Results
Mean age of the study population was 63.7 ± 13.1 years, and 524 patients
(70.1%) were male. Median ACEF-MDRD score in the study population was
2.43 (1.73 - 3.74), and median ACEF-MDRD score in the study groups were
1.51 (1.29 - 1.73), 2.41 (2.13 - 2.80) and 4.60 (3.74 - 5.77),
respectively. 142 patients (19.0%) were dead at the end of the one-year
follow up.
Demographic, anthropometric, clinical and laboratory characteristics of
the patients were summarized in Tables 1 and 2. As expected, there were
significant differences across groups in terms of characteristics.
Patients within the ACEF-MDRDhigh group were more likely
to be older and male as compared to ACEF-MDRDlow group,
and patients within the ACEF-MDRDhigh group are more
likely to be symptomatic, with lower functional capacity. Besides having
a higher creatinine and lower glomerular filtration rate at baseline;
hemoglobin and albumin were significantly lower and NT-proBNP was
significantly higher in ACEF-MDRDhigh group. Finally,
both the frequency of patients with at least one hospitalization and the
total number of repeat hospitalizations were more frequent in the
ACEF-MDRDhigh group, and mortality was significantly
higher in the latter group compared to both ACEF-MDRDmedand ACEF-MDRDlow (Bonferroni-corrected p-value
<0.001 for both pairwise comparisons) (Figure 1).
Kaplan-Meier curves for one-year survival and cumulative hazards for
study groups were provided in Figure 2. There were significant
differences between the ACEF-MDRD tertiles in terms of one-year survival
(log-rank p<0.001). On pairwise comparisons, patients within
the ACEFhigh tertile had a significantly lower one-year
survival as compared to ACEF-MDRDlow and
ACEF-MDRDmed groups (p<0.001). There was also
a trend towards lower survival in the ACEF-MDRDmed group
as compared to ACEF-MDRDlow group, but this was not
statistically significant (p=0.08).
Univariate and multivariate predictors of mortality were provided in
Table 3. After adjustment, each one-point increase in the ACEF-MDRD
score was associated with a 14% (95%CI: 4% - 24%) increase in
one-year mortality. In addition to ACEF-MDRD, other parameters that were
associated with mortality were the presence of congestive symptoms at
admission, lower sodium and higher NYHA class.
ACEF-MDRD had an overall c-statistic of 0.66 ± 0.03 for prediction of
one-year mortality, and for a cut-off point of 2.71, it had a
sensitivity of 71.1%, specificity of 61.9%, positive predictive value
of 30.1% and negative predictive value of 90.1%. All component
variables of ACEF-MDRD had a lower c-statistic for predicting one-year
mortality as compared to ACEF-MDRD (age: 0.62 ± 0.03, left ventricular
ejection fraction: 0.64 ± 0.03, glomerular filtration rate: 0.56 ± 0.03,
overall p=0.001).
On a multivariate regression model consisting of ACEF-MDRD and GWTG-HF
score, both scores were found as independent predictors of one-year
mortality (OR:1.08 (95%CI:1.05 - 1.11), p<0.001 for GWTG-HF
score and OR:1.12 (95%CI: 1.02 - 1.23), p=0.02 for ACEF-MDRD). For
predicting one-year mortality, GWTG-HF score had a c-statistic of 0.70 ±
0.02, and the difference between GWTG-HF score and ACEF-MDRD was not
statistically different (p=0.14) (Figure 3). Overall NRI was 0.107,
indicating an improvement of prediction of mortality with ACEF-MDRD
score over GWTG-HF score. Individual components of the NRI analyses have
shown that correct prediction of one-year mortality was slightly
inferior with ACEF-MDRD (NRIe -0.023) but prediction of survival was
much better when ACEF-MDRD was used (NRIne 0.130).