Table 3.
Effect of Each Exacerbation/Acute Respiratory Event on Rate of FEV1 Decline
| Subject Group | Change in FEV1 (ml/yr) (95% CI) |
|||
|---|---|---|---|---|
| Exacerbations/Acute Respiratory Events of Any Severity |
Severe Exacerbations/Acute Respiratory Events |
|||
| Change in Those with No Exacerbations | Excess Change, per Exacerbation of Any Severity | Change in Those with No Severe Exacerbations | Excess Change, per Severe Exacerbation | |
| PRISm | 5 (−4 to 14) | −6 (−15 to 4) | 5 (−4 to 14) | −17 (−37 to 2) |
| GOLD 0 | −9 (−13 to −4) | −7 (−15 to 2) | −9 (−14 to −5) | −7 (−27 to 13) |
| GOLD 1 | −25 (−34 to −15) | −23 (−44 to −2) | −26 (−35 to −16) | −87 (−151 to −23) |
| GOLD 2 | −19 (−26 to −11) | −10 (−20 to −1) | −21 (−28 to −14) | −20 (−40 to 1) |
| GOLD 3 | −8 (−17 to 0) | −8 (−15 to −1) | −10 (−18 to −3) | −20 (−36 to −4) |
| GOLD 4 | −4 (−16 to 8) | 0 (−9 to 8) | −2 (−13 to 8) | −9 (−29 to 12) |
Definition of abbreviations: CI = confidence interval; GOLD = Global Initiative for Chronic Obstructive Lung Disease; PRISm = preserved ratio impaired spirometry.
Estimates reflect average changes after factoring out expected changes caused by time-varying covariates (age, height, weight, and bronchodilator responsiveness). For example, the change in FEV1 for a GOLD stage 1 subject with one, two, or three exacerbations over the follow-up period can be estimated by adding the excess decline per exacerbation event (−23 ml/yr) to the rate in those without events (−25 ml/yr), yielding a final annual rate of −48 ml/yr, −71 ml/yr, and −94 ml/yr.
Number of subjects available for analysis for PRISm, GOLD 0, GOLD 1, GOLD 2, GOLD 3, and GOLD 4 groups were 267, 1,055, 227, 515, 320, and 113, respectively; number of records available for analysis for the respective groups were 481, 1,891, 404, 913, 543, and 183. Some records were not usable because of missing data for bronchodilator responsiveness, emphysema rate, exacerbations, or some combination of these (see Table 1 and online supplement for more details).