Epidemiology. Volume 17, Number 3, May 2006 Apgar Scores and Risk of Epilepsy after birth was accessible only for children born between 1978 and 1996. Midwives recorded Apgar scores after birth TABLE 1. Incidence Rates of Epilepsy According to Selected Characteristics of the Study Population, Denmark, 1978-2002 following standardized procedures. More than 95% of al births in Denmark take place in public hospitals, and mid- ncidence Rat wives report Apgar scores to the registry from the remaining Person-Years No of Persons per 100, 000 home births following the hospital procedures Characteristics at risk With Epilepsy Person-Year Assessment of Epilepsy B Information on epilepsy was obtained from the Na 9,202445 95.0 8,751,255 7717 tional Hospital Register that contains information on all discharges from Danish hospitals since 1977. Outpatients Gestational age(weeks) 305.5 have been included in the register since 1995. Diagnostic Very preterm 146637 information in the National Hospital Register was based on Preterm(33-36) 80,516 he International Classification of Diseases. &th revision Term(37-41) 14,370,16 D-8)from 1977 to 1993, and the International Classifica Posten(≥42) 1,471,843 tion of Diseases, 1 Oth revision(ICD-10) from 1994 to 2002 Cohort members were classified with epilepsy if they had Birth order been hospitalized or had been in outpatient care with a 8,124,750 7548 diagnosis of epilepsy (ICD-8: 345; ICD-10: G40-G41). The 2nd+ 9828950 time of onset of epilepsy was defined as the first day of Multiple birth Single birth 17,533,469 Data Analys Twin or more 419,903 104.3 Unknown The incidence rate ratio of epilepsy was estimated by a Maternal age(years) log-linear Poisson regression model- with the GENMOD 656.046 procedure in SAs version 8.1(SAS institute, Cary, NC). All incidence rate ratios were adjusted for age and its interaction 4,611,950 4528 with sex and for calendar year. Age and calendar year were 25-29 7053,083 treated as time-dependent variables. Age was categorized in 4.165.921 3669 1466.700 from the first birthday to the 19th birthday, and then age intervals of 20-21 and 22-25 as the oldest 2 groups. Calendar Ye 915 year was categorized in a 1-year period from 1978-2002. P 17, 15,855 values were based on likelihood ratio tests and 95% confi dence intervals( CIs)were calculated using Walds test. The 259.1 adjusted score test suggested that the regression models were Uncertain% Unknown not subject to overdispersion 87,508 141.7 17,587,074 RESULTS Parental history of epilepsy Mother 123,468 The study included 1, 538, 732 live-born children. Dur- Fath 100.343 ing 17, 953, 700 person-years of follow up, 16, 455 children Both 6855 were diagnosed with epilepsy corresponding to an average 17,728,284 incidence rate of 91.7 per 100,000 person-years. Table 1 shows the incidence rate of epilepsy according to the selected Congenit formation was suspected but not confirmed. The information about congenital malformation was missing. characteristics of the population The incidence rate of epilepsy increased consistently with decreasing 1-and 5-minute Apgar scores, especially for 5-minute Apgar scores (Table 2). In our study population, 3 at both 1 and 5 minutes had the highest incidence rate ratio 2466(0.16%)had a 5-minute Apgar score of l to 3 and 9047 of 8.03(95%CI=6. 19-10.42)compared with children with (0.59%)of 4 to 6. The average incidence rate of epilepsy an Apgar score of 10 at both measures(Table 3) was 628 per 100,000 person-years for those with 5-minute Incidence rate ratios of epilepsy differed in preterm and Apgar scores of l to 3 and 86 for those with a 5-minute term infants according to 5-minute Apgar scores (P for Apgar score of 10 interaction <0.001). The highest incidence rate ratios were The incidence rate ratios of epilepsy decreased when found among term infants (Table 4). the Apgar score improved from I to 5 minutes. However, the Infants with 5-minute Apgar scores of less than 10 had incidence rate ratios remained higher for infants with low higher incidence rate ratios of epilepsy throughout childhood 1-minute Apgar scores, even if their scores improved to 10 at and early adulthood compared with those with a score of 10 5 minutes compared with children with an Apgar score of 10 The highest incidence rate ratios were found, however, during at both 1 and 5 minutes. Children with Apgar scores of 1 to the first year of life(Fig. 1) o 2006 Lippincott Williams Wilkins 第58页 Copyright c Lippincott Williams& Wilkins. Unauthorized reproduction of this article is prohibitedafter birth was accessible only for children born between 1978 and 1996. Midwives recorded Apgar scores after birth following standardized procedures. More than 95% of all births in Denmark take place in public hospitals, and mid￾wives report Apgar scores to the registry from the remaining home births following the hospital procedures. Assessment of Epilepsy Information on epilepsy was obtained from the Na￾tional Hospital Register that contains information on all discharges from Danish hospitals since 1977.19 Outpatients have been included in the register since 1995. Diagnostic information in the National Hospital Register was based on the International Classification of Diseases, 8th revision (ICD-8) from 1977 to 1993, and the International Classifica￾tion of Diseases, 10th revision (ICD-10) from 1994 to 2002. Cohort members were classified with epilepsy if they had been hospitalized or had been in outpatient care with a diagnosis of epilepsy (ICD-8: 345; ICD-10: G40 –G41). The time of onset of epilepsy was defined as the first day of contact with the hospital. Data Analysis The incidence rate ratio of epilepsy was estimated by a log-linear Poisson regression model20 with the GENMOD procedure in SAS version 8.1 (SAS institute, Cary, NC). All incidence rate ratios were adjusted for age and its interaction with sex and for calendar year. Age and calendar year were treated as time-dependent variables.21 Age was categorized in 3-month intervals in the first year of life, in 1-year age levels from the first birthday to the 19th birthday, and then age intervals of 20 –21 and 22–25 as the oldest 2 groups. Calendar year was categorized in a 1-year period from 1978 –2002. P values were based on likelihood ratio tests and 95% confi- dence intervals (CIs) were calculated using Wald’s test.21 The adjusted score test suggested that the regression models were not subject to overdispersion.22 RESULTS The study included 1,538,732 live-born children. Dur￾ing 17,953,700 person-years of follow up, 16,455 children were diagnosed with epilepsy corresponding to an average incidence rate of 91.7 per 100,000 person-years. Table 1 shows the incidence rate of epilepsy according to the selected characteristics of the population. The incidence rate of epilepsy increased consistently with decreasing 1- and 5-minute Apgar scores, especially for 5-minute Apgar scores (Table 2). In our study population, 2466 (0.16%) had a 5-minute Apgar score of 1 to 3 and 9047 (0.59%) of 4 to 6. The average incidence rate of epilepsy was 628 per 100,000 person-years for those with 5-minute Apgar scores of 1 to 3 and 86 for those with a 5-minute Apgar score of 10. The incidence rate ratios of epilepsy decreased when the Apgar score improved from 1 to 5 minutes. However, the incidence rate ratios remained higher for infants with low 1-minute Apgar scores, even if their scores improved to 10 at 5 minutes compared with children with an Apgar score of 10 at both 1 and 5 minutes. Children with Apgar scores of 1 to 3 at both 1 and 5 minutes had the highest incidence rate ratio of 8.03 (95% CI
6.19 –10.42) compared with children with an Apgar score of 10 at both measures (Table 3). Incidence rate ratios of epilepsy differed in preterm and term infants according to 5-minute Apgar scores (P for interaction 0.001). The highest incidence rate ratios were found among term infants (Table 4). Infants with 5-minute Apgar scores of less than 10 had higher incidence rate ratios of epilepsy throughout childhood and early adulthood compared with those with a score of 10. The highest incidence rate ratios were found, however, during the first year of life (Fig. 1). TABLE 1. Incidence Rates of Epilepsy According to Selected Characteristics of the Study Population, Denmark, 1978 –2002 Characteristics Person-Years at Risk No. of Persons With Epilepsy Incidence Rate per 100,000 Person-Years Sex Boys 9,202,445 8738 95.0 Girls 8,751,255 7717 88.2 Gestational age (weeks) Very preterm (33) 146,637 448 305.5 Preterm (33–36) 680,516 981 144.2 Term (37–41) 14,370,165 12,721 88.5 Postterm (
42) 1,471,843 1356 92.1 Unknown 1,284,540 949 73.9 Birth order 1st 8,124,750 7548 92.9 2nd 9,828,950 8907 90.6 Multiple birth Single birth 17,533,469 16,017 91.4 Twin or more 419,903 438 104.3 Unknown 327 0 0.0 Maternal age (years) 20 656,046 794 121.0 20–24 4,611,950 4528 98.2 25–29 7,053,083 6158 87.3 30–34 4,165,921 3669 88.1
35 1,466,700 1306 89.0 Cerebral palsy Yes 30,915 600 1940.8 No 17,922,785 15,855 88.5 Congenital malformation Yes 250,121 648 259.1 Uncertain* 28,998 40 137.9 Unknown† 87,508 124 141.7 No 17,587,074 15,643 88.9 Parental history of epilepsy Mother 123,468 397 321.5 Father 100,343 221 220.2 Both 1605 11 685.5 Neither 17,728,284 15,826 89.3 *Congenital malformation was suspected but not confirmed. † The information about congenital malformation was missing. Epidemiology • Volume 17, Number 3, May 2006 Apgar Scores and Risk of Epilepsy © 2006 Lippincott Williams & Wilkins 297 第 58 页