In patients with the aforementioned comorbidities, septic conditions are common and associated with high mortality rates. Early diagnosis, along with prompt and appropriate management, has become a major challenge for emergency departments. However, it is often difficult to determine whether sepsis is the primary factor behind clinical decompensation, especially in patients with complex comorbidities where symptoms may be nonspecific and overlap with other causes of deterioration. This diagnostic uncertainty complicates the timely initiation of targeted treatment, making the role of biomarkers even more crucial.

The measurement of sepsis biomarkers is widely used in clinical practice to enhance diagnostic accuracy, but there remains a need for a more reliable biomarker. A biomarker with higher sensitivity and negative predictive value (NPV) is essential for the early initiation of treatment. Several European and American studies have demonstrated the added value of MDW as an early predictor of sepsis in patients admitted to intensive care units, as well as its diagnostic performance when combined with the qSOFA score.

In the literature, the MDW threshold is established at 21.5, offering optimal diagnostic power with good sensitivity and specificity, supporting its clinical application and its approval by the United States Food and Drug Administration (FDA) and the European Conformity (CE).

In Tunisia, few studies have focused on the effectiveness of this non-invasive tool in septic patients in emergency settings and its reliability in this context, highlighting the relevance of our research.

We will test the effectiveness of MDW in the early diagnosis of sepsis as a factor of decompensation in patients with comorbidities: renal failure, heart failure, and COPD.

Inclusion Criteria:

• Patients aged over 18 years admitted to the emergency department for decompensation of congestive heart failure or renal failure, or exacerbation of COPD.

Exclusion Criteria:

• Patients who received antibiotic treatment in the past 7 days, pregnant women, children, non-consenting patients, patients with a history of malignant hematologic disease, polytransfused patients or those who recently received a transfusion, and patients whose MDW was not reported due to ineffective monocyte counting.

Patients with comorbidities (heart failure , renal failure and COPD)