Fever of unknown origin-predictors of outcome. A prospective multicenter study on 164 patients

Metagenomic next-generation sequencing in patients with fever of unknown origin: A comprehensive systematic literature review and meta-analysis

Metagenomic Next-Generation Sequencing (mNGS) holds promise in diagnosing fever of unknown origin (FUO) by detecting diverse pathogens. We systematically reviewed the literature to evaluate mNGS's accuracy, clinical efficacy, and limitations in FUO diagnosis. Nine studies revealed mNGS's positivity rate ranging from 66.7% to 93.5% for bacterial bloodstream infections and systemic infections. Meta-analysis of three studies involving 857 patients, including 354 with FUO, showed a sensitivity of 0.91 (95% CI: 0.87-0.93) and specificity of 0.64 (95% CI: 0.58-0.70). Despite lower specificity, mNGS demonstrated a higher Diagnostic Odds Ratio (DOR) of 17.0 (95% CI: 4.5-63.4) compared to conventional microbiological tests (CMTs) at 4.7 (95% CI: 2.9-7.6). While mNGS offers high sensitivity but low specificity in identifying causative pathogens for FUO, its superior DOR suggests potential for more accurate diagnoses and targeted interventions. Further research is warranted to optimize its clinical application in FUO management.

Geographic Upon Noninfectious Diseases Accounting for Fever of Unknown Origin (FUO): A Systematic Review and Meta-analysis

Background

Diagnostic outcomes for fever of unknown origin (FUO) remain with notable numbers of undiagnosed cases. A recent systemic review and meta-analysis of studies reported geographic variation in FUO-related infectious diseases. Whether geography influences types of FUO noninfectious diagnoses deserves examination.

Methods

Medline (PubMed), Embase, Scopus, and Web of Science databases were searched systematically using medical subject headings published from January 1, 1997, to March 31, 2021. Prospective clinical studies investigating participants meeting adult FUO defining criteria were selected if they assessed final diagnoses. Meta-analyses were based on the random-effects model according to World Health Organization (WHO) geographical regions.

Results

Nineteen studies with significant heterogeneity were analyzed, totaling 2,667 participants. Noninfectious inflammatory disorders had a pooled estimate at 20.0% (95%CI: 17.0-23.0%). Undiagnosed illness had a pooled estimate of 20.0% (95%CI: 14.0-26.0%). The pooled estimate for cancer was 15.0% (95%CI: 12.0-18.0%). Miscellaneous conditions had a pooled estimate of 6.0% (95%CI: 4.0-8.0%). Noninfectious inflammatory disorders and miscellaneous conditions were most prevalent in the Western Pacific region with a 27.0% pooled estimate (95%CI: 20.0-34.0%) and 9.0% (95%CI: 7.0-11.0%), respectively. The highest pooled estimated for cancer was in the Eastern Mediterranean region at 25.0% (95%CI: 18.0-32.0%). Adult-onset Still’s disease (114 [58.5%]), systemic lupus (52 [26.7%]), and giant-cell arteritis (40 [68.9%]) predominated among the noninfectious inflammatory group. Lymphoma (164 [70.1%]) was the most common diagnosis in the cancer group.

Conclusions

In this systematic review and meta-analysis, noninfectious disease diagnostic outcomes varied among WHO-defined geographies. Evaluation of FUO should consider local variations in disease prevalence.

Prospective Studies Comparing Structured vs Nonstructured Diagnostic Protocol Evaluations Among Patients With Fever of Unknown Origin: A Systematic Review and Meta-analysis

Importance

Patients meeting the criteria for fever of unknown origin (FUO) can be evaluated with structured or nonstructured approaches, but the optimal diagnostic method is unresolved.

Objective

To analyze differences in diagnostic outcomes among patients undergoing structured or nonstructured diagnostic methods applied to prospective clinical studies.

Data Sources

PubMed, Embase, Scopus, and Web of Science databases with librarian-generated query strings for FUO, PUO, fever or pyrexia of unknown origin, clinical trial, and prospective studies identified from January 1, 1997, to March 31, 2021.

Study Selection

Prospective studies meeting any adult FUO definition were included. Articles were excluded if patients did not precisely fit any existing adult FUO definition or studies were not classified as prospective.

Data Extraction and Synthesis

Abstracted data included years of publication and study period, country, setting (eg, university vs community hospital), defining criteria and category outcome, structured or nonstructured diagnostic protocol evaluation, sex, temperature threshold and measurement, duration of fever and hospitalization before final diagnoses, and contribution of potential diagnostic clues, biochemical and immunological serologic studies, microbiology cultures, histologic analysis, and imaging studies. Structured protocols compared with nonstructured diagnostic methods were analyzed using regression models.

Main Outcomes and Measures

Overall diagnostic yield was the primary outcome.

Results

Among the 19 prospective trials with 2627 unique patients included in the analysis (range of patient ages, 10-94 years; 21.0%-55.3% female), diagnoses among FUO series varied across and within World Health Organization (WHO) geographic regions. Use of a structured diagnostic protocol was not significantly associated with higher odds of yielding a diagnosis compared with nonstructured protocols in aggregate (odds ratio [OR], 0.98; 95% CI, 0.65-1.49) or between Western Europe (Belgium, France, the Netherlands, and Spain) (OR, 0.95; 95% CI, 0.49-1.86) and Eastern Europe (Turkey and Romania) (OR, 0.83; 95% CI, 0.41-1.69). Despite the limited number of studies in some regions, analyses based on the 6 WHO geographic areas found differences in the diagnostic yield. Western European studies had the lowest percentage of achieving a diagnosis. Southeast Asia led with infections at 49.0%. Noninfectious inflammatory conditions were most prevalent in the Western Pacific region (34.0%), whereas the Eastern Mediterranean region had the highest proportion of oncologic explanations (24.0%).

Conclusions and Relevance

In this systematic review and meta-analysis, diagnostic yield varied among WHO regions. Available evidence from prospective studies did not support that structured diagnostic protocols had a significantly better rate of achieving a diagnosis than nonstructured protocols. Clinicians worldwide should incorporate geographical disease prevalence in their evaluation of patients with FUO.

Geographic Variation of Infectious Disease Diagnoses Among Patients with Fever of Unknown Origin (FUO) – A Systematic Review and Meta-analysis

Background

Fever of unknown origin (FUO) investigations yield a substantial number of patients with infectious diseases. This systematic review and meta-analysis aimed to quantify more common FUO infectious diseases etiologies and to underscore geographic variation.

Methods

Four databases (PubMed, Embase, Scopus, and Web of Science) were searched for prospective studies reporting FUO rates among adult patients from 1 January 1997 to 31 March 2021. The pooled proportion for infectious diseases etiology was estimated using the random-effects meta-analysis model.

Results

Nineteen prospective studies were included with 2667 total cases. No studies were available for Africa or the Americas. Overall, 37.0% (95.0% confidence interval [CI], 30.0%–44.0%) of FUO patients had an infectious disease etiology. Infections were more likely from Southeastern Asia (pooled proportion, 0.49 [95% CI, .43–.55]) than from Europe (pooled proportion, 0.31 [95% CI, .22–.41]). Among specifically reported infectious diseases (n = 832), Mycobacterium tuberculosis complex predominated across all geographic regions (n = 285 [34.3%]), followed by brucellosis (n = 81 [9.7%]), endocarditis (n = 62 [7.5%]), abscesses (n = 61 [7.3%]), herpesvirus (eg, cytomegalovirus and Epstein-Barr virus) infections (n = 60 [7.2%]), pneumonia (n = 54 [6.5%]), urinary tract infections (n = 54 [6.5%]), and enteric fever (n = 40 [4.8%]).

Conclusions

FUO patients from Southeastern Asia were more likely to have an infectious diseases etiology when compared to other regions. The predominant factor for this finding appears to be differences in disease prevalence among various geographical locations or other factors such as access to timely care and diagnosis. Noting epidemiological disease factors in FUO investigations could improve diagnostic yields and clinical outcomes.

The changing pattern of fever of unknown origin in the Republic of North Macedonia

INTRODUCTION

The study aimed to compare the etiologic spectrum of diseases causing fever of unknown origin (FUO) and methods for definitive diagnosis in a tertiary care hospital in the Republic of North Macedonia during two different time periods.

PATIENTS AND METHODS

There were analysed retrospectively the causes for FUO and final diagnostic approaches in 185 patients with classic FUO that were treated at the University Hospital for Infectious Diseases in Skopje during two time periods. Seventy nine patients were treated during 1991 to 1995 and 106 patients during 2011 to 2015.

RESULTS

When comparing these two periods, infections were present in 46.8% and 29.2% (p = 0.014), non-infective inflammatory disorders in 22.8% and 25.5% (p = 0.674), neoplasms in 10.1% and 13.2% (p = 0.522), miscellaneous in 8.9% and 12.3% (p = 0.461) and undiagnosed cases in 11.4% and 19.8% (p = 0.124), respectively. The most common causes for FUO during the first period were abscesses (8.9%), tuberculosis and systemic lupus erythematosus (7.6% each), whereas in the second period the commonest causes were adult onset Still disease and solid organ neoplasm (7.6% each), polymyalgia rheumatica, abscesses and visceral leishmaniasis (5.7% each). The newer imaging techniques and clinical course evaluation had superior diagnostic significance during the second period.

CONCLUSION

A changing pattern of diseases causing FUO during the examined periods was evident. Infections continue to be the most common cause but with decreasing incidence when compared to 20 years ago. Even nowadays clinical evaluation and follow-up still remain the vital diagnostic tools in determining the etiology of FUO.

Esophageal Carcinosarcoma that Was Diagnosed as a Granulocyte-colony Stimulating Factor and Interleukin-6-producing Tumor with a Tumor Fever

A 51-year-old man visited our hospital with a main complaint of precordial pain, difficulty swallowing, and pyrexia. The patient was diagnosed with esophageal carcinosarcoma, based on the characteristic morphology noted on upper gastrointestinal endoscopy and histology tests, and he underwent surgical treatment. His preoperative blood granulocyte-colony stimulating factor (G-CSF) and interleukin-6 (IL-6) levels were high, and the surgical specimens were positive in both immunohistochemical tests; therefore, he was diagnosed with a G-CSF- and IL-6-producing tumor. When pyrexia is seen as a paraneoplastic symptom, it is important to consider and investigate the possibility of a cytokine-producing tumor.

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.

[Prolonged fever: specific issues in the young adult population]

Early studies on prolonged fever date back to the 1960s. Fifty years later, prolonged unexplained fever remains a diagnostic challenge to the general internists. Although the aetiologies of prolonged fevers have not changed much in the general population, the distribution between the various causes is not the same anymore. A regular decrease in infectious and neoplastic causes is noticed whatever the age. Prolonged fevers related to inflammatory disorders and fevers that remain of unknown origin still represent approximately 30 to 50% of the cases. In the young adult population, as in the older patients, prolonged fevers can be attributed to four groups: infection, inflammation, neoplasic and other aetiologies (including drug-related fevers). In the young adult population, the management of prolonged fever presents some specific issues that are the purpose of this review coupled with our own experience. The prognosis of undiagnosed prolonged fever is usually favourable, as a life-threatening aetiology is exceptionally diagnosed during the follow-up if the initial management was complete and accurate.

Fever of unknown origin in elderly patients

Introduction. Causes of fever of unknown origin are different. It is considered that it can be caused with over 200 different clinical entities. Aetiological causes differ according to different categories of age. Febricity in the elderly is at most the result of autoimmune processes, malignancies, bacterial infections and vasculitis. Objective. The aim of this study was to determine the most common characteristics of fever, the most common laboratory, bacterial and viral tests and to analyze applied therapy in patients with unknown febrile state, and to affirm final diagnosis in elderly patients, as well as younger than 65 years old, and to define outcome of disease in both groups of patients. Methods. Research comprised 100 patients who had been treated at the Infectious Disease Clinic of the Clinical Centre of Vojvodina in Novi Sad, during a three-year period, and in whom fever of unknown origin had been diagnosed. Patients were divided into two homogenous groups of 50 people. The first one (S) consisted of patients older than 65 years, and the second, control group (K) was constituted of patients younger than the age of 65. All of them were chosen by random sample method. Results. Average results of standard laboratory parameters of infection were obtained, such as erythrocyte sedimentation rate (ESR), fibrinogen, CRP, and especially leukocyte, and those were significantly higher in the group of elderly patients. The cause had not been found in 10% of elderly patient group, and in the younger group, not even in the third of patients. Among known causative agents dominant were infections, usually of respiratory and urinary tract, in both tested groups. Even 28% of the elderly had sepsis, and 10% endocarditis. Malignant diseases were more frequent in group of the elderly patients, and immune i.e. systematic disorders were evenly noticed in both groups of patients. Conclusion. Despite advanced studies in medicine, and existence of modern diagnostic procedures, fever of unknown origin is still today differential diagnostic problem.

Fever of unknown origin: 98 cases from Saudi Arabia

BACKGROUND AND OBJECTIVES

Fever of unknown origin (FUO) is mainly secondary to infectious, neoplastic or inflammatory diseases. To increase the body of knowledge on this diagnosis in the region, we collected information on all patients admitted to our institution with FUO in a 13-year period.

METHODS

We conducted a retrospective chart review of all immunocompetent males and females aged 13 years and older admitted between January 1995 and June 2008 who fulfilled the criteria for FUO. Data collection included demographics, laboratory investigations, imaging studies, procedures and discharge diagnoses. For true FUO, we recorded the duration of follow-up and the outcome.

RESULTS

The 98 patients who met the criteria included 44 males and 54 females with a mean (SD) age of 41.3 (18.5) years and range of 14 to 85 years. The most frequent diagnostic etiology was infectious in 32 (32.7%). Seventeen (17.3%) patients were undiagnosed or had true FUO. Of 9 patients followed up, 8 recovered and 1 expired. The mean duration of follow-up was 20.6 months (range, 0-168 months).

CONCLUSION

Infectious diseases, especially TB, continue to be the leading etiology of FUO in our area. Our data did not identify any predictor of certain FUO diagnoses except for older age and neoplastic etiology. True FUO patients generally did well. Reporting local experience is important in guiding clinicians about the epidemiologic patterns of FUO in their regions.