The impact of treatment noncompliance on mortality in people with type 2 diabetes

OBJECTIVE: To assess the association of compliance with treatment (medication and clinic appointments) and all-cause mortality in people with insulin-treated type 2 diabetes. RESEARCH DESIGN AND METHODS: Data were extracted from U.K. general practice records and included patients (N = 15,984) who had diagnostic codes indicative of type 2 diabetes or who had received a prescription for an oral antidiabetic agent and were treated with insulin. Records in the 30 months before the index date were inspected for clinical codes (recorded at consultation) indicating medication noncompliance or medical appointment nonattendance. Noncompliance was defined as missing more than one scheduled visit or having at least one provider code for not taking medications as prescribed. Relative survival postindex date was compared by determining progression to all-cause mortality using Cox proportional hazards models. RESULTS: Those identified as clinic nonattenders were more likely to be smokers, younger, have higher HbA(1c), and have more prior primary care contacts and greater morbidity (P < 0.001). Those identified as medication noncompliers were more likely to be women (P = 0.001), smokers (P = 0.014), and have higher HbA(1c), more prior primary care contacts, and greater morbidity (all P < 0.001). After adjustment for confounding factors, medication noncompliance (hazard ratio 1.579 [95% CI 1.167-2.135]), clinic nonattendance of one or two missed appointments (1.163 [1.042-1.299]), and clinic nonattendance of greater than two missed appointments (1.605 [1.356-1.900]) were independent risk factors for all-cause mortality. CONCLUSIONS: Medication noncompliance and clinic nonattendance, assessed during routine care by primary care physicians or their staff, were independently associated with increased all-cause mortality in patients with type 2 diabetes receiving insulin