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Age-period-cohort analysis of 1990-2003 incidence time trends of childhood diabetes in Italy: the RIDI study.

Bruno G, Maule M, Merletti F, Novelli G, Falorni A, Iannilli A, Iughetti L, Altobelli E, d'Annunzio G, Piffer S, Pozzilli P, Iafusco D, Songini M, Roncarolo F, Toni S, Carle F, Cherubini V, RIDI Study Gro - Diabetes (2010)

Bottom Line: The incidence rate was 12.26 per 100,000 person-years and significantly higher in boys (13.13 [95% CI 12.66-13.62]) than in girls (11.35 [10.90-11.82]).The best model, however, included sex, age, and a linear time trend (drift).Age-period-cohort analysis shows that the variation over time has a linear component that cannot be ascribed to either the calendar period or the birth cohort.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, University of Turin, Turin, Italy. graziella.bruno@unito.it

ABSTRACT

Objective: To investigate age-period-cohort effects on the temporal trend of type 1 diabetes in children age 0-14 years in Italian registries.

Research design and methods: This report is based on 5,180 incident cases in the period 1990-2003 from the Registry for Type 1 Diabetes Mellitus in Italy (RIDI). Multilevel (random intercept) Poisson regression models were used to model the effects of sex, age, calendar time, and birth cohorts on temporal trends, taking into account the registry-level variance component.

Results: The incidence rate was 12.26 per 100,000 person-years and significantly higher in boys (13.13 [95% CI 12.66-13.62]) than in girls (11.35 [10.90-11.82]). Large geographical variations in incidence within Italy were evident; incidence was highest in Sardinia, intermediate in Central-Southern Italy, and high in Northern Italy, particularly in the Trento Province, where the incidence rate was 18.67 per 100,000 person-years. An increasing temporal trend was evident (2.94% per year [95% CI 2.22-3.67]). With respect to the calendar period 1990-1992, the incidence rates increased linearly by 15, 27, 35, and 40% in the following time periods (P for trend < 0.001). With respect to the 1987-1993 birth cohort, the incidence rate ratio increased approximately linearly from 0.63 (95% CI 0.54-0.73) in the 1975-1981 cohort to 1.38 (1.06-1.80) in the 1999-2003 cohort. The best model, however, included sex, age, and a linear time trend (drift).

Conclusions: Large geographical variations and an increasing temporal trend in diabetes incidence are evident among type 1 diabetic children in Italy. Age-period-cohort analysis shows that the variation over time has a linear component that cannot be ascribed to either the calendar period or the birth cohort.

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Incidence rates of type 1 diabetes among Italian children 0–14 years old in the years 1990–2003 in the three Italian macro-areas (Center-South, Island [Sardinia], and North).
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Figure 1: Incidence rates of type 1 diabetes among Italian children 0–14 years old in the years 1990–2003 in the three Italian macro-areas (Center-South, Island [Sardinia], and North).

Mentions: An increasing temporal trend was evident both examining the whole Italian area and the three Italian macro-areas separately; in Sardinia we found a tendency toward lower risk in more recent years (Fig. 1). Overall, the rates increased from 10.22 per 100,000 person-years in 1990–1992 to 14.78 per 100,000 in 2002–2003 (Table 1). Controlling for age and sex, the annual increase was 2.94% (95% CI 2.22–3.67).


Age-period-cohort analysis of 1990-2003 incidence time trends of childhood diabetes in Italy: the RIDI study.

Bruno G, Maule M, Merletti F, Novelli G, Falorni A, Iannilli A, Iughetti L, Altobelli E, d'Annunzio G, Piffer S, Pozzilli P, Iafusco D, Songini M, Roncarolo F, Toni S, Carle F, Cherubini V, RIDI Study Gro - Diabetes (2010)

Incidence rates of type 1 diabetes among Italian children 0–14 years old in the years 1990–2003 in the three Italian macro-areas (Center-South, Island [Sardinia], and North).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927951&req=5

Figure 1: Incidence rates of type 1 diabetes among Italian children 0–14 years old in the years 1990–2003 in the three Italian macro-areas (Center-South, Island [Sardinia], and North).
Mentions: An increasing temporal trend was evident both examining the whole Italian area and the three Italian macro-areas separately; in Sardinia we found a tendency toward lower risk in more recent years (Fig. 1). Overall, the rates increased from 10.22 per 100,000 person-years in 1990–1992 to 14.78 per 100,000 in 2002–2003 (Table 1). Controlling for age and sex, the annual increase was 2.94% (95% CI 2.22–3.67).

Bottom Line: The incidence rate was 12.26 per 100,000 person-years and significantly higher in boys (13.13 [95% CI 12.66-13.62]) than in girls (11.35 [10.90-11.82]).The best model, however, included sex, age, and a linear time trend (drift).Age-period-cohort analysis shows that the variation over time has a linear component that cannot be ascribed to either the calendar period or the birth cohort.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, University of Turin, Turin, Italy. graziella.bruno@unito.it

ABSTRACT

Objective: To investigate age-period-cohort effects on the temporal trend of type 1 diabetes in children age 0-14 years in Italian registries.

Research design and methods: This report is based on 5,180 incident cases in the period 1990-2003 from the Registry for Type 1 Diabetes Mellitus in Italy (RIDI). Multilevel (random intercept) Poisson regression models were used to model the effects of sex, age, calendar time, and birth cohorts on temporal trends, taking into account the registry-level variance component.

Results: The incidence rate was 12.26 per 100,000 person-years and significantly higher in boys (13.13 [95% CI 12.66-13.62]) than in girls (11.35 [10.90-11.82]). Large geographical variations in incidence within Italy were evident; incidence was highest in Sardinia, intermediate in Central-Southern Italy, and high in Northern Italy, particularly in the Trento Province, where the incidence rate was 18.67 per 100,000 person-years. An increasing temporal trend was evident (2.94% per year [95% CI 2.22-3.67]). With respect to the calendar period 1990-1992, the incidence rates increased linearly by 15, 27, 35, and 40% in the following time periods (P for trend < 0.001). With respect to the 1987-1993 birth cohort, the incidence rate ratio increased approximately linearly from 0.63 (95% CI 0.54-0.73) in the 1975-1981 cohort to 1.38 (1.06-1.80) in the 1999-2003 cohort. The best model, however, included sex, age, and a linear time trend (drift).

Conclusions: Large geographical variations and an increasing temporal trend in diabetes incidence are evident among type 1 diabetic children in Italy. Age-period-cohort analysis shows that the variation over time has a linear component that cannot be ascribed to either the calendar period or the birth cohort.

Show MeSH
Related in: MedlinePlus