Differentiating severe and non-severe lower respiratory tract illness in patients hospitalized with influenza: Development of the Influenza Disease Evaluation and Assessment of Severity (IDEAS) scale

Abstract

Background Experimental studies have shown that vaccination can reduce viral replication to attenuate progression of influenza-associated lower respiratory tract illness (LRTI). However, clinical studies are conflicting, possibly due to use of non-specific outcomes reflecting a mix of large and small airway LRTI lacking specificity for acute lung or organ injury. Methods We developed a global ordinal scale to differentiate large and small airway LRTI in hospitalized adults with influenza using physiologic features and interventions (PFIs): vital signs, laboratory and radiographic findings, and clinical interventions. We reviewed the literature to identify common PFIs across 9 existing scales of pneumonia and sepsis severity. To characterize patients using this scale, we applied the scale to an antiviral clinical trial dataset where these PFIs were measured through routine clinical care in adults hospitalized with influenza-associated LRTI during the 2010–2013 seasons. Results We evaluated 12 clinical parameters among 1020 adults; 210 (21%) had laboratory-confirmed influenza, with a median severity score of 4.5 (interquartile range, 2–8). Among influenza cases, median age was 63 years, 20% were hospitalized in the prior 90 days, 50% had chronic obstructive pulmonary disease, and 22% had congestive heart failure. Primary influencers of higher score included pulmonary infiltrates on imaging (48.1%), heart rate ≥110 beats/minute (41.4%), oxygen saturation <93% (47.6%) and respiratory rate >24 breaths/minute (21.0%). Key PFIs distinguishing patients with severity < or ≥8 (upper quartile) included infiltrates (27.1% vs 90.0%), temperature ≥ 39.1°C or <36.0°C (7.1% vs 27.1%), respiratory rate >24 breaths/minute (7.9% vs 47.1%), heart rate ≥110 beats/minute (29.3% vs 65.7%), oxygen saturation <90% (14.3% vs 31.4%), white blood cell count >15,000 (5.0% vs 27.2%), and need for invasive or non-invasive mechanical ventilation (2.1% vs 15.7%). Conclusion We developed a scale in adults hospitalized with influenza-associated LRTI demonstrating a broad distribution of physiologic severity which may be useful for future studies evaluating the disease attenuating effects of influenza vaccination or other therapeutics.

Performance of established disease severity scores in predicting severe outcomes among adults hospitalized with influenza—FluSurv‐NET, 2017–2018

“…Additionally, in older adults, exacerbation of chronic conditions may contribute substantially to severe disease outcomes, limiting the performance of disease severity scores designed to predict outcomes from pneumonia or sepsis. An approach that first groups patients into classes based on objective measures of disease severity at admission, rather than relying on age and baseline health status, may allow for the development of scores that are better able to predict severe influenza‐associated outcomes [ 24 ].…”

Age, comorbidity burden and late presentation are significant predictors of hospitalization length and acute respiratory failure in patients with influenza

“…The European Centre for Disease Prevention and Control 2 and the US Centers for Disease Control and Prevention 3 have defined a set of patient groups who are at higher risk of unfavorable influenza outcomes, particularly elderly people and persons with chronic conditions. At the same time, a number of influenza-specific severity scores have been developed (IDEAS scale 4 , FluA-p score 5 , FLU-PRO 6 ), but most remain underused, as their implementation can sometimes be challenging for the clinician due to the inclusion of either laboratory parameters or a large number of variables. In addition, the spread and impact of influenza virus infection is also influenced by the characteristics of the population (individual and socio-economic) in a given geographical area/region 7 – 9 .…”

Clinical Evaluation of the ButterfLife Device for Simultaneous Multiparameter Telemonitoring in Hospital and Home Settings

“…Furthermore, respiratory rate is of critical importance to monitor the health status of COVID-19 patients, as a more severe lung involvement causes an increasing respiratory rate [ 28 ]. Compared with body temperature measurements, monitoring respiration fluctuations may serve as a more specific biomarker for COVID-19 prognosis, since most flu-like syndromes do not cause shortness of breath [ 29 ]. However, there is no device able to automatically measure respiratory rate to the best of our knowledge.…”