Risk of epilepsy in patients with systemic lupus erythematosus – a retrospective cohort study

Figures & data

Figure 1 Mean age-specific incidence and prevalence of epilepsy identified in the general population and in patients with SLE from 1997–2010 in Taiwan.

Abbreviation: SLE, systemic lupus erythematosus.

Table 1 Demographic characteristics and comorbidities in patients with and without SLE

Variable	SLE		P-value
	Yes	No
	N=32,301	N=129,204
Sex	n (%)	n (%)
Female	27,828 (86.1)	111,312 (86.1)	0.99
Male	4,473 (13.9)	17,892 (13.9)
Age, mean (SD)#	44.3 (17.9)	44.3 (17.9)	0.67
≤20 years	3,088 (9.56)	12,349 (9.56)	0.95
20–39 years	10,366 (32.1)	41,467 (32.1)
40–59 years	12,222 (37.8)	48,885 (37.8)
≥60 years	6,625 (20.5)	26,503 (20.5)
Comorbidity
Psychiatric disorder	1,309 (4.05)	2,220 (1.72)	<0.0001
Aseptic meningoencephalitis	415 (1.28)	143 (0.11)	<0.0001
Intracerebral hemorrhage	272 (0.84)	768 (0.59)	<0.0001
Infarction	1,050 (3.25)	3,038 (2.35)	<0.0001
Headache	489 (1.51)	611 (0.47)	<0.0001
Peripheral neuropathy	316 (0.98)	145 (0.11)	<0.0001

Notes: Chi-square test

# two-sample t-test.

Abbreviations: SLE, systemic lupus erythematosus; N, total number; n, sample number; SD, standard deviation.

Table 2 Sex- and age-specific incidence of epilepsy and the SLE cohort-to-non-SLE cohort IRR and adjusted HR

Variables	SLE						IRR (95% CI)	Adjusted HR† (95% CI)
	Yes			No
	Event	PY	Rate#	Event	PY	Rate#
All	158	173,659	9.10	233	732,531	3.18	2.86 (2.76, 2.97)***	2.33 (1.89, 2.88)***
Sex
Female	131	151,173	8.67	169	632,186	2.67	3.24 (3.12, 3.37)***	2.46 (1.94, 3.13)***
Male	27	22,486	12.0	64	100,344	6.38	1.88 (1.70, 2.08)***	1.85 (1.17, 2.93)**
Age, years
≤20 years	38	20,997	18.1	15	88,066	1.70	10.6 (9.36, 12.1)***	8.05 (4.30, 15.0)***
20–39 years	57	64,270	8.87	32	257,212	1.24	7.13 (6.67, 7.62)***	4.58 (2.88, 7.30)***
40–59 years	41	61,875	6.63	67	264,550	2.53	2.62 (2.46, 2.78)***	2.02 (1.36, 3.01)***
≥60 years	22	26,516	8.30	119	122,703	9.70	0.86 (0.77, 0.95)**	0.90 (0.57, 1.42)
Women
≤20 years	33	17,674	18.7	13	74,224	1.75	10.7 (9.29, 12.2)***	7.73 (3.93, 15.2)***
20–39 years	44	57,735	7.62	28	230,276	1.22	6.27 (5.84, 6.72)***	3.89 (2.33, 6.52)***
40–59 years	38	55,154	6.89	52	233,225	2.23	3.09 (2.90, 3.29)***	2.36 (1.53, 3.63)***
≥60 years	16	20,611	7.76	76	94,460	8.05	0.96 (0.86, 1.08)	0.95 (0.55, 1.64)
Men
≤20 years	5	3,322	15.1	2	13,842	1.44	10.4 (7.48, 14.5)***	9.03 (1.65, 49.3)*
20–39 years	13	6,536	19.9	4	26,935	1.49	13.4 (10.9, 16.5)***	8.40 (2.56, 27.6)***
40–59 years	3	6,722	4.46	15	31,325	4.79	0.93 (0.74, 1.17)	0.81 (0.23, 2.81)
≥60 years	6	5,906	10.2	43	28,243	15.2	0.67 (0.53, 0.84)***	0.75 (0.32, 1.78)

Notes:

# Incidence rate per 10,000 PY

† multivariate analysis including age, sex, and comorbidities.

* P<0.05

** P<0.01

*** P<0.001.

Abbreviations: SLE, systemic lupus erythematosus; IRR, incidence rate ratio; HR, hazard ratio; Event, epilepsy; PY, person-years; CI, confidence interval.

Table 3 Difference in the incidence of seizure types and the SLE cohort-to-non-SLE cohort IRR

Variables	SLE						IRR (95% CI)
	Yes			No
	Event	PY	Rate#	Event	PY	Rate#
Generalized	41	173,659	2.36	56	732,531	0.76	3.09 (2.97, 3.21)***
Partial	11	173,659	0.63	14	732,531	0.19	3.31 (3.18, 3.46)***
Unclassified	106	173,659	6.10	163	732,531	2.23	2.74 (2.64, 2.85)***

Notes:

# Incidence rate per 10,000 PY

*** P<0.001.

Abbreviations: SLE, systemic lupus erythematosus; IRR, incidence rate ratio; Event, epilepsy; PY, person-years; CI, confidence interval.

Table 4 Incidence rates of epilepsy by comorbidity and the SLE cohort-to-non-SLE cohort IRR and adjusted HR

Variables	SLE						IRR (95% CI)	Adjusted HR† (95% CI)
	Yes			No
	Event	PY	Rate#	Event	PY	Rate#
Psychiatric disorder
No	138	166,012	8.31	205	719,949	2.85	2.92 (2.81, 3.03)***	1 (reference)
Yes	20	7,647	26.2	28	12,582	22.3	1.18 (0.95, 1.45)	3.31 (2.40, 4.58)***
Aseptic meningoencephalitis
No	138	171,203	8.06	226	731,815	3.09	2.61 (2.51, 2.71)***	1 (reference)
Yes	20	2,456	81.4	7	716	97.8	0.83 (0.49, 1.41)	5.35 (3.46, 8.27)***
Intracerebral hemorrhage
No	145	172,330	8.41	207	728,426	2.84	2.96 (2.85, 3.07)***	1 (reference)
Yes	13	1,329	97.8	26	4,105	63.3	1.54 (1.07, 2.23)*	5.75 (4.03, 8.19)***
Infarction
No	126	167,978	7.50	153	716,325	2.14	3.51 (3.38, 3.65)***	1 (reference)
Yes	32	5,681	56.3	80	16,205	49.4	1.14 (0.93, 1.39)	7.62 (5.87, 9.88)***
Headache
No	154	170,747	9.02	224	729,272	3.07	2.94 (2.83, 3.05)***	1 (reference)
Yes	4	2,912	13.7	9	3,258	27.6	0.50 (0.32, 0.77)**	1.42 (0.78, 2.58)
Peripheral neuropathy
No	152	172,004	8.84	231	731,714	3.16	2.80 (2.70, 2.90)***	1 (reference)
Yes	6	1,655	36.3	2	817	24.5	1.48 (0.75, 2.92)	1.20 (0.57, 2.56)

Notes:

# Incidence rate, per 10,000 PY

† multivariate analysis including age, sex, and comorbidities.

* P<0.05

** P<0.01

*** P<0.001.

Abbreviations: SLE, systemic lupus erythematosus; IRR, incidence rate ratio; HR, hazard ratio; Event, epilepsy; PY, person-years; CI, confidence interval.

Figure 2 Kaplan–Meier method estimating the cumulative incidence of epilepsy in the SLE cohort and non-SLE cohort by age.

Notes: (A) Overall; (B) <20 years old; (C) 20–39 years; (D) 40–59 years; and (E) ≥60 years.
Abbreviation: SLE, systemic lupus erythematosus.