title: Incidence and characteristics of the 2009 influenza (H1N1) infections in inflammatory bowel disease patients.
abstract: BACKGROUND
  In 2009, influenza A (H1N1) infections spread worldwide. Because the use of immunomodulators is associated with an increased risk of infection, inflammatory bowel disease (IBD) patients who are on immunomodulators might be concerned about H1N1 influenza infections. The aim of this study was to investigate the age distribution and risk factors associated with H1N1 influenza of IBD patients in 2009-2010.
  
  
  METHODS
  A multicenter, prospective study was conducted, and 570 IBD patients were enrolled. Patients were followed up for 10 months to identify any new infections. The incidence and age distribution of the H1N1 influenza infections were analyzed. IBD patients with H1N1 influenza infections and 2 matched, noninfected IBD patients were selected to assess the effect of specifying the medication on the incidence of infections.
  
  
  RESULTS
  A total of 38 patients (6.7%) developed H1N1 influenza infections. The incidence of H1N1 influenza infections in patients aged less than 20 years was significantly higher than that among patients in other age groups (p<0.01). The age distribution for H1N1 influenza infections in IBD patients was comparable to those in the general population. No patients needed hospitalization due to influenza infection. A total of 29 patients (76%) recovered from the H1N1 influenza symptoms within 7 days and 20 patients (53%) received antiviral treatment. The percentage of patients who used steroids or thiopurine was comparable between the cases of H1N1 influenza infection and the control group.
  
  
  CONCLUSIONS
  Our prospective study showed that younger IBD patients were frequently infected with the influenza A (H1N1) virus as well as general population. Admission and fatal cases due to H1N1 influenza infections were not observed.
authors: Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan. mnaganuma.gast@tmd.ac.jp
authors: Makoto
authors: M
authors: Naganuma
authors: Toshimitsu
authors: T
authors: Fujii
authors: Reiko
authors: R
authors: Kunisaki
authors: Naoki
authors: N
authors: Yoshimura
authors: Masakazu
authors: M
authors: Takazoe
authors: Yoshiaki
authors: Y
authors: Takeuchi
authors: Eiko
authors: E
authors: Saito
authors: Masakazu
authors: M
authors: Nagahori
authors: Keiko
authors: K
authors: Asakura
authors: Toru
authors: T
authors: Takebayashi
authors: Mamoru
authors: M
authors: Watanabe
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000893:Anti-Inflammatory Agents / Q000009:adverse effects / Q000627:therapeutic use; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000150:complications* / Q000188:drug therapy; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000209:etiology*; D007564:Japan; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
chemical_list: D000893:Anti-Inflammatory Agents; D007166:Immunosuppressive Agents