ABSTRACT
Introduction Ageing affects homeostasis and immunosenescence, resulting inaberrant fever and immune responses to infection in older adults.This study assesses heritability of basal temperature and exploreseffects of ageing on basal temperature and temperature inresponse to SARS-CoV-2 infection. Methods Observational study using multiple cohorts. Participants: (a) Twinvolunteers: 1089 healthy adults enrolled in Twins-UK, mean age59 (17);tympanic temperature measurements;(b) Community-based: 3972 adults using the COVID Symptom Study mobileapplication, age 43 (13);self-reported test-positive for SARS-CoV-2 infection;self-reported temperature measurements;(c)Hospitalised: cohorts of 520 and 757 adult patients withemergency admission to two teaching hospitals between01/03/2020-04/05/2020, age 62 (17) and 68 (17) respectively;RT-PCR-confirmed SARS-CoV-2 infection. Analysis (a) heritability analysed using saturated and ACE univariatemodels;linear mixed-effect model for associations between basaltemperature and age, sex and BMI. (b&c) multivariable linearregression for associations between temperature and age, sex and BMI;multivariable logistic regression for associations betweenfever(>/= 37.8°C) and age, sex and BMI. Results Basal temperature in twins demonstrated 50% heritability(95%CI[42-57%]). In healthy twin, community-based and hospitalised cohorts, increasing age is associated with lowertemperatures, and increasing BMI with higher temperatures: (a)Twins (age:p < 0.001;BMI:p = 0.002);(b) Community-based (age:p < 0.001;BMI: p < 0.001);(c) Hospitalised (1st hospital: age: p = 0.106;BMI: p = 0.033;2nd hospital: age: p < 0.001;BMI: p = 0.010).Increasing age was negatively and BMI positively associated withfever (1st hospital: Age: OR = 0.99, p = 0.033;BMI: OR = 1.00, p = 0.045;2nd hospital: Age: OR = 0.99, p = 0.010;BMI: OR 1.02, p = 0.038). Conclusions Heritability of basal temperature suggests a genetic component tothermoregulation. Associations observed between increasing ageand lower temperatures and higher BMI and higher temperaturesare important in understanding effects of ageing and obesity onbasal temperature and the fever response. In older adults, findingshave important implications for defining fever thresholds and diagnosing infections, including SARS-CoV-2.
ABSTRACT
Introduction COVID-19 exhibits a more severe disease course in older adults with frailty. Awareness of atypical presentations is critical to facilitate early disease identification. This study aimed to assess how frailty affects presenting symptoms of COVID-19 in older adults. Methods Observational study of two distinct cohorts: (i) Hospitalised patients aged 65 and over;unscheduled admission to a large London teaching hospital between March 1st, 2020-May 5th, 2020;COVID-19 confirmed by RT-PCR of nasopharyngeal swab (n = 322);(ii) Community-based adults aged 65 and over enrolled in the COVID Symptom Study mobile application between March 24th (application launch)-May 8th, 2020;self-report or report-by-proxy data;reported test-positive for COVID-19 (n = 535). Multivariable logistic regression analysis performed on age-matched samples of both cohorts to determine associations between frailty and symptoms of COVID-19 including delirium, fever and cough. Results Hospital cohort: there was a significantly higher prevalence of delirium amongst the frail sample, with no difference in fever or cough. Of those presenting with delirium, 10/53 (18.9%) presented with delirium as the only documented symptom. Community-based cohort: there was a significantly higher prevalence of probable delirium in the frail sample, and also of fatigue and shortness of breath. Of those reporting probable delirium, 28/84 (33%) did not report fever or cough. Conclusions This study demonstrates a higher prevalence of delirium as a presenting symptom of COVID-19 infection in older adults with frailty compared to their age-matched non-frail counterparts. Clinicians should suspect COVID-19 in frail older adults presenting with delirium. Early detection facilitates infection control measures to mitigate against catastrophic spread and preventable hospitalisations and deaths amongst this population. Our findings emphasise the need for systematic frailty assessment for all acutely ill older patients in both hospital and community settings, as well as systematic evaluation of any change in mental status.