FormalPara Key Points for Decision Makers

This study provides valuable insights into health care consumption and cost expenditure for HF patients hospitalized across France, utilizing data from the French national hospital discharge database.

Presence of cardiac decompensation, reduced ejection fraction, and comorbidities may be associated with a higher frequency and length of hospitalization, hospital resource utilization, and hospital cost.

1 Introduction

Heart failure (HF) is defined as a structural or functional abnormality of the heart causing symptomatic left ventricular dysfunction and inability to meet the oxygen demand of tissues [1]. HF is categorized into three major phenotypes based on ejection fraction (EF) of the left ventricle: (i) HF with reduced EF (r-EF) (EF ≤ 40%); (ii) HF with preserved EF (p-EF) (EF ≥ 50%); and (iii) HF with mildly reduced EF (41% ≤ EF ≤ 49%) [1]. Reduced physical activity, breathlessness, fatigue, or palpitations are commonly reported by HF patients. The New York Heart Association (NYHA) grades HF patients into four classes (I, II, III, and IV) [2]. NYHA class I patients may not have any symptoms of HF, whereas II, III, and IV patients show mild, moderate, and severe symptoms, respectively [2]. Aortic valve disease, ischemic heart disease, myocarditis, endocarditis, and chronic obstructive pulmonary disease are the major causes of HF [3]. When patients affected by chronic HF experience a rapid deterioration of signs and symptoms leading to hospitalization, their condition is known as decompensated HF [4]. The severity of HF results in increased hospitalizations (20.0% of readmission among patients hospitalized for HF in 2012 [5] and 31.8% in 2015 [6]).

The global prevalence of HF is 64.34 million cases (8.52 per 1000), and HF is more prevalent among women (9.16 per million) compared with men (7.69 per million) [3], probably due to lower mortality in women than men [7]. Moreover, HF is more prevalent in patients older than 60 years (81%) [3]. In France, the prevalent number of hospitalized HF patients was estimated at 165,093 patients in 2014 by the French National Health Insurance Fund (CNAM). In 2020, the prevalence of HF was at 1.28%, and men showed a higher prevalence (1.36%) than women (1.21%) [8]. This is justified by the higher mortality rate of women in France [9]. Age-group-based analysis shows that French patients older than 50 years are at a higher risk for HF, and the prevalence of HF is higher in older age groups [8].

First-line treatment for HF includes renin-angiotensin-aldosterone system inhibitors, a β-blocker, and a mineralocorticoid receptor antagonist (MRA) [2]. A diuretic is also prescribed to relieve the symptoms of congestion [2]. Non-surgical devices such as implantable cardioverter-defibrillators and cardiac resynchronization therapy reduce the risk of hospitalization and prevent sudden fatalities in HF patients with r-EF [2].

HF is associated with a substantial treatment cost. A German study estimated the outpatient visits and hospitalization costs (including rehabilitation stays and drug utilization) for patients with systolic chronic HF to be €3150 per year, with €2328 spent on hospitalization costs alone [10]. A Swedish retrospective study of HF patients with r-EF at 31 primary care centers reported the annual hospitalization cost to be €7610 per patient [11].

Data on health care resource utilization and the economic burden of HF in France are scarce. According to the French health insurance report in 2022, expenditure for cardio-neurovascular diseases amounted to €17.8 billion, which is 10.6% of the total health insurance expenditure, and expenditure for three diseases (including HF [€3.0 billion]) accounted for more than two-thirds of the overall expenditure for cardio-neurovascular diseases. During 2020, marked by the Corona Virus Disease—2019 (COVID-19) pandemic, the overall spending on HF fell by 6.6% [12]. The French National Health Insurance Fund (CNAM) reported that the total spending on HF-related treatments in 2020 was €3031 million and the per-patient cost was €3580 [8].

Given the dearth of published literature, the health economic burden of HF in France necessitates a comprehensive study that can provide valuable insights into current health care resource utilization and hospitalization costs for HF patients in France. Therefore, the present study has been designed to understand the patient characteristics, health care consumption, and hospitalization costs (by type of EF and occurrence of cardiac decompensation) among HF patients in France.

2 Methods

2.1 Study Objectives

The aim of this study was to describe the incidence and characteristics of HF patients hospitalized in France and to estimate the hospital healthcare consumption and the associated costs of HF patients.

2.2 Study Design

This was a retrospective cohort study that included patients with HF aged 18 years or older hospitalized in France (metropolitan and French overseas territories) between January 1, 2019 and December 31, 2019. The index date was the first hospital admission date with an HF diagnosis with or without decompensation during the study period. The look-back period was defined as the 5 years before the index date, during which comorbidities and risk factors were collected. The follow-up period was set to 1 year following the index date.

2.3 Data Source

Hospitalization data were retrieved from the French national hospital discharge database, referred to as the Programme national de Médicalisation des Systèmes d'Information (PMSI). The PMSI collects pseudo-anonymized patient data on hospitalizations (overnight, inpatient stays, and day stays—excluding outpatient consultations) and ambulatory care requiring hospitalization or treatment session (e.g., dialysis). More precisely, the PMSI database includes hospital discharge summaries for each inpatient stay including administrative information (age, gender, and unique identifier of each patient), medical procedures coded in the common classification of medical acts (CCAM) and the following diagnoses coded according to the 10th revision of the World Health Organization international classification of diseases (ICD-10):

  • Primary diagnosis (PD) is a health condition that justifies the patient’s admission to the medical unit determined on discharge from the medical unit

  • Associated diagnosis (AD) is a condition, symptom or any other reason for hospital care coexisting with primary diagnosis, or constituting:

    1. o

      a distinct additional health problem (another condition)

    2. o

      complication of the primary diagnosis

    3. o

      complication of the treatment of the main morbidity

  • Related diagnosis (RD) has a role, in association with the primary diagnosis, and when the latter is not sufficient, to report on the care of the patient in medico-economic terms. Its determination is based on three principles:

    1. o

      It is only necessary to mention when the primary diagnosis is coded within the chapter XXI of ICD-10

    2. o

      The related diagnosis is a chronic or long-term disease or permanent state, present at the time of the stay

    3. o

      The related diagnosis answers the question: for which disease or condition was the care recorded as primary diagnosis carried out

Data from the following four hospital wards are available in the PMSI: Medicine, Surgery, and Obstetrics (MSO); Home Hospitalizations (Hospitalisation à Domicile, HAD); Post-Acute Care and Rehabilitation (Soins de Suite et de Réadaptation, SSR); and Psychiatry (Recueil d'Informations Médicalisé pour la Psychiatrie, RIM-P). In this study, the data were retrieved for the MSO ward alone.

Drugs and medical devices given during a hospitalization are directly included in the Diagnosis-Related Group (DRG) tariffs. It is therefore not possible to know precisely which drugs/medical devices were prescribed and their costs. However, innovative and high-cost drugs and medical devices, also called ‘liste-en-sus’ drugs and medical devices, are collected using 7-digit codes in this database.

2.4 Patient Identification

HF patients without cardiac decompensation were identified with ICD-10 codes I50, I420, I110, I130, or I132, and without ICD-10 codes J9600 (code available since March 2019), R570, K720, or R601, as the primary or associated diagnosis. As an ICD-10 code for cardiac decompensation in HF patients does not exist, it was identified using an algorithm for acute HF defined by the French Health Insurance Fund [13]. According to the algorithm, patients with cardiac decompensation were defined as those who were hospitalized during the study period with ICD-10 codes J9600, R570, K720, R601, I50, I110, I130, I132, or J81 as the PD or AD. EF status was identified with the corresponding ICD-10 codes (ICD-10 codes for p-EF [i.e., EF ≥ 50] were I5000, I5010; ICD-10 codes for r-EF [i.e., EF < 40] were I5002, I5012; ICD-10 codes for mildly reduced EF [i.e., 40 ≤ EF < 50] were I5001 and I5011; ICD-10 codes for unspecified EF were I5009 and I5019). In this study, the mildly reduced EF group was merged with the preserved EF group in statistical analyses. Type 2 diabetes mellitus (T2D) and chronic kidney disease (CKD), known for their important interrelation with heart failure [14], were identified using ICD-10 codes (T2D: E11, CKD: N18), and the algorithm defined by the French Health Insurance Fund for end-stage renal disease (presented in the Electronic Supplementary Material [ESM]).

2.5 Outcomes and Variables

2.5.1 Patients’ Socio-Demographic and Clinical Characteristics

Age, gender, EF status, and comorbidities including T2D and CKD were described for all patients included in this study. T2D and kidney diseases were considered in this study for their important interrelation with heart failure [14].

2.5.2 Incidence and Prevalence of Heart Failure

Incident patients of HF were those diagnosed with HF during the study inclusion period (January 1, 2019–December 31, 2019) with no prior diagnosis of HF during the previous 5 years (January 1, 2014–December 31, 2018). Therefore, the incidence was calculated with the following equation and expressed as number of cases per 100,000 inhabitants:

$${\text{Incidence of heart failure}} = \frac{{{\text{new cases of HF in }}\;2019}}{{{\text{general population aged }} \ge 18{\text{ years in France in}}\;{ }2019}} \times {1}00,000.$$

Prevalent patients of HF were those diagnosed with HF during the study inclusion period (January 1, 2019 to December 31, 2019) and with prior diagnosis of HF during the look-back period (January 1, 2014–December 31, 2018). Therefore, the prevalence was calculated with the following equation and expressed as number of cases per 100,000 inhabitants:

$${\text{Prevalence of heart failure}} = \frac{{{\text{cases of HF in }}2019{\text{ with prior HF diagnosis between }}01{\text{ January }}2014{\text{ to }}31{\text{ December }}2018}}{{{\text{general population aged }} \ge 18{\text{ years in France in }}2019}} \times {1}00,000$$

The general population aged ≥ 18 years in France in 2019 was estimated at 52,408,636 inhabitants by the French National Institute of Statistics and Economic Studies (INSEE).

2.5.3 Mortality and Cardiovascular Death Rates

In-hospital death is identified using a specific code (‘9’) when describing reason for hospital discharge. Cardiovascular death was defined as in-hospital death with a cardiovascular event during the last hospitalization.

All-cause mortality and cardiovascular death rates were calculated using the following equations:

$$\mathrm{All}-\mathrm{cause mortality}=\frac{\mathrm{cases\, of\, death }}{\mathrm{total study population}} \times 100$$
$${\text{Cardiovascular death}} = \frac{{\text{cases of death with a cardiovascular event}}}{{\text{total study population}}} \times 100.$$

2.5.4 Healthcare Resource Utilization (HCRU)

All outcomes were considered in the year after the index date (up to December 31, 2020, at the latest). The outcomes of the study included the frequency and length of HF hospitalizations per patient in the MSO ward; use of high-cost innovative drugs and medical devices (‘liste-en-sus’ drugs and medical devices identified using 7-digit codes) per patient; type and frequency of the most commonly used medical procedures during HF hospitalizations; and the cost estimations of events listed above from the hospital perspective.

HF hospitalization outcomes were further stratified based on the presence or absence of cardiac decompensation, EF status (r-EF and p-EF), and incident/prevalent patients. P-EF and r-EF subgroups were further stratified based on the presence or absence of comorbidities (patients with T2D and CKD [T2D+/CKD+], with T2D and without CKD [T2D+/CKD−], without T2D and with CKD [T2D−/CKD+], and without T2D and without CKD [T2D−/CKD−]).

2.5.5 Hospital Costs in 2019

The cost analysis was conducted using the hospital perspective for year 2019. Under a hospital perspective, the healthcare resources including stays, medical procedures, and innovative or expensive health products were considered.

To approximate the production cost of a hospitalization, the preferred source of data is the National costs study (ENCC) based on DRG [15]. Economic data are based on accounting agreements from the sample of French hospitals that participated in ENCC. The ENCC database provides the direct cost related to the hospitalization (structure costs are not included). The calculation of the cost was conducted as follows:

$${\text{Cost }}\left( {{\text{year}}} \right) \, = \, \sum_{i = [1:N]} \left( {{\text{Tariff}}\_{\text{stay}}_{{{\text{GHM}} - {\text{ENCCi}}}} \left( {\text{year YYYY}} \right) \, *{\text{ Nb}}\_{\text{stays}}_{i} } \right),$$

where i is the DRG associated with the stay; 1 DRG = 1 cost depending on the type of hospital (public or private) and the year in which the health resources were used.

2.6 Data Collection

Data on patient-related variables such as sociodemographic characteristics (age, sex, and residence), type of hospital stay, dates of hospital admission and discharge, diagnoses at hospital admission and discharge, medical procedures, ‘liste-en-sus’ drugs and medical devices, length of hospitalization, comorbidities, and all-cause and cardiovascular death were retrieved from the PMSI database.

2.7 Statistical Analysis

Data extraction, management, and statistical analysis were carried out by IQVIA using SAS® software, version 9.4 (SAS Institute, North Carolina, USA).

All the analyses were descriptive. Continuous variables were described by their number (of valid cases, of missing values if any), mean, standard deviation (SD), and median, interquartile range (IQR), minimum, and maximum.

Categorical variables were reported using the total number (of valid cases, of missing values if any) and relative percentage per category. Missing values on type of EF were also reported in percentage.

The prevalence and incidence of HF were estimated per 100,000 inhabitants. All cost analyses were carried out per patient and per year.

3 Results

3.1 Study Population

As shown in Fig. 1, a total of 430,544 patients were identified in the French administrative healthcare database with a diagnosis code for heart failure in the year of 2019. Of the total, 408,214 patients did not present any event of cardiac decompensation and 22,330 did. Among patients without cardiac decompensation (n = 408,214), > 60% were identified through associated diagnosis (AD), which is used to record a health condition coexisting with the primary diagnosis (PD). Among patients with cardiac decompensation (n = 22,330), all patients were identified through PD.

Fig. 1
figure 1

Flowchart of the study population diagnosed with heart failure at hospitals in France in 2019. AD associated diagnosis, HF heart failure, PD primary diagnosis

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3.2 Sociodemographic Characteristics and Epidemiology

In the French administrative healthcare database, a total of 430,544 patients aged 18 years or older were hospitalized in France for PD or AD of HF between January 1, 2019 and December 31, 2019. Table 1 displays the sociodemographic characteristics of overall HF patients, HF patients with/without decompensation at the index date, and pEF and rEF patients. The mean (SD) age of HF patients was estimated at 79 (13) years, with 51.9% male and 48.1% female. Patients identified with p-EF were older (p-EF: 78 [13] years vs r-EF: 74 [14] years), and the proportion of male patients with p-EF was lower compared with the proportion of male patients with r-EF (p-EF: 52.0% male vs r-EF: 67.2% male).

Table 1 Sociodemographic characteristics of overall HF patients, HF patients with/without decompensation at index date, and patients with preserved and reduced HF
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More than 75% of the study population were prevalent HF patients. Incident HF patients were older (incident: 81 [12] years vs prevalent: 79 [13] years) with a slightly higher proportion of male patients (incident: 52.5% male vs prevalent: 51.8% male) compared with prevalent HF patients (Table 2 of ESM).

Table 2 demonstrates the incidence and prevalence of HF in patients, the percentages of patients with cardiac decompensation, patients categorized into different HF types, and the rates of comorbidities (T2D and CKD), and mortality. The incidence and prevalence of HF per 100,000 were 194 and 627, respectively. About 3.1% of patients with HF experienced at least one event of cardiac decompensation during follow-up. Also, 8.1% of patients who had decompensation at the index date experienced at least one decompensation event at follow-up, whereas only 2.8% of patients with no decompensation at the index date experienced decompensation during follow-up.

Table 2 Incidence and prevalence of heart failure (HF) in overall patients
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EF information ICD-10 codes, introduced in March 2019, were available for 54.2% of the study population. Around 20.2% of HF patients were grouped under p-EF, 9.9% under r-EF; 24.2% under ‘unspecified’ EF, and EF was not recorded for 45.8% of HF patients. T2D and CKD were listed as comorbidities in 4.8% and 3.3% of patients with HF, respectively.

During the study period (12 months), 4.6% of patients had a CV death and all-cause in-hospital mortality was 21.4%.

Higher proportions were observed in incident than prevalent HF patients for cardiac decompensation (at index date: 6.4% vs 4.8%; during follow-up: 5.6% vs 2.3%), reduced ejection fraction (20.6% vs 17.7%) and comorbidities (T2D: 7.3% vs 4.1%; CKD: 5.4% vs 2.7%). Also, all-cause and cardiovascular mortality rates were greater in incident than prevalent HF patients (all-cause: 25.9% vs 20.1%; cardiovascular: 5.2% vs 4.4%) (Table 4 of ESM).

3.3 Number and Length of Stay

Table 3 shows the frequency and length of hospital stays per patient in MSO for HF. Among the 430,544 HF patients included in the study, 408,214 were hospitalized without cardiac decompensation at the index date, and 22,330 with decompensation at index date. The mean (SD) number of HF hospitalizations was 1.7 (1.8) per patient, and the mean (SD) length of stay was 10.4 (10.3) days per patient. The number and length of stays per patient were 3.7 (2.1) and 13.1 (9.0) days, respectively, for patients with decompensation during follow-up and 1.6 (1.7) and 10.3 (10.3) days, respectively, for patients without decompensation during follow-up.

Table 3 Number and length of hospital stays per patient in MSO for HF
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The mean (SD) length of stay for patients hospitalized without cardiac decompensation at index date was 10.3 (10.2) days. For those with cardiac decompensation at the index date, the mean (SD) length of stay was 12.7 (11.3) days. For both groups (patients with and without decompensation at the index date), patients with decompensation during follow-up had more and longer stays than patients with no decompensation during follow-up.

During the study period, 86,895 patients were diagnosed with p-EF and 42,719 patients with r-EF. The mean (SD) number of stays per patient was higher for r-EF patients compared with p-EF patients (r-EF: 1.8 [1.63] vs p-EF: 1.6 [1.20]), whereas the mean (SD) length of stay was similar in both groups (r-EF: 10.0 [9.97] days vs p-EF: 10.3 [9.86] days). Patients with T2D and/or CKD reported frequent and longer stays per patient (Table 6 of ESM).

On average, hospitalizations for HF were slightly more frequent (2 vs 1.5 hospitalizations per patient) and lengthier (10.7 days vs 10.3 days per stay and per patient) in incident than prevalent HF patients. When describing by occurrence of cardiac decompensation during follow-up, for both incident and prevalent HF patients, hospitalizations were even more frequent and lengthier in the presence of a cardiac decompensation then in absence of the event. The length of hospitalization was particularly higher numerically in incident HF patients with decompensation compared with those without the event (10.5 days vs 13.5 days per patient) (Table 7 of ESM).

3.4 Number of ‘liste-en-sus’ Drugs and Medical Devices Used

In this study, ‘liste-en-sus’ medical devices were used in 13.9% (n = 59 963) of the study population and ‘liste-en-sus’ drugs in 2.9% (n = 12 620).

Table 4 displays the number of ‘liste-en-sus’ drugs and medical devices used per patient. The mean (SD) number of innovative drugs and medical devices used per patient for HF hospitalizations was 0.1 (0.51) and 0.3 (0.92), respectively. The consumption of ‘liste-en-sus’ drugs and medical devices per patient was similar between the two groups (with and without decompensation during follow-up). Medical devices used for patients with r-EF and p-EF were 0.7 and 0.3, respectively.

Table 4 ‘Liste-en-sus’ drugs and medical devices: number per patient
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‘Liste-en-sus’ drugs had been used by 2.8% of the incident and 3% of prevalent HF patients. The presence of cardiac decompensation increased the use of these drugs in both incident (5.4% vs 2.6%) and prevalent HF patients (5.6% vs 2.9%). ‘Liste-en-sus’ medical devices were more commonly used, by 11.1% of incident HF patients and 14.8% of prevalent patients. The presence of cardiac decompensation increased the use of these devices, and particularly in prevalent patients (20.5% vs 14.7%) more than incident patients (14.6% vs 10.9%) (Table 9 of ESM).

Generally, the mean (SD) and median (IQR) number of ‘liste-en-sus’ drugs and medical devices were < 1 per patient, with a slightly higher number for ‘liste-en-sus’ medical devices (0.3–0.5 per patient) than ‘liste-en-sus’ drugs (0.1 per patient). Thus, due to low proportions, the number of ‘liste-en-sus’ drugs and medical devices per patient cannot be interpreted. The ten most frequently administered ‘liste-en-sus’ drugs in hospitalized HF patients were mostly treatments for bleeding and, rarely, anti-cancer drugs. The top ten ‘liste-en-sus’ medical devices provided to hospitalized HF patients were mostly heart stimulation leads, pacemaker, stent and articular implants (see ESM).

3.5 Cost of Hospitalization: Hospital Perspective

Figure 2 and Table 5 demonstrate the cost of HF hospitalizations per patient, including medical procedures. The overall mean (SD) cost of hospitalization for HF, excluding ‘liste-en-sus’ drugs and medical devices, was €7649.6 (8793.2) per patient per year. The cost of hospitalization was the highest for patients with decompensation during follow-up (€17,857 [17,429] per patient per year).

Fig. 2
figure 2

Hospital perspective: cost of heart failure hospitalizations (including cost of medical procedures) per patient in euros

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Table 5 Hospital perspective: cost of HF hospitalizations (including cost of medical procedures) per patient in euros
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The lowest cost was observed for patients without decompensation during follow-up (€7321.1 [8159.20] per patient per year). The mean (SD) cost of HF hospitalizations for patients hospitalized with and without cardiac decompensation at the index date was €9125.0 (11,734) and €7568.9 (8596.1) per patient per year, respectively. Patients with decompensation during follow-up had higher hospitalization costs per patient compared with those patients without decompensation during follow-up.

Figure 3 and Table 6 depict the cost of hospitalizations for patients with p-EF and r-EF. The mean (SD) cost of HF hospitalization was higher for patients diagnosed with r-EF compared with p-EF (r-EF: €9473.1 [11,939] per patient er year vs p-EF: €7473.1 [8144.9] per patient per year). The data show that presence of comorbidities (T2D and CKD) increases hospitalization cost.

Fig. 3
figure 3

Hospital perspective: cost of HF hospitalizations per patient in euros—with preserved/reduced EF. CKD chronic kidney disease, EF ejection fraction, HF heart failure, T2D type 2 diabetes

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Table 6 Hospital perspective: cost of HF hospitalizations per patient in euros—with preserved/reduced EF
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The average cost of hospitalizations (including medical procedures) was greater for incident HF patients (€8790.6 per patient per year) than prevalent HF patients (€7296.7 per patient per year). For both incident and prevalent HF patients, the cost of hospitalization was considerably higher in the presence of a cardiac decompensation during follow-up (incident HF patients: €8217.8 vs €18,419 per patient per year; prevalent HF patients: €7053.1 vs €17,441 per patient per year) (Table 12 of ESM).

Table 7 presents the cost of ‘liste-en-sus’ drugs and medical devices for HF patients. Of the patients hospitalized for HF in the study year, 59,963 required ‘liste-en-sus’ medical devices and 12,620 required ‘liste-en-sus’ drugs. The mean (SD) cost was €4233.8 (21,187) per patient per year for ‘liste-en-sus’ medical devices and €3481.4 (12,401) per patient per year for ‘liste-en-sus’ drugs.

Table 7 Hospital perspective: cost of ‘liste-en-sus’ drugs and medical devices per patient related to HF hospitalizations
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For ‘liste-en-sus’ medical devices, the average cost was greater for incident than prevalent HF patients (€5900.6 vs €3848.9 per patient per year). However, in the presence of cardiac decompensation, the average cost was higher for prevalent than incident HF patients (€11,021 vs €8937.9 per patient per year). For ‘liste-en-sus’ drugs, the average cost was slightly higher for prevalent than incident HF patients (€3502.2 vs €3409.8 per patient per year). In the presence of cardiac decompensation, the average cost increased for both prevalent and incident HF patients (€4331.6 and €3475.5 per patient per year, respectively) (Table 14 of ESM).

Table 8 summarizes the total hospital cost per patient for HF including HF hospitalizations, ‘liste-en-sus’ products and medical procedures. The mean hospital cost for HF was estimated at €8341.3 per patient per year. Higher mean hospital costs were observed among patients with cardiac decompensation, reduced EF and incident HF those for the overall study population.

Table 8 Hospital perspective: total hospital cost per patient for HF
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4 Discussion

This retrospective study was designed to describe healthcare consumption and the cost of hospitalization in patients diagnosed with HF in France. To our knowledge, this is the first-of-its-kind study in France to provide valuable insights into healthcare consumption and hospitalization cost for HF patients in France, and to distinguish type of EF in the French national hospital discharge database.

This study included more than twice the number of hospitalized HF patients (n = 430,544) than that reported by the French public health website (n = 165,093 in 2014) [16], mainly because this study considered diagnosis codes for HF in PD and AD (both diagnoses being complementary or coexisting health conditions), while the French public health website identified HF codes for HF in PD only.

The mean age of HF patients hospitalized in France was 79 years, which is consistent with the reports on the French Health Insurance Fund website (77 years) [17], and that reported by Pérel et al. (79 years) [18] and Gabet et al. (78 years) [5]. The ratio of male and female participants in this study was close to 1, which is similar to that reported by Pérel et al. and Gabet et al. [5, 18].

The incidence rate of HF was 194 per 100,000 and prevalence rate was 627 per 100,000 of the French population. Both incidence and prevalence rates were lower than those in previously reported studies [5, 19] (the age-standardized incidence rate published by Gabet et al. was 246.2 per 100,000 population in 2012 [5], and the age-standardized prevalence rate published by Tuppin et al. was 1070 per 100,000 population in 2013 [19]). This could be due to the exclusion of HF coded as ‘related diagnosis’ (i.e., diagnosis coded in association with the PD) in the present study.

The population in this study was stratified based on cardiac decompensation, EF status, and incidence/prevalence of HF at the index date.

About 5% of patients (n = 22,330) developed a cardiac decompensation at index date, and 3% (n = 13,424) during a year of follow-up. These rates of cardiac decompensation are lower than those found in the literature due to discrepancies in the definition of the event and the study setting. For instance, Chang et al. [20] defined cardiac decompensation as heart failure being the primary reason for hospitalization and reported 16.4% of hospitalizations for acute decompensation (n = 713/4359 hospitalizations), among 1077 HF patients (mean age 76.8 years, 582 [54.0%] female) in the US. More recently published clinical trials, EMPEROR preserved [21] and reduced [22], reported hospitalizations for HF to occur in 11.8% of HF patients with a left ventricular EF of > 40% (EMPEROR preserved), and 18.3% among HF patients with a left ventricular EF of < 40% (EMPEROR reduced). In these trials conducted in 20 countries including France, hospitalization for HF included adjudicated primary diagnosis for HF, extended hospital stay for at least 12 h, new or worsening symptom due to HF (e.g., dyspnea, decreased exercise tolerance, fatigue), and evidence of new or worsening HF (e.g., examination findings, laboratory evidence, radiological evidence, electrocardiographic criteria, evidence with heart catheterization). The median follow-up duration was 26.2 months in EMPEROR preserved and 16 months in EMPEROR reduced.

The p-EF population was approximately twice that of the r-EF population. This could be linked to the bias in coding method in France, which encourages coding only for medico-economic purposes (pathological conditions [e.g., r-EF]) and not for documentary purposes. Since coding for EF status was introduced only in March 2019 and due to a coding strike in the last quarter of 2019, the type of EF was not recorded for more than half of the study population. Patients with p-EF were older (mean age: 78 years) than those with r-EF (mean age: 74 years). EF may have been coded as ‘unspecified’ when the type of EF was not identified at the time of coding. Furthermore, the p-EF population had a lower proportion of male patients compared with the r-EF population.

Patients with cardiac decompensation at the index date were more likely to develop another episode of decompensation during follow-up. Proportions of T2D or CKD may have been underestimated as these comorbidities are often diagnosed in the outpatient setting and thus were not collected in this study, which used hospital data only. Similarly for p-EF, physicians tend not to code for conditions not requiring care consumption.

The mean length of HF hospitalization in the MSO ward was consistent with the Gabet et al. study (10 days [5]). In this study, patients who experienced cardiac decompensation at the index date and during follow-up or those patients with comorbidities had frequent and longer stays than those without decompensation or comorbidities. In previous studies, decompensation and comorbidities were reported as important factors influencing the length of hospital stay [23, 24]. In fact, comorbidities such as T2D are associated with readmission, longer hospital stays, and a risk of in-hospital infections and other complications [23,24,25,26].

In this study, the cost of hospital resource utilization was influenced by the presence of cardiac decompensation, comorbidities, and EF status. Similarly, other studies have also indicated that the status of EF [27], T2D [27, 28], and kidney dysfunction [29, 30] are known predictors of cost and healthcare resource utilization for HF patients. An observational study in the US reported that HF patients with T2D and preserved EF ≥ 50% incurred 24.8% and 23.6% higher lifetime costs, respectively, than patients without T2D and with reduced EF ≤50% [27]. Another US study reported that patients with EF ≤40% had a longer hospital stay, more readmissions, and an overall higher hospitalization cost (US$3054 vs US$2770) compared with patients with EF > 40% [31].

Some trends in healthcare resource consumption were observed according to the incidence and prevalence of HF. More than 75% of the study population was composed of prevalent HF patients. Incident HF patients were older and presented a higher proportion of reduced EF and comorbidities compared with prevalent HF patients. Incident HF patients were hospitalized more frequently and for longer, but they received slightly less ‘liste-en-sus’ drugs and medical devices than prevalent HF patients. For hospitalization and ‘liste-en-sus’ medical devices, higher cost was observed in incident compared with prevalent HF patients, while for ‘liste-en-sus’ drugs, higher cost was reported in prevalent compared with incident HF patients.

The key strength of the present study is that it incorporated data from the French hospital discharge database, which collects pseudo-anonymized patient information on hospital stays (~ 11 million hospital stays) and healthcare facilities at a national level. However, the study has certain limitations related to the database, and the results of the study should be interpreted in the context of its limitations. First, data from the French hospital discharge database may include the risk of coding errors, involuntary omissions, as well as a lack of information on medications administered during hospitalizations not considered in the ‘liste-en-sus’. Moreover, there are coding constraints imposed by French health insurance, whose main goal is to determine the invoicing of hospital stays and not to precisely define diagnostics. Nevertheless, Bosco-Lévy et al. [32] reported that diagnosis codes in ICD-10 for I50 in discharge summary databases accurately identify patients with HF (positive predictive value of I50 codes was 60.5% [95% CI 53.7–67.3] for definite HF and 88.0% [95% CI 83.5–92.5] for definite/potential HF). More importantly, it is to be noted that the French hospital discharge database does not include data from the outpatient setting, which may explain underestimation of some health conditions. Also, ICD-10 codes for p-EF and r-EF were available only from March 2019, which explains the low rate of data available on EF status in this study. Finally, cardiovascular death was defined as an event of death with a cardiovascular diagnosis during a hospital stay; hence, the death etiology was not necessarily attributed to CV disease.

The incidence of HF was significantly decreased between 2019 and 2020 (− 10.5% in 2020) although there was a slight increase in previous years. Low identification of acute cardio-neurovascular diseases in 2020 may be responsible for lower incidence of these diseases compared with previous years [33]. It is presumed that COVID-19 or other reasons had an impact on the higher mortality rate in 2020 among patients with cardio-neurovascular diseases; however, this hypothesis is yet to be established [33]. The hospitalization cost of acute HF patients in this period (about €100 million) was also significantly reduced (−6.6%) compared with previous years [33]. In fact, the all-cause hospitalization rate in 2020 reduced due to less identification of critical illness (CI) in every metropolitan region of the country and a lower proportion of acute CI patients among the total CI population [33].

5 Conclusion

The incidence of hospitalization for heart failure was 194 per 100,000 in 2019 in France and most patients were aged over 80 years. Very few patients presented cardiac decompensation at index date (5.2%) and during follow-up (3.1%). Considering the recent implementation of codes for types of ejection fraction of heart failure, only 20.2% and 9.9% of the study population were identified with pEF and rEF, respectively. Also, CKD or T2D were recorded in <5% of the study population as these comorbidities are diagnosed and treated mostly in the outpatient setting. Considering these patients’ characteristics, the mean number and length of HF hospitalizations were 1.7 and 10.4 days per patient. The cost of HF hospitalizations was €8341.3 per patient per year. Patients with cardiac decompensation, comorbidities, and rEF had a numerically higher frequency and longer duration of hospitalizations, and thus, higher hospital costs than those without cardiac decompensation (at index date: mean cost €10,146 vs €8242.5 per patient per year and during follow-up: mean cost €19,928 vs €7968.4 per patient per year), without T2D and CKD (€9689.8–€13,749 vs €8169.6–€10,745 per patient per year) and pEF (mean cost: €10,845 vs €8,242.8 per patient per year).

In summary, based on the French hospital database (PMSI), the cost of HF hospitalizations is €8341.3 per patient per year. This study highlighted the high economic hospital burden of HF in France.