Association between performance measures and glycemic control among patients with diabetes in a community-wide primary care cohort.

BACKGROUND Performance measures are used for assessing quality of care. Higher performance shown by these measures is expected to reflect better care, but little is known whether they predict better patient outcomes. OBJECTIVE To assess the predictive value of performance measures of glucose management on glycemic control, and evaluate the impact of patient characteristics on this association. RESEARCH DESIGN Cohort study (2007-2009). SUBJECTS A total of 15,454 type 2 diabetes patients (mean age, 66.5 y; 48% male) from the GIANTT cohort. MEASURES We included performance measures assessing frequency of HbA1c monitoring, glucose-lowering treatment status, and treatment intensification. Associations between performance and glycemic control were tested using multivariate linear regression adjusted for confounding, reporting estimated differences in HbA1c with 95% confidence intervals (CI). Impact of patient characteristics was examined through interactions. RESULTS Annual HbA1c monitoring was associated with better glycemic control when compared with no such monitoring (HbA1c -0.29%; 95% CI -0.37, -0.22). This association lost significance in patients with lower baseline HbA1c, older age, and without macrovascular comorbidity. Treatment status was associated with better glycemic control only in patients with elevated baseline HbA1c. Treatment intensification after elevated HbA1c levels was associated with better glycemic control compared with no intensification (HbA1c -0.21; 95% CI -0.26, -0.16). CONCLUSIONS Performance measures of annual HbA1c monitoring and of treatment intensification did predict better patient outcomes, whereas the measure of treatment status did not. Predictive value of annual monitoring and of treatment status varied across patient characteristics, and it should be used with caution when patient characteristics cannot be taken into account.