Chronic illness with complexity: Implication for performance measurement of optimal glycemic control

OBJECTIVE: To evaluate the association between chronic illness with complexity (CIC) and optimal glycemic control. PARTICIPANTS: Cross-sectional and longitudinal analyses of Diabetes Epidemiologic Cohort database of Veterans Health Administration (VHA) users with diabetes, less than 75 years old, with HbA1c tests in fiscal year (FY) 1999 and 2000, alive at FY2000 end (N=95,423). DESIGNIMEASUREMENTS: Outcomes were HbA1c<7% in each FY. CIC included three domains: nondiabetes physical illness, diabetes-related, and mental illness/substance abuse conditions. Other independent variables included age, gender, race, marital status, VHA priority status, and diabetes severity. Longitudinal analyses were restricted to patients with HbA1c >= 7% in FY1999 and included hospitalizations between final HbA1c's in FY1999 and FY2000. Multiple logistic regressions examined associations between CIC categories and HbA1c. RESULTS: In FY 1999, 33% had HbA1c <7%. In multivariate analyses, patients with nondiabetes physical illness and mental illness/substance abuse were more likely to have HbAlc <7% in FY1999 [adjusted odds ratios for cancer (AOR), 1.31; 95% CI (1.25-1.37); mental illness only, 1.18; 95% CI (1.14-1.22)]. Those with diabetes-related complications were less likely to have HbAlc <7% in FY1999. Associations generally held in FY2000. However, conditions in the mental illness/substance abuse complexity domain were less strongly associated with HbAlc <7%. Macrovascularrelated hospitalizations were positively associated with HbAlc <7% [AOR, 1.41; 95% CI (1.34-1.49)]. CONCLUSIONS: The association between CIC and HbAlc <7% is heterogeneous and depends on the domain of complexity. The varying associations of CIC categories with optimal glycemic control suggest the need for appropriate risk adjustment when using HbAlc <7% as a valid performance measure for diabetes quality of care.