A population-based study of transient ischemic attack incidence in Novosibirsk, Russia, 1987-1988 and 1996-1997.

BACKGROUND AND PURPOSE Population-based data on transient ischemic attack (TIA) incidence are scarce. This study defines incidence rates of first-ever TIA in Novosibirsk, Russia, during 1987-1997 and compares the incidence of first TIA with that of first stroke. METHODS This is a prospective registry population-based study of all new cases of TIA and stroke in an overall population of 455 765 residents of Novosibirsk. All new TIA and stroke incident cases (whether inpatient or outpatient) that occurred during 1987-1988 and 1996-1997 study periods were recorded and analyzed. A 95% CI was estimated for all age- and sex-specific strata. RESULTS During the 2 study periods, a total of 211 patients with first TIA were registered in the population studied. The crude annual TIA incidence rate per 100 000 residents was 16 (95% CI, 8 to 33) in 1987-1988 and 29 (95% CI, 9 to 87) in 1996-1997; these rates standardized to the European population were 17 (95% CI, 8 to 34) and 27 (95% CI, 9 to 79), respectively. Eighty-three percent of TIAs occurred in the carotid arteries (rate, 48/100 000), 10% occurred in the vertebrobasilar territory (rate, 6/100 000), and 7% of cases had a TIA of uncertain distribution (rate, 2/100 000). CONCLUSIONS Unlike stroke incidence rate, the incidence rate of TIA in Novosibirsk is similar to that in other populations and constitutes approximately 10% of stroke incidence. For the last decade (1987-1997), there was a tendency, although statistically insignificant, toward increasing incidence rate of TIA in the population studied.