Prakriti (constitutional typology) in Ayurveda: a critical review of Prakriti assessment tools and their scientific validity.

Background: Prakriti or constitutional typology is the foundation of personalized health care in Ayurveda. Traditionally, Ayurvedic clinicians have assessed Prakriti in a primarily experience-based and often subjective manner. However, in the past few decades attempts to develop objective tools have been made by researchers from multidisciplinary domains. This review aimed to identify existing Ayurvedic Prakriti assessment tools and evaluate their scientific rigor. Methods: Aligned with the SANRA framework, our narrative review incorporated systematic elements. A Boolean search in PubMed, Scopus, and Cochrane in November 2024 using ("Prakriti") AND ("Ayurveda" OR "Ayurvedic") yielded 635 articles, together with 12 additional articles from citations search. Ninety four studies met the inclusion criteria. Prakriti assessment tools were quantified and evaluated using Scale Development and Validation Framework by Boateng et al., alongside custom set of study quality indicators to assess their methodological rigor. Results: Between 1987 and 2024, 64 unique Prakriti assessment tools (PATs) were identified, each using one or more methods to perform data collection and decision-making tasks. Variations in the selection and application of these methods resulted in the development of diverse methodological frameworks for Prakriti assessment. Of the 64 PATs identified, only 20 PATs underwent any form of validation and among them, just two PATs, the CCRAS-PAS software and ACPI scale met seven of the nine recommended criteria. Most tools lacked dimensionality testing, test-retest reliability, contextual validity and were not tested across diverse populations, indicating a high risk of developer-bias. Additionally, 32 categories of measurable correlates to Prakriti have been studied across 94 studies, but only five of them were studied using validated tools. Conclusion: Much progress has been made in developing methodology and integrating technology for creating Prakriti assessment tools along with attempts to identifying measurable correlates to Prakriti that could potentially serve as Prakriti biomarkers. Currently no tool fully meets the evaluation criteria of the Scale Development and Validation framework, except CCRAS-PAS and ACPI that show partial readiness and can be refined. Further work is needed to establish Prakriti as a clinically validated measurable construct and to integrate Ayurveda into the domain of personalized health care.