ORIGINAL RESEARCH Associations between Physical Activity and 30-Day Readmission Risk in Chronic Obstructive Pulmonary Disease Huong Q. Nguyen1, Lynna Chu1, In-Liu Amy Liu1, Janet S. Lee1, David Suh2, Brian Korotzer3, George Yuen4, Smita Desai5, Karen J. Coleman1, Anny H. Xiang1, and Michael K. Gould1 1
Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California; 2Pulmonary Department, Kaiser Permanente Southern California, West Los Angeles, California; 3Internal Medicine, Kaiser Permanente Southern California, Downey, California; 4Pulmonary Department, Kaiser Permanente Southern California, Anaheim, California; and 5Kaiser Permanente, San Diego, California
Abstract Rationale: Efforts to reduce 30-day readmission have mostly concentrated on addressing deficiencies in care transitions and outpatient management after discharge. There is growing evidence to suggest that physical inactivity is associated with increased hospitalizations. Objectives: We examined whether or not a potentially modifiable factor such as regular physical activity at baseline was associated with lower risk of 30-day readmission in patients with chronic obstructive pulmonary disease (COPD). Methods: Patients from a large integrated health system were included in this retrospective cohort study if they were hospitalized for COPD (following the Centers for Medicare and Medicaid Services and National Quality Forum proposed criteria) and discharged between January 1, 2011 and December 31, 2012, aged 40 years or older, on a bronchodilator or steroid inhaler, alive at discharge, and continuously enrolled in the health plan 12 months before the index admission and at least 30 days post discharge. Our main outcome was 30-day allcause readmission. Regular physical activity was routinely assessed at the time of all outpatient visits and expressed as the total minutes of moderate or vigorous physical activity (MVPA) per week.
Measurements and Main Results: The sample included a total of 4,596 patients (5,862 index admissions) with a mean age of 72.3 6 11 years. The 30-day readmission rate was 18%, with 59% of readmissions occurring in the first 15 days. Multivariate adjusted analyses showed that patients reporting any level of MPVA had a significantly lower risk of 30-day readmission compared with inactive patients (1–149 min/wk of MVPA: relative risk, 0.67; 95% confidence interval, 0.55–0.81; >150 min/wk of MVPA: relative risk, 0.66; 95% confidence interval, 0.51–0.87). Other significant independent predictors of increased readmission included anemia, prior hospitalizations, longer lengths of stay, more comorbidities, receipt of a new oxygen prescription at discharge, use of the emergency department or observational stay before the readmission (all, P , 0.05), and being unpartnered (P = 0.08). Conclusions: Our findings further support the importance of physical activity in the management of COPD across the care continuum. Although it is possible that lower physical activity is a reflection of worse disease, promoting and supporting physical activity is a promising strategy to reduce the risk of readmission. Keywords: chronic obstructive pulmonary disease; physical activity; readmission
(Received in original form January 14, 2014; accepted in final form February 20, 2014 ) Supported by the Kaiser Permanente Southern California, Implementation Science Program. A portion of these findings were submitted in abstract form to the American Thoracic Society 2014 International Conference in San Diego, CA. Author Contributions: H.Q.N. contributed substantially to the study design, analysis, interpretation, and the preparation of this manuscript. H.Q.N. had full access to the data and will vouch for the integrity of the work as a whole, from inception to published article. L.C. contributed to the data acquisition, interpretation, and the preparation of this manuscript. I.-L.A.L. contributed to the data analysis, interpretation, and the preparation of this manuscript. J.S.L. contributed to the data acquisition, interpretation, and the preparation of this manuscript. D.S. contributed to the interpretation and the preparation of this manuscript. B.K. contributed to the interpretation and the preparation of this manuscript. G.Y. contributed to the interpretation and the preparation of this manuscript. S.D. contributed to the interpretation and the preparation of this manuscript. K.J.C. contributed to the interpretation and the preparation of this manuscript. A.H.X. contributed to the interpretation and the preparation of this manuscript. M.K.G. contributed to the study design, analysis, interpretation, and the preparation of this manuscript. Correspondence and requests for reprints should be addressed to Huong Q. Nguyen, Ph.D., R.N., Research Scientist, Department of Research and Evaluation, Kaiser Permanente Southern California, 100 S. Los Robles Avenue, 2nd Floor, Pasadena, CA 91101. E-mail: [email protected] This article has an online supplement, which is accessible from this issue’s table of contents at www.atsjournals.org Ann Am Thorac Soc Vol 11, No 5, pp 695–705, Jun 2014 Copyright © 2014 by the American Thoracic Society DOI: 10.1513/AnnalsATS.201401-017OC Internet address: www.atsjournals.org
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ORIGINAL RESEARCH The Centers for Medicare and Medicaid Services began publicly reporting 30-day risk-standardized readmission rates for heart failure, acute myocardial infarction, and pneumonia and penalizing hospitals for having higher than expected all-cause readmission rates in late 2012 (1, 2). Reducing 30-day hospital readmissions has become a major focus of many health care systems, with most efforts concentrating heavily on addressing deficiencies in care transitions and outpatient management after discharge (3–5). In 2015, the list of conditions will expand to include patients admitted for an exacerbation of chronic obstructive pulmonary disease (COPD) (1). COPD is a chronic progressive disease that is characterized by exacerbations requiring a change in medication or more intensive treatment (6). A number of these episodes are severe enough to require admission to the hospital, with such hospitalizations accounting for nearly 75% of the total direct health care costs for COPD (7). Patients who are hospitalized for a severe COPD exacerbation are at high risk for readmission and death (8–10). National statistics from 2008 show that the 30-day COPD-specific and all-cause readmission rates after an index COPD admission were 7 and 21%, respectively (11). Compared with the index hospitalization, readmission for COPD as the principal diagnosis cost 18% more, whereas costs due to readmissions for all other causes cost over 50% more than the index hospital stay (11). Nearly two-thirds of readmissions from an index COPD admission are due to non-COPD causes (12). Numerous readmission risk prediction models have been developed to identify which patients might benefit most from care transition interventions and to risk-adjust readmission rates for the purposes of comparisons. Most of these models incorporate variables for medical comorbidity and previous health resource use, with few that include potentially modifiable variables, such as physical functioning, that could be a target for intervention (13). Given the mounting evidence linking physical inactivity to increased hospitalizations and mortality in COPD (14–19), we examined whether regular physical activity captured as part of routine clinical care before the index admission was associated with lower risk of 30-day readmission in COPD. Some of the 696
results from this study have been previously reported in the form of an abstract (20).
Methods Study Design
This was a retrospective cohort study of members from a large integrated health care system with 14 medical centers located in southern California. Human subject approval was obtained from the Kaiser Permanente Institutional Review Board. Patients were selected for inclusion if they were hospitalized for COPD and discharged between January 1, 2011 and December 31, 2012. COPD hospitalizations were defined according to the Centers for Medicare and Medicaid Services and National Quality Forum proposed criteria: International Classification of Diseases, Ninth Revision principal diagnosis of COPD (491.21, 491.22, 491.8, 491.9, 492.8, 493.20, 493.21, 493.22, and 496) or principal diagnosis of respiratory failure (518.81, 518.82, 518.84, 799.1) and a secondary diagnosis of acute exacerbation of COPD (491.21, 491.22, 493.21, 493.22) and age 40 years or older (21). We applied additional inclusion criteria, including being on at least one maintenance bronchodilator or steroid inhaler in the 12 months before the index admission, alive at discharge, and continuously enrolled in the health plan in the 12 months before index admission and at least 30 days post discharge. Patients who were cared for in an observational stay unit (,24 h of care) were excluded from this analysis. An individual could contribute multiple index admissions during this observation period. Primary Outcome
Thirty-day readmission was defined as any repeat admission within 30 days after being discharged alive from an index hospital stay between January 1, 2011 and December 31, 2012. For patients whose hospitalization included transfers between hospitals or within the same hospital, the hospitalization was counted as one event and not counted as a readmission. The resultant length of stay and discharge diagnoses were combined from the individual stays. All readmissions to both Kaiser and non-Kaiser facilities were captured. Primary Independent Variable Regular physical activity. During the intake process for all outpatient visits, every patient in our health system is asked the following
two questions regarding their regular physical activity (exercise vital sign [EVS]): (1) “On average, how many days per week do you engage in moderate to strenuous (vigorous) exercise (like a brisk walk)?” and (2) “On average, how many minutes do you engage in exercise at this level?” These questions are typically asked by medical assistants and licensed vocational nurses, and patients’ responses are entered into the electronic medical record. Response choices for days are categorical (0–7). Minutes are recorded categorically: 0, 10, 20, 30, 40, 50, 60, 90, 120, and 150 or greater. The electronic medical record system software then multiplies the two self-reported responses to display total minutes per week of moderate or vigorous physical activity (MVPA) for the health care provider to review; we used this calculated value as the exposure variable for our analysis. The EVS closest to the index admission date was used for our primary analysis. Approximately 97% of the EVS data included in the analysis were obtained within 12 months before the index admission (median of 71 d). Due to the skewed MVPA data, we categorized patients as being completely inactive (0 min/wk), insufficiently active (1–149 min/wk), or active, meeting national physical activity recommendations (>150 min/wk). The EVS has evidence of construct validity in the general health plan population (22, 23). Covariates
We extracted administrative and clinical data in the 12 months (January 1, 2010 through December 31, 2011) before the index admission for the entire sample. Sociodemographics. Sociodemographics were obtained from our membership files and included age, sex, marital status, race, and insurance status. Body mass index was obtained from the most recent outpatient encounter before the index admission. Disease severity and comorbidities. Disease severity was based on available spirometry data, and post-bronchodilator FEV1% predicted was used. Only 54% of the sample had any spirometry data available for analysis. A Charlson comorbidity score was calculated for each patient. We also included additional morbidities reportedly associated with hospitalization risk in COPD but not included in the Charlson index, including anemia, anxiety, depression, pulmonary hypertension, and hypertension.
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ORIGINAL RESEARCH Health resource use. Health resource use included hospitalizations in the 12 months preceding the index event, length of stay of the index event, emergency department or observational stay within 30 days of the index admission but occurring before the readmission event, and discharge disposition at the index admission. Use of inhalers and oxygen supplementation was based on pharmacy and durable medical equipment data from the 12 months before the index admission; to distinguish long-term systemic corticosteroid use versus short-term use to treat COPD exacerbations, patients had to have at least 90 days of continuous steroid use with a refill gap of less than14 days. New oxygen use after the index discharge was based on durable medical equipment data indicating date of oxygen delivery, and only those delivered within the 30 days of discharge were included. Receipt of inpatient palliative care consult during the index admission was also included. Health behaviors. Health behaviors included smoking status, vaccination history, and participation in pulmonary rehabilitation. Smoking status was obtained from the most recent outpatient encounter before their index admission. We were not able to obtain smoking status at the index admission. Vaccination history included influenza and pneumococcal vaccinations in the previous 1 to 2 years and up to 5 years, respectively. Participation in pulmonary rehabilitation up to 4 years before the index admission was recorded.
admission, excluded patients with a primary diagnosis of acute respiratory failure (518.8x), and analyzed a subgroup of patients who had spirometry data (54% of the larger sample) to further adjust for disease severity. All significance levels for the generalized estimating equations models were two-sided with a P value less than 0.05. Analyses were conducted using SAS 9.2 (SAS Institute Inc).
Results Cohort Selection
We identified 6,042 patients with COPD as their principal discharge diagnosis or who had acute respiratory failure with a secondary diagnosis of acute COPD exacerbation (Figure 1). Patients were excluded if they were less than 40 years old (n = 356), had not been prescribed either a bronchodilator or steroid inhaler before the index admission (n = 905), died during the index stay (n = 139), or had an
observational stay (n = 46). The final analytical sample included 4,596 patients who had 5,862 index admissions. Approximately 19% of the patients had more than one index admission during the study period. Descriptive Statistics
The sample had a mean age of 72.3 6 11 years and was composed of 68% whites, 12% Hispanics, 4% Asians/Pacific Islanders, and 15% Blacks, with a comparable distribution of men and women (Tables 1 and 2). Approximately 23% had at least one COPD-related hospitalization in the previous 12 months. The mean FEV1% predicted was 57.4 6 22% for 2,489 patients who had a spirometry test (54% of the sample). Comorbid conditions were common, with a mean Charlson index score of 3.9 6 2.7 and distribution of comorbidities as follows: hypertension (84%), heart failure (35%), diabetes (33%), depression (20%), cancer (20%), and anemia (15%). The mean length of stay for
Statistical Analysis
Bivariate analyses of potential risk factors for 30-day readmission were performed using t tests for continuous variables and Chi-square tests for categorical variables. Significant predictors from the bivariate analyses were included in the final model to test the independent effect of each risk factor using generalized estimating equations with an exchangeable covariance structure to account for patients contributing more than one index admission. Covariates were included in the final model if they contributed substantially to model fit or were of clinical significance. Sensitivity analyses were performed to determine if the effects of physical activity were similar when we used a composite EVS measure of all available values (median or mode) in the 12 months before the index
Figure 1. Sample flow chart. AECOPD = acute exacerbation of chronic obstructive pulmonary disease; COPD = chronic obstructive pulmonary disease; ICD-9 = International Classification of Diseases, Ninth Revision.
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ORIGINAL RESEARCH Table 1. Characteristics of patients with an index chronic obstructive pulmonary disease admission from 2011 to 2012 Patient-Level Variables
Age Mean (SD) Sex Male Female Marital status Unpartnered Partnered Missing BMI Underweight (,18.5) Normal weight (18.5–24.9) Overweight (25–29.9) Obese (.30) Missing Race White Black Hispanic Asian/Pacific Islander Others Missing Smoking status Never Passive Former Current Missing Hospitalization in previous year No. of patients with no prior hospitalization No. of patients with prior COPD hospitalization No. of patients with prior non-COPD hospitalization FEV1% predicted N Mean (SD) FEV1% predicted GOLD I GOLD II GOLD III GOLD IV Missing Medications Short-acting b-agonist Short-acting anticholinergic LABA LAMA ICS LAMA & ICS LABA & ICS Systemic corticosteroids (long-term use) Methylxanthines Oxygen use before index admission New oxygen use post index admission Comorbidities Anemia (present on admission) Heart failure Pulmonary hypertension Diabetes Hypertension Depression Anxiety Solid tumor without metastasis Metastatic cancer
Total Index (n = 4,596)
30-Day Readmission No (n = 3,653)
Yes (n = 941)
72.1 (10.8)
73.0 (10.6)
72.3 (10.8)
P Value
, 0.01 0.36
1,609 (44) 2,044 (56)
431 (46) 512 (54)
2,040 (44) 2,556 (56)
1,735 (47) 1,749 (48) 169 (5)
497 (53) 410 (43) 36 (4)
2,232 (49) 2,159 (47) 205 (4)
273 1,166 950 1,261 3
(7) (32) (26) (35) (0)
81 305 242 315 0
(9) (32) (26) (33) (0)
354 1,471 1,192 1,576 3
(8) (32) (26) (34) (0)
2,491 513 438 154 19 38
(68) (14) (12) (4) (1) (1)
627 162 95 41 4 14
(66) (17) (10) (4) (0) (1)
3,118 675 533 195 23 52
(68) (15) (12) (4) (1) (1)
468 22 2,322 831 10
(13) (1) (64) (23) (0)
100 (11) 5 (1) 666 (71) 172 (18) 0 (0)
568 27 2,988 1,003 10
(12) (1) (65) (22) (0)
2,228 (61) 755 (21) 670 (18)
417 (44) 294 (31) 232 (25)
2,645 (58) 1,049 (23) 902 (20)
, 0.01
0.67
0.23
0.001
,0.001
0.13 1,976 57.7 (21.9)
513 56.0 (21.4)
2,489 57.4 (21.8) 0.70
307 879 588 202 1,677
(8) (24) (16) (6) (46)
69 235 157 52 430
(7) (25) (17) (6) (46)
376 1,114 745 254 2,107
(8) (24) (16) (6) (46)
3,367 2,000 1,538 1,258 2,750 1,095 1,527 368 119 659 414
(92) (55) (42) (34) (75) (30) (42) (10) (3) (18) (11)
870 584 436 377 732 335 431 142 28 188 129
(92) (62) (46) (40) (78) (36) (46) (15) (3) (20) (14)
4,237 2,584 1,974 1,635 3,482 1,430 1,958 510 147 847 543
(92) (56) (43) (36) (76) (31) (43) (11) (3) (18) (12)
0.93 ,0.001 0.02 , 0.01 0.13 ,0.01 0.03 ,0.001 0.65 0.18 0.05
478 1,195 424 1,156 3,028 733 250 659 73
(13) (33) (12) (32) (83) (20) (7) (18) (2)
220 436 150 370 813 207 81 168 28
(23) (46) (16) (39) (86) (22) (9) (18) (3)
698 1,631 574 1,526 3,841 940 331 827 101
(15) (35) (12) (33) (84) (20) (7) (18) (2)
,0.001 ,0.001 ,0.001 ,0.001 0.01 0.20 0.06 0.87 0.07 (Continued )
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ORIGINAL RESEARCH Table 1. (Continued ) Patient-Level Variables
Charlson Index N Mean (SD) Insurance at index admission Medicare Medicaid Commercial Private pay Missing Immunization Flu vaccination since Jan. 1, 2010 Pneumonia vaccination within last 5 yr Ever participated in pulmonary rehab Yes No
Total Index (n = 4,596)
30-Day Readmission No (n = 3,653)
Yes (n = 941)
3,648 3.7 (2.62)
942 4.5 (2.80)
P Value
,0.001 4,590 3.8 (2.68) 0.02 2,655 59 873 30 36
(73) (2) (24) (1) (1)
720 23 187 7 6
(76) (2) (20) (1) (1)
3,375 82 1,060 37 42
(73) (2) (23) (1) (1)
2,828 (77) 2,311 (63)
760 (81) 658 (70)
3,588 (78) 2,969 (65)
212 (6) 3,441 (94)
54 (6) 889 (94)
266 (6) 4,330 (94)
0.034 ,0.001 0.93
Definition of abbreviations: BMI = body mass index; GOLD = Global Initiative for Chronic Obstructive Pulmonary Disease; ICS = Inhaled corticosteroids; LABA = long-acting b-agonists; LAMA = long-acting anticholinergic. Data are presented as n (%) unless otherwise noted. For patients with multiple index admissions, patient characteristics associated with the first hospitalization during the 2-year study period were used.
the index admission was 4.1 6 6.1 days and 4.2 6 6.2 days for the readmission. A small percentage of the patients ever participated in pulmonary rehabilitation before the index admission (6%) or received a palliative care consult during the hospitalization (6%). Approximately 71% of patients reported no moderate to vigorous physical activity (MVPA inactive), 17% were insufficiently active, and another 10% reported engaging in at least 150 minutes of MVPA before their index admission. 30-Day Readmission Timing and Patterns
The all-cause 30-day readmission rate was 18%, with 59% of readmissions occurring in the first 15 days after discharge (Figure 2). To ensure that we excluded any potential transfers that were not already captured, we further excluded any readmission that occurred within 24 hours of the discharge. The distribution across the 10 most common readmission diagnoses (24) during cumulative periods after discharge (Days 0–3, 0–7, 0–15, and 0–30) is shown in Figure 3. Approximately 45% of the readmissions were associated with a principal discharge diagnosis of COPD, followed by other respiratory/ventilator disorders, pneumonia, gastrointestinal disorders, sepsis/shock, heart failure, arrhythmias/conduction disorders, renal disorders, acute myocardial infarction,
electrolyte disturbances, and nutrition/ metabolic disorders. The overall pattern of readmission diagnoses was largely similar over the cumulative periods after discharge.
Unadjusted Analyses of Factors Associated with 30-Day Readmission
Sex, body mass index, race/ethnicity, use of combination inhalers, use of oxygen supplementation before the index
Table 2. Characteristics of index admissions for patients with chronic obstructive pulmonary disease from 2011 to 2012 30 Day Readmission No (n = 4,803) Length of stay, d 1–2 3 4–6 7–13 >14 Discharge disposition Home Postacute Hospital Hospice Other Missing Emergency dept./observational stay Yes No Inpatient palliative care consult Yes No Usual physical activity 0 min/wk 1–149 min/wk .150 min/wk Missing
Yes (n = 1,059)
Total Index (n = 5,862)
1,108 1,133 1,735 705 122
(23) (24) (36) (15) (3)
193 215 396 194 61
(18) (20) (37) (18) (6)
1,301 1,348 2,131 899 183
(22) (23) (36) (15) (3)
4,284 292 7 139 38 43
(89) (6) (0) (3) (1) (1)
900 102 1 9 20 27
(85) (10) (0) (1) (2) (3)
5,184 394 8 148 58 70
(88) (7) (0) (3) (1) (1)
436 (9) 4,367 (91)
198 (19) 861 (81)
634 (11) 5,228 (89)
276 (6) 4,527 (94)
66 (6) 993 (94)
342 (6) 5,520 (94)
3,316 866 497 124
827 141 77 14
4,143 1,007 574 138
P Value ,0.001
,0.001
,0.001
0.54
(69) (18) (10) (3)
(78) (13) (7) (1)
(71) (17) (10) (2)
,0.001
Data are presented as n (%).
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ORIGINAL RESEARCH
Figure 2. Thirty-day readmissions by day (0–30) after hospitalization for chronic obstructive pulmonary disease (COPD).
admission, depression, anxiety, and receipt of an inpatient palliative care consult during the index admission were not significantly associated with risk of 30-day readmission (Table 3). Factors associated with a significantly increased 30-day readmission included age, being unpartnered, having a history of any hospitalization in the previous year, new oxygen prescription at discharge, use of systemic steroids, presence of anemia at admission, pulmonary hypertension, hypertension, having more comorbidities, having a visit to the emergency department or an observational stay within 30 days of discharge that occurred before the
readmission, and length of stay longer than 3 days (all, P , 0.05). Discharge to postacute care or another hospital was associated with increased risk of readmission (P , 0.001), whereas discharge to hospice was associated with lower risk (P , 0.001). Participation in any MVPA before the index admission was also associated with lower risk of readmission (P , 0.001). Multivariate Adjusted Analyses of Factors Associated with 30-Day Readmission
After adjustments for all other key covariates, patients who reported any
MVPA at baseline before the index admission had a significantly lower risk of 30-day readmission compared with inactive patients (Table 4). Specifically, patients meeting the national recommendation of engaging in at least 150 min/wk of MVPA had a 34% lower risk of 30-day readmission compared with inactive patients (relative risk [RR], 0.66; 95% confidence interval [CI], 0.51–0.87). Patients engaged in lower levels of MVPA were also less likely to be readmitted (RR, 0.67; 95% CI, 0.55–0.81). Factors that remained significantly associated with increased risk of 30-day readmission in this adjusted model included having a history of any prior hospitalizations, a new prescription for oxygen, presence of anemia at admission, more comorbidities, a visit to the emergency department or an observational stay, and length of stay longer than 3 days (all, P , 0.01); being unpartnered approached statistical significance (P = 0.08). Sensitivity Analyses
We performed sensitivity analyses to determine if the effects of regular physical activity on 30-day readmission would remain robust to three different scenarios. First, we analyzed either the median or modal value of all EVS data in the 12 months preceding the hospitalization and found similar effects (see online supplement). Second, we excluded patients with a principal diagnosis of acute respiratory failure and a secondary diagnosis of COPD. The effect of physical inactivity was similar in this analysis (insufficiently active vs.
Figure 3. Distribution of 30-day readmission principal diagnoses after hospitalizations for chronic obstructive pulmonary disease (COPD). cond = conduction; GI = gastrointestinal; MI = myocardial infarction; resp./vent. = respiratory/ventilatory.
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ORIGINAL RESEARCH Table 3. Unadjusted bivariate generalized estimating equations model predicting 30-day readmission in patients with chronic obstructive pulmonary disease Parameter Age Sex Marital status BMI
Race/ethnicity
Insurance type Smoking status Vaccinations Usual physical activity Medications Oxygen use Hospitalizations Comorbidities
Palliative care Length of stay, d
ED/observational stay Disposition
RR Age: per increase of 1 yr Female vs. male Unpartnered vs. partnered Normal weight (18.5–24.9) Underweight (,18.5) Overweight (25–29.9) Obese (.30) White Asian/Pacific Islander Black Hispanic Others Commercial/private pay vs. Medicare/Medicaid Never/passive Former Current Flu vaccination within 2 yr vs. none Pneumovax within 5 yr vs. none 0 min/wk MVPA (inactive) 1-149 min/wk MVPA (insufficient) >150 min/wk MVPA (active) LABA/ICS or LAMA/ICS vs. none Systemic corticosteroids vs. none Oxygen before index admission vs. none New oxygen post index admission vs. none No previous hospitalizations Prior COPD hospitalization Prior non-COPD hospitalization Charlson index score, 0–1 Charlson index score, 2 Charlson index score, 31 Pulmonary hypertension vs. none Hypertension vs. none Depression vs. none Anxiety vs. none Anemia (present on admission) vs. none Chronic obstructive asthma vs. COPD Received consult vs. no 1–2 3 4–6 7-13 >14 Yes vs. no Home Hospice Postacute/hospital Other/missing
1.01 0.95 1.20 1.00 1.10 0.97 0.98 1.00 0.84 0.87 0.98 0.75 0.81 1.00 1.27 0.96 1.16 1.33 1.00 0.67 0.61 1.04 1.49 1.07 1.29 1.00 1.82 1.82 1.00 1.14 1.88 1.39 1.32 1.12 1.22 1.94 0.95 1.06 1.00 1.09 1.29 1.52 2.79 2.23 1.00 0.28 1.65 2.76
P Value
95% CI 1.00 0.82 1.04
1.01 1.09 1.38
0.03 0.45 0.01
0.84 0.80 0.82
1.44 1.16 1.16
0.48 0.71 0.81
0.51 0.48 0.58 0.44 0.69
1.40 1.57 1.66 1.29 0.96
0.50 0.64 0.95 0.30 0.02
1.02 0.74 0.97 1.15
1.59 1.25 1.38 1.55
0.03 0.79 0.10
Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California; 2Pulmonary Department, Kaiser Permanente Southern California, West Los Angeles, California; 3Internal Medicine, Kaiser Permanente Southern California, Downey, California; 4Pulmonary Department, Kaiser Permanente Southern California, Anaheim, California; and 5Kaiser Permanente, San Diego, California
Abstract Rationale: Efforts to reduce 30-day readmission have mostly concentrated on addressing deficiencies in care transitions and outpatient management after discharge. There is growing evidence to suggest that physical inactivity is associated with increased hospitalizations. Objectives: We examined whether or not a potentially modifiable factor such as regular physical activity at baseline was associated with lower risk of 30-day readmission in patients with chronic obstructive pulmonary disease (COPD). Methods: Patients from a large integrated health system were included in this retrospective cohort study if they were hospitalized for COPD (following the Centers for Medicare and Medicaid Services and National Quality Forum proposed criteria) and discharged between January 1, 2011 and December 31, 2012, aged 40 years or older, on a bronchodilator or steroid inhaler, alive at discharge, and continuously enrolled in the health plan 12 months before the index admission and at least 30 days post discharge. Our main outcome was 30-day allcause readmission. Regular physical activity was routinely assessed at the time of all outpatient visits and expressed as the total minutes of moderate or vigorous physical activity (MVPA) per week.
Measurements and Main Results: The sample included a total of 4,596 patients (5,862 index admissions) with a mean age of 72.3 6 11 years. The 30-day readmission rate was 18%, with 59% of readmissions occurring in the first 15 days. Multivariate adjusted analyses showed that patients reporting any level of MPVA had a significantly lower risk of 30-day readmission compared with inactive patients (1–149 min/wk of MVPA: relative risk, 0.67; 95% confidence interval, 0.55–0.81; >150 min/wk of MVPA: relative risk, 0.66; 95% confidence interval, 0.51–0.87). Other significant independent predictors of increased readmission included anemia, prior hospitalizations, longer lengths of stay, more comorbidities, receipt of a new oxygen prescription at discharge, use of the emergency department or observational stay before the readmission (all, P , 0.05), and being unpartnered (P = 0.08). Conclusions: Our findings further support the importance of physical activity in the management of COPD across the care continuum. Although it is possible that lower physical activity is a reflection of worse disease, promoting and supporting physical activity is a promising strategy to reduce the risk of readmission. Keywords: chronic obstructive pulmonary disease; physical activity; readmission
(Received in original form January 14, 2014; accepted in final form February 20, 2014 ) Supported by the Kaiser Permanente Southern California, Implementation Science Program. A portion of these findings were submitted in abstract form to the American Thoracic Society 2014 International Conference in San Diego, CA. Author Contributions: H.Q.N. contributed substantially to the study design, analysis, interpretation, and the preparation of this manuscript. H.Q.N. had full access to the data and will vouch for the integrity of the work as a whole, from inception to published article. L.C. contributed to the data acquisition, interpretation, and the preparation of this manuscript. I.-L.A.L. contributed to the data analysis, interpretation, and the preparation of this manuscript. J.S.L. contributed to the data acquisition, interpretation, and the preparation of this manuscript. D.S. contributed to the interpretation and the preparation of this manuscript. B.K. contributed to the interpretation and the preparation of this manuscript. G.Y. contributed to the interpretation and the preparation of this manuscript. S.D. contributed to the interpretation and the preparation of this manuscript. K.J.C. contributed to the interpretation and the preparation of this manuscript. A.H.X. contributed to the interpretation and the preparation of this manuscript. M.K.G. contributed to the study design, analysis, interpretation, and the preparation of this manuscript. Correspondence and requests for reprints should be addressed to Huong Q. Nguyen, Ph.D., R.N., Research Scientist, Department of Research and Evaluation, Kaiser Permanente Southern California, 100 S. Los Robles Avenue, 2nd Floor, Pasadena, CA 91101. E-mail: [email protected] This article has an online supplement, which is accessible from this issue’s table of contents at www.atsjournals.org Ann Am Thorac Soc Vol 11, No 5, pp 695–705, Jun 2014 Copyright © 2014 by the American Thoracic Society DOI: 10.1513/AnnalsATS.201401-017OC Internet address: www.atsjournals.org
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ORIGINAL RESEARCH The Centers for Medicare and Medicaid Services began publicly reporting 30-day risk-standardized readmission rates for heart failure, acute myocardial infarction, and pneumonia and penalizing hospitals for having higher than expected all-cause readmission rates in late 2012 (1, 2). Reducing 30-day hospital readmissions has become a major focus of many health care systems, with most efforts concentrating heavily on addressing deficiencies in care transitions and outpatient management after discharge (3–5). In 2015, the list of conditions will expand to include patients admitted for an exacerbation of chronic obstructive pulmonary disease (COPD) (1). COPD is a chronic progressive disease that is characterized by exacerbations requiring a change in medication or more intensive treatment (6). A number of these episodes are severe enough to require admission to the hospital, with such hospitalizations accounting for nearly 75% of the total direct health care costs for COPD (7). Patients who are hospitalized for a severe COPD exacerbation are at high risk for readmission and death (8–10). National statistics from 2008 show that the 30-day COPD-specific and all-cause readmission rates after an index COPD admission were 7 and 21%, respectively (11). Compared with the index hospitalization, readmission for COPD as the principal diagnosis cost 18% more, whereas costs due to readmissions for all other causes cost over 50% more than the index hospital stay (11). Nearly two-thirds of readmissions from an index COPD admission are due to non-COPD causes (12). Numerous readmission risk prediction models have been developed to identify which patients might benefit most from care transition interventions and to risk-adjust readmission rates for the purposes of comparisons. Most of these models incorporate variables for medical comorbidity and previous health resource use, with few that include potentially modifiable variables, such as physical functioning, that could be a target for intervention (13). Given the mounting evidence linking physical inactivity to increased hospitalizations and mortality in COPD (14–19), we examined whether regular physical activity captured as part of routine clinical care before the index admission was associated with lower risk of 30-day readmission in COPD. Some of the 696
results from this study have been previously reported in the form of an abstract (20).
Methods Study Design
This was a retrospective cohort study of members from a large integrated health care system with 14 medical centers located in southern California. Human subject approval was obtained from the Kaiser Permanente Institutional Review Board. Patients were selected for inclusion if they were hospitalized for COPD and discharged between January 1, 2011 and December 31, 2012. COPD hospitalizations were defined according to the Centers for Medicare and Medicaid Services and National Quality Forum proposed criteria: International Classification of Diseases, Ninth Revision principal diagnosis of COPD (491.21, 491.22, 491.8, 491.9, 492.8, 493.20, 493.21, 493.22, and 496) or principal diagnosis of respiratory failure (518.81, 518.82, 518.84, 799.1) and a secondary diagnosis of acute exacerbation of COPD (491.21, 491.22, 493.21, 493.22) and age 40 years or older (21). We applied additional inclusion criteria, including being on at least one maintenance bronchodilator or steroid inhaler in the 12 months before the index admission, alive at discharge, and continuously enrolled in the health plan in the 12 months before index admission and at least 30 days post discharge. Patients who were cared for in an observational stay unit (,24 h of care) were excluded from this analysis. An individual could contribute multiple index admissions during this observation period. Primary Outcome
Thirty-day readmission was defined as any repeat admission within 30 days after being discharged alive from an index hospital stay between January 1, 2011 and December 31, 2012. For patients whose hospitalization included transfers between hospitals or within the same hospital, the hospitalization was counted as one event and not counted as a readmission. The resultant length of stay and discharge diagnoses were combined from the individual stays. All readmissions to both Kaiser and non-Kaiser facilities were captured. Primary Independent Variable Regular physical activity. During the intake process for all outpatient visits, every patient in our health system is asked the following
two questions regarding their regular physical activity (exercise vital sign [EVS]): (1) “On average, how many days per week do you engage in moderate to strenuous (vigorous) exercise (like a brisk walk)?” and (2) “On average, how many minutes do you engage in exercise at this level?” These questions are typically asked by medical assistants and licensed vocational nurses, and patients’ responses are entered into the electronic medical record. Response choices for days are categorical (0–7). Minutes are recorded categorically: 0, 10, 20, 30, 40, 50, 60, 90, 120, and 150 or greater. The electronic medical record system software then multiplies the two self-reported responses to display total minutes per week of moderate or vigorous physical activity (MVPA) for the health care provider to review; we used this calculated value as the exposure variable for our analysis. The EVS closest to the index admission date was used for our primary analysis. Approximately 97% of the EVS data included in the analysis were obtained within 12 months before the index admission (median of 71 d). Due to the skewed MVPA data, we categorized patients as being completely inactive (0 min/wk), insufficiently active (1–149 min/wk), or active, meeting national physical activity recommendations (>150 min/wk). The EVS has evidence of construct validity in the general health plan population (22, 23). Covariates
We extracted administrative and clinical data in the 12 months (January 1, 2010 through December 31, 2011) before the index admission for the entire sample. Sociodemographics. Sociodemographics were obtained from our membership files and included age, sex, marital status, race, and insurance status. Body mass index was obtained from the most recent outpatient encounter before the index admission. Disease severity and comorbidities. Disease severity was based on available spirometry data, and post-bronchodilator FEV1% predicted was used. Only 54% of the sample had any spirometry data available for analysis. A Charlson comorbidity score was calculated for each patient. We also included additional morbidities reportedly associated with hospitalization risk in COPD but not included in the Charlson index, including anemia, anxiety, depression, pulmonary hypertension, and hypertension.
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ORIGINAL RESEARCH Health resource use. Health resource use included hospitalizations in the 12 months preceding the index event, length of stay of the index event, emergency department or observational stay within 30 days of the index admission but occurring before the readmission event, and discharge disposition at the index admission. Use of inhalers and oxygen supplementation was based on pharmacy and durable medical equipment data from the 12 months before the index admission; to distinguish long-term systemic corticosteroid use versus short-term use to treat COPD exacerbations, patients had to have at least 90 days of continuous steroid use with a refill gap of less than14 days. New oxygen use after the index discharge was based on durable medical equipment data indicating date of oxygen delivery, and only those delivered within the 30 days of discharge were included. Receipt of inpatient palliative care consult during the index admission was also included. Health behaviors. Health behaviors included smoking status, vaccination history, and participation in pulmonary rehabilitation. Smoking status was obtained from the most recent outpatient encounter before their index admission. We were not able to obtain smoking status at the index admission. Vaccination history included influenza and pneumococcal vaccinations in the previous 1 to 2 years and up to 5 years, respectively. Participation in pulmonary rehabilitation up to 4 years before the index admission was recorded.
admission, excluded patients with a primary diagnosis of acute respiratory failure (518.8x), and analyzed a subgroup of patients who had spirometry data (54% of the larger sample) to further adjust for disease severity. All significance levels for the generalized estimating equations models were two-sided with a P value less than 0.05. Analyses were conducted using SAS 9.2 (SAS Institute Inc).
Results Cohort Selection
We identified 6,042 patients with COPD as their principal discharge diagnosis or who had acute respiratory failure with a secondary diagnosis of acute COPD exacerbation (Figure 1). Patients were excluded if they were less than 40 years old (n = 356), had not been prescribed either a bronchodilator or steroid inhaler before the index admission (n = 905), died during the index stay (n = 139), or had an
observational stay (n = 46). The final analytical sample included 4,596 patients who had 5,862 index admissions. Approximately 19% of the patients had more than one index admission during the study period. Descriptive Statistics
The sample had a mean age of 72.3 6 11 years and was composed of 68% whites, 12% Hispanics, 4% Asians/Pacific Islanders, and 15% Blacks, with a comparable distribution of men and women (Tables 1 and 2). Approximately 23% had at least one COPD-related hospitalization in the previous 12 months. The mean FEV1% predicted was 57.4 6 22% for 2,489 patients who had a spirometry test (54% of the sample). Comorbid conditions were common, with a mean Charlson index score of 3.9 6 2.7 and distribution of comorbidities as follows: hypertension (84%), heart failure (35%), diabetes (33%), depression (20%), cancer (20%), and anemia (15%). The mean length of stay for
Statistical Analysis
Bivariate analyses of potential risk factors for 30-day readmission were performed using t tests for continuous variables and Chi-square tests for categorical variables. Significant predictors from the bivariate analyses were included in the final model to test the independent effect of each risk factor using generalized estimating equations with an exchangeable covariance structure to account for patients contributing more than one index admission. Covariates were included in the final model if they contributed substantially to model fit or were of clinical significance. Sensitivity analyses were performed to determine if the effects of physical activity were similar when we used a composite EVS measure of all available values (median or mode) in the 12 months before the index
Figure 1. Sample flow chart. AECOPD = acute exacerbation of chronic obstructive pulmonary disease; COPD = chronic obstructive pulmonary disease; ICD-9 = International Classification of Diseases, Ninth Revision.
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ORIGINAL RESEARCH Table 1. Characteristics of patients with an index chronic obstructive pulmonary disease admission from 2011 to 2012 Patient-Level Variables
Age Mean (SD) Sex Male Female Marital status Unpartnered Partnered Missing BMI Underweight (,18.5) Normal weight (18.5–24.9) Overweight (25–29.9) Obese (.30) Missing Race White Black Hispanic Asian/Pacific Islander Others Missing Smoking status Never Passive Former Current Missing Hospitalization in previous year No. of patients with no prior hospitalization No. of patients with prior COPD hospitalization No. of patients with prior non-COPD hospitalization FEV1% predicted N Mean (SD) FEV1% predicted GOLD I GOLD II GOLD III GOLD IV Missing Medications Short-acting b-agonist Short-acting anticholinergic LABA LAMA ICS LAMA & ICS LABA & ICS Systemic corticosteroids (long-term use) Methylxanthines Oxygen use before index admission New oxygen use post index admission Comorbidities Anemia (present on admission) Heart failure Pulmonary hypertension Diabetes Hypertension Depression Anxiety Solid tumor without metastasis Metastatic cancer
Total Index (n = 4,596)
30-Day Readmission No (n = 3,653)
Yes (n = 941)
72.1 (10.8)
73.0 (10.6)
72.3 (10.8)
P Value
, 0.01 0.36
1,609 (44) 2,044 (56)
431 (46) 512 (54)
2,040 (44) 2,556 (56)
1,735 (47) 1,749 (48) 169 (5)
497 (53) 410 (43) 36 (4)
2,232 (49) 2,159 (47) 205 (4)
273 1,166 950 1,261 3
(7) (32) (26) (35) (0)
81 305 242 315 0
(9) (32) (26) (33) (0)
354 1,471 1,192 1,576 3
(8) (32) (26) (34) (0)
2,491 513 438 154 19 38
(68) (14) (12) (4) (1) (1)
627 162 95 41 4 14
(66) (17) (10) (4) (0) (1)
3,118 675 533 195 23 52
(68) (15) (12) (4) (1) (1)
468 22 2,322 831 10
(13) (1) (64) (23) (0)
100 (11) 5 (1) 666 (71) 172 (18) 0 (0)
568 27 2,988 1,003 10
(12) (1) (65) (22) (0)
2,228 (61) 755 (21) 670 (18)
417 (44) 294 (31) 232 (25)
2,645 (58) 1,049 (23) 902 (20)
, 0.01
0.67
0.23
0.001
,0.001
0.13 1,976 57.7 (21.9)
513 56.0 (21.4)
2,489 57.4 (21.8) 0.70
307 879 588 202 1,677
(8) (24) (16) (6) (46)
69 235 157 52 430
(7) (25) (17) (6) (46)
376 1,114 745 254 2,107
(8) (24) (16) (6) (46)
3,367 2,000 1,538 1,258 2,750 1,095 1,527 368 119 659 414
(92) (55) (42) (34) (75) (30) (42) (10) (3) (18) (11)
870 584 436 377 732 335 431 142 28 188 129
(92) (62) (46) (40) (78) (36) (46) (15) (3) (20) (14)
4,237 2,584 1,974 1,635 3,482 1,430 1,958 510 147 847 543
(92) (56) (43) (36) (76) (31) (43) (11) (3) (18) (12)
0.93 ,0.001 0.02 , 0.01 0.13 ,0.01 0.03 ,0.001 0.65 0.18 0.05
478 1,195 424 1,156 3,028 733 250 659 73
(13) (33) (12) (32) (83) (20) (7) (18) (2)
220 436 150 370 813 207 81 168 28
(23) (46) (16) (39) (86) (22) (9) (18) (3)
698 1,631 574 1,526 3,841 940 331 827 101
(15) (35) (12) (33) (84) (20) (7) (18) (2)
,0.001 ,0.001 ,0.001 ,0.001 0.01 0.20 0.06 0.87 0.07 (Continued )
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ORIGINAL RESEARCH Table 1. (Continued ) Patient-Level Variables
Charlson Index N Mean (SD) Insurance at index admission Medicare Medicaid Commercial Private pay Missing Immunization Flu vaccination since Jan. 1, 2010 Pneumonia vaccination within last 5 yr Ever participated in pulmonary rehab Yes No
Total Index (n = 4,596)
30-Day Readmission No (n = 3,653)
Yes (n = 941)
3,648 3.7 (2.62)
942 4.5 (2.80)
P Value
,0.001 4,590 3.8 (2.68) 0.02 2,655 59 873 30 36
(73) (2) (24) (1) (1)
720 23 187 7 6
(76) (2) (20) (1) (1)
3,375 82 1,060 37 42
(73) (2) (23) (1) (1)
2,828 (77) 2,311 (63)
760 (81) 658 (70)
3,588 (78) 2,969 (65)
212 (6) 3,441 (94)
54 (6) 889 (94)
266 (6) 4,330 (94)
0.034 ,0.001 0.93
Definition of abbreviations: BMI = body mass index; GOLD = Global Initiative for Chronic Obstructive Pulmonary Disease; ICS = Inhaled corticosteroids; LABA = long-acting b-agonists; LAMA = long-acting anticholinergic. Data are presented as n (%) unless otherwise noted. For patients with multiple index admissions, patient characteristics associated with the first hospitalization during the 2-year study period were used.
the index admission was 4.1 6 6.1 days and 4.2 6 6.2 days for the readmission. A small percentage of the patients ever participated in pulmonary rehabilitation before the index admission (6%) or received a palliative care consult during the hospitalization (6%). Approximately 71% of patients reported no moderate to vigorous physical activity (MVPA inactive), 17% were insufficiently active, and another 10% reported engaging in at least 150 minutes of MVPA before their index admission. 30-Day Readmission Timing and Patterns
The all-cause 30-day readmission rate was 18%, with 59% of readmissions occurring in the first 15 days after discharge (Figure 2). To ensure that we excluded any potential transfers that were not already captured, we further excluded any readmission that occurred within 24 hours of the discharge. The distribution across the 10 most common readmission diagnoses (24) during cumulative periods after discharge (Days 0–3, 0–7, 0–15, and 0–30) is shown in Figure 3. Approximately 45% of the readmissions were associated with a principal discharge diagnosis of COPD, followed by other respiratory/ventilator disorders, pneumonia, gastrointestinal disorders, sepsis/shock, heart failure, arrhythmias/conduction disorders, renal disorders, acute myocardial infarction,
electrolyte disturbances, and nutrition/ metabolic disorders. The overall pattern of readmission diagnoses was largely similar over the cumulative periods after discharge.
Unadjusted Analyses of Factors Associated with 30-Day Readmission
Sex, body mass index, race/ethnicity, use of combination inhalers, use of oxygen supplementation before the index
Table 2. Characteristics of index admissions for patients with chronic obstructive pulmonary disease from 2011 to 2012 30 Day Readmission No (n = 4,803) Length of stay, d 1–2 3 4–6 7–13 >14 Discharge disposition Home Postacute Hospital Hospice Other Missing Emergency dept./observational stay Yes No Inpatient palliative care consult Yes No Usual physical activity 0 min/wk 1–149 min/wk .150 min/wk Missing
Yes (n = 1,059)
Total Index (n = 5,862)
1,108 1,133 1,735 705 122
(23) (24) (36) (15) (3)
193 215 396 194 61
(18) (20) (37) (18) (6)
1,301 1,348 2,131 899 183
(22) (23) (36) (15) (3)
4,284 292 7 139 38 43
(89) (6) (0) (3) (1) (1)
900 102 1 9 20 27
(85) (10) (0) (1) (2) (3)
5,184 394 8 148 58 70
(88) (7) (0) (3) (1) (1)
436 (9) 4,367 (91)
198 (19) 861 (81)
634 (11) 5,228 (89)
276 (6) 4,527 (94)
66 (6) 993 (94)
342 (6) 5,520 (94)
3,316 866 497 124
827 141 77 14
4,143 1,007 574 138
P Value ,0.001
,0.001
,0.001
0.54
(69) (18) (10) (3)
(78) (13) (7) (1)
(71) (17) (10) (2)
,0.001
Data are presented as n (%).
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ORIGINAL RESEARCH
Figure 2. Thirty-day readmissions by day (0–30) after hospitalization for chronic obstructive pulmonary disease (COPD).
admission, depression, anxiety, and receipt of an inpatient palliative care consult during the index admission were not significantly associated with risk of 30-day readmission (Table 3). Factors associated with a significantly increased 30-day readmission included age, being unpartnered, having a history of any hospitalization in the previous year, new oxygen prescription at discharge, use of systemic steroids, presence of anemia at admission, pulmonary hypertension, hypertension, having more comorbidities, having a visit to the emergency department or an observational stay within 30 days of discharge that occurred before the
readmission, and length of stay longer than 3 days (all, P , 0.05). Discharge to postacute care or another hospital was associated with increased risk of readmission (P , 0.001), whereas discharge to hospice was associated with lower risk (P , 0.001). Participation in any MVPA before the index admission was also associated with lower risk of readmission (P , 0.001). Multivariate Adjusted Analyses of Factors Associated with 30-Day Readmission
After adjustments for all other key covariates, patients who reported any
MVPA at baseline before the index admission had a significantly lower risk of 30-day readmission compared with inactive patients (Table 4). Specifically, patients meeting the national recommendation of engaging in at least 150 min/wk of MVPA had a 34% lower risk of 30-day readmission compared with inactive patients (relative risk [RR], 0.66; 95% confidence interval [CI], 0.51–0.87). Patients engaged in lower levels of MVPA were also less likely to be readmitted (RR, 0.67; 95% CI, 0.55–0.81). Factors that remained significantly associated with increased risk of 30-day readmission in this adjusted model included having a history of any prior hospitalizations, a new prescription for oxygen, presence of anemia at admission, more comorbidities, a visit to the emergency department or an observational stay, and length of stay longer than 3 days (all, P , 0.01); being unpartnered approached statistical significance (P = 0.08). Sensitivity Analyses
We performed sensitivity analyses to determine if the effects of regular physical activity on 30-day readmission would remain robust to three different scenarios. First, we analyzed either the median or modal value of all EVS data in the 12 months preceding the hospitalization and found similar effects (see online supplement). Second, we excluded patients with a principal diagnosis of acute respiratory failure and a secondary diagnosis of COPD. The effect of physical inactivity was similar in this analysis (insufficiently active vs.
Figure 3. Distribution of 30-day readmission principal diagnoses after hospitalizations for chronic obstructive pulmonary disease (COPD). cond = conduction; GI = gastrointestinal; MI = myocardial infarction; resp./vent. = respiratory/ventilatory.
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ORIGINAL RESEARCH Table 3. Unadjusted bivariate generalized estimating equations model predicting 30-day readmission in patients with chronic obstructive pulmonary disease Parameter Age Sex Marital status BMI
Race/ethnicity
Insurance type Smoking status Vaccinations Usual physical activity Medications Oxygen use Hospitalizations Comorbidities
Palliative care Length of stay, d
ED/observational stay Disposition
RR Age: per increase of 1 yr Female vs. male Unpartnered vs. partnered Normal weight (18.5–24.9) Underweight (,18.5) Overweight (25–29.9) Obese (.30) White Asian/Pacific Islander Black Hispanic Others Commercial/private pay vs. Medicare/Medicaid Never/passive Former Current Flu vaccination within 2 yr vs. none Pneumovax within 5 yr vs. none 0 min/wk MVPA (inactive) 1-149 min/wk MVPA (insufficient) >150 min/wk MVPA (active) LABA/ICS or LAMA/ICS vs. none Systemic corticosteroids vs. none Oxygen before index admission vs. none New oxygen post index admission vs. none No previous hospitalizations Prior COPD hospitalization Prior non-COPD hospitalization Charlson index score, 0–1 Charlson index score, 2 Charlson index score, 31 Pulmonary hypertension vs. none Hypertension vs. none Depression vs. none Anxiety vs. none Anemia (present on admission) vs. none Chronic obstructive asthma vs. COPD Received consult vs. no 1–2 3 4–6 7-13 >14 Yes vs. no Home Hospice Postacute/hospital Other/missing
1.01 0.95 1.20 1.00 1.10 0.97 0.98 1.00 0.84 0.87 0.98 0.75 0.81 1.00 1.27 0.96 1.16 1.33 1.00 0.67 0.61 1.04 1.49 1.07 1.29 1.00 1.82 1.82 1.00 1.14 1.88 1.39 1.32 1.12 1.22 1.94 0.95 1.06 1.00 1.09 1.29 1.52 2.79 2.23 1.00 0.28 1.65 2.76
P Value
95% CI 1.00 0.82 1.04
1.01 1.09 1.38
0.03 0.45 0.01
0.84 0.80 0.82
1.44 1.16 1.16
0.48 0.71 0.81
0.51 0.48 0.58 0.44 0.69
1.40 1.57 1.66 1.29 0.96
0.50 0.64 0.95 0.30 0.02
1.02 0.74 0.97 1.15
1.59 1.25 1.38 1.55
0.03 0.79 0.10
