Introduction:  Previous studies suggest insufficient adherence to vitamin and mineral supplementation after bariatric surgery. 

Objective: This trial evaluated a smartphone application’s effectiveness in improving adherence to vitamin and mineral supplementation postoperatively. 

Methods: A two-arm, randomized controlled trial comprising 140 patients undergoing bariatric surgery (gastric bypass or sleeve gastrectomy). Participants were randomized 1:1 post-surgery to 12-week intervention, using the smartphone application PromMera, or standard care. The PromMera application was designed to promote vitamin and mineral use and physical activity after bariatric surgery. The primary end point was adherence to vitamin and mineral supplementation, objectively assessed with pharmacy claim data the first-year post-surgery. Additional endpoints were adherence subjectively assessed with change in MARS-5 score, measured pre-intervention, and at 18 weeks and one year post surgery and development of nutritional deficiencies one-year post-surgery.

Results: Initiation rate and overall adherence to supplementation were high in both groups. Change in objectively measured adherence rate from before intervention to 1 year post surgery, measured with pharmacy refill data, did not differ between groups for vitamin B12  (-9.6% [SD 27%] vs. -9.3% [SD 30%]; p=0.48) or calcium/vitamin D (-12.3% [SD 29%] vs. -11.5% [SD 32%]; p=0.44). A modest effect on the secondary end point (subjectively measured adherence, using the Medication Adherence Report Scale-5 [MARS-5]) was seen immediately after the intervention (intervention group 0.00 [SD 1.3] vs. control group -1.2 [SD 3.5]; p=0.021), but this effect did not persist 1 year post surgery. No differences were detected in the prevalence of biochemical deficiencies.

Conclusions The use of the smartphone application PromMera did not obtain a lasting improvement in adherence to vitamin and mineral supplementation one year post bariatric surgery.