Figures
- Figure 1–
Age distribution in the final sample (n=74,187) of a) Caucasians, b) African–Americans, c) North East Asians and d) South East Asians. The large number of 8-yr-olds did not lead to any bias in predicted values [14].
- Figure 2–
Predicted values for a, b) forced expiratory volume in 1 s (FEV1), c, d) forced vital capacity (FVC) and e, f) FEV1/FVC by sex and ethnic group. a, c, e) Males and b, d, f) females. Graphs were generated using mean height for age in Caucasians to illustrate proportional differences between ethnic groups of the same height and age; in practice, differences in height for age further affect predicted values. The rise and fall in FEV1/FVC around adolescence is due to differential changes in FEV1 and FVC [15].
- Figure 3–
Coefficient of variation (CoV) for forced expiratory volume in 1 s (FEV1) in healthy Caucasian males in four large recent studies, and in the collated Global Lungs Initiative (GLI) material. Graphs were generated using mean height for age in Caucasians to illustrate proportional differences between ethnic groups of the same height and age; in practice, ethnic differences in height for age further affect predicted values. Findings for National Health and Nutritional Examination Survey (NHANES) IV [29] and NHANES III were practically identical. SAPALDIA: Swiss Cohort Study on Air Pollution and Lung Heart Diseases in Adults; HSE: Health Survey for England.
- Figure 4–
a) Age-related cross-sectional annual change in forced expiratory volume in 1 s (FEV1) is larger in tall subjects rather than short subjects. This shown for Caucasian males of height 160 cm, 175 cm and 190 cm. b) Standardising FEV1 for height by taking the ratio FEV1/heightk, where k is ∼2, largely removes differences in age-related changes between adult males and females. These findings have no bearing on within-subject longitudinal decline.
- Figure 5–
Between-subject coefficients of variation (CoV) of a, b) forced expiratory volume in 1 s (FEV1), c, d) forced vital capacity (FVC) and e, f) FEV1/FVC in Caucasians, African–Americans, and North and South East Asians by age. a, c, e) Males, and b, d, f) females.
- Figure 6–
The lower limit of normal (LLN), based on the 5th centile (-1.64 z-scores), values for forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) in a) Caucasian females and b) males. As can be seen, the use of 80% of predicted as the LLN gives rise to age-related bias. Graphs were generated using mean height for age in Caucasians.
- Figure 7–
Percentage of healthy male and female nonsmokers (n=74,187) in whom a) forced expiratory volume in 1 s (FEV1) is <80% predicted or b) FEV1/forced vital capacity (FVC) is <0.70. If it is assumed that FEV1/FVC is <0.70 (instead of below the 5th centile lower limit of normal) implies pathological airflow limitation, cases are missed in those <50 yrs of age, whereas over diagnosis occurs above that age. Thus, at 80 yrs of age, 20–25% of the reference population would have low values compatible with pathological airflow limitation instead of the expected 5%; this represents 75–80% false-positive test results (b).
- Figure 8–
a) Illustration of how z-scores relate to percentiles. b) Pictogram showing test results as z-scores (arrows) for a male from North China, aged 34 yrs, height 166 cm. White area in the bars delineates observations that are above the mean -1.64 z-score (lower limit of normal (LLN) 5%) and light grey delineates mean -1.96 z-score (LLN 2.5%). Reproduced from [133] with permission from the publisher.
Tables
- Table 1– Summary of datasets included in the initial analysis#
Group Countries Males Females N Age range yrs N Age range yrs African–American 1 1529 6–85 2029 6.1–87 India and Pakistan 2 2837 4–86 3003 3–79 Latin America 5 2337 6.7–89.4 2578 7.4–89.7 Mexican–American 1 1622 6.2–86 2282 6.5–87 Iran 1 3398 5–85 2739 5–80 Oman 1 638 6–65 618 6–65 North East Asia 2 2176 15.3–91 4526 15.5–90 South East Asia 4 4187 3.3–88 6371 3.1–92 North Africa 2 541 6–78 602 6–90 Caucasian 14 24229 2.5–95 28844 2.5–95 Other 199 6.2–93 474 5.8–91 Total 33 43693 2.5–95 54066 2.5–95 #: total sample included 97,759 subjects.
- Table 2– Subjects in the groups for which prediction equations were derived#
Group Males Females Total N Age range yrs N Age range yrs Caucasian 25827 2.5–95 31568 2.5–95 57395 African–American 1520 6–85 2025 6.1–87 3545 North East Asian 1414 16–91 3578 16–88 4992 South East Asian 3095 3.3–86 5160 3.2–92 8255 Total 31856 42331 74187 #: the countries of origin are listed in table E1 in the online supplementary data.
- Table 3– Percentage difference in mean pulmonary function by sex and ethnic group compared to Caucasians
Group Females Males FEV1 FVC FEV1/FVC FEF25–75% FEV1 FVC FEV1/FVC FEF25–75% African–American -13.8 -14.4 0.6 -11.7 -14.7 -15.5 0.8 -12.9 North East Asian -0.7 -2.1 1.1 -7.7 -2.7 -3.6 0.9 -3.2 South East Asian -13.0 -15.7 2.9 -4.3 -9.7 -12.3 2.8 -0.9 FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FEF25–75%: forced expiratory flow at 25–75% of FVC.
- Table 4– Comparison of predicted values in adult Caucasian males according to different authors
Author [ref.] a) 17.9 yrs, 160 cm Author [ref.] b) 18.0 yrs, 160 cm FEV1 FVC FEV1/FVC FEV1 FVC FEV1/FVC Polgar [7] 3.09 3.42 NA ECSC/ERS [8] 3.67 4.23 0.83 Rosenthal [82] 2.70 3.69 0.84 Hankinson [17]¶ 3.58 4.12 0.84 Zapletal [83] 2.93 3.53 0.85 Stanojevic [13]# 3.46 4.09 0.85 Stanojevic [13]# 3.45 4.08 0.85 GLI 2012 3.61 4.13 0.88 Wang [6] 3.49 3.93 0.87 GLI 2012 3.61 4.12 0.88 Author [ref.] c) 17.9 yrs, 180 cm Author [ref.] d) 18.0 yrs, 180 cm FEV1 FVC FEV1/FVC FEV1 FVC FEV1/FVC Polgar [7] 4.30 4.69 NA ECSC/ERS [8] 4.53 5.38 0.83 Rosenthal [82] 4.27 5.17 0.82 Hankinson [17]¶ 4.53 5.39 0.84 Zapletal [83] 4.11 4.99 0.85 Stanojevic [13]# 4.56 5.45 0.85 Stanojevic [13]# 4.55 5.44 0.85 GLI 2012 4.69 5.49 0.86 Wang [6] 4.46 5.20 0.86 GLI 2012 4.68 5.47 0.86 Author [ref.] e) 25 yrs, 175 cm Author [ref.] f) 55 yrs, 175 cm FEV1 FVC FEV1/FVC FEV1 FVC FEV1/FVC Crapo [84] 4.45 5.32 0.84 Crapo [84] 3.71 4.67 0.79 ECSC/ERS [8] 4.31 5.09 0.83 ECSC/ERS [8] 3.44 4.31 0.77 Hankinson [17]¶ 4.44 5.36 0.83 Hankinson [17]¶ 3.63 4.74 0.77 HSE [49] 4.43 5.29 0.85 HSE [49] 3.60 4.63 0.79 Knudson [85] 4.39 5.24 0.84 Knudson [85] 3.52 4.35 0.81 Stanojevic [13]# 4.42 5.36 0.83 Stanojevic [13]# 3.63 4.75 0.77 GLI 2012 4.46 5.32 0.85 GLI 2012 3.65 4.66 0.79 FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; GLI: Global Lungs Initiative; ECSC: European Community for Steel and Coal; ERS: European Respiratory Society; HSE: Health Survey for England 1995–1996; NA: not available. #: all age; ¶: National Health and Nutritional Examination Survey (NHANES) III. The transition from one set of equations to another on the 18th birthday (a versus b or c versus d) is not smooth using older equations. The discontinuity, and the disparity between predicted values is much worse in those who are short for their age (a versus b), than in those of average height (c versus d). In adult males there is fair agreement between predicted values, although those derived from the ECSC/ERS are systematically lower than others for subjects ≥25 yrs of age (e versus f).
Supplementary material
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