Sepsis is clearly defined as a life-threatening organ dysfunction arising from a dysregulated host response to infection. This is a major challenge in critical care medicine and a leading cause of morbidity and mortality globally [1]. The clinical course of the disease is an extremely unpredictable spectrum, rapidly progressing from localized infection to severe systemic inflammation, multiple organ dysfunction syndrome (MODS), and finally to septic shock. Septic shock is a profound cellular and metabolic abnormality clinically associated with a greater risk of mortality than sepsis alone, as evidenced by persistent hypotension requiring vasopressors to maintain a mean arterial pressure of 65 mm Hg or greater and a serum lactate level greater than 2 mmol/L despite adequate volume resuscitation [2]. Sepsis is responsible for a significant percentage of Intensive Care Unit (ICU) admissions worldwide which puts a great burden on the healthcare system. Recent epidemiological data suggest that sepsis incidence continues to rise, driven by aging populations, the increasing prevalence of chronic immunosuppressive comorbidities, and the growing threat of antimicrobial resistance [3].

Sepsis is a big problem in developing countries like India. The incidence of sepsis in India has been estimated to be 540-640 per 100,000 population with nearly 9 million cases annually [4]. The mortality in these settings is alarmingly high and varies often between 25% and 50% depending on the availability of resources at the institution and the demographics of the patients [5]. Such critically ill patients are often referred late in the course of the disease to tertiary care centers in India that are flooded with such patients and need an in depth understanding of localized disease patterns and clinical outcomes [6]. Management of sepsis involves early recognition, rapid and aggressive fluid resuscitation, adequate source control, and early administration of appropriate broad spectrum antimicrobial agents. Despite following international protocols like the Surviving Sepsis Campaign (SSC) guidelines, outcomes are still suboptimal in many resource-limited settings.

Effective risk stratification is vital to optimize care and ensure judicious use of limited ICU resources. Severity of illness scoring systems, most notably the Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores, have been well validated. These scores are used to estimate the risk of death based on objective physiological derangements present on admission [7]. In addition to composite scores, the need for invasive therapeutic interventions (e.g., mechanical ventilation for acute respiratory distress syndrome [ARDS] and continuous vasopressor infusions for refractory distributive shock) are strong, tangible markers of severe organ dysfunction and are consistently associated with worse patient outcomes [8].

The enormous heterogeneity of the disease and regional differences in pathogen profiles and healthcare infrastructure create a continuous need for current, setting-specific clinical data. Good predictors of mortality using clinical variables can vary widely by specific ICU setting and population demographic characteristics admitted. Understanding these specific predictors is crucial for improving admission criteria, tailoring aggressive treatment pathways and improving the overall quality of critical care delivery. Hence, this retrospective observational study was thoughtfully planned to assess the clinical features, specific management and conclusive predictors of mortality in critically ill adult patients admitted with a primary diagnosis of sepsis or septic shock to tertiary care teaching institute in Bengaluru, Karnataka, India.

Study Design and Setting This research was structured as a retrospective, single-center, observational cohort study. The investigation was conducted in the multidisciplinary intensive care unit of tertiary care teaching institute in Bengaluru, Karnataka, India. This institution serves as a critical tertiary referral center for the region, equipped to manage a wide array of complex medical and surgical emergencies. The study analyzed data consecutively collected over a defined three-month period. Study Population and Selection Criteria The study population comprehensively included all adult patients, defined as those aged 18 years and above, who were consecutively admitted to the ICU during the stipulated three-month study timeframe with a primary, confirmed diagnosis of sepsis or septic shock. The diagnosis of sepsis and septic shock was established using the criteria outlined by the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). To maintain the integrity of the severity scoring, patients with an ICU length of stay of less than 24 hours were explicitly excluded from the analysis. This exclusion prevented the skewing of data by patients who experienced transient instability or precipitous death before full clinical evaluation could be performed. Additionally, patients transferred to other healthcare facilities prior to a definitive clinical outcome (discharge or death), or those with significantly incomplete electronic health records, were excluded. A final, highly controlled cohort of 60 critically ill patients met all stringent inclusion criteria. Data Collection and Variable Definition A rigorous data extraction protocol was executed by trained clinical researchers. Detailed clinical, demographic, and physiological information was retrospectively mined from the hospital’s electronic health records and daily ICU nursing flowsheets. The variables extracted included basic patient demographics (chronological age and biological sex) and a comprehensive history of chronic pre-existing comorbidities, notably type 2 diabetes mellitus, systemic hypertension, chronic kidney disease, and chronic obstructive pulmonary disease. The primary suspected source of infection upon admission was meticulously categorized (e.g., respiratory tract, intra-abdominal, urinary tract, or soft tissue). The severity of the critical illness was objectively quantified using two well-established composite scoring systems: the Acute Physiology and Chronic Health Evaluation (APACHE) II score and the Sequential Organ Failure Assessment (SOFA) score. Both scores were calculated based on the most severe physiological variables and laboratory parameters documented during the initial 24 hours of ICU admission. Regarding clinical interventions, the necessity for invasive mechanical ventilation at any point during the ICU admission was recorded as a binary variable, indicating profound respiratory failure. Furthermore, the sustained requirement for vasopressor support (such as norepinephrine, epinephrine, or vasopressin) to combat refractory hypotension and maintain a mean arterial pressure of at least 65 mmHg was documented, confirming the presence of septic shock. The primary clinical endpoints of the study were the total length of stay in the intensive care unit (measured in full days) and the definitive patient outcome upon ICU discharge, categorized binarily as either 'survivor' or 'non-survivor'. Statistical Analysis Plan All collated data were subjected to rigorous statistical evaluation using the appropriate software. Continuous variables, encompassing patient age, APACHE II scores, SOFA scores, and length of ICU stay, were tested for normal distribution using the Shapiro-Wilk test. Normally distributed continuous data were expressed as mean values accompanied by their standard deviation (± SD) and were compared between the survivor and non-survivor cohorts using the independent samples Student's t-test. Categorical variables, including gender, specific comorbidities, diagnostic categories representing the source of infection, and the requirement for specific life-support interventions, were summarized as absolute frequencies and percentages. These categorical variables were compared using the Chi-square test or Fisher's exact test, as appropriate for the sample sizes within the contingency tables. A two-tailed p-value of less than 0.05 was prospectively established as the threshold for statistical significance for all analytical tests.

During the predefined three-month study period, a total of 60 adult patients admitted to the ICU met the strict inclusion criteria for sepsis or septic shock and were included in the final analytical cohort. The overarching baseline demographic and clinical characteristics of this patient population highlight the severe nature of their illness upon presentation. The cohort displayed a moderate male predominance, comprising 35 males (58.3%) and 25 females (41.7%). The mean age of the entire study group was 52.8 ± 15.1 years. A significant proportion of the patients presented with pre-existing chronic conditions, with diabetes mellitus (43.3%) and hypertension (35.0%) being the most prevalent comorbidities. The primary source of the septic insult was predominantly respiratory in origin, accounting for 45.0% of the admissions, followed by intra-abdominal infections (25.0%) and complicated urinary tract infections (15.0%). The profound severity of illness across the cohort was reflected in the elevated mean admission severity scores, with a mean APACHE II score of 18.8 ± 6.8 and a mean SOFA score of 6.7 ± 3.4. Of the 60 patients, 31 (51.7%) met the clinical criteria for septic shock upon admission or during their ICU stay, requiring vasopressor support.

Table 1: Baseline Demographic and Clinical Characteristics of the Study Cohort (n = 60)

The primary outcome analysis revealed that the overall intensive care unit mortality rate for this critically ill cohort was 35.0%, corresponding to 21 non-survivors out of the 60 admitted patients. The remaining 39 patients (65.0%) were successfully treated and discharged from the ICU. A detailed comparative analysis was subsequently performed to isolate specific clinical and demographic variables that differed significantly between the survivor and non-survivor subgroups, as delineated in Table 2.

Chronological age proved to be a highly significant predictor of mortality. The mean age of the non-surviving cohort was substantially higher (62.4 ± 11.2 years) compared to the surviving cohort (47.6 ± 14.3 years), demonstrating robust statistical significance (p < 0.01). Gender, conversely, did not exert a statistically significant influence on the outcome (p = 0.81).
Both severity scoring systems analyzed in this study were profoundly elevated in the non-survivor group. The mean baseline APACHE II score was drastically higher in those who died (25.4 ± 6.1) compared to those who survived (15.2 ± 4.8; p < 0.01). Similarly, the degree of early organ dysfunction, quantified by the SOFA score, was significantly worse in non-survivors (9.8 ± 3.2) versus survivors (5.1 ± 2.1; p < 0.01). The application of invasive, life-sustaining interventions was intrinsically tied to mortality. An overwhelming 85.7% (18 out of 21) of the non-survivors necessitated invasive mechanical ventilation, compared to only 30.8% (12 out of 39) of the survivors (p < 0.01). Likewise, profound hemodynamic collapse requiring vasopressor support was present in 90.5% (19 out of 21) of the non-survivors, whereas only 35.9% (14 out of 39) of the survivors required such cardiovascular intervention (p < 0.01). Finally, the total duration of the ICU stay was markedly prolonged for the non-surviving patients (10.2 ± 4.5 days) compared to the survivors (6.1 ± 2.8 days; p < 0.01).

Table 2: Comparative Analysis of Predictor Variables Between Survivors and Non-Survivors

This retrospective analysis provides an in-depth description of the clinical phenotype and the important predictors of mortality among patients admitted with sepsis and septic shock to a tertiary care intensive care unit. In our cohort, the overall ICU mortality rate was 35.0%. This finding is very much in corroboration with recent epidemiological data from similar critical care settings across India. Mortality in relation to sepsis is consistently reported to be between 30 and 45% in multicenter registries and local cohort studies [9]. Such a high and sustained mortality rate underscores the devastating physiological toll of dysregulated systemic infection, often exacerbated by delays in initial presentation, resource limitations and high burden of antimicrobial resistant pathogens common to the region. By statistical analysis, we demonstrated that advanced age, very high severity scores at baseline (APACHE II and SOFA), and the need for invasive organ support (mechanical ventilation and vasopressors) were powerful independent predictors of death. The robust relationship between advanced age and increased mortality observed in our study (mean age of 62.4 years in non-survivors vs 47.6 years in survivors) is a well-established paradigm in sepsis pathophysiology [10]. With aging, innate and adaptive immune responses become senescent and physiological reserves across all organ systems are critically reduced. This state of relative ‘frailty’ severely blunts the patient’s capacity to tolerate and recover from profound hemodynamic and inflammatory stress. In addition, older patients always have a much wider range of chronic comorbidities. Diabetic nephropathy, ischemic heart disease and chronic lung disease are pre-existing conditions that complicate the clinical picture in a complex manner, limit the margin for aggressive fluid resuscitation and accelerate the path towards multiple organ dysfunction syndrome (MODS) [11].Severity scoring systems are the backbone of objective prognostication in the ICU. In our study, both APACHE II and SOFA scores calculated during the first 24 hours of admission showed an excellent discriminative accuracy, with significantly higher baseline scores in non-survivors. This strong finding supports the continuous and essential usefulness of the APACHE II system which combines physiological and laboratory parameters, which are routine and universally available, in predicting mortality with a high degree of accuracy [12]. The concurrent increase of SOFA scores suggests that the degree of established early organ failure at admission is likely the most important determinant of ultimate survival. Strong and linear association between increasing initial severity scores and catastrophic outcomes is consistently reiterated in robust evidence from multiple ICUs across the Indian subcontinent, highlighting the imperative need for uniform physiological evaluation at the time of ICU triage to accurately plot clinical expectations [13]. Our cohort data additionally emphasized the dire prognostic implications of the initiation of invasive organ support modalities. Of the patients who died of their illness, the majority received invasive mechanical ventilation (85.7%) and strong vasopressor support (90.5%). Mechanical ventilation in sepsis usually means the onset of severe acute respiratory distress syndrome (ARDS) or catastrophic respiratory failure due to severe systemic inflammation, capillary leak or severe metabolic acidosis [14]. Studies done in medical ICUs in India, have confirmed that the overlap of severe sepsis and the need for mechanical ventilation is a highly lethal clinical situation that increases the risk of death exponentially [15]. Hence, the presence of septic shock is marked by a need for vasopressors and is characterized by refractory vasodilation, myocardial depression, and severe cellular hypoxia. The two things needed to keep them alive are almost always a sign that they are in the advanced stages of multiple organ failure, which is deep-rooted and often irreversible. The modern intensivist, especially in tertiary referral centers with high patient volumes, needs to translate these robust statistical findings into daily clinical practice. A paradigm of hyper-vigilance should immediately follow the rapid identification of patients presenting with advanced age and high admission severity scores. These predictive parameters allow clinicians to optimize triage, prioritize the rapid escalation of advanced therapeutic modalities (such as early goal-directed therapy or renal replacement therapy), and ensure the judicious allocation of critical resources such as ventilator beds. Importantly, objective prognostic data can facilitate early, honest, and scientific goals-of-care conversations with the families of high-risk patients to align medical interventions with patient values and avoid false hope. While the clinical correlations are robust, the interpretation of this data must be aware of the study's inherent limitations. The retrospective single-center design is inherently reliant on the completeness of the archival medical records and does not permit the real-time measurement of dynamic inflammatory biomarkers. The sample size of 60 patients, collected within a short span of three months from a single medical college also limits the wide and unreserved generalizability of particular statistical outcomes to far different demographic populations or better-resourced private healthcare settings. Future academic pursuits should aim to establish large-scale prospective multicenter longitudinal registries across the diverse geographic terrain of India.

In conclusion, in this analysis of critically ill adult patients admitted with sepsis and septic shock to a tertiary care medical college ICU in India, the overall mortality rate was high (35.0%). Advanced chronologic age coupled with markedly increased baseline APACHE II and SOFA scores were early, powerful, and independent predictors of mortality. Moreover, the clinical course requiring aggressive organ support (ie, invasive mechanical ventilation and vasopressor infusions) was overwhelmingly associated with a fatal outcome, further emphasizing the lethal nature of profound multiorgan failure. Timely identification of these high-risk clinical markers is critical for effective risk stratification, guiding resource-intensive therapeutic management, and improving the quality and precision of care delivered to this highly vulnerable patient population.

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