Screening for COVID-19 in Older Adults: Pulse Oximeter vs. Temperature

Abstract

Public health screening for COVID-19 and its mutations are becoming a routine activity, as we assess the safety of resuming interactions with each another. Control efforts have included social distancing, hygiene, masks, and lockdowns. Where available, testing can confirm exposure to COVID-19. Prior to testing, screening is conducted, typically consisting of assessing one's temperature and asking questions related to symptoms and exposures. However, the efficacy of symptom-based screening (temperature and self-report) for COVID-19 has been called into question in recent studies for both the general population and healthcare workers (1, 2). Older adults are another population in which symptom-based screening for COVID-19 should be questioned. As the pandemic unfolded, older adults have been hardest hit. The statistics are staggering, with older adults making up 45–80% of all hospitalizations, 53% of intensive care admissions, and 80% of deaths (3, 4). However, the media's tone has been that this was not alarming but expected due to age and comorbidities. This paper offers suggestions to mitigate these statistics. The presence of fever is a key clinical indicator of infection and inflammation (5). Thus, the initial objective screening for COVID-19 has been using temperature measurements to diagnose the presence of infection. Of the general population, 98% of the COVID-19 patients was found to have a fever, along with other symptoms (6). Fever is defined as a temperature of 100.4°F (38.0°C) or greater (4). However, studies have found that older adults show a lower core body temperature, described as below 98.6°F (36.4°C), using the standard definition of a fever is a less useful indicator of infection with older adults (7, 8). Other studies have found that baseline temperatures may be as low as 94°F (34.4°C) for older adults (9). In a study of 35,488 participants with a mean age of 52.9 years, the baseline temperatures declined with age (−0.02°C every decade, p < 0.001) (10). In a sample of 18,630 (aged 20–98 years) with a mean age 58.0 years with equal numbers of male/female participants, researchers found an average basal oral body temperature of 97.3°F (36.2°C) (11). A study of 2410 hospitalized patients with influenza aged ≥65 years found a lower temperature threshold 99°F (≥37.2°C) and captured 78% of influenza-positive individuals, while the CDC's threshold for a fever 100°F (37.8°C) captured only 57% (12). Lower baseline temperatures may result in overlooking fevers. In fact, upwards of 30% of older adults with serious infections show a mild or no fever (7, 13). One study found older adults (N = 1,318), presented to the emergency department with influenza 2–5 days after symptom onset (14). In other studies, seeking treatment occurred up to 1 week after symptom onset (15, 16). This delay in seeking health care increases their mortality risk (14). Therefore, the objective measure of a temperature and the threshold of 100.4 F as a fever indicator does not provide a sufficient indicator of infection in older adults and may delay the diagnosis and treatment for COVID-19 (15, 16). Similar to a fever, older adults lack other usual signs and symptoms of illness onset or exacerbation. Atypical presentations could just be a change in cognitive status or mobility. COVID-19 symptoms include fatigue, body aches, weakness and an increasing loss of taste and smell (17). Each of these symptoms may be dismissed as a normal part of aging. Other symptoms, such as coughing, or shortness of breath may be normal for existing chronic conditions such as chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF). Older adults with COVID-19 do show typical symptoms such as shortness of breath, fever, and cough; however, many of them do not (17). Atypical presentations of COVID-19 in older adults include a delay in fever and respiratory symptoms. COVID-19 symptoms may present themselves anywhere from 4–5 to 14 days after exposure, which may be too late for initiating interventions and having positive outcomes (18). In April 2020, an emergency room doctor observed COVID-19 patients without visible signs of dyspnea and a SpO₂ below 90%. He noticed that these patients had a form of oxygen deprivation, which is difficult to detect, called “silent hypoxia,” despite the patients feeling alert and breathing normally (19). Asymptomatic hypoxia (AH) or silent hypoxia is becoming more prevalent in the COVID-19 literature and is associated with extremely poor outcomes (20). In many cases, AH is associated with a delay in care as the presence of hypoxemia is not identified in the absence of dyspnea (21). In a study from prehospital first responder data, a higher discrepancy was found between oxygen saturation (SpO₂) and respiratory rates in COVID-19 Acute Respiratory Failure (ARF) patients compared to earlier non-COVID-19 ARF patients (22). Without an SpO₂ measurement, normal breathing rates could mask profound hypoxia and make the assessment of severity more difficult in an out-of-hospital setting. Providers must remain attentive while checking for a 3–5% drop in SpO₂ after mild activity/ambulation, room air, and the presence of hypoxemia without tachypnea (19, 21). However, these symptoms may not be occurring in a clinical setting but at home. For this, there is a portable device: the pulse oximeter, which may detect “silent hypoxemia” in older adults with COVID-19, to be used at home or in a community senior-living setting (22). Pulse oximeters are a noninvasive and painless device that measures oxygen saturation levels in the blood (22). COVID-19 pandemic studies are finding increasing value in using pulse oximetry devices. Studies include the usefulness of oximeters in low-resource settings and predicting clinical...