Predictive values of referrals for transient ischaemic attack from first-contact health care: a systematic review

Rebecca Kandiyali, Daniel S Lasserson, Penny Whiting, Alison Richards, Jonathan Mant

Over 150 000 cases of suspected transient ischaemic attack (TIA) are referred to outpatient clinics in England each year. The majority of referrals are made by GPs. This study aimed to identify how many patients referred to a TIA clinic actually have TIA (that is, calculate the positive predictive value [PPV] of first-contact healthcare referral) and to record the alternative diagnoses in patients without TIA, in order to determine the optimal service model for patients with suspected TIA. A systematic review of TIA clinic referrals from first-contact health professionals (GPs and emergency department [ED] doctors) was undertaken. Four databases were searched using terms for TIA and diagnostic accuracy. Data on the number of patients referred to a TIA clinic who actually had a TIA (PPVs) were extracted. Frequencies of differential diagnoses were recorded, where reported. Study quality was assessed using the QUADAS-2 tool. Nineteen studies were included and reported sufficient information on referrals from GPs and ED doctors to derive PPVs (n = 15 935 referrals). PPVs for TIA ranged from 12.9% to 72.5%. A formal meta-analysis was not conducted due to heterogeneity across studies. Of those not diagnosed with TIA, approximately half of the final diagnoses were of neurological or cardiovascular conditions. This study highlights the variation in prevalence of true vascular events in patients referred to TIA clinics. For patients without a cerebrovascular diagnosis, the high prevalence of conditions that also require specialist investigations and management are an additional burden on a care pathway that is primarily designed to prevent recurrent stroke. Service commissioners need to assess whether the existing outpatient provision is optimal for people with pathologies other than cerebrovascular disease.