A Pragmatic Historical Assessment Tool: A New Systematic Framework for the Collation and Evaluation of Documented Empirical Effectiveness and Safety of Traditional Plant Medicines in the European Materia Medica.

Abstract

Traditional plant medicines (TPMs) are plant-derived therapeutic products prepared and applied according to longstanding medical customs. Around the world they are widely used in primary and preventative health care. The World Health Organization (WHO) calls in its Traditional Medicine Strategy 2014-2023 for Member States to provide a regulatory framework so that the formal contribution of traditional therapeutics can be advanced in national systems of health care. Evidence of effectiveness and safety is paramount for the regulatory integration of TPMs; however, a presumed lack of such "evidence" is one obstacle for full integration. The consequential health policy question is how to systematically evaluate therapeutic claims relating to herbal remedies when the extant evidence is predominantly based on historical and contemporary clinical usage, i.e., is empiricist in nature. This paper introduces a new method along with several illustrative examples. Our research design employs a longitudinal, comparative textual analysis of standard textbooks of the professional European medical literature from the early modern period (1588/1664) onwards to today. It then triangulated these intergenerationally documented clinical observations on two exemplars (Arnica and St. John's Wort) with corresponding listings in multiple qualitative and quantitative sources. A Pragmatic Historical Assessment (PHA) tool was developed and tested as a method to systematically collate the large amount of pharmacological data recorded in these judiciously selected sources. The evidential validity of longstanding professional clinical knowledge could thus be compared with therapeutic indications approved in official and authoritative sources (pharmacopoeias, monographs) and with those supported by contemporary scientific research (randomised-controlled trials [RCTs], experimental research). There was high congruency between therapeutic indications that are based on repeated empirical observations from professional patient care (empirical evidence), those approved in pharmacopoeias and monographs, and modern scientific evidence based on RCTs. The extensive herbal triangulation confirmed parallel records of all main therapeutic indications of the exemplars across all qualitative and quantitative sources over the past 400 years. Historical clinical medical textbooks and contemporary phytotherapeutic equivalents are the key repository of repeatedly evaluated therapeutic plant knowledge. The professional clinical literature proved to be a reliable and verifiable body of empirical evidence that harmonised with contemporary scientific assessments. The newly developed PHA tool provides a coding framework for the systematic collation and evaluation of empirical data on the effectiveness and safety of TPMs. It is suggested as a feasible and efficient tool to extend evidence typologies that substantiate therapeutic claims for TPMs as part of an evidence-based regulatory framework that formally integrates these medically and culturally important therapeutics.