Engel-Nitz et al The burden of stroke is often measured in terms of the incidence rates of first stroke, but the prevalence of total stroke (ie, first stroke plus recurrent stroke) more accurately reflects the true burden.7,8 Nearly 30% of all strokes are recurrent events, and the risk is highest in the period immediately following a stroke.9 It has been estimated that within 1 year after the first stroke, the risk of recurrence is 15 times the risk of stroke in the general population.10 Of those who have had first stroke, the percentages of men and women aged 40–69 years with a recurrent stroke in 5 years are 13% and 22%, respectively. At the age of 70 years, the risk of recurrent stroke is 23% in men and 28% in women.6 This sug- gests that prevention of stroke recurrence must be a primary goal of acute and long-term management of stroke.11 Recurrent strokes tend to inflict greater neurological impairment and more severe disability than the first stroke, and patients with recurrent strokes tend to have poorer health and economic outcomes than those with first strokes.7,9,12 In a Medicare claims-based analysis conducted by Samsa et al7 survival from first stroke (56.7% at 24 months) was consistently better than that for recurrent stroke (48.3% at 24 months). In addition, patients with recurrent stroke had significantly higher health care costs following their stroke compared with patients with first stroke. Although the literature provides some evidence of the incremental costs and adverse clinical outcomes associated with recurrent stroke in a Medicare patient population, the extent to which the findings apply to a younger, commercially insured population has not been fully explored. This claims- based retrospective analysis was designed to evaluate clinical outcomes and costs associated with noncardioembolic ischemic stroke compared with the general managed care population. Furthermore, the study explored the relative impact of new versus recurrent stroke. Methods Data source This was a retrospective administrative claims data study using eligibility, medical, and pharmacy claims data from a large US managed care plan affiliated with i3 Innovus. The individuals covered by this health plan were geographically diverse across the United States, with enrollees in all four US Census regions. The plan provides fully insured coverage for physician, hospital, and prescription drug services. The data are linked longitudinally using an encrypted patient ID. The database contained enrollment and claims data for 10.7 million commercial health plan enrollees during the identif ication period of January 1, 2002, through 906 submit your manuscript | www.dovepress.com Dovepress Dovepress December 31, 2003. Claims data for the assessment of patient characteristics and outcomes among those identified and retained for analysis ranged from January 1, 2001, through December 31, 2005. sample selection Patients were selected for the ischemic stroke cohort if they were aged at least 18 years, were hospitalized for ischemic stroke during the 2-year identification period, and had no diag- nostic evidence during the identification period of atrial fibril- lation (AF) or mitral valve abnormalities (ICD-9-CM codes 427.31, 746.5, 396.0, 396.1, 394.2, 394.0, 424.0, 391.1, 392.0, 398.90, 398.99). Inpatient hospital claims were examined for evidence of stroke based on a qualifying diagnosis code (ICD- 9-CM codes 362.31–362.34, 430.xx–432.xx, 433.x1, 434.x1, 436.xx, and 438.xx) in the primary diagnosis position on a claim.7 Patients were included in the stroke cohort if they had a diagnosis for ischemic stroke; patients without ischemic stroke either during the index hospitalization or during the pre-index period were excluded. Patients were categorized as new ischemic stroke patients if the hospitalization was for ischemic stroke and there was no evidence of any prior stroke during the pre-index period. Patients were categorized as recurrent stroke patients if there was evidence of ischemic stroke in the 12-month period prior to the index stroke hos- pitalization (pre-index period). Qualifying stroke patients were required to be continuously enrolled in the health plan with medical and pharmacy benefits for 12 months prior to the admission date for the index hospitalization. Variable follow-up observation was permitted until the earliest of death (identified from discharge hospital claims), 48 months of observation, or December 31, 2005. A general population of adult control subjects with at least 1 month of enrollment during the identification period was randomly selected from the database. An index date was set based on the first service date on a medical claim during the patient identification period. Potential controls were retained if they met the 12-month pre-index continuous enrollment requirement and had no evidence of stroke, transient ischemic attack (TIA), AF, or mitral valve abnormalities during the pre- index period. The non stroke control population was matched 3:1 to stroke patients on age, sex, and geographic region. Outcome variables Outcomes were measured in the claims data during the variable follow-up period from the day following discharge among stroke patients or control patients with an index hospitalization, or from the index date among control patients Vascular Health and Risk Management 2010:6