors: Smith
authors: Revenue and Fiscal Affairs OfficeSouth Carolina Budget and ControlColumbia, SCUnited States.
authors: Julie
authors: 0000-0001-5323-1986
authors: J
authors: Royer
authors: National Center for Birth Defects and Developmental DisabilitiesCenters for Disease Control and PreventionAtlanta, GAUnited States.
authors: Rodolfo
authors: 0000-0001-9979-3140
authors: R
authors: Valdez
keywords: fragile X syndrome; muscular dystrophy; spina bifida; surveillance