RESULTS
Characteristics of the patients. We studied 9658 adults with
incident HF, most of them women (5157 patients, 53.4%), and most of
them with HFrEF (5167 patients, 53.5%) (Table 1 suppl ).
Before matching, there were significant differences between the baseline
characteristics of patients in the high income level and those in the
low/middle income level (Table 1 suppl ). These
differences among the baseline characteristics of HF patients by income
were independent of the type of HF, as they were also present in
patients with HFrEF (Table 2 suppl ) and with HFpEF
(Table 3 suppl ). As no difference of mortality between
patients with low and middle income was observed, we determined the
optimal cut-off point for the net annual household income as 30,000
euros. Therefore, we have performed our analyses by comparing PS matched
patients belonging to the highest NAHIL (>30,000 euros) to
those belonging to the low/middle NAHIL (up to 30,000 euros).
After matching, all the measured baseline covariates were balanced
between HF patients with a high NAHIL vs. those with a low/middle NAHIL
(Table 4 suppl ), as well as for patients with HFrEF
(Table 1 ), and with HFpEF (Table 2 ).
Relationship between the income level and mortality. The number
of deaths by income after matching are presented in Table
5 suppl . After matching, during a median follow-up of 8.11 years
(interquartile range, 3.37–10.62), 5616 patients died (78.9%) and 4195
patients died of a cardiovascular cause (59.0%).
The patients with HF and the highest NAHIL presented a survival longer
than that of the patients with a low/middle NAHIL (RR of death for
highest NAHIL [95% CI]: 0.86 [0.80-0.92], P <0.001;Figure 1A ). Similarly, the patients with HFrEF in the highest
NAHIL presented a survival longer than that of the HFrEF patients with a
low/middle NAHIL (RR of death for highest NAHIL: 0.88 [0.82-0.95], P
<0.001; Figure 1B ), and the patients with HFpEF in
the highest NAHIL presented a survival longer than that of the HFpEF
patients with a low/middle NAHIL (RR of death for highest NAHIL: 0.82
[0.75-0.90], P <0.001; Figure 1C ). The HF
patients in the highest income groups showed a cardiovascular mortality
significantly lower than that of the patients in the low/middle income
groups (RR of death for highest income in HF patients [95% CI]:
0.84 [0.76-0.98], P <0.001; Figure 1A
suppl. RR of death for highest income among HFrEF patients [CI
95%]: 0.87 [0.81-0.93], P <0.001; Figure
1B suppl. RR of death for highest income among HFpEF patients [95%
CI]: 0.82 [0.77-0.88], P <0.001; Figure 1C
suppl ).
Relationship between the income and the hospitalizations. The
hospitalizations and 30-day readmissions are presented in
Table 6 suppl and Table 7 suppl ,
respectively. Figure 2 suppl presents the cumulative
number of admissions for HF worsening, per 100 patient years
(Figure 2A suppl ), and that of 30-day readmission for HF
worsening (Figure 2B suppl ) in the matched groups. The
estimated effects of SES for hospitalization and 30-day readmission for
HF by each method considered are presented in Table 8
suppl . Rate ratios for recurrent hospitalizations and 30-day
readmissions were lower than those obtained by the proportional-hazards
models.
Multivariate relationship between the income and the prognosis.In our primary analysis using an intention-to-treat approach, highest
NAHIL exposure was associated with a 16% lower relative risk (RR) of
all-cause death, a 15% lower RR of cardiovascular death, a 17% lower
RR of hospitalization for HF, a 35% lower RR of hospitalization for a
CV cause, a 30% lower risk of hospitalization for HF, and a 34% lower
RR of 30-day readmission for HF, compared with patients in the
low/middle NAHIL, even after adjustment for sociodemographic
characteristics, comorbidities, longitudinal use of medications, and
propensity to be in the highest income group (Table 3 ). In the
second type of analysis, time-dependent exposure to high NAHIL was
associated with an even lower adjusted risk of all-cause and
cardiovascular death, of hospitalization for HF, and of 30-day
readmission for HF, compared with periods with a low/middle NAHIL
(Table 9 suppl ). Similarly, high NAHIL was associated
with a reduced mortality (all-cause and cardiovascular),
hospitalizations and 30-day readmissions in patients with HFrEF, HFpEF,
as well as in men and women with HF (Table 3 and
Table 9 suppl ).
This favorable relationship of high NAHIL to mortality was maintained
independently that the patients, before their inclusion or during the
follow-up, presented cardiovascular events or other comorbidities in
Table 1 and Table 2 (highest adjusted hazard ratio [HR] 0.84; 95%
CI: 0.78-0.90, vs. highest HR 0.74; 95% CI: 0.68-0.80; P <
0.01 in all cases).
Subgroup analyses. These analyses have been performed for
patients with HF (Figure 3A suppl ), HFrEF
(Figure 3B suppl ) and with HFpEF (Figure
3C suppl ). Although, age, sex, atrial fibrillation, BMI and
comorbidity negatively influenced the effects of income on the prognosis
of HF (29), this benefit was also observed in the subgroups of patients
over 70 years, women, diabetics, patients with chronic renal disease or
with atrial fibrillation, overweight patients and those with an elevated
burden of comorbid conditions (Figure 3A-C suppl ).