Association Between Initiation of Pulmonary Rehabilitation After Hospitalization for COPD and 1-Year Survival Among Medicare Beneficiaries

Abstract

Importance: Meta-analyses have suggested that initiating pulmonary rehabilitation after an exacerbation of chronic obstructive pulmonary disease (COPD) was associated with improved survival, although the number of patients studied was small and heterogeneity was high. Current guidelines recommend that patients enroll in pulmonary rehabilitation after hospital discharge.

Objective: To determine the association between the initiation of pulmonary rehabilitation within 90 days of hospital discharge and 1-year survival.

Design, setting, and patients: This retrospective, inception cohort study used claims data from fee-for-service Medicare beneficiaries hospitalized for COPD in 2014, at 4446 acute care hospitals in the US. The final date of follow-up was December 31, 2015.

Exposures: Initiation of pulmonary rehabilitation within 90 days of hospital discharge.

Main outcomes and measures: The primary outcome was all-cause mortality at 1 year. Time from discharge to death was modeled using Cox regression with time-varying exposure to pulmonary rehabilitation, adjusting for mortality and for unbalanced characteristics and propensity to initiate pulmonary rehabilitation. Additional analyses evaluated the association between timing of pulmonary rehabilitation and mortality and between number of sessions completed and mortality.

Results: Of 197 376 patients (mean age, 76.9 years; 115 690 [58.6%] women), 2721 (1.5%) initiated pulmonary rehabilitation within 90 days of discharge. A total of 38 302 (19.4%) died within 1 year of discharge, including 7.3% of patients who initiated pulmonary rehabilitation within 90 days and 19.6% of patients who initiated pulmonary rehabilitation after 90 days or not at all. Initiation within 90 days was significantly associated with lower risk of death over 1 year (absolute risk difference [ARD], -6.7% [95% CI, -7.9% to -5.6%]; hazard ratio [HR], 0.63 [95% CI, 0.57 to 0.69]; P < .001). Initiation of pulmonary rehabilitation was significantly associated with lower mortality across start dates ranging from 30 days or less (ARD, -4.6% [95% CI, -5.9% to -3.2%]; HR, 0.74 [95% CI, 0.67 to 0.82]; P < .001) to 61 to 90 days after discharge (ARD, -11.1% [95% CI, -13.2% to -8.4%]; HR, 0.40 [95% CI, 0.30 to 0.54]; P < .001). Every 3 additional sessions was significantly associated with lower risk of death (HR, 0.91 [95% CI, 0.85 to 0.98]; P = .01).

Conclusions and relevance: Among fee-for-service Medicare beneficiaries hospitalized for COPD, initiation of pulmonary rehabilitation within 3 months of discharge was significantly associated with lower risk of mortality at 1 year. These findings support current guideline recommendations for pulmonary rehabilitation after hospitalization for COPD, although the potential for residual confounding exists and further research is needed.

Figure 1.. Patient Selection in a Study of Pulmonary Rehabilitation After Hospitalization for COPD

COPD indicates chronic obstructive pulmonary disease; ARF, acute respiratory failure. ^aPropensity scores were calculated using a logistic regression model accounting for patient clustering within hospitals in the cohort. This was a nonparsimonious logistic (generalized estimating equations) model that included patient demographics, tobacco use, Medicaid dual-eligibility, comorbidities, claims-based frailty indicator, markers of disease severity, features of index admission, characteristics of hospitals to which patients were admitted (including size, rural/urban status, teaching status, and Census region), and selected interaction terms. Patients discharged from hospitals where pulmonary rehabilitation was not provided were excluded from model development because such patients had no possibility of receiving pulmonary rehabilitation. Parameter estimates were then applied to all patients at all hospitals to compute the propensity score. Based on this score and using a greedy match algorithm, patients who received pulmonary rehabilitation within 90 days of discharge were matched 1-to-1 with patients who never initiated or initiated within days 91 and 365. To avoid immortal time bias, the matched control was required to be alive on the day of the pulmonary rehabilitation participant’s first session. In the matched cohort, distance to nearest pulmonary rehabilitation facility, hospital rural/urban status, and hospital size were imbalanced between the groups.

Figure 2.. Risk of Mortality Associated With Initiation of Pulmonary Rehabilitation After Hospital Discharge

Abbreviations: HR, hazard ratio; OR, odds ratio. ^aPulmonary rehabilitation initiation between days 91 and 365 of index discharge. This group combined with those who never initiated pulmonary rehabilitation is the referent group for all models. ^bSurvival (Cox regression) models; modeling time from index discharge, with time-varying exposure. ^cAll models adjusted for patient demographics, severity markers during hospitalization, prior admissions, prior 90-day home oxygen use, comorbidities, claims-based frailty indicator, and propensity score. ^dLogistic (generalized estimating equations) model among 90-day survivor cohort. ^eStabilized inverse probability of treatment-weighted (SIPTW) logistic (generalized estimating equations) model. ^fStandardized mortality ratio–weighted (SMRW) logistic (generalized estimating equations) model; odds ratio. ^gClaim of home oxygen in 90 days before index admission. ^hLogistic (generalized estimating equations) models. ⁱComorbidity burden: weighted Charlson Comorbidity Index accounts for number and seriousness of comorbid conditions that might alter the risk of mortality among medical patients. The weights were assigned to the conditions based on adjusted relative risks from the model where conditions with relative risk 1.2 or greater and less than 1.5 were assigned a weight of 1; conditions with a risk 1.5 or greater and less than 2.5, a weight of 2; conditions with a relative risk of 2.5 or greater and less than 3.5, a weight of 3; and conditions with relative risk greater than 6, a weight of 6. ^jIn full cohort, in which timing of pulmonary rehabilitation start is counted from patients’ most recent chronic obstructive pulmonary disease discharge; survival (Cox regression) models; hazard ratio. ^kPropensity score–matched cohort. Propensity scores were calculated using a logistic regression model accounting for patient clustering within hospitals in the cohort. This was a nonparsimonious logistic (generalized estimating equations) model that included patient demographics, tobacco use, Medicaid dual-eligibility, comorbidities, claims-based frailty indicator, markers of disease severity, features of index admission, characteristics of hospitals to which the patients were admitted (including size, rural/urban status, teaching status, and Census region), and selected interaction terms. Patients discharged from hospitals where pulmonary rehabilitation was not provided were excluded from model development because such patients had no possibility of receiving pulmonary rehabilitation. Parameter estimates were then applied to all patients at all hospitals to compute the propensity score. Based on this score and using a greedy match algorithm, patients who received pulmonary rehabilitation within 90 days of discharge were matched 1-to-1 with patients who never initiated or initiated within days 91 and 365. To avoid immortal time bias, the matched control was required to be alive on the day of the pulmonary rehabilitation participant’s first session. In the matched cohort, distance to nearest pulmonary rehabilitation facility, hospital rural/urban status, and hospital size were imbalanced between the groups. ^lSurvival (Cox regression models) modeling time from pulmonary rehabilitation initiation after adjusting for hospital readmissions and emergency department visits occurring after the index hospitalization, but prior to the day of pulmonary rehabilitation initiation.

Figure 3.. One-Year Mortality After Initiation of Pulmonary Rehabilitation in the Propensity-Matched Cohort^a

^aPropensity scores were calculated using a logistic regression model accounting for patient clustering within hospitals in the cohort. This was a nonparsimonious logistic (generalized estimating equations) model that included patient demographics, tobacco use, Medicaid dual-eligibility, comorbidities, claims based frailty indicator, markers of disease severity, features of index admission, characteristics of hospitals to which the patients were admitted (including size, rural/urban status, teaching status, and Census region), and selected interaction terms. Patients discharged from hospitals where pulmonary rehabilitation was not provided were excluded from model development because such patients had no possibility of receiving pulmonary rehabilitation. Parameter estimates were then applied to all patients at all hospitals to compute the propensity score. Based on this score and using a greedy match algorithm, patients who received pulmonary rehabilitation within 90 days of discharge were matched 1-to-1 with patients who never initiated or initiated within days 91 and 365. To avoid immortal time bias, the matched control was required to be alive on the day of the pulmonary rehabilitation participant’s first session. In the matched cohort, distance to nearest pulmonary rehabilitation facility, hospital rural/urban status, and hospital size were imbalanced between the groups. ^bPulmonary rehabilitation initiation between days 91 and 365 of index discharge.