Are co-morbidities associated with guideline adherence? The MI-Plus study of Medicare patients

The impact of co-morbid illnesses on adherence to guideline recommendations in chronic illness is of growing concern. We tested a framework [Piette and Kerr, Diabetes Care. 29(3):725-31, 2006] of provider adherence to guidelines in the presence of co-morbid conditions, which suggests that the effect of co-morbid conditions depends on treatment recommendations for the co-morbid conditions and how symptomatic they are.

We conducted an exploratory analysis to assess the framework using chart audit data for 1,240 post-acute myocardial infarction (AMI) Medicare beneficiaries in Alabama. We assessed level of guideline-adherent post-AMI care from chart-based quality indicators and constructed scores reflecting how much care for the co-morbid condition was similar to post-AMI care (concordance) and how symptomatic the co-morbid condition is, based on expert opinion.

Patients had a mean age of 74 years, mean co-morbidities of 2, and 61% were white. Both concordance and symptomatic scores were positively associated with guideline compliance, with correlations of 0.32 and 0.14, respectively (p < 0.001 for each). We found positive correlations between highly concordant co-morbid conditions and post-AMI quality scores and negative correlations between highly symptomatic conditions and post-AMI quality scores; both findings support the framework. However, the framework performed less well for conditions that were not highly concordant or highly symptomatic, and the magnitudes of the associations were not large.

The framework was related to the association of co-morbid conditions with adherence by providers to guideline-recommended treatment for post-AMI patients. The framework holds promise for evaluating and possibly predicting guideline adherence.