Atherogenic index of plasma in stroke: A comprehensive review of its diagnostic, prognostic, and pathophysiological significance

The atherogenic index of plasma (AIP), defined as log [triglycerides (TG)/high-density lipoprotein cholesterol], an emerging lipid-based biomarker reflecting circulating TG and high-density lipoprotein cholesterol levels, has been associated with metabolic syndrome, coronary heart disease, and atherosclerosis. Its role in cardiovascular disease has been well established, yet there is growing interest in its application in cerebrovascular conditions, particularly stroke. Stroke is one of the leading causes of death and disability worldwide; hence, there is a need for integrative biomarkers to help improve risk prediction and accuracy of prognostication. Recent studies suggest that elevated AIP is independently associated with stroke incidence, especially among individuals with diabetes, prediabetes, and metabolic syndrome. Higher AIP levels have been associated with worse stroke severity at presentation, a higher risk of early neurological deterioration, and worse short-term outcomes. This is likely a consequence of AIP indicating vascular inflammation, endothelial dysfunction, and intracranial atherosclerosis. In observational studies, AIP has demonstrated comparable or stronger associations than other markers of insulin resistance, such as the TG-glucose index and the Chinese Visceral Adiposity Index, in specific metabolic populations. It is a low-cost and easily available biomarker, making it useful in primary prevention clinics, stroke units, and for managing metabolic syndrome. Given the increasing number of observational studies and population-based data, a comprehensive synthesis is needed to evaluate AIP's diagnostic, prognostic, and pathophysiological significance in stroke. This narrative review consolidates current findings on AIP's relevance in ischemic stroke and explores its potential integration into stroke risk stratification. Existing evidence is largely observational in nature, limiting causal interpretation.