Background: Subarachnoid hemorrhage is a life-threatening neurological emergency that requires rapid diagnosis to reduce morbidity and mortality. Acute headache is the most common presenting symptom of Subarachnoid hemorrhage; however, it overlaps with many benign conditions, making early differentiation difficult in emergency departments. Although brain computed tomography is the diagnostic gold standard, readily available laboratory markers may assist clinicians in early risk stratification. Complete blood count (CBC) derived inflammatory indices are inexpensive, rapidly obtainable, and routinely measured in emergency settings. This study aimed to evaluate the diagnostic value of CBC derived indices in distinguishing Subarachnoid hemorrhage from other causes of acute headache.
Methods: This study is a retrospective study conducted on patients who presented with acute headache to the emergency department of the educational and therapeutic hospital affiliated with Urmia University of Medical Sciences. Medical records of patients presenting with acute headache between January 2018 and December 2022 were reviewed. A total of 1,025 patients were included. Demographic data and initial laboratory parameters, including white blood cell count (WBC), neutrophil percentage, lymphocyte percentage, neutrophil to lymphocyte ratio (NLR), and platelet to lymphocyte ratio (PLR), were collected. Patients were classified into Subarachnoid Hemorrhage and non-Subarachnoid Hemorrhage groups based on brain CT scan findings and complementary diagnostic evaluations when required. Comparative analyses were performed, and the diagnostic performance of CBC derived indices was assessed using Receiver operating characteristic (ROC) curve analysis.
Results: Among the study population, 22 patients (2.1%) were diagnosed with Subarachnoid Hemorrhage. Patients with Subarachnoid Hemorrhage demonstrated significantly higher mean WBC counts and neutrophil percentages, along with significantly lower lymphocyte percentages, compared with non-Subarachnoid Hemorrhage patients (P<0.001). The mean NLR was higher in the Subarachnoid Hemorrhage group (7.23±4.92) than in the non-Subarachnoid Hemorrhage group (3.67±3.51, P<0.001). ROC curve analysis showed that NLR and neutrophil percentage had the highest diagnostic accuracy, each yielding an Area under the curve (AUC) of 0.76, indicating moderate discriminative ability.
Conclusion: CBC derived inflammatory indices, particularly NLR and neutrophil percentage, may serve as useful adjunctive screening tools for early identification of SAH in patients presenting with acute headache. However, these parameters should complement, rather than replace, definitive neuroimaging methods.
