Applying latent tree analysis to classify Traditional Chinese Medicine syndromes(Zheng)in patients with psoriasis vulgaris

OBJECTIVE:To treat patients with psoriasis vulgaris using Traditional Chinese Medicine(TCM),one must stratify patients into subtypes(known as TCM syndromes or Zheng)and apply appropriate TCM treatments to different subtypes.However,no unified symptom-based classification scheme of subtypes(Zheng)exists for psoriasis vulgaris.The present paper aims to classify patients with psoriasis vulgaris into different subtypes via the analysis of clinical TCM symptom and sign data.METHODS:A cross-sectional survey was carried out in Beijing from 2005-2008,collecting clinical TCM symptom and sign data from 2764 patients with psoriasis vulgaris.Roughly 108 symptoms and signs were initially analyzed using latent tree analysis,with a selection of the resulting latent variables then used as features to cluster patients into subtypes.RESULTS:The initial latent tree analysis yielded a model with 43 latent variables.The second phase of the analysis divided patients into three subtype groups with clear TCM Zheng connotations:'blood deficiency and wind dryness';'blood heat';and'blood stasis'.CONCLUSIONS:Via two-phase analysis of clinic symptom and sign data,three different Zheng subtypes were identified for psoriasis vulgaris.Statistical characteristics of the three subtypes are presented.This constitutes an evidence-based solution to the syndromedifferentiation problem that exists with psoriasis vulgaris.