Table 2.
Rates of COPD Exacerbations Among Weighted Prompt and Delayed Cohorts
| COPD Exacerbations | Number of Events | Rate (PPY) | Rate Ratioa (95% CI)b [A]/[B] | p-valueb | ||
|---|---|---|---|---|---|---|
| Prompt (N = 529) | Delayed (N = 1375) | Prompt [A] | Delayed [B] | |||
| Observation periodc, mean (SD) | 358.0 (137.4) | 369.4 (140.7) | ||||
| Overall exacerbations | 506 | 1708 | 0.98 | 1.23 | 0.79 (0.65, 0.94) | 0.004 |
| Moderate exacerbationsd | 447 | 1430 | 0.86 | 1.03 | 0.84 (0.69, 0.99) | 0.038 |
| Severe exacerbationse | 59 | 278 | 0.11 | 0.20 | 0.57 (0.37, 0.79) | 0.002 |
Notes: Prompt and delayed patients were weighted using the inverse probability of treatment weighting approach based on the propensity score. Variables used in the propensity score calculation included the following: age, sex, year/quarter of index date, US region, type of insurance plan (ie, PPO, HMO, POS, and other types), Quan-CCI score (categories of 0, 1, 2, and 3+), asthma diagnosis, type of COPD-related exacerbation on the index date, patients with multiple events in the index exacerbation, respiratory medication use, all-cause and COPD-related HRU and medical costs, and comorbidities (those with ≥5% prevalence in either cohort). a Rate ratios were calculated from Poisson regression models with log-link. b CIs and p-values were calculated using non-parametric bootstrap procedures with 999 replications. c The observation period spanned from the index date until the earliest of health plan disenrollment or end of data availability. d Moderate COPD exacerbations were defined as an outpatient or ER visit with a COPD exacerbation diagnosis code in the primary position and at least one dispensing/administration of a systemic corticosteroid or guideline-recommended antibiotic within 5 days following, or prior to, the visit. e Severe COPD exacerbations were defined as an inpatient hospitalization with a diagnosis code for COPD exacerbation in the primary position.
Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; ER, emergency room; HMO, health maintenance organization; HRU, healthcare resource utilization; POS, point-of-service; PPO, preferred provider organization; PPY, per person-year; Quan-CCI, Quan-Charlson comorbidity index; SD, standard deviation.