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Table 2 Data available and data included in the analysis.

From: Time trends in exposure of cattle to bovine spongiform encephalopathy and cohort effect in France and Italy: value of the classical Age-Period-Cohort approach

  Data available* Data included Data categorisation** Reference groups***
  Number of tested animals Number of BSE cases Number of tested animals Number of BSE cases Age
(year)
Birth cohort Period
(calculated)
Cohort Age Period
France 17,306,300 660 17,248,284(1) 633(2) 2 to 33 1971 to 2005 1999 to 2007 1994/1995 6 2001
Italy 4,692,377 141 4,506,951(3) 131(4) 2 to 12 1988 to 2005 1999 to 2007 1996 5 2001
  1. * data available from the implementation of complete active surveillance in the countries (January 2001 in Italy, July 2001 in France) to 31 December 2007.
  2. ** one-year intervals were used to define age groups and birth cohorts. The period was calculated using the relationship: period = age + cohort.
  3. *** the reference groups chosen were the groups with the highest unadjusted prevalence. If necessary, a second model was fitted with the groups with the highest adjusted prevalence as a reference.
  4. (1) 58,002 animals with unknown date of birth were removed.
  5. (2) 14 atypical cases, three imported cases, nine secondary cases and one case with unknown date of birth were removed.
  6. (3) 16,248 animals under two years old, and 19 animals with incorrect age and/or date of birth were removed. 169,156 animals over 12 years old were also removed, because only pooled data for these animals were available (class: "= 13 years").
  7. (4) three atypical cases, three classical cases over 12 years old and four imported cases were removed.