Trends in mortality after first hospitalization with Atrial Fibrillation diagnosis in Sweden 1987 to 2006

Abstract

Background

To examine trends in 3-year mortality after a first hospitalization with diagnosed atrial fibrillation in a large cohort with and without important comorbidities.

Methods

The Swedish Hospital Discharge and Cause of Death Registries were linked to investigate trends in mortality for all patients 35 to 84 years hospitalized for the first time with a discharge diagnosis (principal or contributory) of atrial fibrillation in Sweden during 1987 to 2006. We performed an analysis of temporal trends in mortality stratified for presence or absence of co-morbidities affecting survival.

Results

Exactly 376,000 patients (56% male, mean age 72 years) with a first diagnosis of atrial fibrillation during 1987–2006 were identified and followed for 3 years. Patients with one or more of the prespecified comorbidities had the highest mortality and the largest absolute decline in mortality, but patients without these comorbidities had a slightly larger relative decline (absolute risk reduction in 3-year mortality (AAR) from 42.5 to 34.7%, Hazard Ratio (HR) 0.76; 95% confidence interval (95% CI) 0.74 to 0.77 versus ARR 16.2% to 11.7%, HR 0.71; 0.68 to 0.74. In patients aged below 65 years, with no comorbidities, there was minimal change in mortality, and they still had a 2 times increased mortality compared to the general population (SMR 1.95; 1.84 - 2.06).

Conclusions

Survival after a first hospitalization with a diagnosis of atrial fibrillation improved regardless comorbidities. Patients aged < 65 years old without diagnosed comorbidities still had a poor prognosis compared to the general population.

Introduction

Atrial fibrillation is the most common sustained arrhythmia and represents an increasing public health challenge with profound social and economic implications [1]. Recent studies have shown an increased incidence and prevalence in western Europe and the US [2], [3], [4], [5], [6], and the prevalence is expected to rise in the foreseeable future. Atrial fibrillation is associated with an increased risk of premature mortality. Despite an increased number of deaths associated with incident and prevalent atrial fibrillation the case-fatality has decreased during the 80s and 90s in Europe [2], [7], but not in the US [8], [9]. Atrial fibrillation is associated with comorbidities such as ischemic heart disease [10], chronic heart failure [11] and stroke [12], [13]. All these conditions adversely affect prognosis and have shown a general, albeit non-uniform, decline in mortality during the last 30 years [14], [15], [16], [17], [18]. Earlier studies have performed analyses adjusted for comorbidities and/or mortality rates in the general population or within the study cohort, but this approach gives little information regarding risks in different age groups and with different sets of comorbidities.

We examined the risk for all-cause mortality up to three years after a first atrial fibrillation diagnosis, with respect to trends over time and further, to which extent age, gender and co-morbidities were associated with prognosis. We utilized the Swedish hospital discharge registry together with cause-specific Death register.