Factors Affecting Outcomes in Pleural Infection

The present study is a retrospective cohort study. Patients were divided into two groups: non-survivors and survivors at 3 months. The following variables from medical records were investigated: (1) patient factors (sex, presence of dysphagia, compromised-host, smoking history); (2) clinical findings factors, such as CRP, WBC, blood urea nitrogen (BUN), age, purulence of pleural fluid, infection source (community-acquired/hospital-acquired), serum albumin, OHAT score, and etiology (monomicrobial/polymicrobial/no growth); and (3) treatment methods. Dysphagia was defined as coughing when taking a meal or decreasing swallowing ability on evaluation by physicians and speech-language-hearing therapists [7 (link)]. Data on treatment and outcomes were also evaluated for each patient during hospitalization. A compromised-host was defined as a patient with any of the following diseases: rheumatoid arthritis, chronic kidney disease, malignancy, diabetes, cardiovascular diseases, neurological diseases, and steroid use. We used two clinical risk scores: RAPID (total score; min:0 point, max:7 points) and OHAT (total score; min:0 point, max:16 points). The RAPID score was based on five common parameters (Table 1) [6 (link)]. Based on the results of the dental examinations, the presence of teeth with poor prognosis was retrospectively investigated using panoramic dental radiography. They were defined as teeth with abnormal radiographic findings (e.g., apical radiolucency larger than 3 mm in diameter, alveolar bone loss around more than half of the root, untreated root remnants, or vertically fractured roots) [19 ,20 ]. Medical records were used whether those teeth were extracted. Pleural fluid was collected by pleural puncture at the time of admission, and microbiological examinations were performed. Anaerobic containers were used to collect pleural fluid to detect anaerobic bacteria, and Gram staining and pleural fluid cultures were performed. Blood agar (Kohjin Bio Co., Ltd., Saitama, Japan) and chocolate agar media (Kohjin Bio Co., Ltd.) were used to detect general bacteria. Anaero Columbia agar medium with hemin and vitamin K1 (Nippon Becton Dickinson Co., Ltd., Tokyo, Japan) was used to detect anaerobic bacteria; any anaerobic bacteria were then cultivated at 35°C and 9% CO₂. The causative pathogens were then identified in the pleural fluid culture.