title: The duration of cough in patients with H1N1 influenza.
abstract: BACKGROUND
  Cough is one of common symptoms of influenza, the cough duration and prevalence of postinfectious cough (PIC) after viral upper respiratory tract infection has not been well described.
  
  
  OBJECTIVE
  We aim to investigate the duration of cough and prevalence of PIC and its relation with acute symptoms, airway inflammation and cough sensitivity in patients with H1N1 influenza.
  
  
  METHODS
  Patients with acute symptoms of H1N1 influenza were enrolled and followed up until cough relived. Spirometry, induced sputum test, capsaicin challenge test were conducted in patients with PIC. Cough sensitivity was presented as logarithm of provocative concentration inducing five or more coughs (logC5).
  
  
  RESULTS
  A total of 141 cases with H1N1 influenza were enrolled. In patients with H1N1 influenza, 97.2% of them complained cough. The duration of cough was as following: <1 week (73.0%); 1-2 weeks (7.8%); 2-3 weeks (7.8%); ≥3 weeks (8.5%). Twelve (8.5%) patients had cough lasting more than 3 weeks (PIC), 4 (2.8%) patients developed chronic cough (>8 weeks). Acute symptoms, spirometry, bronchial responsiveness and sputum differential cell count were similar between patients with PIC and those without PIC, however, there was a higher prevalence of previous PIC (58.3% vs 14.7%, P < 0.05) and elevated cough sensitivity (lgC5: 1.18 ± 0.58 vs 2.73 ± 0.33, P < 0.01) in patients with PIC as compared with the patients without PIC.
  
  
  CONCLUSIONS
  Acute cough is common in patients with H1N1 PIC, only a few of patients develop chronic cough. Acute symptoms cannot predict PIC which is related with previous PIC and increased cough sensitivity.
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|Pulmonary Department, The Second People's Hospital of Wuhu, Anhui, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Zi-Feng
authors.initials: ZF
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Yang-Qing
authors.initials: YQ
authors.lastname: Zhan
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Bao-Juan
authors.initials: BJ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Jia-Yu
authors.initials: JY
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yi
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Ru-Chong
authors.initials: RC
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Ke-Fang
authors.initials: KF
authors.lastname: Lai
mesh_terms: D000293:Adolescent; D000328:Adult; D016535:Bronchial Hyperreactivity / Q000276:immunology / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods; D002211:Capsaicin / Q000008:administration & dosage / Q000009:adverse effects; D002908:Chronic Disease; D003371:Cough / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology / Q000821:virology*; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000150:complications / Q000503:physiopathology / Q000821:virology*; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000503:physiopathology / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012307:Risk Factors; D013147:Spirometry / Q000379:methods; D013183:Sputum / Q000166:cytology; D055815:Young Adult
chemical_list: D002211:Capsaicin
keywords: cough - cough sensitivity - influenza - postinfectious cough