Age-Period-Cohort Analysis of 1990–2003 Incidence Time Trends of Childhood Diabetes in Italy

TABLE 2

Age-specific incidence rates (per 100,000 person-years) of type 1 diabetes among Italian children 0–14 years old in the years 1990–2003, by birth cohorts 1978–2001, and by calendar periods (diagonals) 1990–1992, …, 2002–2003

Birth cohorts Yearly increase (%) P α*
1978 1981 1984 1987 1990 1993 1996 1999 2001
Age-group (years)
    0–2 5.0 (95) 4.9 (92) 6.4 (114) 7.1 (107) 7.9 (71) 3.9 0.001 0.3
    3–5 10.3 (199) 12.4 (229) 12.1 (223) 12.6 (191) 13.5 (119) 1.6 0.056 0.2
    6–8 10.9 (225) 13.1 (246) 14.4 (263) 14.6 (232) 17.0 (152) 3.3 <0.001 0.2
    9–11 13.4 (297) 15.2 (309) 16.2 (299) 18.2 (293) 17.6 (168) 2.4 0.001 0.2
    12–14 10.8 (273) 11.9 (263) 14.3 (285) 16.5 (268) 17.4 (167) 4.0 <0.001 0.3
RR (95% CI) 0.63 (0.54–0.73) 0.72 (0.64–0.80) 0.82 (0.74–0.90) 0.91 (0.83–0.99) Ref. 0.99 (0.89–1.09) 1.12 (1.00–1.26) 1.18 (1.01–1.38) 1.38 (1.06–1.80)
  • Number of cases are in parentheses. Percent yearly increases, test for age-specific trends adjusted by sex over calendar periods, and estimated variance of the registry-level random intercept (α) are shown in the last column.

  • *Likelihood ratio test of α = 0; P < 0.001 in all age-groups. RR, rate ratio for each birth cohort taking as reference those born in 1987–1993 (1990 mid-year).

This Article

  1. Diabetes vol. 59 no. 9 2281-2287