Fever of unknown origin in Israel

The yield of total body CT in the workup of fever of unknown origin in hospitalized medical patients

INTRODUCTION

Total body computerized tomography (TBCT) is frequently used as a diagnostic tool for fever of unknown origin (FUO) workup instead of a recommended fluorodeoxyglucose positron emission tomography FDG-PET/CT. We have assessed the TBCT diagnostic yield on a large, unselected cohort of patients with FUO.

METHODS

We performed a single-center retrospective cohort study, examining all patients hospitalized in internal medicine between 2012 and 2019 with a documented fever and three negative blood cultures who subsequently had a total-body CT performed. After manually reviewing, we included 408 who met the criteria of FUO. We defined a positive study as a scan that led to the documented final diagnosis.

RESULTS

A total of 164 patients (40.2 %) had a positive TBCT result. The majority of positive CT findings were of infectious etiologies (58.5 %), followed by neoplasms (22.8 %) and inflammatory disorders (14.0 %), with the chest (43.9 %) and abdomen (29.8 %) most affected. Using a logistic regression model, a positive scan results were associated with an elevated CRP (p<0.001). Decision tree analysis showed that 55 % of scans of patients with an elevated CRP (>6 mg/dL), low hemoglobin and high leucocyte count (>18000/ml) were positive. Patients without an elevated CRP had a positive scan in only 26 % of tests, and those with also an elevated albumin (>4 gr/dL) and low CRP had positive scan in only 11 % of cases.

CONCLUSIONS

TBCT has a clinically significant yield under specific clinical scenarios in medical patients with FUO- reaching 55 % in patients with an elevated CRP and leukocyte count and low hemoglobin. It is reasonable to proceed to TTBCT when FDG-PET/CT is unavailable and in well-defined clinical situations.

Rheumatic disorders among patients with fever of unknown origin: A systematic review and meta-analysis

OBJECTIVES

To conduct a systematic literature review and meta-analysis to estimate the proportion of fever of unknown origin (FUO) and inflammation of unknown origin (IUO) cases that are due to rheumatic disorders and the relative frequency of specific entities associated with FUO/IUO.

METHODS

We searched PubMed and EMBASE between January 1, 2002, and December 31, 2021, for studies with ≥50 patients reporting on causes of FUO/IUO. The primary outcome was the proportion of FUO/IUO patients with rheumatic disease. Secondary outcomes include the association between study and patient characteristics and the proportion of rheumatic disease in addition to the relative frequency of rheumatic disorders within this group. Proportion estimates were calculated using random-effects models.

RESULTS

The included studies represented 16884 patients with FUO/IUO. Rheumatic disease explained 22.2% (95%CI 19.6 - 25.0%) of cases. Adult-onset Still's disease (22.8% [95%CI 18.4-27.9%]), giant cell arteritis (11.4% [95%CI 8.0-16.3%]), and systemic lupus erythematosus (11.1% [95%CI 9.0-13.8%]) were the most frequent disorders. The proportion of rheumatic disorders was significantly higher in high-income countries (25.9% [95%CI 21.5 - 30.8%]) versus middle-income countries (19.5% [95%CI 16.7 - 22.7%]) and in prospective studies (27.0% [95%CI 21.9-32.8%]) versus retrospective studies (20.6% [95%CI 18.1-24.0%]). Multivariable meta-regression analysis demonstrated that rheumatic disease was associated with the fever duration (0.011 [95%CI 0.003-0.021]; P=0.01) and with the fraction of patients with IUO (1.05 [95%CI 0.41-1.68]; P=0.002).

CONCLUSION

Rheumatic disorders are a common cause of FUO/IUO. The care of patients with FUO/IUO should involve physicians who are familiar with the diagnostic workup of rheumatic disease.

The management and the diagnosis of fever of unknown origin

Prolonged fever presents a challenge for the patient and the physician. Fever with a temperature higher than 38.3°C on several occasions that lasts for at least 3 weeks and lacks a clear diagnosis after 1 week of study in the hospital is called a fever of unknown origin (FUO). More than 200 diseases can cause FUO, and the information gathered from history taking, physical examination, laboratory and imaging studies should be evaluated with care. History taking and physical examination may provide some localizing signs and symptoms pointing toward a diagnosis. Infection, cancers, noninfectious inflammatory diseases and some miscellaneous diseases are the main etiologies, and some patients remain undiagnosed despite investigations. Tuberculosis, lymphoma and adult-onset Still's disease are the main diseases. Fluorodeoxyglucose PET is a promising imaging modality in FUO. Establishing a uniform algorithm for FUO management is difficult. Every patient should be carefully evaluated individually considering the previous FUO management experience.

Fever of unknown origin: discrimination between infectious and non-infectious causes

OBJECTIVE

The present study aimed to develop and evaluate a simple diagnostic model that could aid physicians to discriminate between infectious and non-infectious causes of fever of unknown origin (FUO).

DESIGN/SETTING/SUBJECTS

Patients with classical FUO were studied in two distinct, prospective, observational phases. In the derivation phase that lasted from 1992 to 2000, 33 variables regarding demographic characteristics, history, symptoms, signs, and laboratory profile were recorded and considered in a logistic regression analysis using the diagnosis of infection as a dependent variable. In the validation phase, the discriminatory capacity of a score based on the derived predictors of infection was calculated for FUO patients assessed from 2001 to 2007.

RESULTS

Data from 112 individuals (mean age 56.5+/-11.2 years) were analyzed in the derivation cohort. The final diagnoses included infections, malignancies, non-infectious inflammatory diseases, and miscellaneous conditions in 30.4%, 10.7%, 33% and 5.4% of subjects, whereas 20.5% of cases remained undiagnosed. C-reactive protein>60 mg/L (odds ratio 6.0 [95% confidence intervals 2.5, 9.8]), eosinophils<40/mm(3) (4.1 [2.0, 7.3]) and ferritin<500 microg/L (2.5 [1.3, 5.2]) were independently associated with diagnosis of infection. Among the 100 patients of the validation cohort, the presence of > or =2 of the above factors predicted infection with sensitivity, specificity, and positive and negative predictive values of 91.4%, 92.3%, 86.5%, and 95.2%, respectively.

CONCLUSIONS

The combination of C-reactive protein, ferritin and eosinophil count may be useful in discriminating infectious from non-infectious causes in patients hospitalised for classical FUO.

Fever of Unknown Origin: Analysis of 71 Consecutive Cases

BACKGROUND

Fever of unknown origin (FUO) is still an important problem in clinical practice. Evaluation of patient characteristics may clarify the utility of diagnostic tests and etiologies of FUO.

METHODS

Fever of unknown origin in 71 patients was investigated at Ankara Numune Education and Research Hospital in Turkey between February 2001 and December 2004.

RESULTS

Mean hospital stay and fever duration was 20.5 days and 44 days, respectively. Etiologies of FUO were as follows: infections 32 (45.1%), collagen vascular disease 19 (26.8%), neoplasm 10 (14.1%), and miscellaneous diseases 4 (5.6%). Diagnosis remained obscure in 6 patients (8.5 %). Tuberculosis was found to be 40% of the infectious causes of FUO. Mean hospital stay and fever duration were prolonged in infectious cases. Female predominance was observed in collagen vascular diseases (P = 0.047). Splenomegaly and lymphadenopathy were common in the neoplasm group (P = 0.017, P = 0.017, respectively). Erythrocyte sedimentation rate, aspartate aminotransferase, alanine aminotransferase and lactate hydrogenase levels were elevated in patients with collagen vascular diseases. Nine (12.7%) patients died during the follow-up period.

CONCLUSIONS

Hospital stay and fever duration were prolonged in the infectious group of FUO patients. Infectious diseases, particularly tuberculosis, were the most important cause of FUO in our series. Tuberculosis should be kept in mind as an important etiology of FUO countries where tuberculosis is endemic.

Fever of unknown origin: a systematic review of the literature for 1995???2004

BACKGROUND

Fever of unknown origin (FUO) identifies a pattern of fever with temperature higher than 38.3 degrees C on several occasions over more than 3 weeks, in which the diagnosis remains uncertain after an initial diagnostic work-up. The identification of the cause of FUO is a challenge in clinical practice despite recent advances in diagnostic techniques. There are more than 200 reported causes of FUO and they can be classified in four diagnostic categories: infections, neoplasms, non-infectious inflammatory diseases and miscellaneous.

METHODS

We performed a systematic research of the literature on classical FUO to retrieve the review articles and case series published from 1995 to 2004, including articles from developing countries. The case series were reviewed to identify the tests commonly used both to qualify a fever as FUO and to determine the cause of the FUO, and to design an updated flow chart for the diagnosis of classical FUO.

RESULTS AND CONCLUSIONS

No standardized diagnostic strategy could be determined. The diagnostic process should be guided by the potential diagnostic clues (PDCs) emerging from the history, physical examination and baseline tests. A standardized flow chart can be applied only in absence of PDCs or when the PDCs are contradictory.Nuclear medicine techniques are a valuable aid in the search for the origin of FUO due to bacterial infections or in the absence of PDCs.