Table 1.
Quality of Spirometry Performance and Reporting
| Criterion | Pre-Intervention | During Intervention | Mean difference | Odds Ratio | p-value |
|---|---|---|---|---|---|
| Total spirometries | 210 | 208 | - | - | - |
| Mean No. of blows per spirometry | 3.8 (3.5, 4.1) | 3.7 (3.4, 4.0) | −0.08 (−0.25, 0.09) | - | 0.37 |
| Mean No. of acceptablea blows per spirometry | 1.9 (1.3, 2.5) | 2.1 (1.5, 2.7) | 0.22 (−0.07, 0.50) | - | 0.16 |
| Probability of spirometries with ≥3 acceptable blows | 0.36 (0.16, 0.63) | 0.49 (0.27, 0.72) | - | 1.7 (1.1, 2.6) | 0.03 |
| Probability of spirometries with ≥2 repeatable blowsb | 0.85 (0.74, 0.92) | 0.93 (0.85, 0.97) | - | 2.2 (1.0, 4.6) | 0.05 |
| Probability of blows with a poor start | 0.06 | 0.05 | - | 0.74 (0.35, 1.6) | 0.58 |
| Probability of blows with an unsatisfactory exhalation | 0.39 | 0.35 | - | 0.84 (0.62, 1.1) | 0.30 |
| Probability of blows with significant artifact | 0.13 | 0.14 | - | 1.2 (0.86, 1.6) | 0.34 |
| Probability of reporting correct FVCc | 0.71 (0.57, 0.85) | 0.78 (0.66, 0.90) | - | 1.43 (0.72, 2.9) | 0.35 |
| Probability of reporting correct FEV1c | 0.73 (0.61, 0.85) | 0.79 (0.68, 0.89) | - | 1.4 (0.62, 3.0) | 0.45 |
| Probability of documenting inadequate spirometryd | 0.08 (0, 0.18) | 0.12 (0, 0.18) | - | 1.4 (0.73, 2.8) | 0.46 |
| Probability of identifying appropriate reason for inadequate spirometrye, f | 0.02 (0, 0.07) | 0.06 (0, 0.13) | - | 2.4 (0.67, 8.8) | 0.20 |
| Probability that spirometer was calibrated before test | 0.96 (0.68, 1.0) | 0.97 (0.77, 1.0) | - | 1.4 (1.1, 1.9) | 0.01 |
| Probability that spirometry met both acceptability and repeatability criteria | 0.32 (0.14, 0.58) | 0.45 (0.25, 0.67) | - | 1.7 (1.0, 3.0) | <0.05 |
95 % confidence intervals are provided in brackets
CI denotes confidence interval
a“acceptable” was defined by the absence of a poor start [i.e. an extrapolated volume < 5 % of FVC or 150 mL (whichever was greater)], a satisfactory exhalation [defined by reaching a plateau in the volume–time curve, with no change in volume (<0.025 L) for ≥ 1 s], and absence of any significant artifact (including evidence of cough during the first second of exhalation, glottis closure that influences the measurement, early termination or cut-off, submaximal effort, leak, or an obstructed mouthpiece) [22]
bamong spirometries with at least 2 acceptable blows (a spirometry was considered “repeatable” when the two largest FVC values and the two largest FEV1 values were each within 150 mL of each other) [22]
camong spirometries with at least 1 acceptable blow
dTechnician comments were searched for documentation that the test was inadequate (among spirometries which did not meet ATS criteria of at least 3 acceptable and 2 repeatable blows) [22]
eTechnician comments were searched for documentation of the reason that the test was inadequate (among spirometries which did not meet ATS criteria of at least 3 acceptable and 2 repeatable blows) [22]
fFor this outcome, applying the bootstrap method to estimate standard errors failed to converge in one-third of the replications. Therefore, results are reported using robust standard errors