Of the 1,005 patients initially enrolled in the registry, 973 completed at least 3 months of follow-up and were included in the present analysis. Only 34 (3.5%) of these patients were accepted as having permanent AF at the time of enrollment (two after failing cardioversion). In the remaining patients, the initial episode of AF terminated spontaneously (n = 503, 51.7%), or was managed with electrical cardiover-sion (n = 436, 44.8%). Following the initial episode of AF, 472 (48.5%) patients were treated with antiarrhythmic drugs. During follow-up, a total of 31 additional patients progressed to permanent AF. No registry patients were treated with pulmonary vein isolation or surgical MAZE procedures during the follow-up period.
Over a mean follow-up of 23.8 ± 9.0 months, 319 patients (32.8%) had one or more documented episodes of recurrent AF. The baseline characteristics of the study population, grouped according to the number of recurrences observed during follow-up, are shown in . Patients in whom the first episode of AF became permanent were older, more often female, and had a higher prevalence of heart failure and valvular disease than patients in the other groups.
Selected Baseline Characteristics of the Study Population (n = 973), Categorized by Initial AF Pattern and Number of Documented Recurrences During Follow-Up
During follow-up, 259 patients were hospitalized a total of 395 times for reasons related to cardiovascular disease, AF, or AF treatment (range 1–9 admissions). The majority of these admissions were for arrhythmia, heart failure, or chest pain/acute coronary syndromes (). Mean length of stay for these admissions was 4.4 ± 7.2 days (median three days), with mean hospital costs of $9,358 ± 9,670 per admission (median $6,258).
Figure 1 Pie chart depicting the distribution of principal diagnoses for 395 hospital admissions related to cardiovascular disease, AF, AF therapy, or complications thereof in the 259 patients who had one or more admissions following enrollment. Categories move (more ...)
Mean levels of resource utilization during follow-up, stratified according to the frequency of AF recurrence, are detailed in . For almost every category examined, resource use increased steadily across categories, with highly statistically significant results for tests of linear trend, adjusting for follow-up duration.
Resource Utilization by Group Over the Entire Follow-Up Period
For the FRACTAL population as a whole, mean annual healthcare costs totaled $4,738 ± $7,495 (median $2,589), 47% of which came from hospital care, 35% for prescription drugs (including INR monitoring), and the remainder for outpatient services. displays the differences in annual costs by category, according to the total number of documented AF recurrences during follow-up.
Figure 2 Mean annual healthcare costs according to the frequency of AF recurrence observed during follow-up. Black rectangles represent prescription drug costs, gray rectangles indicate outpatient costs, and white rectangles indicate hospital costs. P < (more ...)
The results of our multivariable regression analysis on the outcome of total annual costs are shown in . Several cardiac and noncardiac baseline conditions were strongly associated with annual healthcare costs. After adjusting for these, each recurrence of AF, on average, was found to increase annual costs by ~$1,600.
Multivariable Linear Regression on Annualized Total Costs
We performed a sensitivity analysis by decreasing each of the price weights used in our cost calculations by 25%. This reduced average annual costs in each group, as well as the regression-based estimate of the impact of a single AF recurrence by ≈25%, but none of the statistical tests reported above or shown in the tables and figures lost significance. Analogously, increasing the price weights by an equal amount increases average costs in each group in a proportional manner, making the differences between groups larger.