The primary aim of this study was to evaluate the impact of pre-existing creatinine and eGFR levels on patient mortality. When we divided the patients into two groups as survivors and non-survivors, creatinine and eGFR changes were found to be significant between these two groups (p: 0.030 p: 0.008 respectively). Although this showed that the difference between the two groups was significant, univariate analysis was performed to investigate the effect of this situation on mortality. In univariate analysis, 1-year ago creatinine and eGFR values were found to be significant (HR: 2.512, p: 0.05, HR: 0.973 p: 0.002 respectively). In the multivariate regression analysis, eGFR was excluded due to multicollinearity. Since eGFR is calculated using creatinine, it was excluded from the Cox regression analysis due to multicollinearity. The analysis identified that an increase in creatinine levels one year prior significantly impacted mortality rates (HR:9,121, 95% CI:2.686–30.970, p < 0,001). The major finding of our study is that impaired pre-earthquake kidney function is significantly associated with increased in-hospital mortality among patients with earthquake-related crush syndrome. Implementing routine screening for renal impairment in populations residing in earthquake-prone areas could help identify high-risk individuals, allowing for more effective and prioritized allocation of medical resources during and after such events. This also highlights the importance of laboratory data in disaster periods when obtaining a patient’s medical history is often not possible.

The baseline serum creatinine levels were significantly higher in non-survivors than in survivors: 1.04 ± 0.61 mg/dL versus 0.77 ± 0.33 mg/dL, respectively (p = 0.030). This aligns with previous literature indicating that poor kidney function at presentation is a robust predictor of adverse outcomes in trauma patients [8]. The pre-admission eGFR was also lower in non-survivors than in survivors: 85.2 ± 34.7 mL/min/1.73 m² versus 115.8 ± 39.4 mL/min/1.73 m², respectively (p = 0.008). These observations are corroborated by the present study for and point toward the universal application of kidney function as a prognostic marker in trauma [9]. Our study aligns with other studies that kidney dysfunction is already an excellent predictor of poor trauma patient outcomes [10]. Various studies indicate that patients who suffer from CKD or with diminished baseline kidney function will then go on to suffer from complications of AKI, sepsis, and multi-organ failure after the incident [11].

Crush syndrome is a severe condition caused by muscle damage, which releases myoglobin and electrolytes into the bloodstream. It often follows trauma, such as earthquakes or armed conflicts, when victims remain trapped under debris. Rhabdomyolysis can also result from prolonged seizures, drug overdoses, or autoimmune diseases affecting muscle tissue. Incidence rates vary widely—from 5% in Hanshin-Awaji, Japan, to 37% in Kahramanmaraş, Türkiye. Identifying factors behind these differences is key to improving prevention and treatment strategies [12, 13].

Kidney damage is a common complication of crush syndrome and significantly impacts mortality. Studies report its prevalence ranging from 12% to 41% [14, 15]. These variations reflect the complexity of crush syndrome and the need for timely medical care to reduce kidney complications and improve survival. Factors influencing these rates include proximity to healthcare facilities, rescue readiness, time spent under rubble, delay in reaching care, timing of hydration therapy, and when the incident occurred. In our study, the AKI rate was 62.4% and this may have been affected by many factors such as the earthquake occurring at night, the earthquake affecting a wide area, and the rescue and health teams being caught unprepared. AKI developing after Crush Syndrome is an important risk factor for mortality, and in our study, a statistically significant difference was found in terms of AKI rates between the 2 groups of survivors and non-survivors (n: 281 (61.6%), n: 12 (92.3%), respectively) in patients treated in the hospital (p: 0.037) [14,15,16,17,18].

Sever et al., in their study investigating the effects of complications on mortality, divided the patients into two groups as survivors and non-survivors, and found that infection, sepsis, ARDS, DIC, Mechanic Ventilators (MV), CV catheter complications were statistically significantly higher in the non-survivor group. In our study, sepsis, DIC and ARDS complications were also found to be significant (p: 0.012, p: 0.028, p: < 0.05 respectively). In the study conducted by Sever et al., sepsis was found to be significant as a complication, but in our study, since infection was only examined in the fasciotomy area, it was not found to be statistically significant (p:0.629) [19].

Non-survivors showed higher levels of BUN, uric acid, potassium, phosphorus, lactate, and liver enzymes, indicating more severe metabolic disruption. These changes reflect a stronger systemic response to trauma and the impact of renal dysfunction. In crush syndrome, damaged muscles release myoglobin and other contents, triggering inflammation, nephrotoxicity, electrolyte imbalance, acute kidney injury (AKI), and potential multi-organ failure [20,21,22]. In the study conducted by Ozturk et al., increased potassium level, uric acid, lactate levels were found to be associated with increased mortality, and in our study, consistent with this study, the increase in potassium level was found to be associated with mortality (HR: 3,338, 95% CI: 1.540–7,232, p = 0.002). Although many variables were found to be significant in the univariate analysis in our study, only age, potassium and previous creatinine levels were found to be effective in the regression analysis. The highly significantly raised potassium levels among the non-survivors are a cause for concern: 5.41 ± 1.72 mmol/L versus 5.13 ± 0.98 mmol/L, p = 0.008, as hyperkalemia may lead to life-threatening cardiac arrhythmias [23]. In a comprehensive study conducted by Sever et al., which analyzed a total of 401 patients, hyperkalemia was identified as one of the key factors influencing mortality risk [24]. Our findings suggest that close monitoring and early treatment of potassium levels may reduce the risks and mortality associated with crush syndrome.

This study maintains various strengths: it is a multi-center dataset comprising 469 patients from 46 diverse nephrology clinics and therefore enhances generalizability in similar disaster scenarios. The extensive data collection-from demographics to clinical presentations and laboratory parameters down to outcomes-permits an expansive review of possible mortality predictors. The use of standardized definitions further adds to data classification consistency, such as that provided by the KDIGO guidelines for AKI. The added value of incorporating pre-earthquake kidney function measurement allows a better understanding of how baseline health status influences outcomes in disasters-a gap in the existing literature.

This study is subject to several key limitations that must be acknowledged. Firstly, it was designed as a retrospective analysis, which inherently restricts the ability to draw causal conclusions. The retrospective design may be subject to selection bias, as this study relied on available and accurate medical records; thus, patients without recorded pre-earthquake serum creatinine levels were excluded. Additionally this is a large, multicenter registry study, there may be variability or errors in data entry. And, the study was primarily conducted through a web-based platform, which may have influenced participant engagement and data integrity. While we aimed to gather a comprehensive dataset simultaneously, the absence of contributions from multiple medical centers during the data collection phase resulted in a reduced patient population. This limitation is significant because it could affect the generalizability of our findings. Moreover, despite the overall large sample size, we encountered challenges accessing current measurements. Specifically, we could only retrieve the creatinine and estimated glomerular filtration rate (eGFR) results from one year prior for each patient, which may not adequately reflect their current kidney function. This gap highlights the necessity for more extensive research studies that involve a larger cohort of patients to better understand the impacts and trends associated with CKD. These factors together underscore the need for cautious interpretation of the study’s results. Additionally The time between injury and hospital admission is not reported, which could influence both kidney function at presentation and patient outcomes. The low mortality rate of 2.8% among 469 patients limits the statistical power to identify all relevant mortality predictors, which may affect the robustness of multivariate analyses. Moreover, unmeasured confounders included the exact time of crush injury before rescue, the quality and timing of pre-hospital care, and medical resources available at the time of disaster, all of which might have biased the results. Finally, these results may reflect specific characteristics in the healthcare structure and population demographics of Türkiye and therefore generalizability may be limited to other regions with different healthcare systems or population characteristics.

The identification of pre-earthquake kidney dysfunction as a predictor of mortality has important implications for disaster preparedness and clinical management. Screening vulnerable populations—such as individuals with hypertension, diabetes, or advanced age—for kidney impairment in earthquake-prone regions could help identify those at higher risk and enable more effective allocation of medical resources during and after disasters. Early identification of patients with raised baseline creatinine and low eGFR can allow for early intervention, including aggressive fluid management, early use of kidney replacement therapies, and close monitoring of electrolytes. Furthermore, baseline kidney assessments as part of disaster management may also enhance triage systems to ensure that those with impaired kidney function are prioritized for special care. This could reduce not only the mortality rate but also the severe complications associated with AKI, sepsis, and multi-organ failure.

In conclusion this study indicated that pre-earthquake kidney status is one of the most important predictors of mortality and high levels of creatinine one year prior to the earthquake had significant associations with increased mortality in crush syndrome, emphasizing the baseline kidney status and necessitating targeted medical strategies in regard to pre-earthquake kidney status. Although creatinine levels at admission were not independently associated with mortality in the multivariate analysis, the elevated predisaster creatinine could suggest that chronic kidney impairment, rather than acute changes at presentation, may predispose patients to a worse outcome by limiting their physiological resilience during severe trauma. These data add to the body of literature advocating comprehensive preparation for disasters in general, where the assessment of kidney health has to be included to assure better outcomes.