Results confirmed that the four risk domains were each both correlates of EB and efficient at discriminating non-referred from referred children; that their combination regardless of their content (cumulative risk) provided a strong prediction of both later EB and non-referred vs referred sample membership.
To exploit the potential of the full data set with quantitative bacterial data we subsequently applied OPLS/O2PLS discriminant analysis and found that certain species significantly positively or negatively contributed to GCF sample membership and vice versa to PP sample membership.
Score and loading plots were used for an overview of the respective correlation matrices, and regression coefficients for prediction of responses, such as bacterial species/phylotype diversity and the GCF sample or PP sample membership.
The positive contributors to GCF sample membership were mainly species traditionally classified as Gram-negative anaerobes, such as C. rectus/concisus, P. nigrescens, D. pneumosintes and T. forsythia, that are common subgingival microbiota and associated with periodontitis.
On the other hand, the positive contributors to PP sample membership included mainly Gram-positive bacteria, such as mitis- and milleri-group streptococci and anaerobic rods, all of them current or previous members of genus Eubacterium (E. brachy, E. saphenum, E. yurii, S. satelles and P. alactolyticus).
The Jaccard index value measures the sample membership by the proportion of shared OTUs between the two samples.
Moderating effects of these risk factors and child gender on the relation between sample membership and child developmental outcomes were also studied.
Due to the partial heterogeneity in our samples, we will insert sample membership in all analyses as a control variable, to assess whether results are homogenous in all four samples.
Significant interactions between baseline UPI levels and sample membership were explored by generating within-group odds ratios and IRRs of the regression post-release UPI onto pre-release UPI.
The main effects of sample membership, gender and marital status were significant whereas the interaction between gender and study groups was barely significant (p =.049) and showed differences in only two dimensions with a weak effect size.
