Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Barbosa M., Barbosa T., Brito T., Campos J.,

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients 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. - ADVISER Tiago António Queirós Jacinto CLASS 2 Introduction to Medicine I 2009/2010

It analyses how well you can breathe
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Many respiratory diseases such as asthma and COPD can be diagnosed and also monitored using spirometry SUMMARY It analyses how well you can breathe Introduction Research questions and aims Methods Results Conclusion

Respiratory diseases can be monitored using spirometry
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients INTRODUCTION 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

There are several reference formulas
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients INTRODUCTION 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

RESEARCH QUESTIONS AND AIMS
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 RESEARCH QUESTIONS AND AIMS

Unit of analysis: Asthmatic participant
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Target population: Asthmatic patients from the Allergology Department of Hospital de S. João, Porto 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: The inclusion criteria are: (1) being adult, (2) being asthmatic and (3) have performed spirometry Unit of analysis: Asthmatic participant METHODS

DATA COLECTION METHODS Consecutively collected
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients STUDY DESIGN Transversal METHODS DATA COLECTION METHODS Consecutively collected Same technique and instrument

VARIABLES DESCRIPTION Identification
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients VARIABLES DESCRIPTION Identification Age (in years) Gender (male or female) Height (in cm) Value from Spirometry, and Predicted value and Percentage obtained using the reference formulas for: FVC Forced vital capacity FEV1 Forced expiratory volume in the first second TIFFENEAU INDEX FEV1/FVC METHODS Não sabemos se devemos incluir “diagnostico” ou o que devemos chamar à recodificação das variáveis com a percentagem para zeros e uns conforme sejam inferiores ou iguais ou superiores a 80.

(value collected through spirometry) / (predicted value)
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 METHODS

METHODS ID Age (yr) Sex Height (cm) Real FVC (L) Pred FVC Crapo (L)
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients ID Age (yr) Sex Height (cm) Real FVC (L) Pred FVC Crapo (L) Crapo FVC (%) Pred FVC ECCS (L) ECCS FVC (%) Pred FVC Knudson (L) FVC Morris Real FEV1 Pred FEV1 Crapo FEV1 ECCS Real TiffeneauIndex Pred 1 2 . 235 Pred TI Morris (L) TI Morris (%) Crapo FVC rec ECCS FVC Knudson FVC Morris FVC Crapo FEV1 ECCS FEV1 Knudson FEV1 Crapo TI ECCS TI Knudson TI TI FVC Dif CrapoECCS FVC Dif CrapoKnudson CrapoMorris ECCSKnudson ECCSMorris KnudsonMorris FEV1 Dif CrapoECCS FEV1 Dif METHODS Database table Pred = Predicted TI = Tiffeneau Index

Female subjects (n=203) [86,4%]
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 – 70 Height, cm 164,9 (5,2) 144 – 194 FEV1, L 2,9 (0,8) 0,62 – 7,5 FVC, L 3,9 (0,8) 1,33 – 8,94 Tiffeneau index 74,9 (9,5) 33,79 – 100 Male subjects (n=32) [13,6%] 45 (13,9) 18 – 63 169,6 (6,3) 158 – 194 3,6 (1,0) 0,99 – 7,5 4,6 (1,1) 2,93 – 8,94 76,3 (13,2) Female subjects (n=203) [86,4%] 47,7 (10,2) 19 – 70 164,2 (4,6) 144 – 165 2,8 (0,7) 0,62 – 4,2 3,7 (0,7) 1,33 – 5,56 74,6 (8,9) 40,63 – 97,84 RESULTS Sample description

The values of FVC are higher in men
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients In men, for FVC Morris equation, the mean of the predicted values is different from the other results In women, the real FVC is higher than the predicted ones, whose results do not differ much among themselves The values of FVC are higher in men In the full sample, no big differences are detected in the mean values RESULTS Mean (SD) 3,9 (0,8) 3,4 (0,5) 3,6 (0,5) 3,8 (0,9) 3,3 (0,6) Comparison between real and predicted FVC means

There are a major discrepancy in the predicted values of men
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients RESULTS There are a major discrepancy in the predicted values of men FEV1 values for men are higher In the full sample, no big differences are detected in the mean values 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

RESULTS Comparison between real and predicted Tiffeneau Index means
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients RESULTS Mean (SD) 74,9 (9,5) 82,2 (2,1) 81,4 (2,7) 77,0 (3,7) 70,6 (4,0) Comparison between real and predicted Tiffeneau Index means

RESULTS for men for women
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients for men RESULTS for women

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FVC RESULTS

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FEV1 RESULTS

for men Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FVC RESULTS FEV1

for men Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Reference Formulas Predicted Knudson Predicted Crapo Predicted Morris Predicted ECCS difference p-value - 0,3712 <0,001 - 1,7583 -0,1030 0,007 0,3712 - 1,3871 0,2682 1,7583 1,3871 1,6553 0,1030 - 0,2682 - 1,6553 - 0,4530 -1,1621 0,2171 0,4530 0,2908 0,2357 1,1621 - 0,2908 - 0,0551 -0,2171 - 0,2357 0,0551 RESULTS FVC FEV1 Difference between FVC and FEV1 predicted means

for men FVC FEV1 RESULTS Pair |Mean Difference| Knudson - Morris
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FVC FEV1 Pair |Mean Difference| Knudson - Morris 1,7583 ECCS - Morris 1,6553 Crapo - Morris 1,3871 Crapo - Knudson 0,3712 Crapo - ECCS 0,2682 ECCS - Knudson 0,1030 Pair |Mean Difference| Knudson - Morris 1,1621 Crapo - Knudson 0,4530 Crapo - Morris 0,2908 Crapo - ECCS 0,2357 ECCS - Knudson 0,2171 ECCS - Morris 0,0551 RESULTS Pairs sorted by difference between FVC and FEV1 predicted means

for women FVC FEV1 RESULTS
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FVC RESULTS FEV1

for women RESULTS FVC FEV1
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Reference Formulas Predicted Knudson Predicted Crapo Predicted Morris Predicted ECCS difference p-value - 0,1607 <0,001 - 0,1564 0,1372 0,1607 0,0043 0,046 0,2978 0,1564 -0,0043 0,2935 - 0,1372 - 0,2978 - 0,2935 - 0,1114 0,0810 0,0166 0,1114 0,1924 0,1280 - 0,0810 - 0,1924 - 0,0644 -0,0166 - 0,1280 0,0644 RESULTS FVC FEV1 Difference between FVC and FEV1 predicted means

for women FVC FEV1 RESULTS Pair |Mean Difference| Crapo - ECCS 0,2978
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients FVC FEV1 Pair |Mean Difference| Crapo - ECCS 0,2978 ECCS - Morris 0,2935 Crapo - Knudson 0,1607 Knudson - Morris 0,1564 ECCS - Knudson 0,1372 Crapo - Morris 0,0043 Pair |Mean Difference| Crapo - Morris 0,1924 Crapo - ECCS 0,1280 Crapo - Knudson 0,1114 Knudson - Morris 0,0810 ECCS - Morris 0,0644 ECCS - Knudson 0,0166 RESULTS Pairs sorted by difference between FVC and FEV1 predicted means

RESULTS Knudson Crapo Morris ECCS Normal (FEV1≥80%) 89,4 (%) 86,8 (%)
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients RESULTS Knudson Crapo Morris ECCS Normal (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 (%)

FVC RESULTS Knudson _ Crapo Knudson _ Morris Crapo _ Morris
Knudson _ ECCS

FVC RESULTS Knudson _ Morris Knudson _ ECCS Crapo _ ECCS
Crapo _ Morris

Knudson _ ECCS FVC Crapo _ Morris RESULTS Morris _ECCS Crapo _ ECCS

FEV1 RESULTS Knudson _ Crapo Knudson _ Morris Crapo _ Morris
Knudson _ ECCS

FEV1 RESULTS Knudson _ Morris Knudson _ ECCS Crapo _ ECCS
Crapo _ Morris

Knudson _ ECCS FEV1 Crapo _ Morris RESULTS Morris _ECCS Crapo _ ECCS

Concordance in FEV1 predicted values
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Concordance in FEV1 predicted values RESULTS Simple K Concordance K Linear Weighting ECCS - Morris 0,947 good 0,951 ECCS - Knudson 0,807 0,916 Knudson - Morris 0,774 substantial 0,855 Crapo - Knudson 0,752 0,864 Crapo - ECCS 0,659 0,846 Crapo - Morris 0,624 0,796 Concordance in the classification of the severity of the obstructive defect

Concordant classifications Discordant classifications
Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Concordance in FEV1 predicted values RESULTS Reference Equations Concordant classifications Discordant classifications Patients % Knudson – Crapo 223 94,9% 12 5,1% Knudson – Morris 226 96,2% 9 3,8% Knudson – ECCS 227 96,6% 8 3,4% Crapo - Morris 218 92,8% 17 7,2% Crapo – ECCS 219 93,2% 16 6,8% Morris - ECCS 233 99,1% 2 0,9% Concordance in the classification of the severity of the obstructive defect

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Significant differences among the results obtained by these equations in patients with asthma CONCLUSION 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

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients American Thoracic Society. Lung Function Testing: Selection of references values and Interpretative Strategies. Am Rev Respir Dis 1991; 144: 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: Crapo RO, Morris AH, Gardner RM. Reference spirometric values using techniques and equipment that meet ATS recommendations. Am Rev Respir Dis 1981; 123: Enright Pl. Testing your lungs: spirometry [Internet]; [Cited 15 October 2009], Available from: 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: Marek W, Marek E, Mückenhoff K, et al. Lung function in the elderly: do we need new reference values?. Pneumologie 2009; 63: REFERENCES

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: Quadrelli S, Roncoroni A, Montiel G. Assessment of respiratory function: influence of spirometry reference values and normality criteria selection. Respir Med 1999; 93: 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 REFERENCES

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients 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. - ADVISER Tiago António Queirós Jacinto CLASS 2 Introduction to Medicine I 2009/2010

Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Barbosa M., Barbosa T., Brito T., Campos J.,

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Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Barbosa M., Barbosa T., Brito T., Campos J.,

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Presentation on theme: "Differences in the interpretation of FEV1 using four commonly used reference formulas in asthmatic patients Barbosa M., Barbosa T., Brito T., Campos J.,"— Presentation transcript:

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