ABSTRACT
AIM: Few, separate, small retrospective studies in giant cell arteritis (GCA) reported that patients: (a) with diabetes mellitus had less positive temporal artery biopsies (TAB); (b) on angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin II receptor blockers (ARB) experienced fewer relapses; and (c) on statins experienced the same frequency of clinical complications and relapses as non-exposed patients. This retrospective chart review study simultaneously investigated the impact of these 3 factors on a cohort of patients followed in 2 large Canadian centers (Hamilton and Toronto, ON). METHODS: One hundred and thirty-seven patients diagnosed with GCA between 1993 and 2015 were included in the study. Presenting symptoms, TAB results, disease complications and outcomes (relapses, duration of glucocorticoid use) were compared between exposed (diabetes/ACE/ARB/statin) and non-exposed patients, with adjustment for main potential confounding variables. RESULTS: Temporal artery biopsies was less often positive in patients with pre-existing diabetes (relative risk 0.24; 95% CI: 0.069-0.81). Patients who developed diabetes after diagnosis had a lower relapse-free survival (adjusted hazards ratio [HR] 0.28; 95% CI: 0.095-0.84). Patients taking ARBs prior to diagnosis were more likely to successfully discontinue glucocorticoids without a flare in the following 3 months (adjusted HR 2.46; 95% CI: 1.2-5.3). Clinical complications and relapse rates did not differ between patients on statin therapy or not. CONCLUSION: Diabetic patients with GCA were less likely to have a positive TAB, and more likely to relapse. ARB therapy prior to diagnosis showed an association with success at discontinuing glucocorticoids. Statin therapy did not alter the clinical presentation or course of GCA.
