Principal findings

In this single-centre cohort of patients undergoing emergency laparotomy, frailty was prevalent and associated with substantially worse unadjusted postoperative outcomes, including higher complication rates, greater ICU utilisation, longer hospital length of stay, and reduced likelihood of independent discharge. However, after adjustment for age, sex, operative indication, and ASA grade, frailty thresholds derived from three rapid tools (CFS, EmSFI, and mFI-5) were not independently associated with 30- or 90-day mortality. These findings suggest that frailty and ASA capture related but distinct dimensions of peri-operative risk in emergency laparotomy, with frailty more closely aligned to postoperative morbidity and recovery complexity than short-term mortality.

Frailty and postoperative morbidity: consistency with existing literature

The observed association between frailty and postoperative morbidity is consistent with peri-operative frailty literature demonstrating that frailty identifies patients at heightened risk of complications, prolonged hospitalisation, and loss of functional independence, especially following emergency laparotomy. Isand et al. recently demonstrated that patients with frailty undergoing emergency laparotomy experienced a 1.38-fold longer delay to surgery and a 1.24-fold longer postoperative LOS, even after adjusting for indication, sepsis, intraperitoneal soiling, malignancy status, and delay to surgery [14]. In addition, in a narrative review of older adults undergoing elective surgery, Subramaniam et al. highlighted frailty as a strong predictor of adverse postoperative outcomes and argued that frailty screening should act as a practical trigger for enhanced multidisciplinary, person-centred peri-operative management, rather than functioning solely as a risk label [15]. They noted that the interventional evidence base remains limited, but that comprehensive geriatric assessment (CGA) and optimisation has been associated with fewer complications and shorter LOS, and may be most efficiently targeted to patients identified as frail to direct finite geriatric and allied-health resources where benefit is most likely. Although this review focuses on elective surgery, its core implication aligns with our emergency laparotomy findings: frailty is most clinically actionable when used to prompt early multidisciplinary input, mobilisation, delirium prevention, nutrition support, medication review, and anticipatory discharge planning, aimed at mitigating morbidity and supporting recovery, rather than being used as a stand-alone mortality prediction tool.

Importantly, our data also demonstrate a graded relationship between frailty burden and postoperative morbidity, with progressively higher ICU utilisation and reduced independent discharge as the number of positive frailty tools increased. This burden-based signal aligns with the Emergency Laparotomy and Frailty (ELF) study, in which increasing CFS categories were associated with stepwise increases in postoperative complications and institutional discharge, even after accounting for age and comorbidity [8].

Mortality prediction: why ASA outperforms frailty in emergency laparotomy

A key finding of this study is that frailty thresholds did not independently predict short-term mortality once adjustment was made for key clinical covariates, including ASA grade. This contrasts with some elective surgery cohorts, where frailty has demonstrated independent associations with mortality, but aligns closely with contemporary peri-operative anaesthesia literature focused on emergency and high-acuity surgery. McIsaac et al. demonstrated that while frailty is strongly associated with death or new disability, acute physiological illness severity substantially attenuates its independent association with mortality, particularly in urgent and emergent procedures [16]. Another study similarly suggests that peri-operative outcomes in emergency surgery are best explained by the interaction between baseline vulnerability and acute physiological stress, rather than by frailty alone [17].

In emergency laparotomy, where sepsis, haemodynamic instability, metabolic derangement, and organ dysfunction are common, ASA grade may better reflect acute physiological burden at the time of surgery than frailty tools derived primarily from baseline characteristics. In our cohort, inclusion of ASA grade in adjusted models markedly attenuated the association between frailty and mortality. This finding mirrors those of Hackett et al., who reported that ASA grade demonstrated stronger discrimination for mortality than frailty indices in emergency laparotomy, particularly when multiple covariates were included in adjusted models [12]. This does not diminish the clinical relevance of frailty assessment, but rather underscores that frailty and anaesthetic risk stratification address complementary aspects of peri-operative risk.

Interpreting differences between frailty tools

The absence of an independent mortality association across all three frailty tools in adjusted analyses highlights that these instruments assess overlapping but distinct constructs. The Clinical Frailty Scale primarily reflects baseline functional reserve and dependence; the Emergency Surgery Frailty Index incorporates acute clinical and laboratory parameters; and the mFI-5 functions predominantly as a comorbidity-weighted risk index.

Notably, mFI-5 defined frailty retained an independent association with ICU admission in our cohort. This finding aligns with the construction of the mFI-5, which is derived from comorbidity and functional dependence variables and is heavily weighted toward cardiopulmonary disease, diabetes, and chronic illness burden. In validation studies using American College of Surgeons NSQIP data, the mFI-5 demonstrated strong correlation with the original 11-item index and comparable discrimination for postoperative complications and mortality, supporting its role as a pragmatic risk index rather than a direct measure of biological frailty [11]. In emergency laparotomy, such comorbidity-weighted risk may reasonably influence peri-operative escalation decisions, including invasive monitoring and postoperative ICU admission, without necessarily translating into excess short-term mortality once acute illness severity is accounted for. Therefore, mFI-5 based indices may not be directly interchangeable with clinical frailty constructs, instead positioning them as markers of comorbidity-related peri-operative risk [11]. Our findings support this distinction and caution against interpreting mFI-based indices as interchangeable with clinical frailty constructs.

Clinical implications: reframing the role of frailty in emergency laparotomy

Taken together, these findings suggest that frailty assessment in emergency laparotomy should be viewed as a complementary component of peri-operative risk stratification rather than a stand-alone mortality prediction tool. On the basis of our results, we propose a conceptual pre-operative frailty assessment pathway (Fig. 1) that integrates rapid frailty screening with ASA-based physiological risk assessment.

Fig. 1The alternative text for this image may have been generated using AI.

Conceptual pre-operative frailty assessment pathway for emergency laparotomy. Rapid frailty screening using the Clinical Frailty Scale (CFS), Emergency Surgery Frailty Index (EmSFI), and five-item Modified Frailty Index (mFI-5) is integrated with American Society of Anesthesiologists (ASA) grade–based physiological risk stratification. ASA grade anchors mortality-focused escalation planning, while frailty signals inform morbidity- and recovery-oriented multidisciplinary optimisation and discharge planning

In this model, ASA grade anchors mortality-focused escalation planning, while frailty signals inform morbidity- and recovery-oriented optimisation, including early multidisciplinary input and anticipatory discharge planning. This proposed pathway is hypothesis-generating and would require prospective evaluation. Future pilot studies should assess the feasibility, uptake, and clinical impact of embedding structured frailty screening into emergency laparotomy workflows.

Strengths and limitations

This study adds to the literature by directly comparing three rapid frailty tools within a contemporary emergency laparotomy cohort and examining their associations with postoperative outcomes in adjusted analyses. The use of pragmatic, chart-derivable tools reflects real-world practice and aligns with current quality-improvement priorities, particularly in time-critical emergency surgical settings where prospective bedside assessment may not be feasible.

Several limitations warrant consideration. First, the retrospective design and modest sample size limit statistical power, particularly for mortality outcomes, and increase the risk of type II error. Second, frailty was assessed retrospectively using documentation-derived data rather than prospective bedside evaluation. Although prior studies have demonstrated reasonable agreement between retrospective and prospective frailty scoring, particularly for the Clinical Frailty Scale, incomplete or variable documentation may have led to misclassification, likely biasing associations toward the null [18, 19]. Third, while frailty tools are most commonly validated in populations aged ≥ 65 years, younger adults were included to reflect real-world emergency laparotomy practice; interpretation of frailty measures in patients aged < 65 years should therefore be cautious [20]. As a single-centre study, findings may not be fully generalisable to institutions with different patient demographics, peri-operative pathways, or access to multidisciplinary support. Finally, outcomes were limited to 90-day follow-up due to the absence of registry linkage or longitudinal mortality data, and longer-term functional and survival outcomes could not be assessed.