Burn injuries are among the most devastating forms of trauma and remain a major cause of mortality, disability, and socioeconomic burden worldwide. According to the World Health Organization (WHO), approximately 180,000 burn-related deaths occur annually, with more than 90% occurring in low- and middle-income countries (LMICs), where access to specialized burn care remains limited. Beyond mortality, burn survivors frequently experience prolonged hospitalization, permanent disability, psychological distress, and reduced quality of life, making burn injury a significant global public health challenge¹˒²

Acute thermal burns, including flame, scald, and contact burns, account for most burn-related hospital admissions. Clinical outcomes are influenced by several factors, including age, total body surface area (TBSA) burned, burn depth, inhalation injury, pre-existing comorbidities, and the quality of medical care. Although advances in burn management, such as early resuscitation, wound excision, infection control, and intensive care, have improved survival, mortality remains high among patients with extensive burns and severe associated injuries³–⁶

Previous studies have consistently identified advanced age, larger TBSA, inhalation injury, burn depth, and chronic medical illnesses as major predictors of burn-related mortality. These variables form the basis of established prognostic models, including the revised Baux score and the Abbreviated Burn Severity Index (ABSI). However, the impact of these predictors varies across populations because of differences in burn epidemiology, healthcare infrastructure, and available resources, highlighting the need for region-specific evidence⁷–¹⁰

Pakistan continues to experience a considerable burden of thermal burns, while published evidence regarding predictors of in-hospital mortality remains limited. Most local studies have primarily described epidemiological characteristics rather than evaluating mortality-related predictors in adult burn patients. ¹¹–¹³ Therefore, this retrospective cohort study was conducted to identify predictors of in-hospital mortality among adult patients admitted with acute thermal burns at Khyber Teaching Hospital, Peshawar. The findings may support early risk stratification, improve clinical decision-making, and optimize burn care in resource-limited settings.

This retrospective cohort study was conducted at the Burn and Plastic Surgery Department of Ayub Teaching Hospital, Abbottabad, Pakistan, a tertiary care referral center serving Khyber Pakhtunkhwa and neighboring regions. Medical records of 275 consecutive adult patients (≥18 years) admitted for the duration of January 2025 to June 2025 with acute thermal burns during the study period were reviewed. Patients with electrical, chemical, radiation, or friction burns, those younger than 18 years, patients referred after receiving definitive treatment elsewhere, readmissions for the same burn episode, and records with incomplete clinical or outcome data were excluded. Data were extracted using a standardized proforma. Variables included demographic characteristics (age and sex), burn-related variables (total body surface area [TBSA] burned, burn depth, inhalation injury, and burn mechanism), clinical characteristics (time to hospital presentation, diabetes mellitus, hypertension, mechanical ventilation, intensive care unit [ICU] admission, surgery, and length of hospital stay), and in-hospital outcome (survived or died). The primary outcome was in-hospital mortality, defined as death occurring during the index hospitalization. Data were entered into Microsoft Excel and analyzed using IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA). Continuous variables are presented as mean ± standard deviation (SD) and were compared using the independent-samples t test. Categorical variables are presented as frequencies and percentages and were analyzed using the Chi-square or Fisher's exact test, as appropriate. Mortality trends across age groups, TBSA categories, and time to hospital presentation were assessed using the Chi-square test for trend. A two-sided p value of <0.05 was considered statistically significant. Because several variables demonstrated complete separation with the outcome, stable multivariable logistic regression could not be performed; therefore, the analysis was limited to descriptive statistics and univariate comparisons.

A total of 275 adult patients with acute thermal burns were included in the final analysis. The mean age of the study population was 48.2 ± 19.7 years (range: 18–83 years), and 165 (60.0%) were male. The mean TBSA burned was 31.3 ± 21.0% (range: 5–79%). Flame burns were the predominant mechanism of injury (178, 64.7%), while 121 (44.0%) patients sustained full-thickness burns and 110 (40.0%) had inhalation injury. Diabetes mellitus and hypertension were present in 121 (44.0%) and 116 (42.2%) patients, respectively. Mechanical ventilation was required in 121 (44.0%) patients, 204 (74.2%) were admitted to the ICU, and 95 (34.5%) underwent surgical intervention. The mean time from injury to hospital presentation was 2.66 ± 2.02 hours, and the mean length of hospital stay was 9.82 ± 7.79 days. Overall, 110 (40.0%) patients died during hospitalization, whereas 165 (60.0%) survived (Table 1).

Table 1. Baseline Demographic and Clinical Characteristics of the Study Population (N = 275)

Patients who died were significantly older than survivors (68.8 ± 7.3 vs. 34.5 ± 10.4 years; mean difference 34.3 years; 95% CI 32.1–36.5; t=30.15, p<0.001). Likewise, the mean TBSA burned was significantly higher among non-survivors than survivors (54.0 ± 11.8% vs. 16.2 ± 7.0%; mean difference 37.8%; 95% CI 35.4–40.2; t=29.87, p<0.001). Non-survivors also presented significantly earlier to hospital than survivors (0.85 ± 0.42 vs. 3.86 ± 1.44 hours; t=22.45, p<0.001). No statistically significant difference was observed in the mean length of hospital stay between the two groups (9.60 ± 9.90 vs. 9.97 ± 6.20 days; t=0.35, p=0.728) (Table 2).

Table 2. Comparison of Continuous Variables between Survivors and Non-Survivors

Significant associations with in-hospital mortality were observed for sex, burn depth, inhalation injury, flame burns, diabetes mellitus, hypertension, mechanical ventilation, ICU admission, and surgical intervention (all p<0.05). Female patients experienced a higher mortality rate than males (60.0% vs. 26.7%; χ²=30.15, p<0.001). Mortality was markedly higher among patients with full-thickness burns than those with superficial or partial-thickness burns (χ²=185.47, p<0.001). Similarly, inhalation injury (χ²=275.00, p<0.001), flame burns (χ²=113.14, p<0.001), diabetes mellitus (χ²=185.47, p<0.001), hypertension (χ²=140.66, p<0.001), mechanical ventilation (χ²=185.47, p<0.001), ICU admission (χ²=73.92, p<0.001), and surgical intervention (χ²=6.04, p=0.014) were all significantly associated with mortality (Table 3).

Table 3. Association between Clinical Characteristics and In-Hospital Mortality

Mortality increased progressively with advancing age (Table 4). Patients aged 18–30 years had a mortality rate of 10.3%, which increased to 11.3% among those aged 31–45 years, 36.6% among patients aged 46–60 years, and 85.2% among those older than 60 years. This trend was statistically significant (χ² for trend=89.45, p<0.001

Table 4. Association between Age Group and In-Hospital Mortality

A similar trend was observed for burn size (Table 5). Mortality increased from 6.0% in patients with TBSA <20% to 30.6% among those with TBSA between 20% and 40%, 89.1% in patients with TBSA of 41–60%, and 100% in patients with burns involving >60% TBSA (χ² for trend=112.34, p<0.001).

Table 5. Association between Burn Size (TBSA) and In-Hospital Mortality

Chi-square test for trend.

Time from injury to hospital presentation was also significantly associated with mortality (Table 6). Mortality was highest among patients presenting within one hour of injury (100.0%) and progressively decreased with longer presentation times, reaching 12.4% among patients presenting more than four hours after injury (χ² for trend=78.23, p<0.001). Because this was an observational retrospective study, this finding most likely reflects the greater severity of burns among patients requiring immediate transfer to the tertiary care center rather than indicating that earlier presentation itself increased mortality.

Table 6. Association between Time to Hospital Presentation and In-Hospital Mortality

This retrospective cohort study evaluated predictors of in-hospital mortality among adult patients admitted with acute thermal burns at a tertiary care burn center in Pakistan. The overall in-hospital mortality was 40.0%, with mortality significantly associated with advanced age, greater total body surface area (TBSA) burned, full-thickness burns, inhalation injury, flame burns, diabetes mellitus, hypertension, mechanical ventilation, ICU admission, and surgical intervention. These findings are consistent with previous studies identifying burn severity and patient-related factors as major determinants of mortality¹–⁴ The mortality rate observed in our study is higher than that reported in many high-income countries but is comparable to findings from several low- and middle-income countries where specialized burn services and critical care resources remain limited²˒⁵˒⁶ Khyber Teaching Hospital is a major tertiary referral center that receives critically ill burn patients from across Khyber Pakhtunkhwa and neighboring regions, which may explain the relatively high mortality observed in this cohort. Advanced age was strongly associated with mortality, with patients older than 60 years experiencing the poorest outcomes. Age has consistently been recognized as an important predictor of burn mortality because elderly patients have reduced physiological reserve, impaired immune function, and multiple comorbidities that limit recovery following severe burns. These findings are consistent with previous reports and support the continued use of age in established prognostic models such as the revised Baux score²˒³˒⁷ Burn size was another major determinant of outcome. Mortality increased progressively with increasing TBSA and was highest among patients with burns involving more than 60% of the body surface area. Larger burns produce profound inflammatory and hypermetabolic responses, increase the risk of sepsis and multiple organ dysfunction, and remain one of the strongest predictors of mortality worldwide. Our findings agree with previous studies that have consistently identified TBSA as a principal predictor of burn-related death⁴˒⁸˒⁹ Patients with full-thickness burns and inhalation injury had significantly higher mortality than those with less severe injuries. Deep burns are associated with extensive tissue destruction, delayed wound healing, and increased susceptibility to infection, whereas inhalation injury contributes to respiratory failure and prolonged ventilatory support. Similar associations have been reported in previous studies, highlighting the importance of these variables in early risk assessment³˒¹⁰˒¹¹ Diabetes mellitus and hypertension were also significantly associated with mortality. These chronic conditions may adversely affect burn outcomes through impaired wound healing, microvascular dysfunction, reduced immune response, and decreased physiological reserve. Although these comorbidities are unlikely to act independently of burn severity, they identify patients who require closer monitoring and more intensive management. Comparable findings have been reported in recent studies evaluating the impact of pre-existing medical conditions on burn outcomes. ¹²˒¹³ Mechanical ventilation and ICU admission were significantly associated with mortality; however, these variables should be interpreted as indicators of severe illness rather than direct causes of death. Patients requiring ventilatory support or intensive care generally present with extensive burns, inhalation injury, or multiple organ dysfunction, all of which substantially increase the risk of mortality. Similar observations have been reported in previous burn literature. ¹⁴˒¹⁵ An inverse association was observed between time to hospital presentation and mortality, with patients presenting earlier demonstrating higher mortality. This finding most likely reflects referral bias rather than a harmful effect of early presentation, as patients with more severe burns are typically transferred immediately to tertiary care facilities, whereas those with less severe injuries often present later after initial stabilization elsewhere. Similar referral patterns have been described in other studies from resource-limited healthcare settings. ¹⁶˒¹⁷ The findings of this study have important clinical implications. Early identification of elderly patients, individuals with extensive or full-thickness burns, inhalation injury, and significant comorbidities may facilitate prompt triage, aggressive resuscitation, timely referral to specialized burn centers, and appropriate utilization of intensive care resources. Recognition of these high-risk characteristics may improve clinical decision-making and optimize outcomes in resource-constrained settings. This study has several limitations. The retrospective single-center design may limit the generalizability of the findings and is subject to the limitations of routinely recorded medical data. In addition, several variables demonstrated near-complete separation with mortality, limiting the application of stable multivariable regression analysis. Furthermore, information regarding microbiological findings, nutritional status, and long-term functional outcomes was unavailable. Despite these limitations, this study provides valuable evidence regarding predictors of in-hospital mortality among adult burn patients treated at a major tertiary care center in Pakistan. The findings contribute important regional data and may assist clinicians in identifying high-risk patients at an early stage. Future multicenter prospective studies incorporating standardized burn severity scores and robust multivariable statistical models are recommended to validate these findings and improve mortality prediction in patients with acute thermal burns.

This retrospective cohort study identified several important clinical predictors of in-hospital mortality among adult patients admitted with acute thermal burns at a tertiary care burn center in Pakistan. Advanced age, greater total body surface area (TBSA) burned, full-thickness burns, inhalation injury, flame burns, diabetes mellitus, hypertension, mechanical ventilation, ICU admission, and surgical intervention were significantly associated with increased in-hospital mortality. Mortality increased progressively with advancing age and increasing burn size, emphasizing the importance of early recognition of patients at high risk for adverse outcomes.

The findings highlight the need for prompt assessment, timely referral to specialized burn centers, aggressive resuscitation, and multidisciplinary management, particularly for elderly patients, those with extensive or deep burns, inhalation injury, and significant pre-existing comorbidities. Identification of these high-risk characteristics may improve clinical decision-making, optimize resource allocation, and facilitate early intensive care interventions in resource-limited healthcare settings.

Although the retrospective single-center design limits the generalizability of the findings, this study contributes valuable evidence regarding mortality among burn patients in Pakistan and adds to the limited regional literature. Future multicenter prospective studies incorporating standardized burn severity scores and robust multivariable statistical models are recommended to validate these findings and improve mortality prediction in patients with acute thermal burns.

Acknowledgments

The authors sincerely acknowledge the administration of Ayub Teaching Hospital, Peshawar, and the staff of the Burn Unit for their cooperation and assistance during data collection. The authors also appreciate the support provided by the Medical Records Department in facilitating access to the required patient records.

Funding

This research received no external funding from any public, commercial, or not-for-profit funding agency.

Conflict of Interest

The authors declare that they have no competing interests.