Case-Control Study of Clinical Features of Influenza in Hospitalized Patients

Abstract

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Performance of case definitions used for influenza surveillance among hospitalized patients in a rural area of India

“…Very few published studies have evaluated influenza case definitions among hospitalized patients with a similarly broad spectrum of acute illness, including non-respiratory illness. 17,27 Although WHO's case definition for severe acute respiratory illness has frequently been used to screen for influenza among hospitalized patients, our findings indicate that the use of this case definition (both among hospitalized children aged < 5 years and among older hospitalized patients) results in a low detection of influenza cases, although those meeting the case definition are likely to harbour an influenza virus. Similarly low sensitivities have been recorded for this case definition in other studies, at least among patients aged ≥ 5 years.…”

“…[15][16][17]19 The present study, in a rural area of India, benefitted from the high volume of admissions to the study hospitals and the high prevalence of influenza in the study population. These features permitted the performances of various case definitions for influenza to be evaluated separately among hospitalized patients belonging to two age groups (i.e.…”

“…9 The performance of influenza case definitions has been evaluated many times but only among ambulatory or hospitalized patients with fever or respiratory symptoms. [10][11][12][13][14][15][16][17][18][19][20] Such evaluations may have missed influenza cases with atypical clinical presentations, particularly those caused by acute exacerbations of underlying disease. In the Hong Kong Special Administrative Region of China and in the United States of America, > 75% of all cases of influenza-associated severe disease have been found to be classified not as influenza but under the underlying condition (e.g.…”

Infections Requiring Hospitalization in Patients on Hemodialysis

“…The ILI data compiled by the Centers for Disease Control and Prevention (CDC) on the basis of a sample of 2900 outpatient health care providers in all states, representing .30 million patient visits each year, show wide variation in the timing and strength of each (presumed) influenza season. ILI, defined as "fever (temperature of 100°F [37.8°C] or greater) and a cough and/or a sore throat without a known cause other than influenza," is a commonly encountered clinical entity (11)(12)(13)(14). Although the CDC data provide weekly estimates of the percentage of all outpatient visits caused by ILI at a national level, some studies (11)(12)(13)(14) suggest that considerably ,50%, perhaps as low as 20%, of such clinical syndromes may be caused by true influenza.…”

“…ILI, defined as "fever (temperature of 100°F [37.8°C] or greater) and a cough and/or a sore throat without a known cause other than influenza," is a commonly encountered clinical entity (11)(12)(13)(14). Although the CDC data provide weekly estimates of the percentage of all outpatient visits caused by ILI at a national level, some studies (11)(12)(13)(14) suggest that considerably ,50%, perhaps as low as 20%, of such clinical syndromes may be caused by true influenza. ILI, therefore, probably reflects a set of clinical symptoms that can be caused by a large number of viruses infecting the upper and lower respiratory tracts, including rhinovirus, adenovirus, respiratory syncytial virus, parainfluenza virus, and human metapneumovirus.…”