Lactate Enhanced Quick Sequential Organ Failure Assessment Score (Lqsofa) as a Tool to Predict the Prognosis in Patients of Sepsis in Surgical Intensive Care Unit

INTRODUCTION

Sepsis is a critical medical condition resulting from infections that activate extensive inflammation and subsequent organ dysfunction.^[1] Even though sepsis has a significant impact on public health, it is frequently underrecognized. Due to its high rates of morbidity and mortality underscores its importance as a major concern for healthcare systems.^[1] According to a recent report published by the World Health Organization (WHO), sepsis was responsible for 48.9 million cases and 11 million deaths globally in 2020, accounting for approximately 20% of all deaths worldwide.^[2,3] The report also highlighted that nearly half of these sepsis cases, around 20 million, occurred in children under the age of 5. Furthermore, it was estimated that, for every 1,000 hospitalized patients, approximately 15 would develop sepsis as a healthcare-associated complication.

The severity of sepsis is highlighted by incidence rates ranging from 240 to 1,031 cases per 100,000 individuals across different studies.^[4-7] Mortality rates can reach 20-40%, rising to 80% in cases of septic shock.^[6] While sepsis affects individuals worldwide, significant regional differences are evident, with the highest incidence and mortality rates found in low- and middle-income countries.^[3]

According to the Sepsis III guidelines (2016), sepsis is defined as a life-threatening condition involving acute organ dysfunction resulting from an abnormal host response to an infection.^[7] [Singer M,] The Sequential Organ Failure Assessment (SOFA) score and its simplified version, the quick SOFA (qSOFA) score,^[8] are widely used tools for prognostication in sepsis. However, the qSOFA has limitations in predicting outcomes due to its simplicity, which may not capture the full spectrum of physiological derangements in critically ill patients. In the area of medical healthcare, lactate has gained attention as a key biomarker of tissue hypoperfusion and metabolic stress, which serve as an independent predictor of adverse sepsis outcomes and emphasizing its role in monitoring patient management. Conventionally, lactic acidosis in sepsis is attributed to anaerobic glycolysis due to inadequate oxygen delivery. However, it has become clear that the mechanism of hyperlactataemia in sepsis is multifactorial. A higher level usually portends worse outcomes, and there is growing evidence of lactate clearance being a standalone prognostic marker.^[9]

Recent evidence highlighted the potential of the lactate-enhanced quick Sequential Organ Failure Assessment (LqSOFA) as a promising prognostic tool for mortality prediction in patients with sepsis. This approach integrates bedside lactate measurement with the qSOFA score to enhance risk stratification. In a comprehensive analysis of 12,555 cases, Amith Shetty et al.^[10] demonstrated that including a lactate threshold (≥2 mmol/L) into the LqSOFA score (≥2) significantly increased its sensitivity for predicting adverse outcomes to 65.5%. While existing studies have explored various rapid assessment methods, there is a notable paucity of research directly comparing these tools with serum lactate.^[11] Whereas Liu et al. (2019)^[12] evaluated serum lactate, qSOFA, and SOFA scores for mortality prediction in sepsis but did not include LqSOFA in their analysis.

Despite these advancements, comparative evidence on rapid prognostic tools, especially LqSOFA, remains limited. In this background, the present study aims to evaluate the accuracy of the q-SOFA score along with serum lactate level to predict the prognosis in patients of sepsis in the Surgical ICU.

MATERIAL AND METHODS

The present prospective observational study was conducted in a tertiary health care center in Bhopal and enrolled patients with sepsis admitted to the Surgical Intensive Care Unit (SICU) between May 1, 2023, to April 30, 2025. The present study was initiated following approval from the Institutional Ethical Committee and after obtaining informed written consent from all participants.

Patients with suspected sepsis, identified based on the criteria established in the Sepsis Guidelines 2016 (SEPSIS 3)^[7], were included in the study. Exclusion criteria encompassed patients without sepsis and those who left against medical advice. A total of 107 patients diagnosed with infective surgical conditions were included, and their clinical and laboratory data were systematically collected.

At the time of admission, each patient underwent a thorough clinical evaluation, including detailed history-taking and physical examination. A baseline laboratory workup was conducted for all participants. Standard treatment protocols for sepsis management were adhered to during the study. The study introduced a novel LqSOFA2 score, which combined the qSOFA score with a lactate level of ≥2 mmol/L. An additional point was assigned to patients with lactate levels meeting or exceeding this threshold, aligning with the single-point weightage of each qSOFA variable.

Upon admission, qSOFA and LqSOFA scores were calculated, and serum lactate levels were measured within the first 24 hours. The SOFA score was calculated on days one, three, and seven. The study aimed to evaluate the predictive accuracy of qSOFA, lactate, and the LqSOFA2 score in mortality prediction and to compare their respective performance metrics.

Each patient was closely monitored throughout their SICU stay. Outcomes were recorded based on in-hospital mortality (primary outcome) and length of stay in the SICU (secondary outcome). Data regarding these parameters were systematically documented and analysed.

RESULTS

The distribution of qSOFA scores was as follows: 44.86% scored 0, 19.63% scored 1, 12.15% scored 2, and 23.36% scored 3. The mean qSOFA score was 1.14 ± 1.22, indicating moderate severity [Table 1 and Graph 1].

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Graph 1:

Quick SOFA in patient of Sepsis in surgical ICU. SOFA: Sequential organ failure assessment, ICU: Intensive care unit.

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Higher qSOFA scores correlated with longer SICU stays: mean lengths ranged from 4.18 ± 2.37 days (score 0) to 4.64 ± 3.00 days (score 3), with this association being statistically significant (p=0.020) [Table 2 and Graph 2].

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Graph 2:

Association of q-SOFA score with length of SICU stay. qSOFA: quick Sequential organ failure assessment, SICU: Surgical intensive care unit.

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Hospital mortality increased with qSOFA scores: no deaths in score 0, 4.76% mortality in score 1, and 23-24% mortality in scores 2 and 3 (p=0.001) [Table 3 and Graph 3].

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Graph 3:

Association of q-SOFA score with hospital mortality. qSOFA: quick Sequential organ failure assessment.

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LqSOFA scores

LqSOFA scores ranged from 0 to 4, with increasing scores associated with longer SICU stay (mean 4.08 days at score 0 to 4.64 days at score 4, p=0.009) [Table 4 and Graph 4].

Table 4: Association of Lq-SOFA score with length of SICU stay.

Lq-SOFA score No of cases		Length of SICU stay (Days)
		1-3	4-6	>7	Average No of days
		No of cases	No of cases	No of cases
0	36	19	9	8	4.08
1	20	9	7	4	4.25
2	13	6	4	3	4.30
3	13	4	5	4	4.61
4	25	10	8	7	4.64

LqSOFA: Lactate enhanced quick sequential organ failure assessment, SICU: Surgical intensive care unit

Fisher’s exact test- 19.413 P-value- 0.009

p ≤ 0.05 → Significant

• p > 0.05 → Not significant.

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Graph 4:

Association of Lq-SOFA score with length of SICU stay. LqSOFA: Lactate enhanced quick sequential organ failure assessment, SICU: Surgical intensive care unit.

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Mortality was 0% at scores 0–1 and increased significantly at scores 3 and 4 (p=0.001) [Table 5 and Graph 5].

Table 5: Association of Lq-SOFA score with hospital mortality.

LQ-SOFA score	No of cases	Hospital mortality	Survived
0	36	0 (0.00%)	36 (100.00%)
1	20	0 (0.00%)	20 (100.00%)
2	13	1 (7.70%)	12 (92.30%)
3	13	3 (23.08%)	10 (76.92%)
4	25	6 (24.00%)	19 (76.00%)

LqSOFA: Lactate enhanced quick sequential organ failure assessment, Fisher’s exact test=14.036

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Graph 5:

Association of Lq-SOFA score with hospital mortality. LqSOFA: Lactate enhanced quick sequential organ failure assessment.

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Prognostic accuracy

LqSOFA demonstrated superior predictive performance with sensitivity 73.8%, specificity 63.1%, and AUC 0.831 (95% CI 0.656–0.868). qSOFA alone had sensitivity 71.3%, specificity 62.8%, and AUC 0.793, while lactate alone showed sensitivity 79% but lower specificity (45.36%) and AUC 0.727 [Table 6, Graphs 6-9].

Table 6: Accuracy of q-SOFA score, lactate & Lq-SOFA individually in predicting the prognosis in these patients.

Parameter	q-SOFA (Cut-off: 2)	Lactate (Cut off: ≥2mmol/L	Lq-SOFA (Cut-off: 3)
Sensitivity (%)	71.3%	79%	73.8%
Specificity (%)	62.8.%	45.36%	63.1%
AUC (95% CI)	0.793 (0.636-.834)	0.727 (0.618-0.815)	0.831 (0.656-0.868)
Critical cut-off	2	≥2mmol/l	3
P-value	0.001	0.019	0.001

LqSOFA: Lactate enhanced quick sequential organ failure assessment, q-SOFA: quick Sequential organ failure assessment

p ≤ 0.05 → Significant

• p > 0.05 → Not significant.

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Graph 6:

ROC curve: q-SOFA. q-SOFA: quick Sequential organ failure assessment, ROC: Receiver operating characteristic.

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Graph 7:

ROC curve: Lactate. ROC: Receiver operating characteristic.

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Graph 8:

ROC curve: Lq-SOFA. Lq-SOFA: Lactate enhanced quick sequential organ failure assessment, ROC: Receiver operating characteristic.

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Graph 9:

AUC curve: q-SOFA+LACTATE+Lq-SOFA. Lq-SOFA: Lactate enhanced quick sequential organ failure assessment, AUC: Area under curve, q-SOFA: quick Sequential organ failure assessment.

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DISCUSSION

This study assessed the demographic and clinical profiles of 107 patients diagnosed with sepsis and admitted to the Surgical Intensive Care Unit (SICU) at People’s Hospital, Bhopal. A particular focus was placed on evaluating the prognostic performance of qSOFA, serum lactate, and the lactate-enhanced qSOFA (LqSOFA) in predicting in-hospital mortality and SICU length of stay. The mean age of the cohort was 48.37 ± 11.25 years, which is comparable to findings reported by Daga MK et al. (2021)^[9] and Kumar R et al. (2023),^[13] suggesting a predominance of middle-aged adults affected by surgical sepsis in the Indian population. This contrasts with Western data, such as that of Liu Z et al. (2019)^[12], which reported a higher mean age of 68 years. These differences may reflect demographic, healthcare access, or reporting disparities between regions. A male predominance (72.9%) was observed, consistent with both national and international literature. Sex-based variations in sepsis incidence may be influenced by biological susceptibility, occupational exposure, or differences in healthcare-seeking behavior. Soft tissue infections, both diabetic and non-diabetic, as well as intra-abdominal pathologies, including perforation, peritonitis, and acute pancreatitis, were the most common primary diagnoses. This spectrum highlights the diverse presentations of surgical sepsis and underscores the need for prompt, multidisciplinary intervention.

Nearly half (46.72%) of the patients had one or more comorbidities, such as diabetes mellitus, hypertension, or cardiovascular disease. These findings support earlier work by Patil C et al. (2024)^[14], which linked the presence of comorbidities to higher SOFA scores and worse outcomes, emphasizing the prognostic value of comorbidity assessment. The mean qSOFA score was 1.14 ± 1.22, with most patients scoring 0 or 1. A significant increase in hospital mortality was observed with higher qSOFA scores (p = 0.001), with patients scoring ≥2 experiencing mortality rates between 23.08% and 24.00%. These results are congruent with previous studies by Sohn YW et al. (2019)^[15] and Jung et al. (2018)^[16], reinforcing the role of qSOFA as a simple yet effective clinical tool for risk stratification.

Elevated serum lactate levels (≥2 mmol/L) were present in 58.88% of patients, with a mean value of 2.4 mmol/L. Higher lactate levels were significantly associated with both prolonged SICU stay (p = 0.031) and increased hospital mortality (p = 0.006). These findings are consistent with prior studies by Ralphe Bou Chebl et al. (2017)^[17], validating lactate as a sensitive early indicator of tissue hypoperfusion and sepsis severity.

The mean LqSOFA score was 1.91 ± 1.64. A significant positive correlation was found between higher LqSOFA scores and both increased SICU stay (p = 0.009) and mortality (p = 0.001). Notably, no deaths occurred in patients with LqSOFA scores of 0–1, while mortality progressively increased with higher scores. These results echo those of Daga MK et al. (2021)^[9] and Mondal JI et al. (2023)^[18], suggesting that LqSOFA offers superior risk prediction compared to qSOFA or lactate alone. Among the three tools evaluated, LqSOFA demonstrated the highest predictive accuracy for mortality, with an AUC of 0.831. In contrast, qSOFA and serum lactate yielded lower AUCs of 0.793 and 0.727, respectively. Although lactate alone showed the highest sensitivity (79%), it had the lowest specificity (45.36%), highlighting its utility when used in combination with other parameters rather than as a standalone marker. These findings are consistent with those of Gill A et al. (2022)^[19], who demonstrated improved sensitivity and specificity when lactate was integrated with qSOFA. The incorporation of serum lactate into the qSOFA score significantly enhances its prognostic utility, facilitating more accurate triage, risk assessment, and resource allocation in critically ill surgical patients. This is particularly relevant in low-resource settings where timely and efficient decision-making is paramount. Future studies should explore broader implementation and assess the external validity of LqSOFA in diverse healthcare environments.

CONCLUSION

This study demonstrates that the Lactate-enhanced quick Sequential Organ Failure Assessment (LqSOFA) score serves as a more accurate and reliable prognostic tool compared to qSOFA or serum lactate levels alone in predicting outcomes among sepsis patients admitted to the SICU. The inclusion of serum lactate significantly improves the sensitivity and predictive value of the qSOFA score, enabling earlier identification of patients at higher risk of mortality and prolonged SICU stay.

The findings underscore the clinical utility of LqSOFA as a rapid bedside assessment tool, particularly valuable in resource-limited and high-intensity surgical settings where timely decision-making is critical. Integration of LqSOFA into sepsis management protocols may facilitate improved patient triage, prompt initiation of targeted therapy, and ultimately better clinical outcomes. Further multi-centric studies are warranted to validate these findings and support their wider clinical adoption.