Compute the ATS/ERS 2019 spirometry session grade from maneuvers already judged acceptable
Source:R/quality.R
pft_quality.RdComputes the Graham et al. ATS/ERS 2019 (Table 10) session grade, A-F, for ONE measure (FEV1 or FVC) from the values of maneuvers that have already been judged acceptable. The grade depends only on the number of accepted maneuvers and their repeatability (the difference between the two largest values).
Arguments
- values
Numeric vector of measurements (litres) from each maneuver already judged acceptable, for ONE person, ONE measure (FEV1 or FVC), and ONE maneuver set (pre- or post-bronchodilator).
NAvalues are dropped. Length 0 is allowed and yields grade"F".- age
Patient age, in years. The repeatability thresholds tighten for children aged 6 or younger; the threshold is the greater of the absolute child value (0.100 / 0.150 / 0.200 L for A / C / D) and 10% of the highest measured value, per Table 10's footnote. Defaults to
NA_real_, which uses the adult thresholds.
Details
This function does not assess maneuver acceptability or overall test quality. See "Precondition" below.
Grade definitions (Table 10, paper p. e83). Adult thresholds in
parentheses; child (age <= 6) thresholds are max(absolute, 0.10 · max(values)):
A: >= 3 acceptable maneuvers; best two within 0.150 L (0.100 L for child).
B: 2 acceptable maneuvers; best two within 0.150 L (0.100 L for child).
C: >= 2 acceptable maneuvers; best two within 0.200 L (0.150 L for child).
D: >= 2 acceptable maneuvers; best two within 0.250 L (0.200 L for child).
E: >= 2 acceptable maneuvers with best-two diff exceeding the D threshold, OR exactly 1 acceptable maneuver.
F: 0 acceptable maneuvers.
Grade U ("0 acceptable AND >= 1 usable") from Table 10 is NOT currently distinguished from F. The API receives only accepted values, so with zero accepted values it cannot tell 0 acceptable += 1 usable (U) apart from 0 acceptable + 0 usable (F), andreturns "F" unconditionally. Implementing U would requireextending the API to take a separate vector of usable-but-not-acceptable maneuvers.
Precondition – acceptability must already be established
values must contain only measurements from maneuvers that an
appropriately trained technologist or reviewer has already judged
acceptable, using the complete flow-volume and volume-time curves and
the full ATS/ERS 2019 acceptability criteria. pft_quality()
receives scalar values only, so it cannot determine acceptability:
it cannot evaluate curve morphology, start-of-test or
end-of-forced-expiration criteria, cough, glottic closure, leak,
mouthpiece obstruction, effort, or any other feature that requires
the raw curves or the testing context.
The returned grade therefore supplements, and does not replace, technical review of the test session. It is not an independent assessment of overall PFT quality, and a grade computed from maneuvers that were not reviewed for acceptability is not meaningful.
Per Graham et al. 2019 (p. e83), FEV1 and FVC are graded separately,
and the pre-bronchodilator and post-bronchodilator maneuver sets are
graded separately. Call pft_quality() once per measure per
maneuver set.
References
Graham BL, Steenbruggen I, Miller MR, et al. Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement. Am J Respir Crit Care Med. 2019;200(8):e70-e88. doi:10.1164/rccm.201908-1590ST .
See also
pft_interpret() for the downstream interpretation once
acceptable maneuvers have been selected by technical review.
Examples
pft_quality(c(3.20, 3.12, 3.10)) # Grade A (n>=3 within 0.150)
#> [1] "A"
pft_quality(c(3.20, 3.12)) # Grade B (n=2 within 0.150)
#> [1] "B"
pft_quality(c(3.20, 3.02)) # Grade C (n>=2 within 0.200)
#> [1] "C"
pft_quality(c(3.20, 2.97)) # Grade D (n>=2 within 0.250)
#> [1] "D"
pft_quality(c(3.20, 2.80)) # Grade E (n>=2 diff > 0.250)
#> [1] "E"
pft_quality(c(3.20)) # Grade E (only 1)
#> [1] "E"
pft_quality(numeric(0)) # Grade F (none)
#> [1] "F"