Discussion
In this comprehensive analysis of prevalent and incident AF targets
obtained from medical and pharmacy claim databases based on a large US
adult population, we show that continued reliance only on outpatient and
inpatient claims alone greatly underestimates AF prevalence and
incidence in the general population by over 100%. Second, we show the
comorbidity profile in our AF patients, with the prevalence of
multimorbidity being approx. 10-12% in those aged ≥65 years. Again,
reliance only on outpatient and inpatient claims alone greatly
underestimates multimorbidity in the AF population. Our proposed
methodology can guide future analysis of the quality/cost of care for
progressive medical conditions at the population level.
Our findings differ from the United States CDC(8) that found
approximately 2% of people age < 65 years have AF, while
about 9% of people age ≥ 65 years have AF. Instead, our results
indicate that the working population aged < 65 years has a
0.9% prevalence and the Medicare population aged ≥65 had a 12.7%
prevalence. The difference could possibly be attributed to computation
methodologies and different time spans used (i.e., 2009-2014 for the CDC
estimates and the 2016-2019 period in the current study). Piccini et
al(2) reported a 7.3% prevalence in a study conducted on a 5% random
sample of the Medicare population in the US, relying on the use of 2
outpatient visits or 1 inpatient visit within a 365 day period. The
prevalence reported by Piccini et al(2) for 2007 is still lower
than the overall 12.7% value reported in the present study. There was
an increase in prevalence with the analyzed period (3.7%, 5.7%, 6.8%,
and 7.3%, respectively for 1993, 1998, 2003 and 2007). In elderly
Germans, Ohlmeier et al(9) reported an increased prevalence with the
analysis period 7.7%, 9.4%, 9.8%, and 10.3%, respectively for the
years of 2004 to 2007.
Our results emphasize the impact of joining pharmacy and medical claims
in the calculation of AF prevalence and incidence rates. Using both
types of databases, the overall prevalence rate was 2.2%, being 2.5%
and 1.9%, respectively for males and females; the overall incidence
rate was 3.3 per 1000 person-years (3.6 and 2.9 per 1000 person-years,
respectively for males and females). Our overall AF prevalence was close
to the 2.4% reported by Tu et al(4) in Canada using a similar approach,
and the 2% and 2.13% prevalence reported for Europe(10) and
Germany(11), respectively. It should be noted that the methodologies by
Tu et al(4) is similar to that used in this study with the exceptions
that the claim system in Canada is somewhat different from that used in
the US. Indeed, our incidence rates were lower than those obtained in
Germany(11) for the general population (males – 4.4 cases/1000
person-years; females – 3.9 cases/1000 person-years).
Although OAC use and office visits captured the highest number of
targets in the identified AF population, they cannot be used as a proxy
for identifying the prevalence and incidence of AF cases in the general
population. OACs accounted for about half of AF prevalent cases,
indicating that about 50% of the remaining population are not on
anticoagulants, in line with prior studies (4)(12)(13). Office visits
explained 55% and 43%, respectively of the AF prevalent and incident
cases, with the remainder of AF population not making office visits.
Although males have higher AF prevalence than females, the present study
suggest that older (65 years or older) females (normalized relative to
younger population aged less than 65 years) have a 50% higher
prevalence ratio than older males (normalized to relative to younger
population less than 65 years). This is in line with the incidence rates
obtained in the Medicare population for males and females (12.3 and 18.2
per 1000 person-years, respectively). Additionally, there is an increase
in prevalence with age for the Medicare population from 65-74 to 75-84
to > 85 years.
Hospital admissions accounted for 4% or less of AF prevalent/incident
targets. Furthermore, ER visits captured 14% or less of AF
prevalent/incident cases. In a systematic review of validated methods
for identifying AF using administrative data, Jensen et al(5) found that
10 of 16 studies used only inpatient data. Office observations captured
8.6% of prevalent AF targets in the Medicare population and 5.3% in
the working population or Commercial plan. A similar trend was found for
incident AF targets (11.3% and 9.4%, respectively in Medicare and
Commercial cohorts). Thus, one cannot rely on ER visits, office
observation and hospital admissions as the only sources to establish AF
prevalence and incidence targets. There was an even smaller percentage
of AF cases identified based on rhythm control (14%), in line with Tu
et al(4) and LaPointe et al10. The latter study found
among AF patients younger than 65 years that 16% received rhythm
control medication and 84% had rate control drugs.
The practical implications of our analysis are worth highlighting. The
number of prevalent/incident AF targets doubles when one integrates the
use of medical and pharmacy claim databases in comparison to the
utilization of outpatient and inpatient healthcare services from medical
claim databases. We also show that the multimorbidity is common amongst
AF patients (affecting approximately 1 in 10 patients), which puts such
patients at risk of cardiovascular and non-cardiovascular mortality and
morbidity (14). In particular, for incident AF cases, about 40% of the
older population and 30% of the overall population have 4 or more
co-morbidities; for prevalent cases, these proportions are 30% and
20%, respectively (fig 2 e and f). Collectively, these results
empathize that AF cohorts are at an increased risk of complications such
as stroke and bleeding events; hence, there has been an increasing move
towards a more holistic or integrated approach to AF management(15).
Indeed, integrated care management of AF patients is associated with
improved clinical outcomes(16-18).