Clinical and economic burden of obstructive hypertrophic cardiomyopathy in the United States

Figures & data

Figure 1. Study design and sample selection. The study population was drawn from the US IBM MarketScan Commercial and Medicare Supplemental Database from January 2009 to March 2019. Patients with HCM were identified based on a diagnostic code for HCM and confirmation by either a second HCM diagnostic code more than 30 days apart or a claim for septal reduction therapy on a separate date from the initial HCM diagnosis along with a randomly-selected index date after diagnostic confirmation. After excluding patients aged <18 years, those who did not have ≥12 months of continuous coverage after the index date, and those who did not have a diagnostic code for obstructive HCM, the analytic cohort comprised 11,401 patients with obstructive HCM. Potential controls without HCM were selected if they did not have a diagnosis of cardiomyopathy, heart failure, Fabry disease, amyloidosis, or a history of a septal reduction therapy procedure, and assigned a randomly selected index date. After excluding those without continuous insurance coverage for 12 months after the index date, control patients were matched to each oHCM patient in a 3:1 fashion based on age, sex, geographic region, and index year. Abbreviations. HCM, hypertrophic cardiomyopathy; oHCM, obstructive hypertrophic cardiomyopathy.

Table 1. Patient characteristics.

	oHCM	Matched controls
	N = 11,401	N = 34,203
Demographics
Age at the index date, years	57 ± 4	57 ± 14
Female sex, n (%)	4,810 (42.2)	14,430 (42.2)
Cardiovascular comorbidities
Hypertension, n (%)	7,247 (63.6)^a	12,440 (36.4)
Coronary artery disease, n (%)	3,137 (27.5)^a	2,069 (6.0)
Atrial fibrillation/flutter, n (%)	2,802 (24.6)^a	362 (1.1)
Bradyarrhythmia, n (%)	1,919 (16.8)^a	707 (2.1)
Ventricular tachycardia, n (%)	1,596 (14.0)^a	49 (0.1)
Supraventricular tachycardia, n (%)	539 (4.7)^a	147 (0.4)
Stroke, n (%)	617 (5.4)^a	527 (1.5)
Cardiac arrest, n (%)	91 (0.8)^a	19 (0.1)
Charlson Comorbidity Index
Total score	1.6 ± 1.7^a	0.4 ± 1.0
Congestive heart failure, n (%)	4,941 (43.3)^a	42 (0.1)
Chronic pulmonary disease, n (%)	1,984 (17.4)^a	2,863 (8.4)
Peripheral vascular disease, n (%)	1,804 (15.8)^a	1,124 (3.3)
Diabetes without chronic complications, n (%)	1,654 (14.5)^a	3,659 (10.7)
Cerebrovascular disease, n (%)	1,137 (10.0)^a	1,195 (3.5)
Renal disease, n (%)	896 (7.9)^a	872 (2.5)
Any malignancy, including leukemia and lymphoma, n (%)	777 (6.8)^a	1,707 (5.0)
Diabetes with chronic complications, n (%)	699 (6.1)^a	1,080 (3.2)
Myocardial infarction, n (%)	558 (4.9)^a	273 (0.8)
Mild liver disease, n (%)	511 (4.5)^a	832 (2.4)
Rheumatologic disease, n (%)	275 (2.4)^a	555 (1.6)
Metastatic solid tumor, n (%)	122 (1.1)^b	263 (0.8)
Peptic ulcer disease, n (%)	133 (1.2)^a	158 (0.5)
Dementia, n (%)	108 (0.9)	342 (1.0)
Hemiplegia or paraplegia, n (%)	84 (0.7)^a	97 (0.3)
Moderate or severe liver disease, n (%)	55 (0.5)^a	55 (0.2)
AIDS/HIV, n (%)	24 (0.2)	68 (0.2)

Continuous variables are reported as mean ± standard deviation.

Abbreviation. oHCM, obstructive hypertrophic cardiomyopathy.

^ap<.001 vs. control.

^bp<.05 vs. control.

Table 2. Healthcare resource utilization and cost—overall oHCM population.

	oHCM N = 11,401	Matched controls N = 34,203	IRR/OR/difference (95% CI)^a	p Value
All-cause IP admissions
Any IP admission, n (%)	2,588 (22.7)	2,353 (6.9)	3.97 (3.74–4.22)	<.001
Number of IP admissions	0.3 ± 0.8	0.1 ± 0.3	4.08 (3.83–4.34)	<.001
Number of IP days	2.0 ± 7.3	0.4 ± 2.9	4.65 (4.21–5.11)	<.001
All-cause ER visits
Any ER visit, n (%)	3,049 (26.7)	4,958 (14.5)	2.15 (2.04–2.26)	<.001
Number of ER visits	0.5 ± 1.2	0.2 ± 0.7	2.30 (2.17–2.43)	<.001
All-cause OP visits
Any OP visit, n (%)	11,298 (99.1)	30,282 (88.5)	14.20 (11.67–17.27)	<.001
Number of OP visits	20.9 ± 21.0	10.5 ± 13.9	2.00 (1.95–2.04)	<.001
Physician office	18.6 ± 18.5	9.6 ± 12.7	1.95 (1.90–1.99)	<.001
Lab tests	0.6 ± 2.1	0.2 ± 0.8	2.59 (2.40–2.80)	<.001
Diagnostic imaging	0.0 ± 0.8	0.0 ± 0.2	1.83 (1.15–2.90)	.0110
Others	1.7 ± 6.5	0.7 ± 3.3	2.56 (2.34–2.79)	<.001
Annual costs, $
Inpatient	13,025 ± 64,965	1,621 ± 13,650	11,404 (10,282–12,505)	<.001
Emergency department	873 ± 4,011	276 ± 1,744	597 (522–671)	<.001
Outpatient	9,646 ± 25,260	3,001 ± 16,401	6,645 (6,131–7,126)	<.001
Pharmacy	3,385 ± 10,308	1,910 ± 7,722	1,475 (1,271–1,670)	<.001
Total	26,929 ± 77,720	6,808 ± 25,712	20,121 (18,762–21,446)	<.001

Abbreviations. CI, confidence interval; ER, emergency room; IP, inpatient; IRR, incidence rate ratio; oHCM, obstructive hypertrophic cardiomyopathy; OP, outpatient; OR, odds ratio.

^aORs are reported for binary variables, IRRs for count variables, and absolute differences for cost variables. Count and cost variables are summarized as mean ± standard deviation. The 95% CIs for cost variables were calculated using bootstrapping.

Figure 2. Mean 1-year healthcare cost for oHCM, symptomatic oHCM, and asymptomatic oHCM versus matched controls. Total annual costs and the estimated difference in costs between oHCM patients and matched controls are shown along with subgroup analyses for patients with symptomatic oHCM and asymptomatic oHCM. Total annual cost/patient includes inpatient, emergency department, outpatient, and pharmacy costs. Abbreviation. oHCM, obstructive hypertrophic cardiomyopathy.

Table 3. Healthcare resource utilization and cost—symptomatic oHCM population.

	Symptomatic oHCM N = 5,667	Matched controls N = 17,001	IRR/OR/difference (95% CI)^a	p Value
All-cause IP admissions
Any IP admission, n (%)	2,152 (38.0)	1,181 (6.9)	8.20 (7.58–8.88)	<.001
Number of IP admissions	0.6 ± 1.1	0.1 ± 0.3	7.14 (6.61–7.71)	<.001
Number of IP days	3.7 ± 9.9	0.4 ± 3.0	8.51 (7.46–9.61)	<.001
All-cause ER visits
Any ER visit, n (%)	2,227 (39.3)	2,529 (14.9)	3.70 (3.46–3.96)	<.001
Number of ER visits	0.8 ± 1.6	0.2 ± 0.7	3.63 (3.40–3.89)	<.001
All-cause OP visits
Any OP visit, n (%)	5,665 (100.0)	15,149 (89.1)	346.28 (86.61–1,381.04)	<.001
Number of OP visits	27.6 ± 24.4	10.7 ± 13.8	2.57 (2.50–2.65)	<.001
Physician office	24.2 ± 21.1	9.8 ± 12.6	2.47 (2.40–2.55)	<.001
Lab tests	0.8 ± 2.6	0.2 ± 0.8	3.44 (3.09–3.82)	<.001
Diagnostic images	0.1 ± 1.1	0.0 ± 0.2	3.34 (1.94–5.73)	<.001
Others	2.6 ± 8.6	0.7 ± 3.5	3.65 (3.26–4.08)	<.001
Annual costs, $
Inpatient	24,158 ± 89,668	1,587 ± 14,070	22,571 (20,260–24,855)	<.001
Emergency department	1,436 ± 5,103	247 ± 1,373	1,189 (1,062–1,322)	<.001
Outpatient	13,726 ± 28,885	2,980 ± 18,650	10,746 (9,805–11,607)	<.001
Pharmacy	4,267 ± 12,089	1,954 ± 8,138	2,312 (1,978–2,657)	<.001
Total	43,586 ± 103,756	6,768 ± 27,618	36,818 (34,137–39,406)	<.001

Abbreviations. CI, confidence interval; ER, emergency room; IP, inpatient; IRR, incidence rate ratio; oHCM, obstructive hypertrophic cardiomyopathy; OP, outpatient; OR, odds ratio.

^aORs are reported for binary variables, IRRs for count variables, and absolute differences for cost variables. Count and cost variables are summarized as mean ± standard deviation. The 95% CIs for cost variables were calculated using bootstrapping.

Data availability statement

The datasets generated during and analysed for the current study are not publicly available as they were used under license from IBM Watson Health.