Fever of Unknown Origin in Older Adults: A Prospective Observational Study from North India.

Fever of unknown origin (FUO) has different etiology in different age groups. We aimed to determine the spectrum of FUO in older patients and to establish the underlying etiology.This was a hospital-based prospective observational study conducted between January 2018 to June 2019 at Postgraduate Institute of Medical Education and Research, Chandigarh, India. Fifty-one consecutive patients aged 60 years and above met the qualitative criteria of FUO.The etiological distribution was infections in 21 patients (41.2%), malignancies in 16 (31.4%) and noninfectious inflammatory disorders in 8 (15.7%). Six patients (11.8%) remained undiagnosed. Among infections, 15 patients (29.4%) had tuberculosis, and 10 had an extrapulmonary disease. Twelve out of 16 cases with malignancies had a hematological cause, and eight had lymphoma. ;Regarding decisive methods of diagnosis, 18F-fluorodeoxyglucose positron emission tomography was diagnostic in 17 out of 27 patients (63%) and computed tomography in 21 out of 42 cases (50%). Imaging or endoscopy-guided procedures provided a diagnostic clue in 12 out of 14 patients (85.7%), and bone marrow examination results were useful in 9 out of 19 (47.4%).Infections and malignancies contributed to about three-fourths of cases, with tuberculosis and lymphoma being the commonest etiologies.