Positive Predictive Value of ICD-10-CM Codes for Myocarditis in Claims Data: A Multi-Institutional Study in Taiwan

Figures & data

Figure 1 Process of case ascertainment.

Abbreviations: ECG, Electrocardiography; ECMO, Extracorporeal Membrane Oxygenation; ICD-10-CM, International Classification of Diseases, Tenth Revision, Clinical Modification; IVIG, Intravenous immunoglobulin; PPV, Positive predictive value; VAD, Ventricular assist device.

Table 1 Accuracy of Different Case Definitions to Identify Myocarditis

Case Definitions (ICD-10-CM Codes)		TP, n	FP, n	PPV, %	95% CI
I409	Acute myocarditis, unspecified
	1st position diagnosis	86	3	96.6	90.5–99.3
	2nd position diagnosis	29	6	82.9	66.4–93.4
	3rd position diagnosis	11	4	73.3	44.9–92.2
	Any position diagnosis	131	19	87.3	80.9–92.2
I408	Other acute myocarditis
	1st position diagnosis	16	1	94.1	71.3–99.9
	2nd position diagnosis	9	1	90.0	55.5–99.8
	3rd position diagnosis	0	1	0.0	0.0–97.5
	Any position diagnosis	30	4	88.2	72.6–96.7
I514	Myocarditis, unspecified
	1st position diagnosis	61	7	89.7	79.9–95.8
	2nd position diagnosis	33	28	54.1	40.9–66.9
	3rd position diagnosis	27	25	51.9	37.6–66.0
	Any position diagnosis	139	87	61.5	54.8–67.9
J1182	Influenza due to unidentified influenza virus with myocarditis
	1st position diagnosis	8	1	88.9	51.8–99.7
	2nd position diagnosis	1	0	100.0	2.5–100
	3rd position diagnosis	1	0	100.0	2.5–100
	Any position diagnosis	10	1	90.9	58.7–99.8
I400	Infective myocarditis
	1st position diagnosis	16	2	88.9	65.3–98.6
	2nd position diagnosis	11	1	91.7	61.5–99.8
	3rd position diagnosis	6	3	66.7	29.9–92.5
	Any position diagnosis	40	7	85.1	71.7–93.8
J1082	Influenza due to other identified influenza virus with myocarditis
	1st position diagnosis	15	3	83.3	58.6–96.4
	2nd position diagnosis	2	1	66.7	9.4–99.2
	3rd position diagnosis	4	2	66.7	22.3–95.7
	Any position diagnosis	23	6	79.3	60.3–92.0
I41	Myocarditis in diseases classified elsewhere
	1st position diagnosis	0	0	N/A	N/A
	2nd position diagnosis	0	1	0.0	0.0–97.5
	3rd position diagnosis	0	1	0.0	0.0–97.5
	Any position diagnosis	0	2	0.0	0.0–84.2
B3322	Viral myocarditis
	1st position diagnosis	0	0	N/A	N/A
	2nd position diagnosis	1	1	50.0	1.3–98.7
	3rd position diagnosis	0	0	N/A	N/A
	Any position diagnosis	2	2	50.0	6.8–93.2
I401	Isolated myocarditis
	1st position diagnosis	0	0	N/A	N/A
	2nd position diagnosis	0	0	N/A	N/A
	3rd position diagnosis	0	0	N/A	N/A
	Any position diagnosis	0	1	0.0	0.0–97.5
I090	Rheumatic myocarditis
	1st position diagnosis	0	0	N/A	N/A
	2nd position diagnosis	0	1	0.0	0.0–97.5
	3rd position diagnosis	0	1	0.0	0.0–97.5
	Any position diagnosis	0	3	0.0	0.0–70.8

Abbreviations: CI: confidence interval; FP: false positive; TP: true positive; N/A: not available.

Table 2 False-Positive Myocarditis Cases (N=132)

Classifications	Reasons	N (%)
Reasons for acute troponin elevation	Acute myocardial infarction	16	(12.1)
	Tachyarrhythmias	3	(2.3)
	Hypotension/Shock	7	(5.3)
	Heart failure	25	(18.9)
	Other cardiac inflammation
	Endocarditis	1	(0.8)
	Pericarditis	2	(1.5)
	Cardiac procedures	3	(2.3)
	Acute respiratory distress syndrome	9	(6.8)
	Sepsis	12	(9.1)
	Stroke	1	(0.8)
	Chronic kidney disease	1	(0.8)
	Hyperthyroidism	2	(1.5)
	Strenuous exercise	5	(3.8)
	Sympathomimetic drug intoxication	1	(0.8)
Symptoms similar to myocarditis	Other inflammation diseases	35	(26.5)
	Adverse drug reactions	4	(3.0)
	Tako-tsubo cardiomyopathy	1	(0.8)
Miscoding		1	(0.8)
Remote myocarditis		3	(2.3)

Table 3 Patient Characteristics of Confirmed Myocarditis Cases

	All		<18 Years Old		18–65 Years Old		>65 Years Old
Age, mean (SD)	33.8	(23.1)	9.3	(5.8)	39.6	(7.8)	75.0	(14.0)
Male, n (%)	224	(61.2)	40	(34.5)	170	(78.7)	14	(41.2)
Etiology, n (%)
Virus	91	(24.9)	35	(30.2)	45	(20.8)	11	(32.4)
Bacteria	44	(12.0)	15	(12.9)	24	(11.1)	5	(14.7)
Vaccine	34	(9.3)	17	(14.7)	16	(7.4)	1	(2.9)
Autoimmune	14	(3.8)	3	(2.6)	9	(4.2)	2	(5.9)
Unknown	182	(49.7)	46	(39.7)	121	(56.0)	15	(44.1)
Advanced care, n (%)
ICU	248	(67.8)	92	(79.3)	134	(62.0)	22	(64.7)
ECMO	55	(15.0)	12	(10.3)	37	(17.1)	6	(17.6)
Heart transplant	3	(0.8)	0	(0.0)	3	(1.4)	0	(0.0)
Treatment, n (%)
Anti-viral drugs	65	(17.8)	24	(20.7)	31	(14.4)	10	(29.4)
IVIG	26	(7.1)	22	(55.0)	3	(1.8)	1	(7.1)
Pacemaker	26	(7.1)	4	(3.4)	17	(7.9)	5	(14.7)
VAD	12	(3.3)	2	(1.7)	10	(4.6)	0	(0.0)
Length of hospitalization, Mean days (SD)	12.3	(14.6)	10.8	(12.5)	12.1	(14.3)	18.4	(18.9)
Mortality, n (%)	41	(11.2)	8	(6.9)	27	(12.5)	6	(17.6)
HF complication, n (%)
At discharge	110	(30.1)	14	(12.1)	81	(37.5)	15	(44.1)
Recovered after 6-month follow-up	96	(87.3)	14	(100.0)	68	(84.0)	14	(93.3)

Abbreviations: ECMO, extracorporeal membrane oxygenation; HF, heart failure; ICU, intensive care unit; IVIG, intravenous immunoglobulin; VAD, ventricular assist device.