Fever of unknown origin at a teritiary care teaching hospital in Pakistan.

The aim of this study was to determine the causes of fever of unknown origin (FUO) at a tertiary care teaching hospital in Pakistan. We conducted this cross sectional descriptive study at the Department of Medicine, Civil Hospital Karachi, from January 2006 to December 2011. We reviewed the medical records of all patients aged > 12 years with a primary diagnosis of FUO. We excluded those who did not meet inclusion criteria. Two hundred five patients were analyzed, 111 (54%) were male. The mean age of patients was 38 +/-14 years. The mean duration of fever prior to hospitalization was 37 +/- 16 days and the mean time taken to reach a final diagnosis was 19 +/- 14 days. A diagnosis was established in 171 patients. Infections, especially tuberculosis, were the most common cause of FUO, followed by connective tissue diseases and malignancies. Causes of FUO and their frequencies in the population should be known because FUO is most often caused by an unusual presentation of a common disease, but may also be caused by a rare condition. Common diseases should be suspected first when investigating FUO. Factors causing delay in diagnosis should be identified and overcome to improve outcomes.