Risk of ischaemic stroke in patients with transient global amnesia: a propensity-matched cohort study

Abstract

BackgroundThe exact pathophysiological mechanism of transient global amnesia (TGA) is unknown. It is debatable whether TGA is a risk factor for stroke. Therefore, here we investigated the possibility of TGA as a risk factor for stroke in a real-world setting using large-scale nationwide health claims data.MethodsWe used health claims data from the Korean National Health Insurance Service (NHIS). Patients diagnosed with TGA between 2007 and 2013 were selected. We initially extracted patients without TGA who were preferentially matched for age and sex with the patients with TGA at a ratio of 10:1 from the whole dataset. Further, we performed 1:2 propensity score matching analysis to balance the baseline characteristics between the two groups. In the propensity score-matched dataset, we performed multivariable Cox regression analysis to investigate the association between TGA and stroke type, including ischaemic, haemorrhagic and all stroke types.ResultsPatients with TGA (n=14 673) were selected from the NHIS database. After extracting from the whole database (n=140 486) and propensity score matching their data at a 1:2 ratio, a total of 10 448 and 20 442 patients were finally assigned to the TGA and control groups, respectively. The multivariable Cox regression analysis demonstrated that the TGA group had a higher risk of ischaemic stroke and all types of stroke (adjusted HR=1.194; 95% CI: 1.043 to 1.368; and HR=1.197; 95% CI: 1.056 to 1.357, respectively).ConclusionsAnalysis of the nationwide claims database showed that TGA could be an important risk factor for stroke, especially for ischaemic stroke.

Transient global amnesia and stroke: not that benign?

“… 15 Therefore, a look at the underlying population might help us in putting the findings into context. First, the overall distribution of cardiovascular risk factors in the population differed, with hypertension, hyperlipidaemia and atrial fibrillation being more frequent in the American population 14 compared with the South Korean one, 6 in line with recent global estimates. 16 17 Second, the control cohort selected with matching had specific features.…”

“…In this study, patients with TGA were selected from a database with internally tested coding accuracy, and propensity score matching also involved cardiovascular risk factors, psychiatric disorders, migraine and epilepsy, reinforcing the genuine nature of the trends identified. 6 At the same time, the findings critically diverge from those of a similar investigation applying propensity score-matching on the Nationwide Readmission Database. 14 In this American cohort, 21 202 TGA cases were matched with 21 293 controls, and no difference in the risk of stroke was found.…”

“…In the American study, controls derived from inpatient setting and, compared with TGA, had a marginally higher Charlson comorbidity index 14 that correlates to the risk of stroke. 18 On the other side, the Korean study had prevalent female composition, and the increase in risk of stroke among TGA emerged over a consistently longer follow-up (up to 11 years 6 ) compared with that of the American report (1 year). 14 May people with TGA have a marginally higher risk of stroke, detectable only over a very long-term period?…”

“…In this volume of Stroke and Vascular Neurology, Lee and colleagues add a further episode to the saga, building on data from a large propensity-matched cohort study. 6 Using records from the Korean National Health Insurance Service, they selected 10 447 patients with TGA and 20 493 controls through greedy nearest neighbour method, following both cohorts for up to 11 years to assess the occurrence of stroke. After adjusting for enrolment year—a strategy to mitigate differences in follow-up duration—TGA was associated with a higher risk of stroke compared with control population.…”

“…Hypertension, diabetes and atrial fibrillation substantially increased the risk of stroke among TGA cohort, suggesting potential preventive measures to be implemented under specific circumstances. 6 …”