The Z-score: A new tool in the interpretation of spirometric data

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Published Mar 22, 2018
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Vol. 95 No. 8 (2017): Issue Aug 2017

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Nozha Ben Salah
Dorra Bejar
Houda Snène
Yacine Ouahchi
Nadia Mehiri
Béchir Louzir

Abstract

Spirometry is an important tool in the diagnosis and management of patients with respiratory pathology. An appropriate interpretation of the spirometric data requires the use of a population-specific citationsRaw equation. However, the most widely used equations were established in European populations with limited age groups. The extrapolation of these equations, based on a specific population, and their uses for a different population led to measurement and interpretation biases. In 2012, an international working group conducted a multicenter study and published new citationsRaw equations called The Global Lung Initiative (GLI). These enabled the modeling of spirometric parameters from a very large sample collected in several ethnic groups using modern statistical techniques to establish continuous equations for all ages and in many countries. The GLI also recommends the use of a new statistical tool for the expression of results: The Z-score. This tool allows to express, in a simple way: how many standard deviations a subject is deviated from its citationsRaw value. The Z-score is calculated by the ratio of the difference between the measured value and that predicted with the residual standard deviation.
This simple approach has reduced the false positive results found by the use of the conventional limits of 80% compared to a predicted value or 0.70 in absolute value for the definition of bronchial obstruction that remain still used

Keywords:

spirometry, lower limit of normal, reference value, age, ethnic group, z-score

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References

  1. Pretto JJ, Brazzale DJ, Guy PA, Goudge RJ, Hensley MJ. Reasons for referral for pulmonary function testing: an audit of 4 adult lung function laboratories. Respir Care. 2013 Mar;58(3):507-10.
  2. Degens P, Merget R. Reference values for spirometry of the European Coal and Steel Community: time for change. Eur Respir J. 2008 Mar;31(3):687-688; author reply 688-689.
  3. Stanojevic S, Wade A, Stocks J, Hankinson J, Coates AL, Pan H, et al. Reference ranges for spirometry across all ages: a new approach. Am J Respir Crit Care Med. 2008 Feb 1;177(3):253-60.
  4. Quanjer PH, Stanojevic S, Cole TJ, Baur X, Hall GL, Culver BH, et al. Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations. Eur Respir J. 2012 Dec;40(6):1324-43.
  5. Quanjer PH, Brazzale DJ, Boros PW, Pretto JJ. Implications of adopting the Global Lungs Initiative 2012 all-age reference equations for spirometry. Eur Respir J. 2013 Oct;42(4):1046-54.
  6. Miller MR, Crapo R, Hankinson J, Brusasco V, Burgos F, Casaburi R, et al. General considerations for lung function testing. Eur Respir J. 2005 Jul;26(1):153-61.
  7. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J. 2005 Aug;26(2):319-38.
  8. Wanger J, Clausen JL, Coates A, Pedersen OF, Brusasco V, Burgos F, et al. Standardisation of the measurement of lung volumes. Eur Respir J. 2005 Sep;26(3):511-22.
  9. Macintyre N, Crapo RO, Viegi G, Johnson DC, van der Grinten CPM, Brusasco V, et al. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur Respir J. 2005 Oct;26(4):720-35.
  10. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005 Nov;26(5):948-68.
  11. Miller MR, Crapo R, Hankinson J, Brusasco V, Burgos F, Casaburi R, et al. Considérations générales sur les explorations fonctionnelles respiratoires. Rev Mal Respir 2006 ; 23 : 17S11-17S21
  12. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation de la spirométrie. Rev Mal Respir 2006; 23: 17S23-17S45.
  13. Wanger J, Clausen JL, Coates A, Pedersen OF, Brusasco V, Burgos F, et al. Standardisation de la mesure des volumes pulmonaires. Rev Mal Respir 2006 ; 23 : 17S47-17S60
  14. Macintyre N, Crapo RO, Viegi G, Johnson DC, van der Grinten CPM, Brusasco V, et al. Standardisation de la détermination de la diffusion du monoxyde de carbone par la méthode en apnée. Rev Mal Respir 2006 ; 23 : 17S61-17S78
  15. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, et al. Stratégies d'interprétation des explorations fonctionnelles respiratoires. Rev Mal Respir 2006; 23: 17S79-17S104.
  16. Similowski T, Straus C. [Pulmonary function testing: dissemination in French of the European recommendations]. Rev Mal Respir. 2007 Mar;24(3 Pt 2):2S5-7.
  17. Hankinson JL, Odencrantz JR, Fedan KB. Spirometric reference values from a sample of the general U.S. population. Am J Respir Crit Care Med. 1999 Jan;159(1):179-87.
  18. Quanjer PH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC. Lung volumes and forced ventilatory flows. Report working party: Standardization of lung function testing. Eur Respir J 1993; 6: 5-40.
  19. Brusasco V, Crapo R, Viegi G. [Coming together: the ATS/ERS consensus on clinical pulmonary function testing]. Rev Mal Respir. 2007 Mar;24(3 Pt 2):2S11-14.
  20. El Attar MN, Hadj Mabrouk K, Ben Abdelaziz A, Abdelghani A, Bousarssar M, Limam K, et al. Applicability of the Old European Respiratory Society/European Community for Steel and Coal reference equations for spirometry interpretation in Tunisian adult population. Tunis Med. 2014 Sep;92(8-9):574-80.
  21. Zelter M. [Old data and new statistics may soon result in universal reference equations for pulmonary function testing]. Rev Mal Respir. 2010 Nov;27(9):993-7.
  22. Miller MR. Choosing and using lung function prediction equations. Eur Respir J. 2016 Dec 1;48(6):1535-7.
  23. Ben Saad H, Ben Attia Saafi R, Rouatbi S, Ben Mdella S, Garrouche A, Hadj Mtir A, et al. [Which definition to use when defining reversibility of airway obstruction?]. Rev Mal Respir. 2007 Nov;24(9):1107-15.
  24. Affes Z, Rekik S, Ben Saad H. Defining obstructive ventilatory defect in 2015. Libyan J Med. 2015;10:28946.
  25. Halbert RJ, Natoli JL, Gano A, Badamgarav E, Buist AS, Mannino DM. Global burden of COPD: systematic review and meta-analysis. Eur Respir J. 2006 Sep 1;28(3):523-32.
  26. Pérez-Padilla R, Fernandez-Plata R, Montes de Oca M, Lopez-Varela MV, Jardim JR, Muiño A, et al. Lung function decline in subjects with and without COPD in a population-based cohort in Latin-America. PLoS ONE. 2017;12(5):e0177032.
  27. Trabelsi Y, Ben Saad H, Tabka Z, Gharbi N, Bouchez Buvry A, Richalet JP, et al. Spirometric reference values in Tunisian children. Respiration. 2004 Oct;71(5):511-8.
  28. Ben Saad H, Tfifha M, Harrabi I, Tabka Z, Guenard H, Hayot M, et al. [Factors influencing pulmonary function in Tunisian women aged 45 years and more]. Rev Mal Respir. 2006 Sep;23(4 Pt 1):324-38.
  29. Ben Saad H, Rouatbi S, Raoudha S, Tabka Z, Laouani Kechrid C, Hassen G, et al. [Vital capacity and peak expiratory flow rates in a North-African population aged 60 years and over: influence of anthropometric data and parity]. Rev Mal Respir. 2003 Sep;20(4):521-30.
  30. Bougrida M, Ben Saad H, Kheireddinne Bourahli M, Bougmiza I, Mehdioui H. [Spirometric reference equations for Algerians aged 19 to 73 years]. Rev Mal Respir. 2008 May;25(5):577-90.
  31. Ben Saad H, El Attar MN, Hadj Mabrouk K, Ben Abdelaziz A, Abdelghani A, Bousarssar M, et al. The recent multi-ethnic global lung initiative 2012 (GLI2012) reference values don't reflect contemporary adult's North African spirometry. Respir Med. 2013 Dec;107(12):2000-8.
  32. Peradzyńska J, Krenke K, Szylling A, Krenke R, Kulus M. The Influence of the Reference Values on the Interpretation of Lung Function in Children: Comparison of Global Lung Initiative 2012 and Polish 1998 Reference Values. Adv Exp Med Biol. 2015;858:31-8.
  33. Ortega VE, Kumar R. The Effect of Ancestry and Genetic Variation on Lung Function Predictions: What Is “Normal” Lung Function in Diverse Human Populations? Curr Allergy Asthma Rep. 2015 Apr;15(4):16.
  34. Langhammer A, Johannessen A, Holmen TL, Melbye H, Stanojevic S, Lund MB, et al. Global Lung Function Initiative 2012 reference equations for spirometry in the Norwegian population. Eur Respir J. 2016 Dec;48(6):1602-11
  35. Whitrow MJ, Harding S. Ethnic differences in adolescent lung function: anthropometric, socioeconomic, and psychosocial factors. Am J Respir Crit Care Med. 2008 Jun 1;177(11):1262-7.
  36. Quanjer PH, Kubota M, Kobayashi H, Omori H, Tatsumi K, Kanazawa M, et al. Secular changes in relative leg length confound height-based spirometric reference values. Chest. 2015 Mar;147(3):792-7.
  37. Cole TJ. The secular trend in human physical growth: a biological view. Econ Hum Biol. 2003 Jun;1(2):161-8.
  38. Whitrow MJ, Harding S. Ethnic differences in adolescent lung function: anthropometric, socioeconomic, and psychosocial factors. Am J Respir Crit Care Med. 2008 Jun 1;177(11):1262-7.