The Validity of Intracerebral Hemorrhage Diagnoses in the Danish Patient Registry and the Danish Stroke Registry

Figures & data

Figure 1 Identification of patient records for validation from the DSR and DNPR.

Table 1 Underlying Diagnoses in Non-Verified Cases and in Verified Cases Not Classified as Spontaneous ICH

Non-Verified Cases	Number (%) (n=1,192)
ICH present, but did not fulfill study criteria	515 (43.2)
ICH, traumatic	268
Acute ischemic stroke with hemorrhagic transformation	123
ICH, thrombolysis-related	53
ICH due to subarachnoid hemorrhage	24
ICH, periprocedural^a	21
ICH suspected, but patient died before scan	18
History of ICH (predating study period)	8
Intracranial hemorrhage other than ICH	396 (33.2)
Subarachnoid hemorrhage^b	205
Subdural hematoma	152
Traumatic intracranial hemorrhage, multiple sites	21
History of intracranial hemorrhage	10
Epidural hematoma	8
Ischemic and other cerebrovascular diagnoses	115 (9.7)
Acute ischemic stroke	99
TIA	8
Other cerebrovascular disorders^c	8
Various	166 (13.9)
ICH or intracranial bleed suspected; ruled out by brain scan	41
Cerebral microbleeds^d	13
Seizure	11
Headache, syncope, or vertigo	11
Cerebral tumor	9
Various coding errors^e	81
Verified cases with non-spontaneous ICH,^funderlying cause	Number (%) (n=225)
Brain tumor	105 (46.7)
Arteriovenous malformation	61 (27.1)
Cavernous hemangioma	41 (18.2)
Cerebral sinus thrombosis	7 (3.1)
Dural arteriovenous fistula	6 (2.7)
Various rare causes^g	5 (2.2)

Notes: ^aeg, ventricular catheter insertion. ^bNumber of patients with aneurysmal/traumatic/unspecified: 110/57/38. ^ceg, transient global amnesia, cerebral sinus thrombosis. ^dNo coexisting ICH or any other intracranial hemorrhage. ^e1-2 patients recorded per code under these primarily (>70%) non-neurological codes. ^fClassified as “any ICH” but not “spontaneous ICH”. ^gNot specified to preserve anonymity.

Abbreviation: ICH, intracerebral hemorrhage.

Table 2 Positive Predictive Value of Admission Codes for ICH in Danish National Patient Registry (DNPR) and Danish Stroke Registry (DSR)

	No. Retrieved	No. Verified		PPV (95% CI)
		Any ICH	Spontaneous ICH	Any ICH	Spontaneous ICH
DNPR – inpatient diagnosis
Primary diagnostic position^a	3,169	2,414	2,226	76.2 (74.7–77.6)	70.2 (68.6–71.8)
Other than primary diagnostic position^b	632	312	276	49.4 (45.5–53.3)	43.7 (39.9–47.6)
Any diagnostic position^c	3,801	2,726	2,502	71.7 (70.3–73.1)	65.8 (64.3–67.3)
DSR	2,443	2,113	1,998	86.5 (85.1–87.8)	81.8 (80.2–83.3)

Notes: ^aIncludes 2,116 patients concurrently recorded in DSR. ^bIncludes 240 patients concurrently recorded in DSR. ^cIncludes 2,356 patients concurrently recorded in DNPR.

Abbreviations: ICH, intracerebral hemorrhage; PPV, positive predictive value.

Table 3 Number of Patients Identified and Number of Verified Diagnoses of ICH by Type of Contact in Danish National Patient Registry (DNPR) and by Concurrent Recording in Danish Stroke Registry (DSR)

	Patients with First-Ever Hospital Contact with Intracerebral Hemorrhage Codes, Region of Southern Denmark 2009–2017 (n=3,956)
	DNPR					DSR Only^b	DNPR^a or DSR
	Inpatient, Primary Diagnostic Position		Inpatient, Diagnostic Position Other Than Primary		Outpatient/ ED Only,^b Any Diagnostic Position
	Record in DSR^c	No Record in DSR^d	Record in DSR^c	No Record in DSR^d
Number retrieved	2116	1053	240	392	68	87	3956
Any-ICH diagnosis confirmed
Number	1874	540	206	106	5	33	2764
PPV (95% CI)	88.6 (87.1–89.9)	51.3 (48.3–54.3)	85.8 (80.9–89.7)	27.0 (22.9–31.6)	7.4 (3.2–16.1)	37.9 (28.5–48.4)	69.9 (68.4–71.3)
Spontaneous-ICH confirmed
Number	1771	455	195	81	5	32	2539
PPV (95% CI)	83.7 (82.1–85.2)	43.2 (40.2–46.2)	81.3 (75.8–85.7)	20.7 (16.9–24.9)	7.4 (3.2–16.1)	36.8 (27.4–47.3)	64.2 (62.7–65.7)

Notes: We regarded consecutive hospital contacts coded for ICH and with a gap of no more than 7 days as belonging to the same episode of ICH. ^aDNPR inpatient, outpatient, or ED – any position. ^bNo concurrent inpatient record in DNPR. ^cConcurrent record in DSR. ^dNo concurrent record in DSR.

Abbreviations: ED, emergency department; ICH, intracerebral hemorrhage; PPV, positive predictive value.

Table 4 PPV and Sensitivity of Inpatient First-Ever Codes for ICH in the Danish Stroke Registry and the Danish National Patient Registry Stratified by Year, Age, and Sex

Any ICH	Danish National Patient Registry^a		Danish Stroke Registry
	PPV (95% CI)	Sensitivity (95% CI)	PPV (95% CI)	Sensitivity (95% CI)
Period^b
2009–2011	74.0 (71.2–76.6)	86.7 (84.2–88.8)	86.6 (84.1–88.8)	83.7 (81.1–86.1)
2012–2014	76.7 (74.1–79.2)	90.0 (87.8–91.8)	86.6 (84.1–88.8)	75.9 (73.0–78.6)
2015–2017	77.5 (75.0–79.9)	85.6 (83.3–87.6)	86.3 (83.8–88.4)	70.7 (67.9–73.4)
Age^b (years)
<64	74.9 (72.0–77.6)	87.9 (85.4–90.0)	88.2 (85.4–90.6)	70.3 (66.9–73.4)
65–74	79.2 (76.2–81.9)	87.5 (84.8–89.7)	87.7 (84.9–90.0)	77.5 (74.3–80.4)
75+	75.3 (73.1–77.5)	86.9 (85.0–88.7)	84.9 (82.8–86.9)	79.4 (77.1–81.6)
Sex
Men	77.7 (75.6–79.6)	87.4 (85.6–89.1)	87.6 (85.6–89.3)	77.7 (75.5–79.8)
Women	74.6 (72.4–76.7)	87.2 (85.3–88.9)	85.3 (83.2–87.2)	74.9 (72.6–77.2)
Spontaneous ICH
Period^c
2009–2011	69.8 (66.9–72.6)	87.3 (84.8–89.4)	82.8 (80.1–85.3)	85.6 (83.0–87.9)
2012–2014	69.2 (66.4–72.0)	90.6 (88.4–92.5)	79.9 (76.9–82.5)	78.2 (75.2–80.9)
2015–2017	71.6 (68.9–74.1)	85.4 (83.1–87.6)	82.6 (79.8–85.0)	73.3 (70.4–76.0)
Age^c (years)
<64	63.8 (60.6–66.9)	88.2 (85.5–90.4)	79.4 (76.0–82.4)	74.5 (71.1–77.7)
65–74	74.0 (70.9–77.0)	88.4 (85.7–90.6)	82.8 (79.7–85.6)	79.2 (76.0–82.1)
75+	72.1 (69.8–74.4)	87.0 (86.3–88.8)	82.4 (80.2–84.5)	80.6 (78.3–82.7)
Sex
Men	71.8 (69.6–74.0)	87.7 (85.8–89.3)	82.9 (80.7–84.9)	79.8 (77.6–81.9)
Women	68.6 (66.3–70.9)	87.7 (85.7–89.4)	80.6 (78.2–82.7)	77.5 (75.1–79.7)

Notes: ^aInpatient – primary diagnostic position code. ^bChi-squared for trend: P>0.05. ^cChi-squared for trend: P<0.001.

Abbreviations: CI, confidence interval; ICH, intracerebral hemorrhage; PPV, positive predictive value.

Table 5 Sensitivity of Inpatient First-Ever Codes for ICH in the Danish Stroke Registry and the Danish National Patient Registry Stratified by Year, Age, and Sex

	Danish National Patient Registry^a
	2009–2011	2012–2014	2015–2017	P-value^b
Any ICH
Women <75 years old	87.2 (81.7–91.3)	91.8 (86.8–94.9)	86.5 (81.4–90.3)	>0.05
Women ≥75 years old	85.8 (80.7–89.8)	86.4 (81.5–90.2)	86.8 (82.2–90.3)	>0.05
Men <75 years old	88.0 (83.7–91.3)	91.1 (87.2–93.8)	83.1 (78.5–86.8)	>0.05
Men ≥75 years old	84.8 (78.2–89.6)	91.1 (86.0–94.5)	86.9 (81.6–90.8)	>0.05
Spontaneous ICH
Women <75 years old	88.6 (82.9–92.6)	94.0 (89.0–96.8)	86.3 (80.8–90.4)	>0.05
Women ≥75 years old	85.8 (80.6–89.8)	86.8 (81.8–90.5)	86.9 (82.2–90.5)	>0.05
Men <75 years old	88.7 (84.4–92.0)	92.0 (88.0–94.8)	82.9 (78.1–86.8)	0.03
Men ≥75 years old	85.2 (78.4–90.1)	91.1 (85.8–94.5)	86.6 (81.2–90.6)	>0.05
	Danish Stroke Registry
Any ICH
Women <75 years old	81.9 (75.8–86.8)	72.0 (65.1–78.0)	64.2 (57.8–70.1)	<0.001
Women ≥75 years old	85.4 (80.2–89.4)	79.0 (73.5–83.7)	69.5 (63.8–74.7)	<0.001
Men <75 years old	80.9 (75.9–85.1)	74.2 (68.9–78.9)	70.3 (65.0–75.1)	0.029
Men ≥75 years old	89.4 (83.5–93.4)	78.3 (71.8–83.7)	80.6 (74.6–85.4)	0.046
Spontaneous ICH
Women <75 years old	85.0 (78.8–89.6)	76.0 (68.6–82.1)	68.5 (61.7–64.6)	<0.001
Women ≥75 years old	86.3 (81.1–90.2)	79.5 (73.9–84.2)	71.0 (65.2–76.2)	<0.001
Men <75 years old	82.7 (77.7–86.8)	77.2 (71.6–82.0)	72.7 (67.3–77.6)	0.005
Men ≥75 years old	90.8 (85.0–94.6)	79.8 (73.1–85.1)	81.6 (75.7–86.3)	0.035

Notes: ^aInpatient – primary diagnostic position code. ^bChi-squared for trend.

Abbreviations: CI, confidence interval; ICH, intracerebral hemorrhage; PPV, positive predictive value.

Table 6 Distribution of Patients with Untraceable Medical Records by Year and Contact Recorded in Danish National Patient Registry (DNPR) and/Or Danish Stroke Registry (DSR)

Period	Number (%) of Patients		All
	DNPR Inpatient Contact and DSR^a	Any Other Contact^b
2009–2011	80 (73.4)	36 (26.6)	116
2012–2014	29 (54.7)	28 (45.3)	57
2015–2017	<5	NR^c (>75%)	20

Notes: *Percentage not calculated for counts less than 5 to preserve anonymity. ^aConcurrently recorded in Danish National Patient Registry (DNPR) as inpatient (ICH code at any diagnostic position) and Danish Stroke Registry (DSR). ^bCorresponds to a) patients with records in DNPR (inpatient, emergency department or outpatient), but no concurrent record in DSR; and b) patients with records in DSR only. ^cNot reported to preserve anonymity.

Table 7 Distribution of Patients with Untraceable Medical Records by Source, Year, Age, and Sex

	Danish National Patient Registry^a,b				Danish Stroke Registry^c
	Inpatient, Primary Diagnostic Position		Inpatient, Diagnostic Position Other Than Primary
	Retrieved, Including Untraced	Untraced,^d No. (%)	Retrieved Including Untraced	Untraced,^d No. (%)	Retrieved Including Untraced	Untraced,^d No. (%)
Period
2009–2011	1093	100 (9.1)	600	9 (1.5)	1,810	84 (4.6)
2012–2014	1091	41 (3.8)	621	12 (1.9)	1,634	32 (2.0)
2015–2017	1145	19 (1.7)	738	0 (0)	1,680	<5 (NR^e)
Age (years)
<64	941	40 (4.3)	564	8 (1.4)	1,272	24 (1.9)
65–74	826	33 (4.0)	525	<5 (–*)	1,318	24 (1.8)
75+	1562	87 (5.6)	870	10 (1.1)	2,534	71 (2.8)
Sex
Men	1696	93 (5.5)	1,017	10 (1.0)	2,668	70 (2.6)
Women	1633	67 (4.1)	942	11 (1.2)	2,456	49 (2.0)

Notes: *Percentage not calculated for counts less than 5 to preserve anonymity. ^aDoes not include cases with ICH codes recorded in the Danish National Patient Registry with contacts classified as outpatient/emergency department contact only (retrieved/untraced: 73/5). ^bPatients concurrently recorded in Danish Stroke Registry included. ^cPatients concurrently recorded in Danish National Patient Registry included. ^dDischarge letter and brain scan report could not be traced, primarily due to incompleteness of archives for pre-EMR medical records at certain hospitals in the catchment area. ^eNot reported to preserve anonymity.

Table 8 Location of Spontaneous Intracerebral Hemorrhage

Single ICH (n=2,430)			Multiple ICH (n=109)		All ICH (n=2,539)
Location	Number	%	Number	%	Number	%
Lobar	914	37.6	77	70.6	991	39.0
Deep	839	34.5	13	11.9	852	33.6
Infratentorial	321	13.2	14	12.8	335	13.2
Unclassifiable – large	279	11.5	0	0	279	11.0
Isolated intraventricular hemorrhage	48	2.0	NA	NA	48	1.9
Insufficient information	29	1.2	5	4.6	34	1.3