Costs and Healthcare Resource Utilization for Obstructive Hypertrophic Cardiomyopathy With Septal Reduction Therapy

Abstract

Background. Patients with obstructive hypertrophic cardiomyopathy (oHCM) and severe refractory symptoms may require invasive septal reduction therapies (SRTs), either surgical septal myectomy (SM) or transcatheter alcohol septal ablation (ASA). The main objective of this study was to quantify all-cause and oHCM-related healthcare resource utilization (HCRU) and costs for patients receiving SM or ASA. Methods. This retrospective study utilized medical and pharmacy claims submitted during 2012-2020. HCRU and costs for 119 adults with oHCM who had at least 1 SM (n = 95) or ASA (n = 24) were compared for baseline and follow-up periods. Results. The mean inpatient hospitalization stay was longer for SM (8.3 days) than ASA (6.0 days). Postprocedure HCM-related medication usage was greater following SM (98%) than ASA (88%). The mean number of HCM-related outpatient visits increased from pre- to post procedure (12.2 vs 15.9 in the SM group; 7.2 vs 9.5 in the ASA group), with most patients having at least 1 cardiology visit post procedure (86% of the SM group; 83% of the ASA group). Total mean HCM-related costs (reported in United States currency) increased with both procedures ($27,045 vs $119,772 in the SM group; $11,278 vs $54,351 in the ASA group), driven by increased inpatient hospitalization ($10,325 vs $112,923 in the SM group; $5509 vs $47,450 in the ASA group) and surgical costs ($6665 vs $92,031 in the SM group; $52 vs $44,815 in the ASA group). Conclusions. Our results indicate increasing costs for patients undergoing SRT, driven by inpatient hospitalizations and surgical costs. Commercially insured and Medicare Advantage patients with oHCM experience high healthcare costs and economic burden attributable to SRT.

Keywords: alcohol septal ablation, cost-of-illness, economic burden, hypertrophic cardiomyopathy, septal myectomy, septal reduction therapy

Patients with obstructive hypertrophic cardiomyopathy (oHCM) experience restricting symptoms, including syncope, angina, and dyspnea.¹ If severe refractory symptoms persist while the patient is receiving medical therapy, invasive septal reduction therapies (SRTs), either surgical septal myectomy (SM) or transcatheter alcohol septal ablation (ASA), are warranted to reduce left ventricular outflow tract pressure gradients.^2-4 Follow-up studies at single centers have shown that SM and ASA are safe and effective procedures for reducing symptom burden and lead to favorable long-term survival.^1,2,5-8 However, there are limited data on the disease-related total costs and healthcare resource utilization (HCRU) among patients with oHCM undergoing SRT.

A previous study that evaluated the costs of hospitalization post ASA estimated procedural costs at $18,760,⁹ with another study reporting that post-ASA readmissions led to an additional mean hospitalization cost of $8433.¹⁰ The total burden of all-cause and disease-related costs for SRT, including not only procedure costs but also other costs such as outpatient visits and prescription drug use, is unknown. Establishing these costs for patients undergoing either procedure may aid decision-makers and contribute to the future development of programs to reduce financial burden for patients with oHCM who have SRT. The primary objective of this research was to evaluate all-cause and oHCM-related HCRU and costs for patients with oHCM undergoing SM and ASA.

Methods

Study design and cohort identification. This was a retrospective observational study utilizing claims data from the HealthCore Integrated Research Database (HIRD). The database is fully deidentified, hence approval for the study from an institutional review board or ethics committee was not required. The HIRD covers longitudinal medical and pharmacy claims data from health plan members across the United States (US), representing >50 million lives of commercially insured and Medicare Advantage members. We queried the HIRD during the study period of January 1, 2012 through January 31, 2020 to identify adult patients (≥18 years of age) with at least 1 claim of any HCM International Classification of Diseases, 9th Revision/10th Revision, Clinical Modification (ICD-9/10-CM) diagnosis code: HCM: 425.1x, I42.1, I42.2; oHCM: 425.11, I42.1 (Figure 1). Patients with clinically diagnosed oHCM were defined as having at least 1 oHCM diagnosis in a given calendar year, and only patients continuously enrolled in a medical health plan for the given calendar year were included. Only patients with oHCM with at least 1 claim for an SM or ASA procedure were included. To focus on a cohort of patients with newly diagnosed oHCM, patients with oHCM diagnosis for 12 months before SM or ASA were excluded. The patients were assigned to the SM or ASA cohort based on the first procedure they had during a 2-year postdiagnosis period.

Outcomes. Direct medical costs (2019 US$) included inpatient, outpatient, surgery, emergency department, and pharmacy and were the sum of plan paid, patient paid, and any coordination of benefits. Diagnostic procedures included coronary angiography, myocardial imaging (transthoracic echocardiography or transesophageal echocardiography, perfusion, computed tomography, magnetic resonance imaging, or positron emission tomography), cardiac stress testing, electrocardiography (12-lead, Holter), and genetic testing, and the costs were limited to the outpatient setting and reported at an aggregated level, within medical costs. HCM-related surgical procedures included SM, ASA, mitral valve surgery, implantable pacemaker, implantable cardioverter-defibrillator, cardiac resynchronization therapy, and heart transplantation, and were inclusive of all settings. HCM-related medications included beta-blockers, calcium-channel blockers, antiarrhythmics, and anticoagulants. Healthcare medical encounters were considered HCM related if medical claims contained diagnosis codes for HCM, atrial and ventricular arrhythmias, or implantable cardioverter-defibrillator procedures.

Statistical methods. Sample selection and creation of analytic variables were performed using the Instant Health Data platform (Boston Health Economics) and analyses were undertaken with SAS, version 9.3 (SAS Institute, Inc). Univariate analyses were performed for patient demographics and baseline measures were described with univariate statistics. Means and standard deviations were presented for continuous variables, and relative frequencies and percentages were presented for categorical variables. The frequency and percentage of patients with at least 1 fill/claim and number of fills/claims were reported. Disease-related HCRU and costs for inpatient, outpatient, surgery, emergency department, skilled nursing facilities, and pharmacy were presented as number (%) of patients with at least 1 visit and mean number (± standard deviation) of visits and costs were presented for all patients. All-cause and HCM-related HCRU and costs were reported for 2 periods, ie, baseline (defined as the 12-month period before the first SM or ASA procedure) and follow-up (defined as the 12-month period afterward, including the procedure).

Results

Patient characteristics. During the 2-year period after oHCM diagnosis, 119 patients received an SRT. Of these, 95 (80%) had SM, 24 (20%) had ASA, and all had continuous eligibility for a full 12 months before and after the procedure. The cohorts included similar percentages of male patients (n = 48 [51%] in the SM group; n  = 12 [50%] in the ASA group). Patients who received SM were slightly younger than those who received ASA, with a mean age of 57 ± 12 years vs 62 ± 14 years, respectively.

Healthcare resource utilization. For both the SM and ASA cohorts, HCRU increased with SRT (Table 1, Part 1 and Table 1, Part 2). The mean length of HCM-related inpatient hospitalization stay was longer for patients receiving SM (8.3 days) than for those receiving ASA (6.0 days). The mean number of HCM-related outpatient visits increased from the baseline period (12.2 vs 15.9 in the SM group; 7.2 vs 9.5 in the ASA group), with 86% of SM-treated patients and 83% of ASA-treated patients having at least 1 cardiology visit during the follow-up period. The mean number of disease-related cardiology office visits decreased post SM whereas it increased post ASA, but the proportion of patients with at least 1 visit post procedure increased for both cohorts. The mean number of all-cause ­inpatient hospitalizations increased from 0.5 to 1.5 following SRT, and the majority of visits were HCM related. Minimal changes in emergency department and physician office utilization were observed from baseline to follow-up. During the follow-up, HCM-related medication usage was greater following SM (98%) than ASA (88%). Patients received an average of 4 more prescription fills per year after SRT, 2 of which were HCM related after SM or ASA. Approximately 30% to 37% of the prescription fills were beta-blockers, calcium-channel blockers, antiarrhythmics, and/or anticoagulation medications.

Costs. Healthcare costs were greater for patients who received SM vs those who received ASA (Table 2) at follow-up. The mean total HCM-related healthcare costs increased for both procedures (from $27,045 per year to $119,772 per year in the SM group; from $11,278 per year to $54,351 per year in the ASA group). At baseline, the majority of HCM-related costs were outpatient visits and inpatient hospitalizations (Figure 2). At follow-up, costs were mostly driven by increased inpatient hospitalization costs (total costs, 53% in the SM group; 48% in the ASA group) and procedure costs (total costs, 44% in the SM group; 45% in the ASA group).

The HCM-related costs accounted for 90% and 72% of the patients’ total costs during follow-up from the SM and ASA cohorts, respectively (Figure 3). Total HCM-related costs at baseline vs follow-up were driven by increased costs of inpatient hospitalizations ($10,325 vs $112,923 in the SM group; $5509 vs $47,450 in the ASA group) and surgical costs ($6665 vs $92,031 in the SM group; $52 vs $44,815 in the ASA group) (Table 2). Surgical procedures constituted about 84% and 97% of the total costs in the SM cohort and the ASA cohort, respectively. No patients in either cohort underwent heart transplantation. Compared with baseline, HCM-related medication costs for the SM cohort decreased in the follow-up period ($974 vs $744) along with outpatient visit costs ($14,202 vs $5782). Conversely, in the ASA cohort, for baseline vs follow-up there was an increase in HCM-related medication costs ($827 vs $1201) and outpatient visit costs ($4645 vs $5431). All HCM-related outpatient costs decreased post SM, but only diagnostic procedure costs decreased post ASA. All-cause costs decreased in all of the outpatient subcategories (Table 2).

Discussion

The main findings of this study showed that, generally, patients who underwent SRT had increased HCRU across all categories, with the exception of emergency department visits and the mean number of cardiology visits, which both decreased in the SM cohort. Patients undergoing SRT in both cohorts experienced substantially increased healthcare costs, driven mostly by inpatient hospitalizations and surgical costs. A large proportion of total and surgical costs were attributable to HCM, and patients who received SM experienced an even greater cost burden than those who received ASA. Our findings show that commercially insured and Medicare Advantage patients with oHCM experience high healthcare costs and economic burden attributable to HCM.

Patients who received SM were slightly younger than the patients who received ASA (57 years vs 62 years). The average age of the patients receiving ASA in this study was similar to 2 previous investigations that evaluated the costs of ASA from the National Inpatient Sample,^9,10 but the cohorts in the current study had a larger proportion of males.⁹ The average age of our SM cohort was older than the average in a study evaluating outcomes of SM from the National Inpatient Sample³ and a single-center study.¹¹ The proportion of males in our SM cohort (51%) was within the range reported in previous studies (40%³ and 56%¹¹).The number of SRT procedures in this study was much lower than in the previous studies and the majority of ASAs in this study were inpatient procedures. The low number of SRTs captured in the current study could be associated with the type of patient insurance, the procedure settings (inpatient vs outpatient), and/or the type of healthcare system. The National Inpatient Sample used in previous investigations represents a large, all-payer database for inpatient admissions, which is a major strength in capturing surgical procedures; the HIRD captures patients from commercial health plans and Medicare Advantage.

Panaich et al reported a mean cost of hospitalization for SM of $41,715 (2010 US$), with an average length of stay of 8.89 ± 0.35 days.³ The average length of HCM-related inpatient stays in the current SM cohort was similar at 8.30 ± 5.38 days; however, the mean costs of HCM-related inpatient hospitalization ($113,675) and surgical costs ($109,385) were substantially greater. Similarly, in the current study, the HCM-related average length of stay (6.0 ± 6.91 days) for ASA was much greater compared with 2 previous studies, which had an average of 3.4 days⁹ and 4.9 days.¹⁰ Chothani et al also reported a mean cost of hospitalization of $18,760 ± 13,540),⁹ which is substantially lower than our mean HCM-related inpatient cost ($47,450 ± 36,548) and surgical cost ($44,815 ± 34,176). After adjusting for inflation, the HCM-related inpatient and surgical costs identified in our study remain higher than those previously reported.

This study has provided new insights and important economic and clinical implications for decision makers in HCM. A large proportion of the total costs with SRT was attributable to HCM, suggesting that only a small portion of costs incurred are due to comorbidities. Overall, the group experienced high healthcare costs attributable to HCM-related surgical procedures and inpatient hospitalizations. The results further showed HCM-related medication and outpatient visit costs decreased post SM, but increased post ASA. This may reflect better clinical outcomes for patients undergoing SM in this cohort and, although we were unable to evaluate any associations more rigorously by adjusting for patient characteristics, previous studies at HCM centers conclude that SM is the preferred intervention and has improved benefits, including consistently abolishing subaortic gradient and impedance to left ventricular outflow and better long-term gradient and symptom relief vs ASA.^2,12-16 In this study, the HCM-related total and surgical costs were much higher for patients receiving SM. For patients who are candidates for both SM and ASA per American Heart Association/American College of Cardiology guidelines,⁴ this dramatic difference in cost between the 2 procedures could play an important role in decision making by patients and surgical operators in the future. Future research should use real-world data to build an economic model that describes the trends in cost of care in relation to SRT and outcomes for oHCM.

Study limitations. Claims data also have limitations, and these are illustrated in our analysis. First, administrative data only include information associated with an insurance claim; mortality is not captured. Thus, any patients who died after SRT during the follow-up period would not be documented. Second, the analysis of costs and HCRU required a certain length of follow-up to estimate HCRU and costs; this might result in excluding patients with severe conditions who died early after diagnosis, without undergoing SRT. Third, we were unable to collect patient-level demographics and clinical characteristics that could provide further insights into the HCRU and costs of patients undergoing SRT. The confidentiality of claims data is protected by law in the US and, due to the size of the SM and ASA cohorts, patients may have been identifiable if we had reported clinical characteristics and comorbidities, or hospital information such as geographic area. Fourth, all patients included in the study were enrolled in commercial or Medicare Advantage health insurance plans in the US, and the results may not be generalizable to patients with other types of health insurance, the uninsured, or to those outside the US.

Conclusion

To our knowledge, this is the first study to utilize a large national medical and pharmacy claims database to quantify all-cause and HCM-related HCRU and costs for patients with oHCM receiving SRT. Our results indicate a trend toward increasing costs with SM or ASA, driven mostly by inpatient hospitalizations and surgical costs. HCRU increased after surgery for both groups, with length of stay and HCM-related medication use being higher in the SM cohort. Commercially insured and Medicare Advantage patients with oHCM experience high healthcare costs and economic burden attributable to SRT. Establishing the costs for patients undergoing SRT may aid decision makers and contribute to the future development of programs to reduce financial burden for patients with oHCM.

Affiliations and Disclosures

From ¹Health Economics and Outcomes Research, Cytokinetics, Incorporated, South San Francisco, California; ²Hypertrophic Cardiomyopathy Center and Research Institute, Division of Cardiology, Tufts Medical Center, Boston, Massachusetts; ³HealthCore, Inc, Wilmington, Delaware; and ⁴Clinical Research, Cytokinetics, Incorporated, South San Francisco, California.

^aDr Maron is currently at Lahey Hospital and Medical Center, Burlington, Massachusetts; ^bDr Robertson is currently at Tenaya Therapeutics, South San Francisco, California.

Funding: This study was funded by Cytokinetics, Incorporated, South San Francisco, California, USA. The authors acknowledge Geraldine Thompson (Engage Scientific Solutions, Horsham, United Kingdom) for editorial assistance, which was funded by Cytokinetics, Incorporated.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Maron is a steering committee member at Cytokinetics, Incorporated. C.-C. Teng, Dr Stanek, and J. Tan are employees of HealthCore, Inc. Dr Butzner is an employee of Cytokinetics, Incorporated. P. Sarocco and Dr Robertson were employees of Cytokinetics, Incorporated at the time the research was conducted.

Manuscript accepted June 23, 2022.

Address for correspondence: Mike Butzner, DrPH, MPH, 350 Oyster Point Blvd, South San Francisco, CA 94080. Email: mbutzner@cytokinetics.com

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