Impact of Comorbidity Type on Measures of Quality for Diabetes Care

Objective: Studies provide conflicting results about the impact of comorbid conditions on the quality of chronic illness care. We assessed the effect of comorbidity type (concordant, discordant, or both) on the receipt of guideline-recommended care among patients with diabetes. Research Design: Patients were assigned to 1 of 4 condition groups: diabetes-concordant (hypertension, ischemic heart disease, hyperlipidemia), and/or diabetes-discordant (arthritis, depression, chronic obstructive pulmonary disease) conditions, or neither. We evaluated hemoglobin A1c, blood pressure, and low-density lipoprotein cholesterol readings at index and measured overall good quality of diabetes care, including a 6-month follow-up interval. We assessed the effect of condition group on overall good quality of care with logistic regression and generalized ordered logistic regression. Results: We assigned 35,872 patients to the diabetes comorbid condition groups, ranging from 2.0% in the discordant-only group to 58.0% in the concordant-only group. Patients with both types of conditions were more likely than those with no comorbidities to receive overall good quality for glycemic [odds ratio (OR), 2.13; 95% confidence interval (CI), 1.86-2.41], blood pressure (OR, 1.62; 95% CI, 1.40-1.84), and low-density lipoprotein cholesterol (OR, 3.57; 95% CI, 3.08-4.05) control within 6 months of an index visit. They were also more likely to receive overall good quality for all 3 quality measures combined (OR, 2.17; 95% CI, 1.96-2.39). Conclusions: Patients with the greatest clinical complexity were more likely than less complex patients to receive high quality diabetes care, suggesting that increased complexity does not necessarily predispose chronically ill patients to receiving poorer care. However, caution should be used in treating certain patient groups, such as the elderly, for whom adherence to multiple condition-specific guidelines may lack benefit or cause harm.