Major Finding: Compared with the use of oral or rectal thermometers to detect patients with fever, an infrared thermal detection system had a sensitivity of 70%, a specificity of 92%, a positive predictive value of 42%, and a negative predictive value of 97%.

Data Source: Emergency department study of 566 patients screened for fever by ITDS and usual methods.

Disclosures: The device manufacturer OptoTherm lent the machine, but didn't fund the study. Dr. Hewlett had no other disclosures.

ATLANTA — An infrared thermal detection system noninvasively screened for fever in a study of 566 patients presenting to an emergency department.

Infrared thermal detection systems (ITDS) have been used in several countries to screen travelers for fever, particularly in airports. At the Decennial International Conference on Healthcare-Associated Infections, Dr. Angela Hewlett presented findings from her study of the use of an ITDS as part of an infection control strategy during the recent 2009 influenza A(H1N1) pandemic.

“Fever is a primary symptom of seasonal influenza, H1N1, avian influenza, SARS [severe acute respiratory syndrome], and a lot of other contagious infectious diseases. Much interest has been generated on how best to screen patients, visitors, and other people entering a health care facility for illness in order to protect hospitalized patients from the spread of disease,” said Dr. Hewlett, an infectious disease specialist at the University of Nebraska, Omaha.

In an interview, Dr. Hewlett noted that the study was done in an ED because that is the best place to find patients with fever. The ITDS approach “is not meant to replace routine triage temperature measurements in the ED or other settings, but rather to be used for screening as an infection control modality during extreme circumstances where screening becomes necessary, like in a pandemic.”

Screening can be labor intensive in such situations, especially during pandemics when health care worker absenteeism may be high. ED backups can occur while questions are being asked and temperatures are being measured.

The study was conducted from Nov. 18, 2009, through Jan. 9, 2010—the height of the H1N1 pandemic—in the emergency department at the University of Nebraska's medical center. The device used in this study, OptoTherm's ThermoScreen Infrared Fever Screening System, uses a thermal imaging camera to measure skin temperature by quantifying infrared energy emitted from the face. “It can actually measure temperature in a split second and does not require any contact with the patient,” Dr. Hewlett said.

The ITDS was placed in the triage area and was used to screen every patient who came in. Triage nurses also took patients' temperatures using routine oral or rectal thermometers. In all, 566 patients, ranging in age from 15 days to 89 years (mean 32 years), were screened using the ITDS. Of those, the ITDS identified 71 (12.5%) as having a temperature of at least 100° F, compared with 43 (7.6%) who were identified with routine methods.

Using the triage temperature as the standard for the detection of fever, the ITDS had a sensitivity of 70%, a specificity of 92%, a positive predictive value (PPV) of 42%, and a negative predictive value (NPV) of 97%. Among the 454 adult patients aged 18 and older, sensitivity was 65%, specificity was 93%, PPV was 34%, and NPV was 98%. In the 112 children aged 17 years and younger, those values were sensitivity 75%, specificity 87%, PPV 56%, and NPV 94%, and in the 41 children aged 2 years and under, the values were 71%, 85%, 71%, and 85%, respectively.

Although the false-positive rate was high, the device readily excluded nonfebrile individuals, with a 97% chance that a patient did not have a fever if the ITDS measurement was negative, Dr. Hewlett noted.

“The ITDS proved to be a very effective screening tool to identify patients with fever across all ages and genders,” she said. Quick identification of patients and visitors who may be ill reduces the danger that influenza and other diseases will spread within a health care facility.

The device could be useful in a variety of settings, Dr. Hewlett said in the interview. “The ITDS has potential infection-control applications in many other settings, including screening patients, employees, and visitors at the entrance to a hospital or other health care facility. It also could be used as a quick triage method in the ambulatory setting, where patients can be screened for fever and those with a potentially contagious disease could be placed in a separate room, provided masks, etc., so that they do not transmit illness to other patients.”

Although the device isn't cheap, “it could be argued that if screening prevented even a single case of nosocomial influenza in a hospitalized patient—resulting in a longer length of hospital stay or transfer to the ICU—the device would probably pay for itself,” she said.

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OptoTherm's ThermoScreen Infrared Fever Screening System could be useful for screening in a pandemic.

Source Courtesy OptoTherm, Inc.

Infrared System Detects Fever Instantly Without Touch