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Bronchodilator response per the Pellegrino 2005 standard

Source: R/interpretation_2005.R
pft_bdr_2005.Rd

Classifies bronchodilator response (BDR) by the Pellegrino et al. ERJ 2005 dual criterion: significant when the relative change from baseline is strictly greater than 12% AND the absolute change is strictly greater than 200 mL. Replaced in 2022 by pft_bdr()'s simpler "> 10% of predicted" rule.

Both inequalities are strict, matching the paper's disambiguating wording on p. 959: "(>12% of control and >200 mL)". A change that hits either boundary exactly (e.g. exactly 12% or exactly 200 mL) is not significant under this criterion.

Usage

pft_bdr_2005(pre, post)

Arguments

pre, post

Numeric vectors of pre- and post-bronchodilator measurements, in litres, same length.

Value

A data frame with one row per input observation and three columns: pct_change (i.e. (post - pre) / pre * 100), abs_change (i.e. post - pre in litres), and is_significant (logical, TRUE when pct_change > 12 AND abs_change > 0.2). NA propagates wherever either of pre / post is NA.

Column naming

This function's pct_change column is percent-of-baseline change (the 2005 criterion). The 2022 pft_bdr() emits a similarly-named but different column, pct_pred_change, which is percent-of-predicted change ((post - pre) / predicted * 100, the 2022 criterion). The two functions deliberately use distinct column names so a result frame can carry both without ambiguity.

Boundary convention (why strict >)

The Pellegrino et al. ERJ 2005 paper is internally inconsistent on operator symbols: Table 6 uses inclusive symbols (>=12%, >=200 mL), while the running text on p. 959 disambiguates the rule as "(>12% of control and >200 mL)" – strict > on both criteria. This implementation follows the running-text convention, matching the more specific of the two source formulations. Callers who prefer the inclusive Table 6 convention can trivially test equality themselves against the pct_change and abs_change columns; a mixed-convention wrapper is out of scope for this package.

References

Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948-968. doi:10.1183/09031936.05.00035205 . Criterion stated in the "Bronchodilator response" section (p. 958) and disambiguated on p. 959; Table 6 uses inclusive symbols.

See also

pft_bdr() for the current Stanojevic 2022 criterion (>10% of predicted). Unlike the 2022 form, the 2005 version does not need the patient's predicted FEV1 / FVC – only the pre and post measurements.

Examples

# +25% relative AND +500 mL absolute -> both strict bounds cleared,
# SIGNIFICANT under the 2005 criterion.
pft_bdr_2005(pre = 2.0, post = 2.5)
#> # A tibble: 1 × 3
#>   pct_change abs_change is_significant
#>        <dbl>      <dbl> <lgl>         
#> 1         25        0.5 TRUE          

# +12% relative exactly and +300 mL absolute: NOT significant, because
# the 2005 criterion requires strictly >12% (not >=12%).
pft_bdr_2005(pre = 2.5, post = 2.8)
#> # A tibble: 1 × 3
#>   pct_change abs_change is_significant
#>        <dbl>      <dbl> <lgl>         
#> 1         12      0.300 FALSE         

# +5% relative and +100 mL absolute: neither bound cleared, NOT
# significant.
pft_bdr_2005(pre = 2.0, post = 2.1)
#> # A tibble: 1 × 3
#>   pct_change abs_change is_significant
#>        <dbl>      <dbl> <lgl>         
#> 1       5.00      0.100 FALSE