Validation of Pediatric Idiopathic Generalized Epilepsy Diagnoses from the Danish National Patient Register During 1994‒2019

Figures & data

Table 1 Characteristics for Children with Medical Record-Validated Idiopathic Generalized Epilepsy During 1994‒2019

	CAE (n=115)	JAE (n=97)	JME (n=192)	GTCS Alone (n=27)
Female	74 (64%)	58 (60%)	121 (63%)	11 (41%)
Birth year, median (range)	2005 (1991–2014)	1998 (1984–2009)	1995 (1978–2008)	1998 (1978–2005)
Onset year, median (range)	2011 (1996–2018)	2009 (1994–2018)	2009 (1988–2018)	2011 (1994–2018)
Age at onset (years), median, IQR	5.9 (4.6–7.2)	10.9 (9.7–12.9)	13.7 (12.0–15.0)	13.9 (12.8–14.9)
Potential follow-up (years), median, IQR^a	9.5 (6.9–13.8)	10.7 (6.9–14.0)	10.9 (6.9–16.1)	8.1 (4.8–16.5)
Absence	115 (100%)	97 (100%)	104 (54%)	0
Myoclonia	5 (4%)^b	16 (16%)^b	192 (100%)	0
GTCS	22 (19%)	65 (67%)	174 (91%)	27 (100%)
Different ASM drugs during follow-up, mean	2.1	2.4	2.6	1.7
Lamotrigine, n (%)	74 (64%)	78 (80%)	144 (75%)	17 (63%)
Valproic acid, n (%)	93 (81%)	52 (54%)	117 (61%)	14 (52%)
Levetiracetam, n (%)	18 (16%)	49 (51%)	136 (71%)	11 (41%)
Ethosuximide, n (%)	30 (26%)	13 (13%)	5 (3%)	0
Zonisamide, n (%)	5 (4%)	15 (15%)	23 (12%)	≤3 (≤11%)
Topiramat, n (%)	7 (6%)	9 (9%)	28 (15%)	≤3 (≤11%)
Clobazam, n (%)	10 (9%)	19 (20%)	50 (26%)	≤3 (≤11%)

Notes: ^aPotential follow-up refers to time from the index date to end-of-follow-up (December 31, 2020). ^bMyoclonia were subtle occurring during the absence seizures.

Abbreviations: ASM, anti-seizure medicine; CAE, childhood absence epilepsy; GTCS, generalized tonic-clonic seizure; IQR, interquartile range; JAE, juvenile absence epilepsy; JME, juvenile myoclonic epilepsy.

Figure 1 Flow Chart.

Abbreviations: ICD-10, international classification of diseases version 10; IGE, idiopathic generalized epilepsy; GGE, genetic generalized epilepsy.

Table 2 Positive Predictive Value and Sensitivity of Specific ICD-10 Codes for Pediatric Idiopathic Generalized Epilepsy, 1994–2019

ICD-10 Code	Name of Category (Period)	CAE (n=115)		JAE (n=97)		JME (n=192)		GTCS alone (n=27)
		PPV (95% CI)	Sen (95% CI)	PPV (95% CI)	Sen (95% CI)	PPV (95% CI)	Sen (95% CI)	PPV (95% CI)	Sen (95% CI)
G40.3C	Juvenile myoclonic epilepsy (1994–2005) Childhood absence epilepsy (2006–2019)	35% (29–42%)	71% (62–79%)	5% (3–9%)	12% (7–21%)	14% (10–19%)	17% (12–23%)	1% (0–4%)	11% (2–29%)
G40.3E	Epilepsia petit mal impulsiva (1994–2005) Juvenile absence epilepsy (2006–2019)	14% (10–20%)	24% (17–33%)	35% (28–42%)	70% (60–79%)	8% (4–12%)	8% (4–13%)	0% (0–0%)	4% (0–19%)
G40.3F	Idiopathic generalized epilepsy (1994–2005) Juvenile myoclonic epilepsy (2006–2019)	0% (0–2%)	1% (0–3%)	8% (5–12%)	21% (13–29%)	65% (59–71%)	85% (80–90%)	4% (2–8%)	41% (22–59%)
G40.3G	Clonic epileptic seizure (1994–2005) Epilepsy with GTCS only (2006–2019)	n=0	n=0	6% (1–19%)	2% (0–5%)	22% (10–39%)	4% (2–8%)	25% (12–42%)	33% (17–54%)
G40.3L	Epileptic absences in children (1994–2019)	23% (8–45%)	4% (1–8%)	18% (5–40%)	4% (1–10%)	n=0	n=0	n=0	n=0
G40.3N	Petit mal, juvenile (1994–2019)	n=0	n=0	29% (4–71%)	2% (0–7%)	29% (4–71%)	1% (0–4%)	n=0	n=0
G40.7	Petit mal without GTCS (1994–2005) Absences without grand mal (2006–2019)	17% (11–24%)	18% (11–25%)	6% (2–11%)	7% (2–14%)	2% (0–7%)	2% (0–5%)	2% (0–6%)	7% (1–24%)
G40	Epilepsy (1994–2019)	3% (0–13%)	1% (0–5%)	15% (6–30%)	6% (2–13%)	38% (23–54%)	8% (4–13%)	10% (3–24%)	15% (4–34%)
G40.3	Generalized idiopathic epilepsy (1994–2019)	14% (11–18%)	44% (3–54%)	17% (13–21%)	63% (52–72%)	32% (27–37%)	60% (53–67%)	5% (3–8%)	70% (50–86%)
G40.9	Epilepsy unspecified (1994–2019)	10% (8–13%)	46% (37–56%)	13% (10–16%)	70% (60–79%)	27% (23–31%)	73% (67–80%)	4% (2–6%)	78% (58–91%)

Abbreviations: CAE, childhood absence epilepsy; CI, confidence interval; GTCS, generalized tonic-clonic seizure; JAE, juvenile absence epilepsy; JME, juvenile myoclonic epilepsy; PPV, positive predictive value; Sen, sensitivity.

Table 3 Positive Predictive Values of Combination of ICD-10 Codes, Age at Code Registration, and Antiseizure Medicine Redemption for Idiopathic Generalized Epilepsy, 1994–2019

IGE Syndrome	Codes for the IGE Syndrom (Period)	Codes Only		Codes+ASM		Codes+ASM+Onset^a
		PPV (95% CI)	Sen (95% CI)	PPV (95% CI)	Sen (95% CI)	PPV (95% CI)	Sen (95% CI)
CAE (n=115)	G40.3C (2006–2019) G40.3E (1994–2005) G40.7 (1994–2019)	28% (23–34%)	77% (69–85%)	38% (32–45%)	76% (67–83%)	44% (34–53%)	41% (32–50%)
JME (n=192)	G40.3C (1994–2005) G40.3F (2006–2019)	61% (55–67%)	88% (83–92%)	62% (56–68%)	88% (83–92%)	64% (58–69%)	88% (83–92%)
	G40.3F	65% (59–71%)	85% (80–90%)	66% (60–72%)	85% (80–90%)	68% (62–74%)	85% (80–90%)
JAE (n=97)	G40.3E (2006–2019)	35% (28–42%)	68% (58–77%)	40% (32–47%)	68% (58–77%)	44% (36%–52%)	68% (57–77%)
GTCS alone (n=27)	G40.3G (2006–2019)	26% (12–43%)	33% (17–54%)	27% (13–46%)	33% (17–54%)	31% (15–51%)	33% (17–54%)

Notes: ^a“Onset” was defined as age at code registration by the International League Against Epilepsy criteria as CAE<8 years, JME≥8 years, JAE≥8 years, and GTCS alone>5 years.

Abbreviations: ASM, anti-seizure medicine; CAE, childhood absence epilepsy; CI, confidence interval; GTCS, generalized tonic-clonic seizure; JAE, juvenile absence epilepsy; JME, juvenile myoclonic epilepsy; PPV, positive predictive value; Sen, sensitivity.