Congruence methods/polynomial regression in behavioral medicine

It is known that patients’ medication-related concerns and necessity-beliefs predict adherence. However, evaluation of the interplay between these two dimensions has been limited because of methods that reduce them to a single dimension (difference scores).

In my publication, The Necessity-Concerns-Framework: A Multidimensional Theory Benefits from Multidimensional Analysis, an exploratory polynomial regression found that patients with ambivalent attitudes towards their medications (strong concerns and strong necessity beliefs) had lower reported adherence than did patients with indifferent attitudes (weak concerns and weak necessity beliefs). These results, the overall known issues of difference scores and other methods that collapse separate dimensions, and the multidimensional nature of the necessity-concerns framework all strongly indicate that polynomial regression should be used in future studies of patients’ medication-related evaluations and their medication adherence.