Cardiac Device Implantation in the United States from 1997
through 2004: A Population-based Analysis
Chunliu Zhan, MD, PhD1, William B. Baine, MD1, Artyom Sedrakyan, MD, PhD1, and Claudia
Steiner, MPH, MD2
1Center for Outcomes and Evidence, Agency for Healthcare Research and Quality, Rockville, MD, USA;2Center for Delivery, Organization,
and Markets, Agency for Healthcare Research and Quality, Rockville, MD, USA.
OBJECTIVE: Use of cardiac devices has been increasing
rapidly along with concerns over their safety and
effectiveness. This study used hospital administrative
data to assess cardiac device implantations in the
United States, selected perioperative outcomes, and
associated patient and hospital characteristics.
METHODS: We screened hospital discharge abstracts
from the 1997–2004 Healthcare Cost and Utilization
Project Nationwide Inpatient Samples. Patients who
underwent implantation of pacemaker (PM), automatic
cardioverter/defibrillator (AICD), or cardiac resynchroni-
zation therapy pacemaker (CRT-P) or defibrillator (CRT-D)
were identified using ICD-9-CM procedure codes. Out-
comes ascertainable from these data and associated
hospital and patient characteristics were analyzed.
MEASUREMENTS AND MAIN RESULTS: Approximate-
ly 67,000 AICDs and 178,000 PMs were implanted in
2004 in the United States, increasing 60% and 19%,
respectively, since 1997. After FDA approval in 2001,
CRT-D and CRT-P reached 33,000 and 7,000 units per
year in the United States in 2004. About 70% of the
patients were aged 65 years or older, and more than
75% of the patients had 1 or more comorbid diseases.
There were substantial decreases in length of stay, but
marked increases in charges, for example, the length of
stay of AICD implantations halved (from 9.9 days in
1997 to 5.2 days in 2004), whereas charges nearly
doubled (from $66,000 in 1997 to $117,000 in 2004).
Rates of in-hospital mortality and complications fluctu-
ated slightly during the period. Overall, adverse out-
comes were associated with advanced age, comorbid
conditions, and emergency admissions, and there was
no consistent volume–outcome relationship across dif-
ferent outcome measures and patient groups.
CONCLUSIONS: The numbers of cardiac device implan-
tations in the United States steadily increased from
1997 to 2004, with substantial reductions in length of
stay and increases in charges. Rates of in-hospital
mortality and complications changed slightly over the
years and were associated primarily with patient frailty.
KEY WORDS: pacemaker; implantable cardioverter-defibrillator; cardiac
resynchronization therapy; administrative data; ICD-9-CM.
J Gen Intern Med 23(Suppl 1):13–9
© Society of General Internal Medicine 2007
therapy systems (CRTs) are medical devices that regulate
cardiac rate and rhythm and coordinate myocardial contrac-
tion.1Overall, these cardiac devices have been shown to
improve symptoms, quality of life, and survival,2,3fueling
increasing enthusiasm for their use.4–8The increased use,
along with concerns about safety and effectiveness of the
devices and the financial incentives associated with their use,
has increased the need for data to track utilization and
Multiple sources of data on cardiac devices exist. First,
clinical trials are continually being conducted to study new
indications and technologies.3,9–13Second, reports of case
series and retrospective reviews of medical records at local
institutions offer lessons learned from practice about operative
procedures and prevention of complications.14–18Third, device
registries have been established to collect information on
devices, operators, and implantation techniques, as well as
on some aspects of outcomes.19For example, the Center for
Medicare & Medicaid Services (CMS) established an AICD
registry in January 2005 and required hospitals to submit
data on every implantation for Medicare payment.20,21Fourth,
the Food and Drug Administration (FDA), through MedSun
and other reporting mechanisms, collects data from operators
and manufacturers on device flaws, malfunctions, and ad-
verse events, and issues advisories and recalls.22–26Fifth,
surveys of operators and manufacturers have been conducted
to monitor use in the Unites States4,5,27and worldwide.28
Lastly, administrative data or hospital claims data have been
used to track utilization in broad patient populations.6,7
Each of these data sources has advantages and weakness.
Clinical trials provide robust data on efficacy, but are limited
by their choice of patients and clinical settings. Case reports
and retrospective reviews are rooted in real experience, but are
limited in generalizability and by the size of observation sets.
Registries usually have narrow focuses, such as on device
flaws and malfunction. FDA voluntary reports are limited to
what is voluntarily reported. Although lacking in clinical
details and susceptible to coding errors, administrative data
have several advantages over other data sources: primarily
large size and nationwide coverage.29Administrative data-
based analysis is a convenient and efficient method when
properly approached and can provide valuable information to
supplement surveys, registries, case series, and clinical trials
to study utilization, patient and hospital characteristics,
patient outcomes, and associated factors.
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