Objectives Pneumonia is a major cause of death among inpatients at psychiatric hospitals. Psychiatric hospital-acquired pneumonia (PHAP) is defined as pneumonia developed in inpatients at psychiatric hospitals. PHAP is a type of nursing and healthcare-associated pneumonia (NHCAP). The purpose of this study was to clarify the risk factors for mortality among PHAP patients. Methods We retrospectively reviewed the clinical files of patients transferred to Tokyo Metropolitan Matsuzawa Hospital from psychiatric hospitals for PHAP treatment during the 10-year period from September 2007 to August 2017. We analyzed the clinical differences between the survivors and non-survivors and assessed the usefulness of severity classifications (A-DROP, I-ROAD, and PSI) in predicting the prognosis of PHAP. Results This study included a total of 409 PHAP patients, 87 (21.3%) of whom expired and 322 (78.7%) of whom survived. The mortality rates, according to the A-DROP classifications, were 4.9% in the mild cases, 21.6% in the moderate cases, 40.7% in the severe cases, and 47.6% in the very severe cases. The mortality rates, according to the I-ROAD classifications, were 9.5% in group A, 34.7% in group B, and 36.2% in group C. The mortality rates, according to the PSI classifications, were 0% in class II and III, 23.1% in class IV, and 44.9% in class V. The mortality rate increased as the severity increased. We identified 3 factors (age ≥65 years, body mass index ≤18.5 kg/m2, and bilateral pneumonic infiltration) as significant predictors of mortality. We therefore added two factors (body mass index ≤18.5 kg/m2 and bilateral pneumonic infiltration) to the A-DROP classification and established a modified A-DROP classification with a range of 0 to 7. The area under the receiver operation characteristic curves for predicting mortality were 0.699 for the A-DROP classification and 0.807 for the modified A-DROP classification. Conclusion The mortality rate in PHAP patients tended to increase with increasing classifications of severity. The modified A-DROP classification may be useful for predicting the prognosis of PHAP patients.
Keywords: hospital-acquired pneumonia; pneumonia; psychiatric hospital; scoring system; underweight.