title: Etiologic classification of TIA and minor stroke by A-S-C-O and causative classification system as compared to TOAST reduces the proportion of patients categorized as cause undetermined.
abstract: BACKGROUND
  The assortment of patients based on the underlying pathophysiology is central to preventing recurrent stroke after a transient ischemic attack and minor stroke (TIA-MS). The causative classification of stroke (CCS) and the A-S-C-O (A for atherosclerosis, S for small vessel disease, C for Cardiac source, O for other cause) classification schemes have recently been developed. These systems have not been specifically applied to the TIA-MS population. We hypothesized that both CCS and A-S-C-O would increase the proportion of patients with a definitive etiologic mechanism for TIA-MS as compared with TOAST.
  
  
  METHODS
  Patients were analyzed from the CATCH study. A single-stroke physician assigned all patients to an etiologic subtype using published algorithms for TOAST, CCS and ASCO. We compared the proportions in the various categories for each classification scheme and then the association with stroke progression or recurrence was assessed.
  
  
  RESULTS
  TOAST, CCS and A-S-C-O classification schemes were applied in 469 TIA-MS patients. When compared to TOAST both CCS (58.0 vs. 65.3%; p < 0.0001) and ASCO grade 1 or 2 (37.5 vs. 65.3%; p < 0.0001) assigned fewer patients as cause undetermined. CCS had increased assignment of cardioembolism (+3.8%, p = 0.0001) as compared with TOAST. ASCO grade 1 or 2 had increased assignment of cardioembolism (+8.5%, p < 0.0001), large artery atherosclerosis (+14.9%, p < 0.0001) and small artery occlusion (+4.3%, p < 0.0001) as compared with TOAST. Compared with CCS, using ASCO resulted in a 20.5% absolute reduction in patients assigned to the 'cause undetermined' category (p < 0.0001). Patients who had multiple high-risk etiologies either by CCS or ASCO classification or an ASCO undetermined classification had a higher chance of having a recurrent event.
  
  
  CONCLUSIONS
  Both CCS and ASCO schemes reduce the proportion of TIA and minor stroke patients classified as 'cause undetermined.' ASCO resulted in the fewest patients classified as cause undetermined. Stroke recurrence after TIA-MS is highest in patients with multiple high-risk etiologies or cryptogenic stroke classified by ASCO.
authors.affiliation: Department of Clinical Neurosciences, Radiology, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Jamsheed A
authors.initials: JA
authors.lastname: Desai
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Abuzinadah
authors.forename: Oje
authors.initials: O
authors.lastname: Imoukhuede
authors.forename: Manya L
authors.initials: ML
authors.lastname: Bernbaum
authors.forename: Jayesh
authors.initials: J
authors.lastname: Modi
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Shelagh B
authors.initials: SB
authors.lastname: Coutts
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000150:complications* / Q000175:diagnosis; D002545:Brain Ischemia / Q000150:complications* / Q000175:diagnosis; D002539:Cerebral Arterial Diseases / Q000150:complications* / Q000175:diagnosis; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012307:Risk Factors; D020521:Stroke / Q000209:etiology*