Prognosis of transient ischemic attacks and minor stroke in an Australian community-based population: a greater role for GP management?

Problem

Transient ischemic attacks and minor strokes (TIAMS) are common and entail risk of subsequent stroke. Rapid secondary prevention implementation is vital, and most guidelines recommend urgent referral to secondary care. There has been a substantial improvement in prognosis of TIAMS managed in secondary care, coincident with the institution of rapid access pathways following the landmark 2007 EXPRESS and SOS-TIA trials. The overall prognosis for TIAMS in contemporary practice, managed across the spectrum of primary and secondary care, is less certain.We aimed to establish recurrent stroke incidence in all patients of 16 general practices, in the Newcastle-Hunter Valley-Manning Valley region of Australia, who experienced a TIAMS.

Approach

We conducted an inception cohort study. Multiple overlapping ascertainment methods (the general practices; after-hours GP co-operative; hospitals EDs, outpatient clinics, and inpatient records) identified participating practice’s patients with possible TIAMS.Data collection (August 2012-July 2017) was via extraction from participant’s clinical notes from all above sources and from interviews at baseline, three- and 12-months. Adjudication of participant index events (and subsequent events) as TIA, minor stroke, stroke, or TIAMS-mimic was by a three-member panel of senior GPs/stroke physicians.The incidence of subsequent stroke in the TIAMS and TIAMS-mimic groups was calculated. Time to subsequent event was assessed with Kaplan Meier Curves.

Findings

Of 613 participants (response rate 49%), 298 (49%) were adjudicated to have had a TIAMS (175 TIA, 123 minor stroke). Of all TIAMS, 26% were managed entirely by a GP, 55% were either referred to ED by a GP or presented to ED. Of all TIAMS, 9 (3.0%) had a subsequent stroke during 12-months follow-up. The median time to stroke was 34 days. The Kaplan Meier Time to First Recurrent Stroke following a TIAMS index event did not display the prominent early recurrence (‘front-loaded risk’) of initial epidemiological studies.Of 315 mimics, 2 (0.6%) had a subsequent stroke.These findings are of considerably lower incidence of recurrent stroke than in historical TIA cohorts and also lower incidence than in more recent (post-EXPRESS/SOS-TIA) secondary care cohorts.Possible explanations for this low recurrent stroke incidence may include the spectrum of TIAMS severity in this community-based study being less than that in previous studies of patients reaching secondary care. It may also reflect translation to practice, including primary care practice, of the need for urgent secondary prevention suggested by the findings of EXPRESS/SOS-TIA and subsequent studies.

Consequences

The findings have implications for health care systems in areas where prompt access to secondary care for TIAMS is difficult or not practicable. TIAMS prognosis may still generally be good in these settings and emphasis may be best directed at referral of highest risk patients or of difficult diagnostic scenarios.