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Accurate measurement of height and age for lung function testing


Height

Height should be measured, as self-reported height is unreliable. Differences between actual and self-reported height may be up to 6.9 cm, and are generally largest in elderly subjects [1-6]. The FEV1 and FVC are a function of heightk, where k ~ 2.2. In a 110 cm tall child, or a 180 cm tall adult, a 1 cm error leads to an error in the predicted lung function index of 2% and 1.2%, respectively. Not only should standing height be measured, but the stadiometer should be calibrated every year, and in calculating predicted values height should be entered with 1 decimal accuracy [7,8].

Age

The effect of errors in age on predicted values cannot be so easily estimated because of the variable contribution of the spline in age. If age is systematically underestimated by 0.75 years by rounding off, then the percentage error is as listed in the table.

  Males Females
Age (yr) FEV1 %error FVC %error FEV1 %error FVC %error
3 vs 3.75 -2.8 -3.4 -2.9 -3.6
10 vs 10.75 -1.3 -1.4 -2.6 -2.7
15 vs 15.75 -3.4 -2.9 -3.4 -2.9
50 vs 50.75 +0.4 +0.4 +0.6 +0.7
85 vs 85.75 +0.7 +0.5 +0.9 +1.0

The errors vary with age, the largest errors occurring in childhood. Therefore, in calculating predicted values, age should be entered with 1 decimal accuracy [7,8].

References

  1. Parker JM, Dillard TA, Phillips YY. Impact of using stated instead of measured height upon screening spirometry. Am J Respir Crit Care Med 1994; 150(6 Pt 1):1705-1708. PubMed
  2. Brener ND, Mcmanus T, Galuska DA, Lowry R, Wechsler H. Reliability and validity of self-reported height and weight among high school students. J Adolesc Health 2003; 32: 281-287. PubMed
  3. Braziuniene I, Wilson TA, Lane AH. Accuracy of self-reported height measurements in parents and its effect on mid-parental target height calculation. BMC Endocrine Disorders 2007; 7: 2. Manuscript
  4. Jansen W, van de Looij-Jansen P. M, Ferreira I, de Wilde EJ, Brug J. Differences in measured and self-reported height and weight in Dutch adolescents. Ann Nutr Metab 2006; 50: 339-346. Abstract
  5. Lim LLY, Seubsman S-A, Sleigh A. Validity of self-reported weight, height, and body mass index among university students in Thailand: Implications for population studies of obesity in developing countries. Population Health Metrics 2009; 7: 15. Manuscript
  6. Wada K, Tamakoshi K, Tsunekawa T, et al. Validity of self-reported height and weight in a Japanese workplace population. Intern J Obesity 2005; 29: 1093–1099. PubMed
  7. Quanjer PH, Stanojevic S, Cole TJ, et al. and the ERS Global Lung Function Initiative. Multi-ethnic reference values for spirometry for the 3-95 years age range: the Global Lung Function 2012 equations. Eur Respir J 2012; 40: 1324-1343. PubMed
  8. Quanjer PH, Hall GL, Stanojevic S, Cole TJ, Stocks J, on behalf of the Global Lungs Initiative. Age- and height-based prediction bias in spirometry reference equations. Eur Respir J 2012; 40: 190–197. PubMed
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