Association Between Patient Portal Engagement and Weight Loss Outcomes in Patients After Bariatric Surgery: Longitudinal Observational Study Using Electronic Health Records
Authors: Zhang Xinmeng , Kang Kaidi , Yan Chao , Feng Yubo , Vandekar Simon , Yu Danxia , Rosenbloom S Trent , Samuels Jason , Srivastava Gitanjali , Williams Brandon , Albaugh Vance L , English Wayne J , Flynn Charles R , Chen You 
Published: December 2024

Background
Bariatric surgery is an effective intervention for obesity, but comprehensive postoperative self-management is essential for optimal outcomes. While patient portals are generally seen as beneficial in engaging patients in health management, the link between their use and post–bariatric surgery weight loss remains unclear.

Objective
This study aimed to investigate the association between patient portal engagement and postoperative BMI reduction among patients after bariatric surgery.

Methods
This retrospective longitudinal study included patients who underwent Roux-en-Y gastric bypass or sleeve gastrectomy at Vanderbilt University Medical Center between January 2018 and March 2021. Patient portal engagement was measured during 4 stages: early (within 3 months after surgery), early midterm (3-6 months), late midterm (6-9 months), and late (9-12 months). Using generalized estimating equations, we estimated the associations between patients’ portal engagements at these stages and the percentage of BMI reduction (%BMIR) at 3, 6, and 12 months after surgery. Covariates included duration since surgery, patient’s age at the time of surgery, sex, race and ethnicity, type of bariatric surgery, severity of comorbid conditions, and socioeconomic disadvantage.

Results
The study included 1415 patients, predominantly female (n=1145, 80.9%), with a racial composition of 76.9% (n=1088) White and 19.9% (n=282) Black. Overall, 805 (56.9%) patients underwent Roux-en-Y gastric bypass and 610 (43.1%) underwent sleeve gastrectomy. By 1 year after surgery, the median %BMIR was 31.5% (IQR 25.2%-36.8%), and the median number of active days on the patient portal was 54 (IQR 33-80). Early portal engagement was significantly associated with %BMIR at various postoperative times. Specifically, each additional 10 days of early portal engagement was associated with a 0.37% (95% CI –0.55% to –0.18%; P<.001) lower expected %BMIR at 3 months, a 1.11% (95% CI 0.82%-1.41%; P<.001) higher expected %BMIR at 6 months, and a 0.78% (95% CI 0.25%-1.31%; P=.004) higher expected %BMIR at 12 months. Furthermore, early midterm portal engagement was associated with a 0.36% (95% CI –0.69 to –0.03; P=.03) lower expected %BMIR at 6 months, but it was not significant at 12 months (P=.88). Late midterm and late portal engagement were not significantly associated with %BMIR at 12 months (P=.27 and P=.12, respectively). Furthermore, early engagement in various portal functions, such as messaging and accessing medical records, was significantly associated with a lower %BMIR at 3 months and a higher %BMIR at both 6 and 12 months (all P<.05).

Conclusions
Higher patient portal engagement within 3 months after surgery—suggestive of stronger adherence to postoperative instructions and improved communication with care teams—is associated with less favorable weight loss immediately after surgery but enhanced postoperative weight loss outcomes at 6 and 12 months. However, the limitations of retrospective data-driven studies highlight the need for future intervention-based studies to validate these associations and establish causality.