Fever of undetermined origin: not what it used to be

The spectrum of diseases causing fever of unknown origin in Turkey: a multicenter study

OBJECTIVE

The purpose of this trial was to determine the spectrum of diseases with fever of unknown origin (FUO) in Turkey.

METHODS

A prospective multicenter study of 154 patients with FUO in twelve Turkish tertiary-care hospitals was conducted.

RESULTS

The mean age of the patients was 42+/-17 years (range 17-75). Fifty-three (34.4%) had infectious diseases (ID), 47 (30.5%) had non-infectious inflammatory diseases (NIID), 22 (14.3%) had malignant diseases (MD), and eight (5.2%) had miscellaneous diseases (Mi). In 24 (15.6%) of the cases, the reason for high fever could not be determined despite intensive efforts. The most common ID etiologies were tuberculosis (13.6%) and cytomegalovirus (CMV) infection (3.2%). Adult Still's disease was the most common NIID (13.6%) and hematological malignancy was the most common MD (7.8%). In patients with NIID, the mean duration of reaching a definite diagnosis (37+/-23 days) was significantly longer compared to the patients with ID (25+/-12 days) (p=0.007). In patients with MD, the mean duration of fever (51+/-35 days) was longer compared to patients with ID (37+/-38 days) (p=0.052).

CONCLUSIONS

Although infection remains the most common cause of FUO, with the highest percentage for tuberculosis, non-infectious etiologies seem to have increased when compared with previous studies.

Fever of unknown origin (FUO). I A. prospective multicenter study of 167 patients with FUO, using fixed epidemiologic entry criteria. The Netherlands FUO Study Group

Internal medicine wards in all 8 university hospitals in the Netherlands participated in this prospective study of fever of unknown origin (FUO) from January 1992 until January 1994 in order to update information on the spectrum of diseases causing FUO. We used fixed epidemiologic entry criteria to achieve completeness of enrollment and to avoid unintended selection bias. After entry, immunocompetent patients were included using criteria for FUO according to Petersdorf and Beeson (30). A standardized diagnostic protocol was used, and potentially diagnostic clues (PDCs) and their use in the diagnostic process were prospectively registered. Thus, the criteria of classic FUO have been adjusted to modern times: immunocompromised patients are excluded, and the time-criterion "1 week in hospital without a diagnosis" has been replaced by a quality-criterion stating that certain investigations must be performed as a minimum, and PDCs must be followed adequately for at least 1 week, without a diagnosis being reached. A total of 167 immunocompetent patients with FUO were thus retrieved, of whom 43 (25.7%) had infections, 21 (12.6%) had neoplasms, and 40 (24.0%) had noninfectious inflammatory diseases. No diagnosis was made in 50 patients (29.9%), 37 of whom recovered spontaneously. This study confirms the changing spectrum of diseases causing FUO. Indeed, as shown by another recent study, the group of patients with FUO in whom no diagnosis can be made is expanding, and mostly it concerns self-limiting or benign fevers. Others have suggested that this trend is not really occurring (29). We did not place patients with diseases of unknown origin in the "nondiagnosis" group, and indeed made presumptive diagnoses when necessary. Nevertheless, this category of undiagnosed fevers is increasing. We believe that the higher percentage of undiagnosed cases can be attributed to the greater use of advanced diagnostic techniques attendant on an increased number of self-limited illnesses in patients meeting criteria for FUO. Because of ongoing development in diagnostic techniques and the prospective influence on the spectrum of diseases causing FUO, studies should be performed regularly to update information on this subject. Because the number of outpatient evaluations for FUO is expected to increase, patients seen on an outpatient basis should be included in future studies. To avoid unwanted selection bias, fixed epidemiologic entry criteria should be used to ensure completeness of enrollment. To shorten the period of collecting data, multicentric studies can be done using standardized diagnostic protocols. In patients with recurrent fever or fever lasting longer than 6 months, the chance of reaching a diagnosis is significantly lower, and especially in this group one should exercise the greatest caution to avoid abundant and extensive diagnostic procedures. The diagnostic process in patients with FUO remains an intriguing problem in medicine. Recent microbiologic techniques may be useful as an approach to the relatively large proportion of patients in whom we now fail to make a diagnosis.

Fever of unknown origin (FUO). II. Diagnostic procedures in a prospective multicenter study of 167 patients. The Netherlands FUO Study Group

From January 1992 until January 1994, we used a standardized diagnostic protocol for the 167 immunocompetent patients with fever of unknown origin (FUO) admitted on the internal medicine wards in all 8 university hospitals in the Netherlands. This protocol consisted of a standardized coded history and standardized physical examination for all 167 patients. A number of additional obligatory investigations had to be performed in the first week of admission for all patients, and all potentially diagnostic clues (PDCs) thus retrieved had to be registered. In the presence of PDCs, specific investigations had to be performed based on the differential diagnosis. In the absence of PDCs or in the presence of only misleading PDCs, patients underwent a screening 2-staged diagnostic protocol. In 162 (97%) patients, PDCs were present after 1 week of admission. In 61 patients these PDCs were all misleading. The likelihood of reaching a diagnosis in patients with PDCs was not significantly higher than that in patients without PDCs, probably because of the high proportion of misleading PDCs. The likelihood of establishing a diagnosis was significantly lower (< 10%) only for patients with recurrent fever, normal erythrocyte sedimentation rate (ESR), and normal hemoglobin. All other PDCs were not significantly different in patients with a diagnosis compared with patients without a diagnosis. The screening 2-staged diagnostic protocol proved useful in 10 of 43 patients in whom it was used. The screening value of immunologic and microbiologic serology and endocrine investigations was nil; these investigations probably should be performed only when PDCs for the disease searched for are present. Scintigraphic techniques, echocardiography, and other imaging procedures were never helpful in our population in the absence of PDCs. Many patients with FUO had nonspecific anemia and disturbed liver chemistry. In the presence of these findings alone, without other more specific PDCs, the likelihood of reaching a diagnosis with help of bone marrow aspiration was nil, and with help of liver biopsy, it was low. Enteric biopsy was never helpful. If lymphadenopathy was confined to the cervical or inguinal region (with negative chest X-ray and abdominal ultrasound), lymph node biopsy was not helpful, in contrast to patients having generalized lymphadenopathy, in whom the technique had a yield of 79%. As shown in this study, the search for PDCs remains an important tool for establishing the diagnosis in patients with FUO, although in many cases these PDCs appear to be misleading. Directed diagnostic workup--using the PDCs retrieved by repeated, meticulous history taking and physical examination--remains the most efficient and intellectually satisfactory way to solve the problem of FUO in the individual patient. A standard protocol in patients with FUO in whom the obligatory investigations, as used by us, do not lead to the diagnosis can be limited to the tests that proved to be of some use as screening procedure: temporal biopsy in patients older than 55 years; fundoscopy; serology (Western blot) for Yersinia enterocolitica; serum for cryoglobulin at an early stage of the diagnostic process; and bone biopsy, liver biopsy, abdominal computed tomography (CT), and chest CT at a later stage. Repeating a thorough history-taking, physical examination, and obligatory investigations and waiting for PDCs to appear probably is better than ordering more screening investigations in the hope that something abnormal will come up. Supportive treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) can be helpful at this stage. Only rarely do patients deteriorate while using NSAIDs without presenting new PDCs. In these rare patients, further diagnostic workup should be performed or a therapeutic trial with, for example, antibiotics, steroids, or antituberculous agents started.

Fever of unknown origin

Fever of unknown origin (FUO) is defined as a temperature elevation of 101 degrees F (38.3 degrees C) or higher for 3 weeks or longer, the cause of which is not diagnosed after 1 week of intensive in-hospital investigation. This article discusses the causes, diagnosis, and treatment of FUOs.

Fever of unknown origin in elderly patients

OBJECTIVE

To describe the spectrum of diseases that may give rise to fever of unknown origin in elderly patients and to delineate the diagnostic approach in these patients.

DESIGN

Subgroup analysis of a prospectively collected case series followed more than 2 years.

SETTING

General Internal Medicine Service based at University hospital, Leuven, Belgium.

PATIENTS

Forty-seven consecutive patients, older than 65 years, meeting the classic criteria of fever of unknown origin.

MEASUREMENTS

The final diagnosis established and the clinical value of diagnostic procedures.

RESULTS

Infections, tumors and multisystem diseases (encompassing rheumatic diseases, connective tissue disorders, vasculitis including temporal arteritis, polymyalgia rheumatica, and sarcoidosis) were found in 12 (25%), six (12%) and 15 patients (31%), respectively. Drug-related fever was the cause in three patients (6%), miscellaneous conditions were found in five patients (10%), and six patients (12%) remained undiagnosed. Microbiologic investigations were diagnostic in eight cases (16%), serologic tests yielded one diagnosis, immunologic investigations had a diagnostic value in four cases, standard X-rays yielded a diagnostic contribution in 10 cases, ultrasonography and computed tomography were diagnostic in 11 cases, Gallium scintigraphy had a diagnostic contribution in 17 cases, and biopsies yielded the final diagnosis in 18 cases.

CONCLUSIONS

Multisystem diseases emerged as the most frequent cause of fever of unknown origin in the elderly, and temporal arteritis was the most frequent specific diagnosis. Infections, particularly tuberculosis, remain an important group. The percentage of tumors was higher in our elderly patients than in the younger ones but still clearly lower than in other recent series of FUO in adults. The number of undiagnosed cases was significantly lower in elderly patients than in younger individuals (P < or = 0.01). The investigation of elderly patients with FUO should encompass routine temporal artery biopsy and extensive search for tuberculosis if the classic tests such as blood count, chemistry, urinalysis, cultures, chest X-rays, and abdominal ultrasonography do not yield any clue. Gallium scintigraphy should be considered as the next step and not as a last-resort procedure.

Pyrexia of unknown origin: changing spectrum of diseases in two consecutive series

Comparison was made of the aetiology and methods of diagnosis in two series of patients meeting the classic criteria of pyrexia of unknown origin during 1968-1981 and during 1982-1989 seen in the Department of Internal Medicine at La Paz University Hospital, Madrid, Spain. There was a statistically significant decrease in the percentage of infections and an increase in neoplasms and connective tissue disorders in the second series. The percentage of patients diagnosed by laparatomy was similar in both series but the diagnosis yield at laparotomy was greater in the second period. Pyrexia of unknown origin continues to be a condition which can defy clinical expertise in in spite of advances in diagnostic techniques.

Fever of unknown origin, a literature survey

This review summarizes the different causes of fever of unknown origin reported in the internationally indexed literature from 1961 till 1990. In 1961 Petersdorf published his landmark report that, for the first time, proposed criteria that cases have to meet to be considered as fever of unknown origin. We only retained cases and series that met these criteria. We meticulously compared the reported case series and tried to explain the differences between these series.

Prolonged unexplained pyrexia: a review of 221 paediatric cases from Kuwait

Over a three year period (January 1985 through December 1987), 221 children with prolonged pyrexia were admitted to the paediatric departments in two regional hospitals in Kuwait. Infections, connective tissue diseases and malignancies constituted 78%, 5% and 2%, respectively, and 15% of the cases remained undiagnosed. Brucella was the most common infectious agent encountered (38% of all cases), followed by typhoid fever (9%). The duration of fever was more helpful in the differential diagnosis than its height or pattern. The erythrocyte sedimentation rate and the white blood count were of limited value, and the C-reactive protein was positive in bacterial infections, malignancies and connective tissue diseases. Since a child presenting with prolonged pyrexia in this country has over a 70% chance of having a bacterial infection, both diagnostic and therapeutic procedures should be performed as an emergency measure. Particular emphasis should be put on the exclusion of brucellosis.

Soft tissue hematoma as a cause of fever in the adult

Hematoma as an isolated cause of temperature elevation in adult patients is rarely reported. We describe a patient with a large hematoma involving his right leg that caused significant pyrexia. The computerized axial tomography findings are discussed, as well as the possible mechanisms responsible for the temperature elevation.

The relevance of pyrexia in adults as a presenting symptom in the accident and emergency department

Over a 3-month period all adults presenting to the Accident and Emergency Department of St Mary's Hospital, Paddington, London, England, with a pyrexia of 37.6 degrees C or more were entered into this study. A questionnaire was used to document the incidence of pyrexia, the age, sex, specific diagnosis and the subsequent management of pyrexial patients. A total of 11,062 adults came through the Department during this time, of whom 834 (7.5%) were admitted. One hundred and eight-eight adults had a pyrexia of 37.6 degrees C or greater and, of these, 62 (33%) were admitted. Seventy-two per cent of patients aged 45 years or older were admitted, compared with 22% in the younger age groups. These results were statistically significant for the correlation between likelihood of admission and age. This study demonstrates that, for patients presenting to an accident and emergency department, pyrexia is a useful indicator of illness which may necessitate admission, especially in the elderly.

Graves' disease presenting as pyrexia of unknown origin

Fever is a common clinical manifestation of inflammatory processes of the thyroid and thyroid crisis. On the other hand, fever alone as a presenting symptom of thyrotoxicosis, without other manifestations, is extremely rare. A female patient is described in whom fever persisted for two months prior to hospitalization, but without clinical symptoms or signs to lead to suspicion of thyroid disease. After exhaustive investigation it was found that the patient was suffering from hyperthyroidism. Fever disappeared gradually on antithyroid therapy, recurred when the drugs were withdrawn for a rechallenge trial, and cleared up again after renewal. Four other cases of persistent fever as a presenting symptom of hyperthyroidism were found on a review of previous publications. Thyrotoxicosis should, therefore, be included in the differential diagnosis of pyrexia of unknown origin.

Fever in hospitalized medical patients: characteristics and significance

The occurrence of fever and the clinical profile of febrile patients on the medical service of a teaching hospital were studied prospectively. Thirty-six per cent of 972 patients developed fever (temperature exceeding 38 degrees C). Their 13% mortality rate and 13.2-day average hospital stay exceeded the 3% mortality and seven-day hospitalization for afebrile patients (p less than 0.0001 for both). Most fever episodes occurred during the first two hospital days. Approximately 30% of first and subsequent fever episodes were caused by bacterial infections; illnesses involving tissue necrosis (e.g., stroke, myocardial infarction) accounted for 20%. Five conditions comprised 53% of diagnoses: respiratory and urinary tract infections, neoplasm, myocardial infarction, and drug reaction. Only one patient had a fever of uncertain origin. Several clinical clues used frequently to identify bacterial infections were reevaluated. Patients with bacterial infections had higher temperatures on the first febrile day (mean 38.9 degrees C) and were more likely to have had prior infections than those with other causes of fever (mean 38.3 degrees C, p less than 0.001). Older patients (greater than 75 years) had a lower febrile response to bacterial infections than younger patients. Fever in hospitalized medical patients is a common and important concomitant of increased mortality and length of hospitalization.