Characteristics of Patients Lost to Follow-up after Bariatric Surgery.

After bariatric surgery lifelong follow-up is recommended. Evidence of the consequences and reasons for being lost to follow-up (LTFU) is sparse. In this prospective study follow-up data of all patients who underwent bariatric surgery between 2008 and 2017 at a certified obesity centre were investigated. LTFU patients were evaluated through a structured telephone interview. Overall, 573 patients (female/male 70.9%/29.1%), aged 44.1 ± 11.2 years, preoperative BMI 52.1 ± 8.4 kg/m underwent bariatric surgery. Out of these, 33.2% had type 2 diabetes mellitus and 74.4% had arterial hypertension. A total of 290 patients were LTFU, of those 82.1% could be reached. Baseline characteristics of patients in follow-up (IFU) and LTFU were comparable, but men were more often LTFU ( = 0.01). Reported postoperative total weight loss (%TWL) and improvements of comorbidities were comparable, but %TWL was higher in patients remaining in follow-up for at least 2 years ( = 0.013). Travel issues were mentioned as the main reason for being LTFU. A percentage of 77.6% of patients reported to regularly supplement micronutrients, while 71.0% stated regular monitoring of their micronutrient status, mostly by primary care physicians. Despite comparable reported outcomes of LTFU to IFU patients, the duration of the in-centre follow-up period affected %TWL. There is a lack of sufficient supplementation and monitoring of micronutrients in a considerable number of LTFU patients.