Susceptibility, a foundational concept in homeopathy, denotes an individual's reactive capacity that governs disease manifestation, remedy response and potency selection. Despite its central role, susceptibility has remained a qualitative construct without standardized measurement. This study aimed to conceptualize and develop a content-validated instrument to measure susceptibility to different potencies of homeopathic medicines.

An exploratory sequential mixed-methods design (qual → QUAN) was employed. Conceptual domains were identified through classical literature review and expert free-listing, with item salience estimated using Smith's salience index. Face validity was assessed by four independent raters, followed by Delphi-based content validation with another five-member expert panel using average congruency percentage (ACP), content validity ratio (CVR), content validity index (CVI), including I-CVI (content validity index: item-specific) and S-CVI (content validity index: scale-specific), and kappa statistics. A pilot test by 15 postgraduate trainees (end-users) evaluated clarity and feasibility. An exploratory receiver operating characteristic (ROC) analysis was conducted to preliminarily calibrate score thresholds against expert-rated susceptibility levels (low, medium, high).

From an initial pool of 37 items, 28 were retained after salience analysis and 20 after Delphi validation. Content validity indices met acceptable standards (ACP ≥ 80%; CVR ≥ 0.99; I-CVI Avg. 0.793; S-CVI Avg. 0.786; Fleiss kappa −0.037, 95% confidence interval −0.120 to 0.045). The final 19-item tool spans intellectual, emotional, pathological, environmental and behavioral domains. ROC analysis demonstrated excellent discriminative performance across all pairwise comparisons (asymptotic p < 0.001), with curves closely approximating the upper-left boundary, indicating high sensitivity and specificity. Optimal cut-off points were identified, enabling empirical classification of susceptibility as low (<60.7), moderate (60.7–66.9) or high (>66.9).

This study presents the first standardized, content-validated and pilot-tested instrument to quantify susceptibility in homeopathy. The exploratory ROC findings provide preliminary empirical thresholds for classifying susceptibility levels, supporting more consistent and objective potency selection. Further psychometric testing, including reliability and construct validity, will be reported elsewhere.

This paper contains all of the data that were collected or examined during the trial. The corresponding author can be contacted for any additional queries.

Anil Kumar Mandi, Taniya Islam, Joynab Khatun, Pritom Patra: methodology, validation, conducting the investigation, data curation, writing—original draft, review, editing. Satyajit Naskar, Subhasish Ganguly, Sangita Saha, Pulakendu Bhattacharya: methodology, validation, conducting the investigation, resources, writing, review and editing, supervision, project administration, funding acquisition. Subhranil Saha, Munmun Koley: conceptualization, methodology, formal analysis, data curation, writing—original draft, review, editing.

The project was carried out as the postgraduate dissertation work of the first author, and the report was submitted to the West Bengal University of Health Sciences, Kolkata, in October 2024.

(1) Dr. Pannalal Dey, Former Principal, Burdwan Homoeopathic Medical College and Hospital; (2) Dr. Purnendu Basu, Emeritus Professor, Department of Organon of Medicine, National Institute of Homoeopathy, Kolkata; (3) Dr. Syed Afsar Ali, Department of Organon of Medicine, National Institute of Homoeopathy; (4) Dr. Subhasish Ganguly, Department of Organon of Medicine, D. N. De Homoeopathic Medical College and Hospital; (5) Dr. Munmun Koley, Department of Health and Family Welfare, Government of West Bengal, East Bishnupur State Homoeopathic Dispensary, Chandi Daulatabad Block Primary Health Centre, South 24 Parganas, West Bengal.

(1) Dr. Gobind Narayan Gupta, Department of Organon of Medicine, National Institute of Homoeopathy; (2) Dr. Sukhendu Sarkar, Associate Professor, Department of Organon of Medicine, Pratap Chandra Memorial Homoeopathic Medical College and Hospital; (3) Dr. Rudranil Chatterjee, Associate Professor, Department of Organon of Medicine, Mahesh Bhattacharyya Homoeopathic Medical College and Hospital; (4) Dr. Srinivasulu Gadugu, Professor, Department of Organon of Medicine, JSPS Government Homoeopathic Medical College and Hospital; (5) Dr. Biplab Kumar Kundu, Emeritus Professor, Metropolitan Homoeopathic Medical College and Hospital.

Received: 15 October 2025

Accepted: 31 December 2025

Article published online:
30 April 2026

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