Outcomes associated with invasive and noninvasive ventilation among patients hospitalized with exacerbations of chronic obstructive pulmonary disease

Abstract

Importance: Small clinical trials have shown that noninvasive ventilation (NIV) is efficacious in reducing the need for intubation and improving short-term survival among patients with severe exacerbations of chronic obstructive pulmonary disease (COPD). Little is known, however, about the effectiveness of NIV in routine clinical practice.

Objective: To compare the outcomes of patients with COPD treated with NIV to those treated with invasive mechanical ventilation (IMV).

Design, setting, and participants: This was a retrospective cohort study of 25 628 patients hospitalized for exacerbation of COPD who received mechanical ventilation on the first or second hospital day at 420 US hospitals participating in the Premier Inpatient Database.

Exposures: Initial ventilation strategy.

Main outcomes and measures: In-hospital mortality, hospital-acquired pneumonia, hospital length of stay and cost, and 30-day readmission.

Results: In the study population, a total of 17 978 (70%) were initially treated with NIV on hospital day 1 or 2. When compared with those initially treated with IMV, NIV-treated patients were older, had less comorbidity, and were less likely to have concomitant pneumonia present on admission. In a propensity-adjusted analysis, NIV was associated with lower risk of mortality than IMV (odds ratio [OR] 0.54; [95% CI, 0.48-0.61]). Treatment with NIV was associated with lower risk of hospital-acquired pneumonia (OR, 0.53 [95% CI, 0.44-0.64]), lower costs (ratio, 0.68 [95% CI, 0.67-0.69]), and a shorter length of stay (ratio, 0.81 [95% CI, 0.79-0.82]), but no difference in 30-day all-cause readmission (OR, 1.04 [95% CI, 0.94-1.15]) or COPD-specific readmission (OR, 1.05 [95% CI, 0.91-1.22]). Propensity matching attenuated these associations. The benefits of NIV were similar in a sample restricted to patients younger than 85 years and were attenuated among patients with higher levels of comorbidity and concomitant pneumonia. Using the hospital as an instrumental variable, the strength of association between NIV and mortality was modestly attenuated (OR, 0.66 [95% CI, 0.47-0.91]). In sensitivity analyses, the benefit of NIV was robust in the face of a strong hypothetical unmeasured confounder.

Conclusions and relevance: In a large retrospective cohort study, patients with COPD treated with NIV at the time of hospitalization had lower inpatient mortality, shorter length of stay, and lower costs compared with those treated with IMV.

Figure 1. Study Selection Criteria/Recruitment Table

DRG indicates diagnosis-related group; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; IMV, invasive mechanical ventilation; NIV, noninvasive ventilation.

Figure 2. Association Between Noninvasion Ventilation and Outcomes

Association between noninvasive ventilation and mortality, hospital-acquired pneumonia, readmission, length of stay, and costs, overall and inpatient stratified comorbidity burden, comorbid pneumonia, and among those younger than 85 years. Subgroup analyses are covariate adjusted. COPD indicates chronic obstructive pulmonary disease; DRG, diagnosis-related group; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; IMV, invasive mechanical ventilation; NIV, noninvasive ventilation; SIPTW, stabilized inverse-probability-of-treatment weighting; SMRW, standardized mortality ratio weighting. ^aAdjusted for unbalanced covariates.

Figure 3. Sensitivity Analysis to Estimate the Potential Impact of Unmeasured Confounding

The odds of outcome related to unmeasured confounder are indicated by r; P₀, proportion of invasively ventilated patients with the confounder; P₁, proportion of noninvasively ventilated patients with the confounder. For example, an unmeasured confounder, “a” with r = 2 times the odds for mortality would have to be present in P₀ ≅ 80% of the invasively ventilated patients, and less than P₁ ≅ 15%of the noninvasively ventilated patients to render the mortality impact for invasive ventilation nonsignificant.