Heart failure mortality following cancer treatment: a linked health data analysis of blood, lymphatic and breast cancer patients (1996-2009)

Background and introduction: Cardiotoxicity resulting in heart failure (HF) is a
devastating complication of cancer treatment.
Purpose: To describe the characteristics and time to death of blood, lymphatic
and breast cancer patients who died of heart failure. Of those who died of heart
failure two groups were compared, those who had an index hospital admission
prior to death (HFA) and those who did not (NHFA).
Methods: Three health data sets for the period of 1996–2009 including Queensland
Cancer Registry (QCR), Death Registry and Hospital Administration records
for HF and chemotherapy admissions were linked for this study. Index HF admission
must have occurred after cancer diagnosis. Data were analysed by comparing
demographic characteristics between HFA and NHFA patients and a multivariate
Cox proportional hazards model was fitted to compare the survival outcomes
between the two groups. A proportional hazard assumption was tested and confirmed
to satisfy assumptions. Kaplan-Meier survival analysis was performed and
groups were compared by log-rank test.
Results: Within this cohort of 4894 patients, 734 were coded as HF related death
(50.1% Female), 279 (38.0%) had at least one HF admission (41.9% Female) in
the period of post cancer diagnosis. Median age of patients with HFA prior to
death was 71 years (IQR 62–78) and 66 years (IQR 56–74) for NHFA. There
were 72% HFA and 88% NHFA in the blood and lymphatic cancer group. Patients
with HFA received fewer chemotherapy cycles (median=4, IQR 2–9) than
the NHFA patients (median=6, IQR 2–12). Patients with an index HFA had 2.5
times increased risk of HF mortality than NHFA patients (HR 2.50 [95% CI, 2.14–
2.92] when adjusted for age, sex, marital status, country of birth, cancer site and
number of chemotherapy doses). 31% of HFA and 33% of NHFA patients died
of HF within one year and 60% and 62%, respectively, died within three years
of commencement of cancer treatment. In addition 71% of the deceased cancer
patients, who had an index HFA, died within one year of the index HF admission.
Conclusion: In the first three years following cancer diagnosis a high proportion
of patients died of HF following cancer treatment. Once diagnosed with HF
almost three quarters of patients died within 12 months. Further research is underway by our team to explore the mechanisms underpinning these findings to help understand this high mortality.