Frequency and Determinants of Intracranial Atherosclerotic Stroke in Urban Pakistan

Abstract

Intracranial atherosclerosis (ICAD) is a frequent underlying mechanism of ischemic stroke. There is little direct evidence on its frequency and determinants from regions of high prevalence. This study explores the conventional and socioeconomic risk factors of ICAD in a South Asian population. The Karachi Intracranial Stenosis Study is a case-control study of 313 cases of ischemic stroke secondary to ICAD and 331 controls enrolled from 4 major hospitals in Karachi, Pakistan. Stroke subtype was verified by a vascular neurologist using the Trial of Org 10172 in Acute Stroke Treatment classification. Relationships of conventional and socioeconomic risk factors with ICAD-related strokes are reported by calculating odds ratios (ORs) and their 95% confidence intervals (CIs). ICAD was the cause of stroke in 81.1% cases with large-artery atherosclerosis and 19.5% of all stroke events. Along with risk factors like history of hypertension (OR, 3.33; CI, 2.31-4.78), history of diabetes (OR, 2.29; CI, 1.56-3.35), use of tobacco (OR, 1.49; CI, 1.03-2.16), waist-to-hip ratio (OR, 1.58; CI, 1.04-2.41), and family history of stroke (OR, 1.89; CI, 1.21-2.95), other significant social determinants of ICAD strokes were monthly income (OR, 1.59; CI, 1.01-2.51), unemployment (OR, 2.15; CI, 1.21-3.83), and chronic stress (OR, 3.67; CI, 2.13-6.34). These social determinants were independent predictors of the risk of ICAD, in addition to those described in other world populations. ICAD accounted for one fifth of all strokes making it the most common ischemic stroke mechanism. In addition to aggressive risk factor control, data also indicated broader holistic efforts on ameliorating inequity, unemployment, and stress reduction to reduce stroke because of ICAD.