An Investigation into the Miasmatic Classification of Symptoms in Homeopathy: Development of a Checklist of Secondary Symptoms of Psora by Mixed-Methods Research

Background: In homeopathic philosophy, chronic miasms are considered the fundamental causes of 'true, natural' chronic diseases. Hahnemann classified these into three types: psora, syphilis and sycosis. This project primarily aimed to collect and analyze qualitative experts-derived data to develop a consensus-based checklist of secondary symptoms of psora. The secondary aim was to quantitatively evaluate the checklist through partition clustering for compatibility with Hahnemann's miasmatic classification. This paper reports the development of the psora checklist, with two addenda addressing parallel work on syphilis and sycosis. Methods: An exploratory sequential mixed-methods design (qual → QUAN) was used. Key secondary symptoms were identified through a staged qualitative inquiry. Initially, symptoms were conceptualized deductively from the literature. Their salience was then ranked through free-listing by five homeopathy experts; symptoms with salience < 0.1 were excluded. Face validity was assessed. Next, five different experts evaluated item congruence in Delphi rounds to establish content validity. Symptoms with an average congruency percentage (ACP)