Urban–rural differences in pediatric traumatic head injuries: A prospective nationwide study

Figures & data

Table 1 Number of Icelandic children and adolescent 0–19 years old in December 1992, by gender, age, and geographical area

	Boys				Girls				Total (%)
Age in years	0–4	5–9	10–14	15–19	0–4	5–9	10–14	15–19
Reykjavik areaa	6,639	5,559	6,022	5,775	6,377	5,545	5,799	5,611	47,327 (55%)
Rural areasb	5,052	4,792	5,177	4,868	4,682	4,440	4,779	4,629	38,419 (45%)
Total	11,691	10,351	11,199	10,643	11,059	9,985	10,578	10,240	85,746 (100%)

a Notes: Reykjavik area refers to the city of Reykjavik and the surrounding towns and suburbs from Hafnarfjordur in the south to Mosfellsbaer and Kjalarnes in the north.

b Rural areas refer to other parts of Iceland, small towns, villages, and farmland.

Table 2 Incidence rates of traumatic head injuries (ICD-9 850–854) per 1000 with 95% confidence intervals by gender, age and severity of injury. Number of injured patients (N = 550) and the total population at risk (N = 85,746) by gender and age. Number and percentage of patients in each injury severity category

	Boys				Girls				Overall Incidence	Number Injured (%)
Age in years	0–4	5–9	10–14	15–19	0–4	5–9	10–14	15–19
Severity of injury
Minimal	9.32	3.86	4.20	2.54	6.96	4.11	3.5	2.05	4.65	399 (72.5%)
95% CIa	7.7, 11.2	2.8, 5.3	3.2, 5.6	1.7, 3.7	5.6, 8.7	3.0, 5.6	2.5, 4.8	1.3, 3.1	4.2, 5.1
Mild	1.71	1.93	1.79	1.41	1.36	1.40	1.04	1.37	1.50	129 (23.5%)
95% CI	1.1, 2.6	1.3, 3.0	1.2, 2.8	0.9, 2.3	0.8, 2.2	0.8, 2.4	0.6, 1.9	0.8, 2.3	1.3, 1.8
Moderate/Severe		0.19	0.36	0.38	0.45	0.20		0.10	0.21	18 (3.3%)
95% CI	0.0, 0.3	0.1, 0.7	0.1, 0.9	0.2, 1.0	0.2, 1.1	0.1, 0.7	0.0, 0.4	0.0, 0.6	0.1, 0.3
Fatal	0.09		0.09	0.19					0.05	4 (0.7%)
95% CI	0.0, 0.5	0.0, 0.4	0.0, 0.5	0.1, 0.7	0.0, 0.4	0.0, 0.4	0.1, 0.4	0.0, 0.4	0.0, 0.1
Total	11.12	5.99	6.43	4.51	8.77	5.71	4.54	3.52	6.41	550 (100.0%)
95% CI	9.4, 13.2	4.7, 7.7	5.1, 8.1	3.4, 6.0	7.2, 10.7	4.4, 7.4	3.4, 6.0	2.5, 4.9	5.9, 7.0
Number injured	130	62	72	48	97	57	48	36	550
Total population	11,691	10,351	11,199	10,643	11,059	9,985	10,578	10,240	85,746

a Note: Confidence intervals (CI) were calculated with the Wilson score procedure (Agresti and Coull 1998).

Table 4 Incidence rates of traumatic head injuries (ICD-9 850–854) per 1000 with 95% confidence intervals, by residence, gender, and age. Number and percentage of injured patients by gender and age in each of the two geographical areas (N = 550)

	Boys				Girls				Overall
Age in years	0–4	5–9	10–14	15–19	0–4	5–9	10–14	15–19
Reykjavik area
Incidence	16.27	8.63	8.64	4.50	11.45	6.85	6.04	5.17	8.64
95% CIa	13.5, 19.6	6.5, 11.4	6.6, 11.3	3.1, 6.6	9.1, 14.4	5.0, 9.4	4.4, 8.4	3.6, 7.4	7.9, 9.5
Number injured	108 (26.4%)	48 (11.7%)	52 (12.7%)	26 (6.4%)	73 (17.8%)	38 (9.3%)	35 (8.6%)	29 (7.1%)	409 (100.0%)
Rural areas
Incidence	4.35	2.92	3.86	4.52	5.13	4.28	2.72	1.51	3.67
95% CI	2.9, 6.6	1.7, 4.9	2.5, 6.0	3.0, 6.8	3.5, 7.6	2.7, 6.7	1.6, 4.7	0.7, 3.1	3.1, 4.3
Number injured	22 (15.6%)	14 (9.9%)	20 (14.2%)	22 (15.6%)	24 (17.0%)	19 (13.5%)	13 (9.2%)	7 (5.0%)	141 (100.0%)

a Note: Confidence intervals (CI) were calculated with the Wilson score procedure (Agresti and Coull 1998).

Table 3 Incidence rates of traumatic head injuries (ICD-9 850–854) per 1000 with 95% confidence intervalsa within parentheses, by severity of injury and residence. Number and percentage of injured patients by injury severity category in each of the two geographical areas (N = 550), and the total population at risk (N = 85,746)

	Reykjavik area		Rural areas
Severity of injury	Incidence	Number Injured (%)	Incidence	Number Injured (%)
Minimal	6.87 (6.2, 7.7)	325 (79.5)	1.93 (1.5, 2.4)	74 (52.5)
Mild	1.52 (1.2, 1.9)	72 (17.6)	1.48 (1.1, 1.9)	57 (40.4)
Moderate/Severe	0.23 (0.1, 0.4)	11 (2.7)	0.18 (0.1, 0.4)	7 (5.0)
Fatal	0.021 (0.0, 0.1)	1 (0.2)	0.080 (0.0, 0.2)	3 (2.1)
Total	8.64 (7.9, 9.5)	409 (100.0)	3.67 (3.1, 4.3)	141 (100.0)
Population		47,327		38,419

a Note: Confidence intervals were calculated with the Wilson score procedure (Agresti and Coull 1998).

AgrestiACoullBA1998Approximate is better than “exact” for interval estimations of binomial proportionsAm Stat5211926

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