Radiological glenohumeral osteoarthritis in long-term type 1 diabetes. Prevalence and reliability of three classification systems. The Dialong shoulder study

Objective In the present study, we evaluate the intra- and interrater agreement of radiological glenohumeral OA using three different classification systems and estimate the prevalence of radiological and clinical glenohumeral OA in patients with type 1 diabetes mellitus (DM1), for over 45 years and controls (The Dialong study). Materials and methods We included 102 patients with DM1 (49% women, mean age, 61.9 years) and 73 controls (57% women, mean age, 62.6 years). Anterior-posterior shoulder radiographs were interpreted by two observers applying the Kellgren–Lawrence (K–L), Samilson–Prieto (S–P) and Samilson–Prieto Allain (S–PA) classifications. Results The interrater agreement was moderate (weighted kappa, 0.46 to 0.48) for all classifications and the intrarater agreement mainly substantial (0.48–0.86) for both observers. The agreed prevalence of radiological OA was 26 and 18% (OR 1.6 (0.8 to 3.3), p = 0.22, 44 and 26% (OR 2.2 (1.2 to 4.2), p = 0.02) and 30 and 17% (OR 2.1 (1.0 to 4.5), p = 0.05) for the K–L, S–P and S–PA classifications respectively in the diabetes and control groups. The prevalence of moderate or severe radiological OA was 1 to 6% and clinical OA 1 to 2% with no difference between the groups. Conclusion The prevalence of radiological glenohumeral OA was higher in the diabetes group with the Samilson–Prieto classification systems, but not associated with clinical OA. The interrater agreement was moderate. We recommend the Samilson–Prieto Allain classification for glenohumeral OA to avoid interpretation of osteophytes < 1 mm as OA in patient groups with a low pre-test likelihood of glenohumeral OA.