Clinically defined aspiration pneumonia is an independent risk factor associated with long-term hospital stay: a prospective cohort study
Authors: Wakabayashi Takao , Hamaguchi Sugihiro , Morimoto Konosuke ,   on behalf of the Adult Pneumonia Study Group – Japan, Suzuki Motoi , Sando Eiichiro , Dhoubhadel Bhim Gopal , Furumoto Akitsugu , Ishida Masayuki , Ishifuji Tomoko , Kakiuchi Satoshi , Katoh Shungo , Kitashoji Emi , Shimazaki Takaharu , Takaki Masahiro , Watanabe Kiwao , Yoshida Lay Myint , Ariyoshi Koya , Sasaki Kota , Katsura Hidenori , Nanba Hiroki , Abe Masahiko , Yaegashi Makito , Aoshima Masahiro , Hosokawa Naoto , Kaneko Norihiro , Katsura Hidenori , Katsurada Naoko , Nakashima Kei , Otsuka Yoshihito , Suzuki Daisuke , Tanaka Kenzo , Hamashige Naohisa , Chikamori Masayuki , Nakaoka Hiroshi , Asoh Norichika , Ito Hiroyuki , Matsuki Kei , Tsuchihashi Yoshiko , Morimoto Shimpei , Sato Shuntaro 
Published: September 2023

Background

Long-term hospital stay is associated with functional decline in patients with pneumonia, especially in the elderly. Among elderly patients with pneumonia, aspiration pneumonia is a major category. Clinical definition is usually used because it can occur without apparent aspiration episodes. It is still not clear whether a long-term hospital stay is due to aspiration pneumonia itself caused by underlying oropharyngeal dysfunction or simply due to functional decline in elderly patients with multiple comorbidities during acute infection. The aim of this study is to identify whether clinically defined aspiration pneumonia itself was associated with a long-term hospital stay.

Methods

A prospective observational study on community-acquired (CAP) or healthcare-associated pneumonia (HCAP) was conducted from January 2012 through January 2014. Aspiration pneumonia was clinically defined as pneumonia not only occurring in patients after documented aspiration episodes, but also occurring in those with underlying oropharyngeal dysfunction: chronic disturbances of consciousness and/or chronic neuromuscular diseases. We defined thirty-day hospital stay as a long-term hospital stay and compared it with logistic regression analysis. Potential confounders included age, sex, HCAP, body mass index (BMI), long-term bed-ridden state, heart failure, cerebrovascular disorders, dementia, antipsychotics use, hypnotics use, and CURB score which is a clinical prediction tool used to assess the severity, standing for; C (presence of Confusion), U (high blood Urea nitrogen level), R (high Respiratory rate), and B (low Blood pressure). In a sub-analysis, we also explored factors associated with long-term hospital stay in patients with aspiration pneumonia.

Results

Of 2,795 patients, 878 (31.4%) had aspiration pneumonia. After adjusting potential confounders, the aspiration pneumonia itself was significantly associated with long-term hospital stay (adjusted odds ratio 1.44; 95% confidence interval 1.09—1.89,p < 0.01), as were higher age, male sex, high CURB score, HCAP, low BMI, heart failure, cerebrovascular disease, and antipsychotics use. Sub-analysis revealed factors associated with long-term hospital stay in the aspiration pneumonia, which included male sex, and multi-lobar chest X-ray involvement.

Conclusions

Clinically defined aspiration pneumonia itself was independently associated with long-term hospital stay. This result could potentially lead to specific rehabilitation strategies for pneumonia patients with underlying oropharyngeal dysfunction.