Analysis of the percent predicted values of FEV1
using different reference value in asthmatics
Barbosa M., Barbosa T., Brito T., Campos J., Carvalho L., Carvalho R., Costa A., Dias J.,
Dória M., Maciel C., Mosca A., Pires C., Silva F., Viana D. - t2intromed@gmail.com
ADVISER Tiago António Queirós Jacinto
Introduction to Medicine I
CLASS 2
2009/2010
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
Many respiratory diseases such as asthma and COPD can be
now diagnosed and also monitored using spirometry
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It analyses how well you can breathe
Introduction
Research questions and aims
Methods
Expected results
http://www.mountnittany.org/assets/images/krames/102351.jpg
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
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Respiratory diseases can be monitored using spirometry
FEV1 is the amount of air breath out during the first second
Reference formulas convert the values of FEV1 to a
percentage whose optimal range is between 80 and 120
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
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There are several reference formulas
The evolution, changes in society, as well as interpersonal
differences (ethnicity, etc.) are not taken into account
Most formulas are now obsolete
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
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Explore the use of different reference values
Analyze the reference values of FEV1 in asthmatics
Interpret the cause of some misdiagnosis
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
Target population: Asthmatic patients from the Allergology
Department of Hospital de S. João, Porto
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Sampling methods: 100 asthmatic people consecutively chosen
from an acute database of the Allergology Department of Hospital
de S. João
Inclusion criteria: The inclusion criteria are: (1) being adult, (2)
being asthmatic and (3) have performed spirometry
Units of analysis: Asthmatic participants
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
STUDY DESIGN
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Observational
Transversal
Analytical
DATA COLECTION METHODS
Consecutively collected
Same technique and instrument
http://www.adinstruments.com/solutions/images_new/spirometry1.jpg
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
VARIABLES DESCRIPTION
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Age (in years)
Height (in cm)
Weight (in kg)
FVC Forced vital capacity
FEV1 Forced expiratory volume in one second
PEF Expiratory peak flow
Gender
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
STATISTICAL ANALYSIS
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Reference equations published by Crapo et al, Knudson et al and
Morris et al to calculate the FEV1 predicted value
The percent predicted values of FEV1 are the result of the quotient:
(FEV1 collected through spirometry)/(FEV1 predicted value)
These procedures will be accomplished using the Statistical Analysis
Software SPSS
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
Individual
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FVC
(L)
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2
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100
*Tiffeneau Index
PEF
(L)
FEV1
(L)
*FEV1
FVC
K=
Knudson
FEV1
predicted
(L)
K – FEV1
(L)
Knudson
FEV1
percentage
(%)
C=
Crapo
FEV1
predicted
(L)
C – FEV1
(L)
Crapo FEV1
percentage
(%)
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Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
Significant differences among the results obtained by these
equations in patients with asthma
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This fact can be in the origin of misdiagnosis and errors in therapy
due to different conclusions drawn when these values are compared
to the optimal range of 80/120
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http://topnews.in/healthcare/sites/default/files/asthma5.jpg
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
American Thoracic Society, Lung Function Testing: Selection of references values and
Interpretative Strategies; 1991.144: 1202-1218
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Arabalibeik H, Khomami MH, Agin K, Setayeshi S; Classification of restrictive and obstructive
pulmonary diseases using spirometry data. Tehran University of Medical Sciences, Tehran,
Stud Health Technol Inform 2009. 142: 25
Collen, J. et. al., Discordance in Spirometric Interpretations using three commonly used
reference equations vs National Health and Nutrition Examination Study III; 2008.134 10091014.
Crapo, RO; Morris, AH; Gardner, RM (1981) Reference spirometric values using techniques
and equipment that meet ATS recommendations. Am Rev Respir Dis 123:659–664
Enright,Pl.; Testing your lungs: spirometry [Internet]; [Cited 15 October 2009], Available from:
http://www.european-lung
foundation.org/uploads/Document/WEB_CHEMIN_13424_1222861696.pdf
Kerstjens HA, Rijcken B, Schouten JP, Postma DS; Decline of FEV1, by age and smoking status:
facts, figures, and fallacies, Department of Pulmonology, University of Groningen, The
Netherlands, Thorax. 1997 Sep;52(9):820-7
Knudson, RJ; Lebowitz MD; Holberg CJ et al(1983) Changes in the normal maximal expiratory
flow-volume curve with growth and aging. Am Rev Respir Dis 127:725–734
Analysis of the percent predicted values of FEV1 using different reference value in asthmatics
Marek W, Marek E, Mückenhoff K, Smith HJ, Kotschy-Lang N, Kohlhäufl M; Lung function in
the elderly: do we need new reference values? Institut für Arbeitsphysiologie an der AugustaKranken-Anstalt, Bochum, Pneumologie. 2009 Apr;63(4):235-43. Epub 2009 Apr 2.
Memon MA, Sandila MP, Ahmed ST, editors. Spirometric reference values in healthy, nonsmoking, urban Pakistani population, J Pak Med Assoc, 2007.57:193-195
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Miller M et. al. Debating the definition of airflow obstruction: time to move on?. Dept of
Medicine, University Hospital Birmingham NHS Trust, Birmingham, UK, Eur Respir J 2009. 34:
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Morris, JF; Koski, A; Johnson, LC (1971) Spirometric standards for healthy nonsmoking adults.
Am Rev Respir Dis 103:57–67
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Respir Med. 1999 Aug;93(8):523-35
Sood A, Dawson BK, Henkle JQ, Hopkins-Price P, Quails C; Effect of change of reference
standard to NHANES III on interpretation of spirometric 'abnormality'. Southern Illinois
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Analysis of the percent predicted values of FEV1
using different reference value in asthmatics
Barbosa M., Barbosa T., Brito T., Campos J., Carvalho L., Carvalho R., Costa A., Dias J.,
Dória M., Maciel C., Mosca A., Pires C., Silva F., Viana D. - t2intromed@gmail.com
ADVISER Tiago António Queirós Jacinto
Introduction to Medicine I
CLASS 2
2009/2010