title: Recurrent pneumonia among Japanese adults: disease burden and risk factors.
abstract: In Japan and other societies with rapidly aging populations, recurrent pneumonia (RP) is a major clinical problem yet only limited information exists regarding the burden of this disease.
  
  
  
  A prospective study of adult pneumonia was conducted to investigate the incidence of RP and potential risk factors. From February 1, 2012 to January 31, 2013, patients aged ≥ 15 years who were diagnosed with pneumonia were prospectively enrolled in a representative community hospital located in central Japan. Patients were followed for one-year to evaluate the recurrence of pneumonia and characteristics associated with RP. Cox proportional hazards models were constructed to compute adjusted hazard ratios (aHR) and ascertain risk factors significantly associated with RP.
  
  
  
  In total, 841 patients with a median age of 73 years (range 15-101 years) were enrolled totaling 1,048 person-years of observation with a median follow-up time of 475 days. A total of 137 patients had at least one recurrent episode with an incidence rate of 13.1 per 100 person-years (95% confidence interval: 11.1-15.5). In multivariate analysis, a past history of pneumonia (aHR 1.95, 95% CI: 1.35-2.8), chronic pulmonary disease (aHR 1.86, 1.24-2.78) and inhaled corticosteroid usage (aHR 1.78, 1.12-2.84) and hypnotic/sedative medication usage (aHR 2.06, 1.28-3.31) were identified as independent risk factors for recurrent pneumonia, whereas angiotensin converting enzyme-inhibitors usage was associated with a reduction of the risk of RP (aHR 0.22, 0.05-0.91). The detection of P. aeruginosa was significantly associated with RP even after adjusting for chronic pulmonary diseases (aHR = 2.37).
  
  
  
  Recurrent pneumonia constitutes a considerable proportion of the pneumonia burden in Japan. A past history of pneumonia, chronic pulmonary disease, inhaled corticosteroid and hypnotic/sedative medication usage and detection of P. aeruginosa were identified as independent risk factors for recurrent pneumonia and special attention regarding the use of medications in this vulnerable population is needed to reduce the impact of this disease in aging populations.
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan.|Department of Clinical Tropical Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishifuji
authors.affiliation: Department of Clinical Tropical Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.|Department of General Internal Medicine, Kameda Medical Center, Kamogawa, Chiba, Japan.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Sando
authors.affiliation: Department of Pulmonology, Kameda Medical Center, Kamogawa, Chiba, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kaneko
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Family Medicine and Public Health Sciences, School of Medicine, Wayne State University, Michigan, USA.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Kilgore
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan.|Department of Clinical Tropical Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Koya
authors.initials: K
authors.lastname: Ariyoshi
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki, 852-8523, Japan. komorimo@nagasaki-u.ac.jp.
authors.forename: Konosuke
authors.identifier: 0000-0003-2912-9919
authors.initials: K
authors.lastname: Morimoto
authors.affiliation: Department of Infectious Diseases, Kameda Medical Center, Kamogawa, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Hosokawa
authors.affiliation: Department of General Internal Medicine, Kameda Medical Center, Kamogawa, Chiba, Japan.
authors.forename: Makito
authors.initials: M
authors.lastname: Yaegashi
authors.affiliation: Department of Pulmonology, Kameda Medical Center, Kamogawa, Chiba, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Aoshima
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017714:Community-Acquired Infections / Q000453:epidemiology; D015897:Comorbidity; D017281:Cost of Illness; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018410:Pneumonia, Bacterial / Q000453:epidemiology*; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012008:Recurrence; D012307:Risk Factors; D013183:Sputum / Q000382:microbiology; D016019:Survival Analysis; D014556:Urine / Q000382:microbiology; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D006993:Hypnotics and Sedatives
keywords: Community-acquired pneumonia; Elderly; Epidemiology; Recurrent pneumonia