Pilot study for risk assessment of aspiration pneumonia based on oral bacteria levels and serum biomarkers

Abstract

Background: Aspiration pneumonia is a serious problem among elderly patients; it is caused by many risk factors including dysphagia, poor oral hygiene, malnutrition, and sedative medications. The aim of this study was to define a convenient procedure to objectively evaluate the risk of aspiration pneumonia in the clinical setting.

Methods: This prospective study included an aspiration pneumonia (AP) group, a community-acquired pneumonia (CAP) group, and a control (Con) group (patients hospitalized for lung cancer chemotherapy). We used the Oral Health Assessment Tool (OHAT), which assesses oral hygiene, and evaluated performance status, body mass index, serum albumin levels, substance P values in plasma, and oral bacterial counts.

Results: The oral health as assessed by the OHAT of the aspiration pneumonia group was significantly impaired compared with that of the CAP group and the control (5.13 ± 0.18, 4.40 ± 0.26, 3.90 ± 0.22, respectively; p < 0.05). The oral bacterial count in the aspiration pneumonia group (7.20 ± 0.11) was significantly higher than that in the CAP group (6.89 ± 0.12), consistent with the OHAT scores. Oral bacterial count was significantly reduced by oral care.

Conclusions: OHAT and oral bacterial counts can be a tool to assess the requirement of taking oral care and other preventive procedures in patients at high risk of aspiration pneumonia.

Keywords: Aspiration pneumonia; Bacterial count; Oral hygiene.

Fig. 1

Level of substance P. Abbreviations: AP, aspiration pneumonia group; Con, control group; CAP, community-acquired pneumonia group. The blood of patients was collected using EDTA-Na plus aprotinin tubes. After purification, as described in the Methods section, the level of substance P in the plasma was measured by using specific ELISA kits

Fig. 2

OHAT. a OHAT score, b OHAT score ratios, c ROC curve of the AP group vs the Con group (OHAT), d ROC curve of the Con group vs the CAP group (OHAT), e ROC curve of the CAP group vs the AP group (OHAT). a Oral hygiene was assessed by using the OHAT score system. b Each OHAT score ratio is shown. In a panel lavel, each fill pattern is displayed separately for each OHAT score. c The area under the ROC curve is shown. d The area under the ROC curve is shown. e The area under the ROC curve is shown. Abbreviations: AP, aspiration pneumonia group; Con, control group; CAP, community-acquired pneumonia group; OHAT; oral health assessment tool; ROC, Receiver Operating Characteristic

Fig. 3

Oral bacterial counts. a Oral bacterial counts, b Effect of oral care as assessed by bacterial count. a Oral bacteria levels at the time of admission were analyzed using a bacteria count-measuring instrument, which is a dielectrophoretic impedance measuring system. The bacterial concentration (cfu/ml) in 1 ml of a sample is shown in a logarithmic scale. b Oral care was performed by nursing staff. In comparison before and after oral care, the solid lines indicate that oral bacterial counts have decreased, and the dotted lines indicate that oral bacterial counts have increased. Abbreviations: AP, aspiration pneumonia; Con, control; CAP, community-acquired pneumonia