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Temporal changes in post-bariatric nutritional deficiency anemia: a propensity score-matched analysis of 2015-2017
I-Wen Chen1, Chia-Li Kao2, Yi-Chen Lai3
1Department of Anesthesiology, Chi Mei Hospital, Liouying, Tainan, Taiwan.
Background:
Metabolic and bariatric surgery (MBS) is associated with postoperative nutritional deficiencies, yet whether temporal shifts in surgical practice and healthcare delivery have influenced the risk of nutritional anemia remains unclear. We compared the 2-year incidence of postoperative nutritional anemia between patients who underwent MBS between 2015 and 2017 and 2022-2023.
Methods:
Using the TriNetX Global Collaborative Network, we conducted a propensity score-matched cohort study of adult patients undergoing laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass. The primary outcome was the 2-year cumulative incidence of nutritional anemia, assessed from 90 to 730 days postoperatively. The secondary outcomes included iron deficiency anemia (IDA), vitamin B12 deficiency anemia, other anemia, all-cause hospitalization, and emergency department visits.
Results:
After 1:1 propensity score matching, 13,010 patients were included in each cohort. Compared with the early cohort (2015-2017), the late cohort (2022-2023) had a significantly higher risk of nutritional anemia (6.61% vs. 5.30%; hazard ratio [HR] 1.34, 95% confidence interval [CI] 1.22-1.49; p < 0.001), including iron deficiency anemia (HR 1.36, p < 0.001) and vitamin B12 deficiency anemia (HR 1.32, p = 0.025). No significant difference was observed for other anemia (HR 1.05, p = 0.386). The risk of all-cause hospitalization was higher in the late cohort (HR 1.57, p < 0.001), whereas emergency department visits did not differ significantly. Sensitivity and subgroup analyses yielded consistent findings for the primary outcome and iron deficiency anemia, although the association with vitamin B12 deficiency anemia was not uniformly significant across all models.
Conclusion:
In this observational study, the 2022-2023 cohort had a higher risk of coded or clinically detected postoperative nutritional anemia than earlier cohorts. Given the modest absolute risk difference and a diagnosis-code-based outcome, this finding should be interpreted as a higher burden of recognized anemia diagnoses rather than definitive evidence of increased biological anemia incidence. These results support adherence to existing postoperative nutritional monitoring recommendations rather than a more intensive surveillance schedule.
