differences in the interpretation of fev1 using four commonly used reference formulas in asthmatic...
TRANSCRIPT
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
ADVISER Tiago António Queirós Jacinto CLASS 2
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. - [email protected]
Introduction to Medicine I 2009/2010
http://www.mountnittany.org/assets/images/krames/102351.jpg
Many respiratory diseases such as asthma and COPD can be diagnosed and also monitored using spirometry
Introduction
Research questions and aims
Methods
Results
Conclusion
It analyses how well you can breathe
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
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 value is 80 or higher
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
There are several reference formulas
The evolution, changes in society, as well as interpersonal differences are not taken into account
Most formulas are now obsolete
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Explore the use of different reference values
Verify the differences between the four reference formulas
(Crapo, ECCS, Knudson, and Morris), in what concerns to the
predicted values (FEV1, FVC, Tiffeneau Index) in asthmatics
Interpret the cause of some misdiagnosis
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Target population: Target population: Asthmatic patients from the Allergology Department of Hospital de S. João, Porto
Sampling methods: Sampling methods: 235 asthmatic people with more than 18 years old who consecutively performed spirometry in the Allergology Department of Hospital de S. João
Inclusion criteria: Inclusion criteria: The inclusion criteria are: (1) being adult, (2) being asthmatic and (3) have performed spirometry
Unit of analysis: Unit of analysis: Asthmatic participant
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
http://www.adinstruments.com/solutions/images_new/spirometry1.jpg
DATA COLECTION METHODS
Consecutively collected
Same technique and instrument
STUDY DESIGN
Transversal
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
VARIABLES DESCRIPTION
IdentificationIdentification
AgeAge (in years) Gender Gender (male or female) HeightHeight (in cm)
Value from SpirometryValue from Spirometry, and Predicted value Predicted value and PercentagePercentage obtained using the reference formulas for:
FVC FVC Forced vital capacity
FEV1 FEV1 Forced expiratory volume in the first second TIFFENEAU INDEXTIFFENEAU INDEX FEV1/FVC
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
STATISTICAL ANALYSIS
Insert data and apply reference formulas on Microsoft® Office Excel® 2007 Reference formulas published by Crapo et al (1981), ECCS (1993), Knudson et al (1983), and Morris et al (1971)
(value collected through spirometry) / (predicted value)
Transfer to SPSS Statistics 17.0®
Recode percentages to binary code categorical
Calculate differences to FEV1 and FVC between Crapo-ECCS, Crapo-Knudson, Crapo-Morris, ECCS-Knudson, ECCS-Morris andKnudson-Morris
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Variables Mean (SD) Range
Sample (n=235) [100%]Age, yr 47,3 (10,8) 18 – 70Height, cm 164,9 (5,2) 144 – 194FEV1, L 2,9 (0,8) 0,62 – 7,5FVC, L 3,9 (0,8) 1,33 – 8,94Tiffeneau index 74,9 (9,5) 33,79 – 100
Male subjects (n=32) [13,6%]Age, yr 45 (13,9) 18 – 63Height, cm 169,6 (6,3) 158 – 194FEV1, L 3,6 (1,0) 0,99 – 7,5FVC, L 4,6 (1,1) 2,93 – 8,94Tiffeneau index 76,3 (13,2) 33,79 – 100
Female subjects (n=203) [86,4%]
Age, yr 47,7 (10,2) 19 – 70Height, cm 164,2 (4,6) 144 – 165FEV1, L 2,8 (0,7) 0,62 – 4,2FVC, L 3,7 (0,7) 1,33 – 5,56Tiffeneau index 74,6 (8,9) 40,63 – 97,84
Sample description
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
for men
for women
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Mean (SD)
2,9 (0,8) 2,8 (0,4) 2,9 (0,5) 2,7 (0,4) 2,8 (0,5)
Comparison between real and predicted FEV1 means
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
FEV1
FVC
for men Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Difference between FVC and FEV1 predicted means
for men Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
FEV1
FVC
for women Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Difference between FVC and FEV1 predicted means
for women Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Pairs sorted by means difference, in liters, between FVC and FEV1 predicted means for men and women
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
FVC FEV1
Male Female Male Female
Knudson - Morris -1,76 -0,16 -1,16 0,08
ECCS - Morris -1,66 -0,29 0,06 0,06
Crapo - Morris -1,39 0,00 0,29 0,19
Crapo - Knudson 0,37 0,16 0,45 0,11
Crapo - ECCS 0,27 0,30 0,24 0,13
ECCS - Knudson -0,10 -0,14 -0,22 -0,02
> 0,2 L
Knudson Crapo Morris ECCSNormal (FEV1≥80%) 89,4 (%) 86,8 (%) 91,1 (%) 90,6 (%)Low FEV1 10,6 (%) 13,2 (%) 8,9 (%) 9,4 (%)Normal (FVC≥80%) 95,3 (%) 93,2 (%) 86,0 (%) 95,7 (%)Low FVC 4,7 (%) 6,8 (%) 14,0 (%) 4,3 (%)
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Percentages of normal and low FEV1 and FVC obtained with different formulas among the sample
Reference equations Simple K Agreement K Linear Weighting
Agreement
ECCS - Morris 0,947 good 0,951 goodECCS - Knudson 0,807 good 0,916 good
Knudson - Morris 0,774 substantial 0,855 goodCrapo - Knudson 0,752 substantial 0,864 good
Crapo - ECCS 0,659 substantial 0,846 goodCrapo - Morris 0,624 substantial 0,796 substantial
Results of Simple Kappa and Kappa Linear Weighting
Agreement in FEV1 predicted values
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
(0-35% - very severe; 36-50%- severe; 51-60% - moderate/severe; 61-70% - moderate; 71-79% - mild; ≥80% - normal)
Agreement in FEV1 predicted values
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Agreement in the classification of the severity of the obstructive defect
Reference Equations
Concordant classifications Discordant classifications
Patients % Patients %
Crapo - Morris 218 92,8% 17 7,2%
Crapo – ECCS 219 93,2% 16 6,8%
Knudson – Crapo 223 94,9% 12 5,1%
Knudson – Morris 226 96,2% 9 3,8%
Knudson – ECCS 227 96,6% 8 3,4%
Morris - ECCS 233 99,1% 2 0,9%
Agreement in FEV1 predicted values
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Level of agreement between the equations according to age group and sex
Collen J. et al, 2008
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Collen J. et al, 2010
Older reference formulas NHANES III
ECCS
All the results showed significant discrepancies between reference formulas, changing the classification of patients.
LIMITATIONS
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
data collected in just one hospital in a single department
demographic and social factors may influence outcomes
database includes a higher number of females compared to males
more recent equations in order to achieve more reliable and accurate results
according to these differences ,it would be a good option to make a new study only with men
http://topnews.in/healthcare/sites/default/files/asthma5.jpg
Results have significance not only statistically but also in clinical practice
need to change:
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
formulas must be restructured and correctly applied to each patient’s specific characteristics
American Thoracic Society. Lung Function Testing: Selection of references values and Interpretative Strategies. Am Rev Respir Dis 1991; 144: 1202-1218
Arabalibeik H, Khomami MH, Agin K, Setayeshi S. Classification of restrictive and obstructive pulmonary diseases using spirometry data. Stud Health Technol Inform 2009; 142: 25
Collen J, Greenburg D, Holley A, King CS, HnatiuK O; Discordance in Spirometric Interpretations using three commonly used reference equations vs National Health and Nutrition Examination Study III. Chest 2008; 134: 1009-1014
Collen J, Greenburg D, King C et al. Racial discordance in spirometry comparing four commonly used reference equations to the National Health and Nutrition Examination Study III. Respiratory Medicine 2010; 104:705-11
Crapo RO, Morris AH, Gardner RM. Reference spirometric values using techniques and equipment that meet ATS recommendations. Am Rev Respir Dis 1981; 123: 659-664
Enright Pl. Testing your lungs: spirometry [Internet]; [Cited 15 October 2009], Available from: http://www.european-lung-foundation.org/
Kerstjens HA, Rijcken B, Schouten JP, Postma DS. Decline of FEV1 by age and smoking status: facts, figures, and fallacies. Thorax 1997; 52: 820-7
Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B. Changes in the normal maximal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis 1983; 127: 725-734
Marek W, Marek E, Mückenhoff K, et al. Lung function in the elderly: do we need new reference values?. Pneumologie 2009; 63: 235-43
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
Memon MA, Sandila MP, Ahmed ST. Spirometric reference values in healthy, non-smoking, urban Pakistani population. J Pak Med Assoc 2007; 57: 193-5
Miller MR, Hankinson J, Brusasco V, et al. Standardisation of Spirometry. Eur Respir J 2005; 26: 319–38
Miller MR, Pedersen OF, Pellegrino R, Brusasco V. Debating the definition of airflow obstruction: time to move on?. Eur Respir J 2009; 34: 527–8
Morris JF, Koski A, Johnson LC. Spirometric standards for healthy nonsmoking adults. Am Rev Respir Dis 1971; 103: 57–67
Morris JF, Temple WP, Koski A. Normal values for the ratio of one-second forced expiratory volume to forced vital capacity. Am Rev Resp Dis 1973; 108: 1000-3
Quadrelli S, Roncoroni A, Montiel G. Assessment of respiratory function: influence of spirometry reference values and normality criteria selection. Respir Med 1999; 93: 523-35
Quanjer PH, Tammeling GJ, Cotes JE, et al. Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society. Eur Respir J Suppl 1993; 16: 15-40
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'. Int J Chron Obstruct Pulmon Dis 2007; 2: 361-7
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients
ADVISER Tiago António Queirós Jacinto CLASS 2
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. - [email protected]
Introduction to Medicine I 2009/2010
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients