Lung Function in Growth and Aging
Norwegian data PDF Print E-mail

Langhammer A, Johnsen R, Gulsvik A, Holmen TL, Bjermer L. Forced spirometry reference values for Norwegian adults: the Bronchial Obstruction in Nord-Trøndelag study. Eur Respir J 2001; 18: 770-779.

Subjects

During 1995–1997, all residents of the Nord-Trøndelag County aged >20 yrs (n=92,434), were invited to participate in the adult part of The Nord-Trøndelag Health Study (HUNT) [19]. The county is situated in a central area of Norway, and 97% of the residents are of Caucasian origin. Apart from not having a large city, the geographical and demographical structure of the Nord-Trøndelag County is fairly representative of Norway as a whole [20]. The education and income level and the prevalence of current smokers are slightly lower than the average for Norway [21], but the sale of antiasthmatic drugs is close to the Norwegian average [22]. From 65,225 subjects (71% of those invited) who attended the primary screening, a randomly selected sample of 5% (n=3,297) was invited to phase one of the Bronchial Obstruction in Nord-Trøndelag (BONT) study. This consisted of flow/volume spirometry and an interview with a nurse. In total, 2,792 subjects participated.
Spirometric measurements and quality control staff, consisting of 19 nurses and technicians organized into two teams, performed the flow/volume spirometry and the interview. Team I covered the five most densely inhabited municipalities (58,805 inhabitants) and team II covered the 18 smaller municipalities (33,629 inhabitants).
Flow/volume spirometry was recorded with three pneumotachographs (MasterScope spirometer, version 4.15, Erich Jaeger GmbH, Wuerzburg, Germany). The instruments were calibrated twice daily with a 1 L syringe. The staff also performed a daily biological control by assessing their own lung function.
The participants were seated and wore a noseclip, and extension or flexion of the neck was avoided. Height and weight were measured barefoot and in light clothing with standardized equipment. Barometer pressure, temperature and relative humidity were registered every morning, and the integrated volumes were automatically converted from ambient temperature and pressure to body temperature and pressure, saturated conditions.
The staff initially went through formal training and were then continuously monitored during the entire study by the head of the project. In accordance with the 1994 American Thoracic Society (ATS) recommendations [23], they were taught to instruct the subjects to perform three acceptable and reproducible manoeuvres, ensuring that the subjects produced the highest possible peak flows and that the expiration continued for >6 s. If the subjects were unable to do this, up to five manoeuvres were performed. The flow/volume curve with the highest sum of FEV1 and FVC was retained. The computer provided the technicians with feedback as to whether the acceptability and reproducibility criteria were met. The error messages given were in accordance with the 1987 ATS recommendations, with a reproducibility criteria of <100 mL or 5% difference between FEV1 and FVC in the two best tests, and a lower limit back extrapolated volume of 100 mL [24]. In the 1994 ATS recommendations, these limits were 200 mL and 150 mL, respectively [23].

Reference sample

The reference sample was selected from the 5% randomized sample (n=2,792), based on questionnaire results. The selection criteria followed ATS recommendations [8]: 1) life-time never-smokers; 2) no respiratory disease (self-reported or medical doctor diagnosed asthma, emphysema or chronic bronchitis); and 3) no reported respiratory symptoms (wheezing or breathlessness during the last 12 months, persistent coughing or complaints of breathlessness for any reason).

References

8. American Thoracic Society. Lung function testing: selection of reference values and interpretative strategies. American Thoracic Society. Am Rev Respir Dis 1991; 144: 1202–1218.
19. Langhammer A, Johnsen R, Holmen J, Gulsvik A, Bjermer L. Cigarette smoking gives more respiratory symptoms among women than among men. J Epidemiol Community Health 2000; 54: 917–922.
20. Holmen J, Midthjell K, Bjartveit K, et al. The Nord-Trøndelag Health Survey 1984–86. Purpose, background and methods. Participation, non-participation and frequency distributions. Oslo, National Institute of Public Health 1990, report no. 4; p. 176.
21. Lukerstuen Å. Statistical Yearbook of Norway. Oslo/Kongvinger, Statistics Norway, 2000.
22. Øydvin K, ed. Drug Consumption in Norway 1993–1997. Oslo, Norwegian Medicinal Depot, 1999; p. 190.
23. American Thoracic Society. Standardization of Spirometry, 1994 Update. American Thoracic Society. Am J Respir Crit Care Med 1995; 152: 1107–1136.
Last Updated on Saturday, 10 January 2009 16:32