Years of disability-adjusted life gained as a result of thrombolytic therapy for acute ischemic stroke.
OBJECTIVE
Disability-adjusted life year (DALY) metric reflects years of healthy life lost because of living with disability and years of life lost because of premature mortality. Widely used in epidemiological analyses, DALY has not been applied to acute stroke trials.


METHODS
From previous studies, we derived, for each modified Rankin Scale level, disability weights, disability-linked mortality hazard ratios, and age-specific life expectancies. We then analyzed patient level data from the 2 publicly available National Institute of Neurological Disorders and Stroke (NINDS) recombinant tissue plasminogen activator trials. For each subject, we abstracted age, treatment assignment, and 3-month modified Rankin Scale outcome and calculated the DALYs lost resulting from the qualifying stroke.


RESULTS
The disability-linked hazard ratios for premature annual mortality for a modified Rankin Scale score of 0 to 5 were 1.53, 1.52, 2.17, 3.18, 4.55, and 6.55, respectively. In the NINDS recombinant tissue plasminogen activator trials, DALYs (mean+/-SE) lost as a result of the qualifying stroke were substantially less with recombinant tissue plasminogen activator than with placebo (4.64+/-0.17 versus 5.91+/-0.21; P<0.0001), a finding that remained robust after adjustment for baseline prognostic factors. When DALYs gained were apportioned to the 29% of patients experiencing any benefit from lytic therapy, each patient gained an average of 4.4 DALYs. DALY analysis showed greater power than dichotomized modified Rankin Scale analysis in discriminating treatment effects overall and in patients >or=70 years of age.


CONCLUSIONS
For patients who benefit from treatment, <3-hour thrombolytic therapy adds the equivalent of 4.4 years of healthy life, free of disability. The DALY metric provides a continuous scale that increases statistical power, is intuitively understandable, and is applicable to a wide range of conditions and treatments.
Hong
Keun-Sik
KS
Department of Neurology, Clinical Research Center, Ilsan Paik Hospital, Inje University, Goyang, Korea.
Saver
Jeffrey L
JL
D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications / Q000188:drug therapy* / Q000401:mortality; D015331:Cohort Studies; D006233:Persons with Disabilities; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055825:National Institute of Neurological Disorders and Stroke (U.S.); D019057:Quality-Adjusted Life Years; D020521:Stroke / Q000150:complications / Q000188:drug therapy* / Q000401:mortality; D015912:Thrombolytic Therapy / Q000639:trends*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D016896:Treatment Outcome; D014481:United States
D010959:Tissue Plasminogen Activator