Heart failure epidemiology: Evidence on incidence, management and outcomes

Background: Heart failure is one of the most common, costly, and deadly medical conditions, and its prevention and management present a challenge to health systems worldwide. Objectives: This thesis aims to investigate the epidemiology of heart failure in a large, representative general population cohort, so as to establish a solid decision basis for public health and service delivery policies in the United Kingdom and other high-income countries. Methods: Three studies were conducted to investigate temporal trends and patterns of (i) heart failure incidence and prevalence, as well as (ii) the delivery of care and (iii) health outcomes among newly diagnosed heart failure patients. Analyses relied on data from the Clinical Practice Research Datalink (CPRD), which contains anonymised electronic health record information from primary care, secondary care, and death certificates, for a representative sample of the UK population. Results: Analyses of incidence and prevalence showed that, despite a modest decline in age-sex-standardised incidence from 2002 to 2014, the absolute number of individuals with newly diagnosed heart failure increased by 12%, largely due to an increase in population size and age. The absolute number of prevalent heart failure cases increased even more strongly, by 23%. Socio-economically deprived individuals were 61% more likely to develop heart failure and did so 3.5 years earlier in life than those from the most affluent group. The study of patients’ trajectories of care following incident heart failure further revealed important gaps in care that affected screening, continuity of care, and medication titration. Outpatient diagnoses and follow-up after hospital discharge in primary care declined substantially (ranging from 56% in 2002 to 36% in 2014, and 20% to 14%, respectively). Moreover, although primary care referral for diagnostic investigations and appropriate initiation of essential drugs increased significantly, the average daily dose prescribed remained below guideline recommendations and was largely unchanged beyond the first 30 days after diagnosis. Finally, investigations of patients’ health status one year after heart failure diagnosis, revealed novel evidence explaining the standstill in mortality rates observed in many high-income countries since the mid 2000s. A decline in cardiovascular mortality (rate ratio comparing 2013 with 2002: 0.73 [0.67, 0.80]) was offset by an increase in non-cardiovascular deaths (rate ratio comparing 2013 with 2002: 1.22 [1.11, 1.33]), that was largely explained by an increase in respiratory conditions and infections. As a result, at the end of the study period (2013), non-cardiovascular causes accounted for the majority of deaths and hospitalisations. Moreover, at same age and sex, patients from deprived socioeconomic backgrounds were 21% more likely to die within one year of diagnosis than those from affluent backgrounds. Conclusions: These findings have important implications for clinical practice, health policy and future research. Most importantly, results highlight the need to address socioeconomic disparities that affect disease incidence and outcomes; and call for increased efforts to improve the coordination of care among health settings and specialities so as to ensure continuity of care and more effective management of comorbidities associated with heart failure.