title: Influence of atmospheric pressure on the incidence of spontaneous pneumothorax.
abstract: BACKGROUND
  This study analyses the relationship between the incidence of idiopathic spontaneous pneumothorax (ISP) and atmospheric pressure (AP).
  
  
  METHODS
  A total of 288 cases of ISP were included, 229 men and 59 women. The AP of the day of diagnosis, of the 3 prior days and the monthly average was registered. The association between the incidence of ISP and AP was analyzed by calculating standardized incidence ratio (SIR) and Poisson regression.
  
  
  RESULTS
  The AP on the day of admission (mean±standard deviation) (1,017.9±7 hectopascals [hPa]) was higher than the monthly average AP (1,016.9±4.1 hPa) (P=.005). There was a monthly distribution pattern of ISP with the highest incidence in the months of January, February and September and the lowest in April. When AP was less than 1,014 hPa, there were fewer cases registered than what would statistically have been expected (58/72 cases). In contrast, when the pressure was higher than 1,019 hPa, the registered cases were more than expected (109/82 cases) (SIR=1.25; 95% CI: 1.04 to 1.51). The risk of ISP increased 1.15 times (95% CI: 1.05 to 1.25, P=.001) for each hPa of AP, regardless of sex, age and monthly average AP. A dose-response relationship was observed, with progressive increases in risk (IRR=1.06 when the AP was 1,014-1016 hPa; 1.17 hPa when the AP was 1,016-1,019 hPa and 1.69 when AP was superior to 1,019 hPa) (P for trend=.089).
  
  
  CONCLUSIONS
  The AP is a risk factor for the onset of idiopathic spontaneous pneumothorax.
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España. Electronic address: rauldiazpedrero@hotmail.com.
authors.forename: Raúl
authors.initials: R
authors.lastname: Díaz
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Manuel Mariano
authors.initials: MM
authors.lastname: Díez
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: María José
authors.initials: MJ
authors.lastname: Medrano
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Cristina
authors.initials: C
authors.lastname: Vera
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Paloma
authors.initials: P
authors.lastname: Guillamot
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Ana
authors.initials: A
authors.lastname: Sánchez
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Tomás
authors.initials: T
authors.lastname: Ratia
authors.affiliation: Cirugía General, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España.
authors.forename: Javier
authors.initials: J
authors.lastname: Granell
mesh_terms: D000328:Adult; D001274:Atmospheric Pressure; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011030:Pneumothorax / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D012621:Seasons
keywords: Atmospheric pressure; Hectopascales; Hectopascals; Idiopathic pneumothorax; Neumotórax espontáneo; Neumotórax idiopático; Presión atmosférica; Seasonal variation; Spontaneous pneumothorax; Temperatura; Temperature; Variación estacional