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(Stroke. 2008;39:924.)
© 2008 American Heart Association, Inc.

Original Contributions

National US Estimates of Recombinant Tissue Plasminogen Activator Use

ICD-9 Codes Substantially Underestimate

Dawn Kleindorfer, MD; Christopher J. Lindsell, PhD; Lawrence Brass, MD; Walter Koroshetz, MD Joseph P. Broderick, MD

From the University of Cincinnati College of Medicine (D.K., C.J.L., J.P.B.), Ohio; Yale University (L.B.), New Haven, Conn; and the National Institute of Neurological Disorders and Stroke (W.K.), Bethesda, Md.

Correspondence to Dawn Kleindorfer, MD, University of Cincinnati, Department of Neurology, 231 Albert Sabin Way ML 0525, Cincinnati, Ohio 45267-0525. E-mail dawn.kleindorfer{at}uc.edu

Background and Purpose— Current US estimates of recombinant tissue plasminogen activator (rt-PA) use have been based either on extrapolation of regional studies or on administrative database estimates, both of which may have inherent biases. We sought to compare the utilization of rt-PA in acute ischemic stroke in the MEDPAR database to another national hospital database with drug utilization information.

Methods— Cases were defined as DRG 14,15, and 524 and ICD-9 code 99.1, which indicates cerebral thrombolysis, for fiscal year 2001 to 2004. Additionally, the Premier database was queried for rt-PA utilization documented in pharmacy records in those patients admitted for stroke. Change over time and difference between databases were tested using Poisson regression.

Results— When comparing databases, rt-PA use, as identified by ICD-9 code 99.1, was only documented in 0.95% of stroke cases in 2004 in MEDPAR, and 1.2% in the Premier database, which slightly increased by 0.04% to 0.09% over time. Analysis of pharmacy billing records increased the estimate to 1.82%. Exclusion of cases younger than 65years excluded 43% of cases treated with rt-PA. In 2004, 12.7% of cases receiving thrombolytic had either a TIA or a hemorrhagic stroke ICD-9 code.

Conclusions— We estimate the rate of rt-PA use in the United States to be 1.8% to 2.1% of ischemic stroke patients. The rate of thrombolytic use for ischemic stroke was slightly increasing between 2001 and 2004 at a rate of 0.04% to 0.09% per year. A significant proportion of patients treated with rt-PA are likely miscoded as either TIA or hemorrhagic stroke. We conservatively estimate that 10 800 to 12 600 patients received rt-PA in 2004.

Key Words: acute stroke treatment • epidemiology • tPA