Risk factors for hospital-acquired influenza A and patient characteristics: a matched case-control study

Abstract

Background While hospital-acquired influenza A results in an additional cost burden and considerable mortality in patients, its risk factors are unknown. We aimed to describe the characteristics of patients vulnerable to hospital-acquired influenza A and to identify its risk factors to assist clinicians control hospital-acquired infections and reduce the burden of treatment. Methods A case-control study was conducted among hospitalized patients aged ≥18 years at a tertiary level teaching hospital during the 2018–2019 influenza A season. Patient data were retrieved from hospital-based electronic medical records. Hospital-acquired influenza A was defined as a case of influenza A diagnosed 7 days or more after admission, in a patient with no evidence of influenza A infection on admission. The controls without influenza A were selected among patients exposed to the same setting and time period. We identified risk factors using conditional logistic regression and described the characteristics of hospital-acquired influenza A by comparing the clinical data of infected patients and the controls. Results Of the 412 hospitalized patients with influenza A from all the departments in the study hospital, 93 (22.6%) cases were classified as hospital-acquired. The most common comorbidities of the 93 cases were hypertension (41.9%), coronary heart disease (21.5%), and cerebrovascular disease (20.4%). Before the onset of hospital-acquired influenza A, patients presented more lymphocytopenia (51.6% vs 35.5%, P = 0.027), hypoalbuminemia (78.5% vs 57.0%, P = 0.002), and pleural effusion (26.9% vs 9.7%, P = 0.002) than the matched controls. Infected patients also had longer hospital stays (18 days vs 14 days, P = 0.002), and higher mortality rates (10.8% vs 2.2%, P = 0.017) than the matched controls. Lymphocytopenia (odds ratio [OR]: 3.11; 95% confidence interval [CI]: 1.24–7.80; P = 0.016), hypoalbuminemia (OR: 2.24; 95% CI: 1.10–4.57; P = 0.027), and pleural effusion (OR: 3.09; 95% CI: 1.26–7.58; P = 0.014) were independently associated with hospital-acquired influenza A. Conclusions Lymphocytopenia, hypoalbuminemia and pleural effusion are independent risk factors that can help identify patients at high risk of hospital-acquired influenza A, which can extend hospital stay and is associated with a high mortality.

Clinical impact of nosocomial infection with pandemic influenza A (H1N1) 2009 in a respiratory ward in Guangzhou

“…In our study, oseltamivir was administered to most patients once the diagnosis of influenza was suspected or confirmed. In the present study, prolonged hospital stays and increased costs were major consequences, similar to other studies (9,34). Excess mortality was also reported in the literature (9).…”

“…In the present study, prolonged hospital stays and increased costs were major consequences, similar to other studies (9,34). Excess mortality was also reported in the literature (9). However, none of the patients with confirmed cases developed complications, except one patient with bronchiectasis and Penicillium marneffei infection who had a prolonged period of viral shedding, in our study.…”

“…Sporadic nosocomial influenza infections have been reported in mainland China, including in Xi'an and Taizhou (9)(10)(11). Yang et al found that lymphocytopenia, hypoalbuminemia and pleural effusion were independent factors that can help identify patients at high risk of hospital-acquired influenza A infection, which can prolong the hospital stay and is associated with high mortality (9). However, reports on nosocomial influenza outbreaks in southern Chinese hospitals are limited.…”

Characteristics and Prediction Model of Hospital-acquired Influenza Using EMR

“…Laboratory results [13] and the haematological in ammatory parameters neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PNR), and platelet-to-lymphocyte ratio (PLR) [14] were included. Chest X-ray result were selected for radiology results [13].…”

“…Laboratory results [13] and the haematological in ammatory parameters neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PNR), and platelet-to-lymphocyte ratio (PLR) [14] were included. Chest X-ray result were selected for radiology results [13]. Patients' rooms and units were included because hospital room type [15] and staying in the same room or unit with an in uenza patient [6] are risk factors for HAI infection.…”