Upper limit of Microbial dysbiosis index (MD-index)

This may be a naive question but I would like to know the upper limit (maximum value) of the microbial dysbiosis index (MD value) used while performing correlation analysis (SPARCC, SECOM, Spearmen, Kendell). Sum articles assign the MD index between 0 and 1, while other studies use 1 to 5. According to my analysis, the MD index provided by MicrobiomeAnalyst is 1.4608 for order level and 0.6741 for genus level.

Thank you.

Hello, the MD-index in MicrobiomeAnalyst is calculated as log value of (summed abundance of taxa increased in the given case/summed abundance of taxa decreased in the given case), following Gevers et al. So it can be start from 0. Usually, MD-index > 1 is a relative high index and a strong reduction in the species richness can be observed in samples with MD-index > 1.

Thank you for the prompt and clear reply.