Assessing gastroesophageal reflux disease (GERD) threat 5 years following laparoscopic vertical sleeve gastrectomy (LVSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB): which measure of association is appropriate, odds ratio (OR) or relative risk (RR)?

BACKGROUND: In many clinical trials, the outcome variables are often binary (or categorical), and the main interest is to investigate any relationship between these categorical outcomes and intervention strategies for measuring the effect size and strength of association. The two frequently applied statistical methods used for this purpose are the relative risk (RR) and odds ratio (OR). The aim of this paper is to explore the fundamental concepts, definitions, computational methods, interpretations, differences, and lastly the relationship between RR and OR in the context of gastroesophageal reflux disease (GERD) following two bariatric (weight loss) procedures, namely laparoscopic vertical sleeve gastrectomy (LVSG) vs. laparoscopic Roux-en-Y gastric bypass (LRYGB).

METHODS: From January 2015 to March 2024, several electronic databases were searched for randomized controlled trials (RCTs) comparing LVSG and LRYGB and their effects on postoperative GERD at 5-year follow-up. Computation of OR and RR was undertaken to determine this impact, the differences in the effect size and strength of association between these two methods, and to demonstrate the differences between these two concepts.

RESULTS: Our analysis has demonstrated that GERD is far more common in patients' population following a LVSG compared to LRYGB. The RR for GERD is 4.96 times higher for the LVSG cohort compared to the LRYGB group. Similarly, the OR has revealed that the odds of GERD for LVSG patients is 6.4 times that of LRYGB patients at 5-year follow-up.

CONCLUSIONS: Although both OR and RR have demonstrated a large effect size and strong association for GERD following LVSG compared to LRYGB, the OR strength of association is more convincing. The results suggest the primary use of OR is the right approach, as it is showing greater strength of association between exposure, i.e., LVSG, and outcome, i.e., GERD at 5-year follow-up in our analysis.