Epidemiology of heart failure and trends in diagnostic work-up: a retrospective, population-based cohort study in Sweden

Abstract

Purpose: The purpose of this study was to examine the trends in heart failure (HF) epidemiology and diagnostic work-up in Sweden.

Methods: Adults with incident HF (≥2 ICD-10 diagnostic codes) were identified from linked national health registers (cohort 1, 2005-2013) and electronic medical records (cohort 2, 2010-2015; primary/secondary care patients from Uppsala and Västerbotten). Trends in annual HF incidence rate and prevalence, risk of all-cause and cardiovascular disease (CVD)-related 1-year mortality and use of diagnostic tests 6 months before and after first HF diagnosis (cohort 2) were assessed.

Results: Baseline demographic and clinical characteristics were similar for cohort 1 (N=174,537) and 2 (N=8,702), with mean ages of 77.4 and 76.6 years, respectively; almost 30% of patients were aged ≥85 years. From 2010 to 2014, age-adjusted annual incidence rate of HF/1,000 inhabitants decreased (from 3.20 to 2.91, cohort 1; from 4.34 to 3.33, cohort 2), while age-adjusted prevalence increased (from 1.61% to 1.72% and from 2.15% to 2.18%, respectively). Age-adjusted 1-year all-cause and CVD-related mortality was higher in men than in women among patients in cohort 1 (all-cause mortality hazard ratio [HR] men vs women 1.07 [95% CI 1.06-1.09] and CVD-related mortality subdistribution HR for men vs women 1.04 [95% CI 1.02-1.07], respectively). While 83.5% of patients underwent N-terminal pro-B-type natriuretic peptide testing, only 36.4% of patients had an echocardiogram at the time of diagnosis, although this increased overtime. In the national prevalent HF population (patients with a diagnosis in 1997-2004 who survived into the analysis period; N=273,999), death from ischemic heart disease and myocardial infarction declined between 2005 and 2013, while death from HF and atrial fibrillation/flutter increased (P<0.0001 for trends over time).

Conclusion: The annual incidence rate of HF declined over time, while prevalence of HF has increased, suggesting that patients with HF were surviving longer over time. Our study confirms that previously reported epidemiological trends persist and remain to ensure proper diagnostic evaluation and management of patients with HF.

Keywords: diagnosis; heart failure; incidence rate; mortality; prevalence; real-world.

Figure 1

(A) Study timelines (analysis and look-back periods) for cohort 1 (national cohort) and cohort 2 (counties of Uppsala and Västerbotten) and (B) patient flow for cohort 1 (national cohort) and cohort 2 (counties of Uppsala and Västerbotten). Notes: ^aThe look-back for NPR data in cohort 2 extended from the same time points as for cohort 1 and ended on December 31, 2009; ^bLook-back period extended from January 1, 1997 for inpatient care and January 1, 2001 for outpatient care; ^cIncident HF patient population (prevalent HF population classified as those patients in whom HF was diagnosed during the look-back period and who survived into the analysis period). In cohort 1, data from 845,276 patients were extracted from the Swedish NPR on the basis of an observed HF diagnosis between 1997 and 2013, of which data for 174,537 patients met the inclusion criteria of at least two HF diagnoses in the analysis period (2005–2013) with no HF diagnosis in the look-back period (1997–2004). In cohort 2, data from 33,120 patients were extracted from the EMRs on the basis of an observed HF diagnosis between 1994 and 2015 (Uppsala County) and between 1992 and 2016 (Västerbotten County), of which data for 8,702 patients met the inclusion criteria of at least two HF diagnoses in the analysis period (2010–2015) and no HF diagnosis in the look-back period (NPR; 1997–2009, EMR; 1992–2009). The prevalent population (cohort 1, n=273,999; cohort 2, n=16,962) comprised those with a diagnosis of HF in the look-back period who were alive during the analysis period. The incident HF population comprised those with no HF diagnosis in the look-back periods. Abbreviations: EMR, electronic medical record; HF, heart failure; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction; NPR, National Patient Register.

Figure 2

Annual incidence per 1,000 inhabitants and prevalence of HF during 2010–2014 in Sweden (cohort 1) and in the counties of Uppsala and Västerbotten (cohort 2). Notes: (A) Total age-adjusted; and (B) crude incidence and prevalence by age group. Estimates are based on data from the NPR (cohorts 1 and 2) and from primary and secondary care EMRs (cohort 2) for the period 2010–2014. Age-adjusted incidence and prevalence calculated using population weights based on the Swedish population in 2015. ^aSecond HF diagnosis used as the index date. Abbreviations: EMRs, electronic medical records; HF, heart failure; NPr, National Patient Register.

Figure 3

Diagnostic work-up of patients in cohort 2 in the 6 months before and after the year of first HF diagnosis: (A) by index year and (B) according to setting of HF diagnosis. Note: ^aFirst HF diagnosis used as the index date. Abbreviations: Echo, echocardiography; HF, heart failure; NT-proBNP, N-terminal pro-B-type natriuretic peptide.

Figure 4

Trends in the most common causes of death for the prevalent HF population (cohort 1) between 2005 and 2013. Notes: The percentages are relative to the number of all-cause deaths. “n” represents the number of prevalent patients at each year. Trends were significant (P<0.0001, Cochran–Armitage test) for chronic IHD, MI, HF, AF, and flutter over time. Abbreviations: AF, atrial fibrillation; HF, heart failure; IHD, ischemic heart disease; MI, myocardial infarction; NSTEMI, non-ST-elevation myocardial infarction; STEMI, ST-elevation myocardial infarction.