With this interpretation in mind, 87.2% of the number-of-disorder coefficients in the best-fitting model are less than 1.0 across equations, indicating a general pattern of sub-additive interaction in the logistic specification; that is, a pattern in which the joint effects of the interacting predictors are significantly less than those estimated in a model that assumes that no interactions exist. (Table 3) One-third of these sub-additive coefficients are statistically significant, while none of the ORs greater than 1.0 is significant. This pattern of the predictive associations of comorbidity generally being less than the product of their parts becomes stronger as the number of disorders in the comorbid profile increases from a median OR of 0.8 for two disorders to 0.1 for 7+ disorders.
