Patients Lost to Follow-up in Shoulder Arthroplasty: Descriptive Characteristics and Reasons

BACKGROUND: The purpose of this study was to determine the number of patients lost to follow-up yearly in shoulder arthroplasty and investigate the characteristics of the patients lost to follow-up that may differ from those not lost to follow-up. METHODS: All shoulder arthroplasties performed from January 2008 to December 2014 were retrospectively reviewed. The number of patients lost to follow-up was determined yearly. Independent variables included age, sex, body mass index (BMI), diagnosis, type of prostheses, living condition, smoking, alcohol intake, American Society of Anesthesiologists (ASA) score, in-hospital length, surgery length, living area, preoperative Constant score, last Constant score available, and complications. Number of deaths was recorded. RESULTS: This study included 251 patients. There was an accumulation of 86 patients (34.3%) lost to follow-up after a maximum of 8 years. During the first year, 9.9% of the patients were lost to follow-up, 18.3% in the second year, 25.1% in the third year, 28.7% in the fourth year, 31.5% in the fifth year, 33.9% in the sixth year, and 34.3% in the seventh year. Patients with severe obesity had 2.44 times greater risk of being lost to follow-up (hazard ratio [HR], 2.44; p < 0.001). Elderly patients were also at higher risk (HR, 1.05; p < 0.001). Increases in the ASA score raised the risk of being lost (HR, 1.93; p < 0.001). Patients with complications had a lower risk (43%) of being lost (HR, 0.57; p = 0.018) at the 8-year follow-up. At the 2-year follow-up, the patients with acute fractures and fracture sequelae had a higher risk of being lost to follow-up (HR, 2.44; p = 0.002), and the patients with complications were not significantly different from those without complications (HR, 0.54; p = 0.12). CONCLUSIONS: The longer the follow-up in shoulder arthroplasty, the greater the number of patients lost to follow-up, reaching 34.3% by the seventh year. Patients lost to follow-up were not random in shoulder arthroplasty: older patients, severely obese patients, and those with higher ASA scores were at higher risk of being lost to follow-up, but reasons for being lost to follow-up changed through time and depending on when they were assessed.