Psychometric validation of the modified Naranjo algorithm used in homeopathy for chronic cases

The modified Naranjo algorithm assesses the physician assigned cause-effect relationship for homeopathic medicines. It is being adopted in homeopathy researches, but not yet validated systematically. We intended to validate the modified Naranjo algorithm by examining its psychometric properties.

An online survey sought agreement of 25 experts on the 10 items of the tool on 5-point agreement scale. Next, 285 responses from collected prospectively from chronic cases enrolled under the clinical verification program of the council in 2018 were subjected to testing of construct validity using exploratory principal component analysis (PCA). Confirmatory factor analysis (CFA; n=150) was performed to verify the goodness-of-fit of the model. Reliability was tested using internal consistency, test-retest reliability, and inter-rater reliability by kappa statistics.

Experts' responses mean values were 4 or higher (i.e. responses were relevant) and standard deviations were less than 1 (i.e. less heterogeneous). In PCA using varimax, all the items loaded above the pre-specified value of 0.4 and identified 4 components explaining 64.1% of variation. The goodness-of -fit of the 4-component CFA model was acceptable (chi-square 89.253, p<0.001). Internal consistency (Cronbach's alpha 0.7) was borderline; test-retest reliability was acceptable. Kappa statistics was moderate to fair, but poor for few of the items.

Statistical evaluations indicate that the modified Naranjo algorithm is useful, but needs improvement.