title: Long-term smoking increases the need for acute care among asthma patients: a case control study.
abstract: BACKGROUND
  To examine risk factors for asthma patients' emergency room (ER) visits in a well organized asthma care setting.
  
  
  METHODS
  A random sample of 344 asthma patients from a Pulmonary Clinic of a University Hospital were followed through medical records from 1995 to 2006. All the ER visits due to dyspnea, respiratory infections, chest pain, and discomfort were evaluated.
  
  
  RESULTS
  The mean age of the study population was 56 years (SD 13 years), 72% being women. 117 (34%) of the patients had had at least one ER visit during the follow-up (mean 0.5 emergency visits per patient year, range 0-7). Asthma exacerbation, lower and upper respiratory infections accounted for the 71% of the ER visits and 77% of the hospitalizations. The patients with ER visits were older, had suffered longer from asthma and more frequently from chronic sinusitis, were more often ex- or current smokers, and had lower lung function parameters compared to the patients without emergency visits. Previous (HR 1.9, CI 1.3-3.1) and current smoking (HR 3.6, CI 1.6-8.2), poor self-reported health related quality of life (HRQoL) (HR 2.5, CI 1.5-4), and poor lung function (FEV1<65%, HR 2.2, CI 1.3-3.7) remained independent risk factors for ER visits after adjustment for age and gender.
  
  
  CONCLUSIONS
  Asthma patients who are or have been long-term smokers are more likely to require ER care compared to never smokers.
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, PO Box 160, FI-00029 HUS Helsinki, Finland. paula.kauppi@hus.fi.
authors.forename: Paula
authors.initials: P
authors.lastname: Kauppi
authors.forename: Henna
authors.initials: H
authors.lastname: Kupiainen
authors.forename: Ari
authors.initials: A
authors.lastname: Lindqvist
authors.forename: Tari
authors.initials: T
authors.lastname: Haahtela
authors.forename: Tarja
authors.initials: T
authors.lastname: Laitinen
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001249:Asthma / Q000150:complications* / Q000503:physiopathology; D002637:Chest Pain / Q000209:etiology; D002908:Chronic Disease; D018450:Disease Progression; D004417:Dyspnea / Q000209:etiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005541:Forced Expiratory Volume; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012141:Respiratory Tract Infections / Q000209:etiology; D012307:Risk Factors; D012852:Sinusitis / Q000150:complications; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors