Economic Benefit of Increasing Utilization of Intravenous Tissue Plasminogen Activator for Acute Ischemic Stroke in the United States
To the Editor:
We read with interest the sensitivity analysis on the US economic benefit possible from increasing utilization of tissue plasminogen activator in acute stroke by Demaerschalk et al.1
While there are several issues of concern affecting its validity, we believe their analysis seriously under-represented the present dollar value of the savings by using a reference value of (−)$600 per patient from 1996. After adjusting for the annual effect of inflation using US Bureau of Labor Statistics Consumer Price Index data, the actual per treated patient savings is 24% greater, or (−)$745 per patient, in 2005. Using this figure, the best estimate of cost savings in the first year poststroke ranges from 9 to >90 million dollars, with similar changes in the 95% CI limits, depending on the proportion of patients receiving tissue plasminogen activator (see Table below for cost savings per treatment %).
Demaerschalk BM, Yip TR. Economic benefit of increasing utilization of intraveneous tissue plasminogen activator for acute ischemic stroke in the United States. Stroke. 2005; 36: 2500–2503.
Drs Scott and Silbergleit are correct that our estimates of economic benefit of increasing utilization of intravenous tissue plasminogen activator (tPA) for acute stroke in the US1 do not reflect current day savings because our reference values came from 1996 cost data published in 1998.2 Unfortunately, this remains the most current US cost-effectiveness study available for tPA in stroke.
By using the US Department of Labor Bureau of Labor Statistics Consumer Price Index (CPI) inflation calculator (www.bls.gov) to adjust for inflation (reference year 1996 and recent year 2005), the net cost after the first year post-tPA treatment estimate increases to −$756 (95% CI −$4384 to $2524) of savings per treated patient.3 As you have pointed out, this change would result in $9 314 000 best estimate of cost savings for every additional 2% of ischemic stroke patients who are thrombolysed nationwide (see the Table below). Regardless, the inflation-based revised estimates, to which you refer, remain well within the published 95% CI.
Unfortunately, this inflation-based correction does not overcome the fact that the 1998 cost-effectiveness study is becoming outdated. The values corrected to the annual general inflation rates assume that the healthcare costs associated with thrombolysis for stroke have inflated at the same rate. A more accurate estimate could be derived from gathering updated cost data associated with the care of acute stroke patients receiving tPA in 2005 to 2006.
Although we agree that the anticipated cost savings is probably closer to $9 million, not $7 million, per additional 2% increase in the national proportion of thrombolysed patients, the main message remains the same: using tPA for stroke results in a net cost savings to our healthcare system. This combined with the clearly favorable health outcomes among tPA-treated patients supports the continuing efforts to treat a higher proportion of stroke patients with this drug.
Demaerschalk BM, Yip TR. Economic benefit of increasing utilization of intravenous plasminogen activator for acute ischemic stroke in the united states. Stroke. 2005; 36: 2500–2503.
Fagan SC, Morgenstern LB, Petita A, Ward RE, Tilley BC, Marler JR, Levine SR, Broderick JP, Kwiatkowski TG, Frankel M, Brott TG, Walker MD. Cost-effectiveness of tissue plasminogen activator for acute ischemic stroke. NINDS rt-PA stroke study group. Neurology. 1998; 50: 883–890.
Price Index (CPI) inflation calculator. US Department of Labor Bureau of Labor Statistics website. Available at: www.bls.gov. Accessed January 4, 2006.