Frailty-stratified outcomes of minimally invasive vs open abdominal surgery in older adults: a systematic review of safety and functional recovery

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Background Frailty, characterized by diminished physiological reserve and increased vulnerability to stressors, is now established as a superior predictor of adverse surgical outcomes compared with chronological age. Yet its role in guiding the selection of operative approach, specifically, the choice between minimally invasive surgery (MIS) and open abdominal surgery in older adults, a decision also shaped by anatomical and disease-related factors, remains poorly defined. The absence of a synthesized evidence base creates a persistent gap in frailty-informed surgical decision-making, with global implications, as population aging accelerates in both high-income and low-resource healthcare settings. Methods A systematic review was conducted in full accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement and was prospectively registered with the International Prospective Register of Systematic Reviews (CRD420251158148). PubMed and the Cochrane Central Register of Controlled Trials were searched without a lower date restriction. All records were screened independently by 2 reviewers using Rayyan software. Eligible studies compared frailty-stratified postoperative outcomes between MIS and open abdominal surgery in adults aged 65 years or older using validated frailty assessment tools, including the modified Frailty Index and Clinical Frailty Scale. Risk of bias was independently assessed using the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool. A preplanned narrative synthesis following the Synthesis Without Meta-Analysis reporting guideline was conducted, given the substantial clinical and methodological heterogeneity that precluded meta-analysis. Results Five observational cohort studies (n = 16,077 patients; MIS, 2647; open, 13,430) were included, encompassing emergency hernia repair, hepatectomy, distal pancreatectomy, emergency colectomy, and urgent cholecystectomy, conducted in the United States, the United Kingdom, and Italy. MIS was consistently associated with lower 30- and 90-day mortality, fewer postoperative complications (including a graded Clavien-Dindo major complication rate that rose from 6% in nonfrail patients to 24% in severely frail patients undergoing open surgery), and a shorter length of hospital stay across all 5 procedures. Frailty independently predicted worse outcomes across all outcome domains, irrespective of the operative approach. Critically, the relative benefit of MIS was preserved and appeared proportionally accentuated in frail cohorts. All studies demonstrated a serious overall risk of bias on ROBINS-I, primarily due to confounding and selection bias; the overall certainty of evidence was low. Conclusion Across the 5 included studies, MIS was directionally associated with lower mortality, fewer postoperative complications, and shorter hospital stays in older adults, including those with clinically significant frailty. Frailty should be routinely assessed preoperatively and considered alongside anatomical, disease-related, and physiological factors when selecting the operative approach. These findings are relevant across diverse healthcare systems globally, though current evidence derives exclusively from high-income country contexts. However, interpretation is limited by a serious risk of confounding and selection bias, as the included observational studies may have preferentially allocated higher-risk patients or technically complex cases to open surgery. Prospective, procedure-specific, frailty-stratified randomized trials with standardized assessment tools are urgently needed to consolidate and extend these findings internationally. Level of Evidence Level III — Systematic review of observational studies