Multivariate logistic regression of the risk of persistent anemia, if using iron tablets.

The final model presenting all variables making a significant contribution to the risk of persistent anemia, once adjusted for the presence of other variables, in HHT online survey respondents using iron tablets. The model details 424 observations providing a pseudo r2 of 0.14, and overall model p value of <0.0001. P values were calculated post estimation, both by likelihood ratio (LR) tests which assume independence of observations within a cluster (an assumption that was not met with these data), and the non parametric Wald test which does not make such assumptions. There was no clear relationship between persistent anemia and iron tablet-induced nausea, constipation, or abdominal pain (likelihood ratio test p values 0.14, 0.11, and 0.09 respectively). There was also no relationship with age, gender, other otorhinolaryngologic treatments [37] either combined or individually, or other reported HHT treatments for pulmonary, cerebral or hepatic arteriovenous malformations (data not shown).