Clinical and Etiological Profile of Non-Infective Causes of Pyrexia of Unknown Origin in Hospitalized Patients: A Study (Code-T0035)

Background: Fever of Unknown Origin (FUO) has been a perplexing challenge for physicians for decades. It is defined as a persistent fever exceeding 39.3°C (101°F) on multiple occasions, documented by a healthcare practitioner, lasting more than three weeks, and with no clear diagnosis despite appropriate investigations after three outpatient visits or three days of inpatient care. Despite advancements in imaging, functional scans, guided procedures, and molecular techniques, the etiology of FUO remains elusive in many cases. This study aimed to conduct a hospital-based prospective analysis to investigate and evaluate the non-infective causes and etiologies of FUO and their clinical spectrum among patients admitted to a teaching hospital in South Karnataka.

Aims and Objectives

• To identify and determine the proportion of etiological causes of non-infective PUO based on clinical evaluations and laboratory investigations.

Methodology: Patients meeting the classical FUO criteria defined by Durack and Street et al. were enrolled following institutional ethics approval and informed consent. Data was collected using a structured proforma. Comprehensive assessments, including detailed history, physical examinations, and baseline investigations, were performed.

Results: A study of 94 hospitalized patients at ESIC MC & PGIMSR, Bengaluru, identified non-infective causes of fever in 98.7% of cases using a standardized diagnostic protocol. Rheumatological conditions were the most common etiology, followed by malignancies.

Conclusion: This study highlights that non-infective causes, particularly rheumatological conditions, are a significant contributor to PUO. A systematic diagnostic approach ensures high diagnostic yield.

Keywords: Pyrexia of Unknown Origin (PUO), Fever of Unknown Origin (FUO), Non-infective causes, Rheumatological disorders, Malignancy.