title: [Influence of environmental factors on the migratory birds population with chronic obstructive pulmonary disease].
abstract: OBJECTIVE
  To explore the influence of environment factors on the migratory birds population with chronic obstructive pulmonary disease (MDCOPD).
  
  
  METHODS
  A total of 82 stable MDCOPD patients from Beijing area, who went to Hainan Branch of PLA General Hospital and the People's Hospital of Sanya for treatment between September 2012 and May 2014, were recruited in this study.At Sanya, from October to April of the following year (wintertime), all the patients were evaluated by COPD assessment test (CAT) and modified medical research council (mMRC) questionnaire, and follow-up was performed every 2 months.From May to September (summertime), when the MDCOPD patients came back to Beijing area, the patients were evaluated by CAT and mMRC questionnaire again, and still follow-up was performed every 2 months.The scores of before and after living environment changed were compared.Acute exacerbations or hospitalizations were recorded if any occurred in the patients during the follow up period, and the patients were reevaluated by the two questionnaires 1 month later after they became stable.At the same time, the daily air quality index (AQI) from the national urban air quality publishing platform and the temperature and relative humidity from the local weather network were recorded.
  
  
  RESULTS
  The score of CAT in Sanya was significantly lower than that in Beijing ((20.0 ± 8.0) vs (26.4 ± 7.1) scores, P < 0.001); the score of mMRC in Sanya was also significantly lower than Beijing ((1.9 ± 0.8) vs (2.9 ± 0.9) scores, P = 0.001). Based on the latest guidelines, the classification of COPD patients changed from D (in Beijing) to C (in Sanya) according to mMRC scores, while the CAT scores from the two cities did not cause the change of classification.The difference of temperature between wintertime of Sanya and summertime of Beijing was not significant ((23.1 ± 4.2) vs (24.3 ± 2.3) °C, P = 0.674); the wintertime's AQI in Sanya was significantly lower than the summertime's AQI in Beijing ((49.4 ± 8.9) vs (113.1 ± 14.2) µg/m³, P < 0.001); the relative humidity of wintertime in Sanya was significantly higher than that of summertime in Beijing ((90.6 ± 4.9)% vs ((58.0 ± 10.0)%, P = 0.001).
  
  
  CONCLUSIONS
  When the MDCOPDs live in the area where has a better air quality and higher relative humidity, their quality of life and activity tolerance can be improved obviously.
authors.affiliation: Department of Respiration, Hainan Branch of PLA General Hospital, Sanya 572013, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Yan
authors.affiliation: Department of Respiration, Sanya People's Hospital, Sanya 572000, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Lin
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Jia
authors.forename: Pengfei
authors.initials: P
authors.lastname: Liu
authors.forename: Kun
authors.initials: K
authors.lastname: Xiao
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Guan
authors.forename: Hongyan
authors.initials: H
authors.lastname: Tan
authors.affiliation: Department of Respiration, Chinese PLA General Hospital, Beijing 100853, China; Email: xielx@263.net.
authors.forename: Lixin
authors.initials: L
authors.lastname: Xie
mesh_terms: D025041:Animal Migration; D000818:Animals; D000068476:Beijing; D001717:Birds; D029424:Pulmonary Disease, Chronic Obstructive; D011795:Surveys and Questionnaires