The Association between blood glucose and length of hospital stay due to Acute COPD exacerbation

1. The Association between blood glucose and length of hospital stay due to Acute COPD exacerbation Yusuf Kasirye, Melissa Simpson, Naren Epperla, Steven Yale

2. Blood glucose and acute COPD exacerbations • Introduction • Methods • Results • Discussion

3. Introduction • Chronic Obstructive Pulmonary Disease (COPD) is the fourth most common cause of death in the United States, affecting ~ 24 million people • Several studies have looked at hospitalizations due to acute COPD exacerbations (AECOPD) and comorbidities such as diabetes mellitus and metabolic syndrome

4. Introduction • Two studies of hospital admissions found a marginal association between DM and length of hospital stay • Did not examine blood glucose levels • Another study found that increased blood glucose is associated with longer hospitalization • Analyzed highest inpatient BG value only • Looked at length of stay as <9 days (good) compared to ≥ 9 days (bad)

5. Introduction • The purpose of this study is to examine the association between inpatient blood glucose (BG) levels and the following clinical outcomes in patients hospitalized for AECOPD: • In hospital complications • Length of hospitalization • Thirty day re-hospitalization (all cause) • Ninety day mortality (all cause)

6. Methods Study population and design • Retrospective cohort of 209 patients hospitalized for AECOPD (physician validated) from 1-1-2—4 to 12-31-2008 at St. Joseph’s hospital (Marshfield WI) • Inclusion criteria: • COPD diagnosis (according to GOLD criteria) at some point prior to index hospitalization • AECOPD diagnosis at admission and discharge • A BG measurement within 6 hours of hospitalization • ≥ 2 BG measurements during hospitalization (analyzed both fasting and random blood glucose measurements)

7. Methods Outcomes • In-hospital complications: the presence of cardiac, respiratory, neurologic, renal, or septic complications during index hospitalization • Length of hospital stay: the time from admission until discharge from hospital, measured in days • Thirty day readmission: hospitalization for any cause within 30 days of the discharge date of index hospitalization • Ninety day all cause mortality: death due to any cause within 90 days of index hospitalization

8. Methods Statistical analysis • Outcomes modeled as follows: • LOS: analyzed both as a discrete and categorical (≤2 days vs. > 2 days) outcome • Thirty day readmission: analyzed as a categorical outcome • Ninety day all-cause mortality: analyzed as a categorical outcome. • Blood glucose was analyzed as a continuous variable and was calculated as mean per day (ng/ml), odds ratios reported for a 100 ng/ml decrease in BG • Logistic regression analyses accounting for repeated BG measurement during hospitalization were used for odds ratio estimation (SAS, proc genmod, Cary NC) • Age and DM were forced into adjusted models, other covariates were included if they had a significance level of ≤ 0.05 or changed the beta estimate for BG by ≥ 10%

9. Results In-hospital complications

10. Results LOS

11. Results LOS • Unadjusted, BG modeled continuously was not associated with LOS (OR: 1.25, 95% CI: 0.87-1.81, p-value: 0.22) • Adjusting for age and DM, decreased BG was associated with a longer LOS (OR for 100 ng/ml decrease: 1.39, 95% CI 1.04-1.87, p-value: 0.03)

12. Results Thirty day readmission • Thirty six people were readmitted within 30 days of discharge from index hospitalization • BG was not associated with 30 day readmission • Unadjusted OR: 1.34, 95% CI: 0.78-2.28, p-value 0.29 • Adjusting for DM, age, and BMI: 1.34, 95% CL 0.75-2.41, p-value: 0.33

13. Results Ninety day mortality • Eight people died due to any cause within 90 days of index hospitalization • BG was not associated with 90 day all cause mortality • Unadjusted OR: 2.68, 95% CI: 0.92-7.79, p-value 0.07 • Adjusting for DM, age, and BMI: 1.93, 95% CL 0.55-6.75, p-value: 0.30

14. Results Mediation analysis • Tested how much of the association between in-hospital complications and length of stay could be attributed to BG. • Found that 4% of that association is due to BG (p = 0.07)

15. Discussion • Decreased BG has a marginal and weak association with in-hospital complications and longer LOS • BG may be reflective of overall health in this population • No association with 30 days readmission or 90 day all-cause mortality • BG (as we measured it) probably of little prognostic utility in AECOPD patients

16. Discussion • Different than the study by Baker et al. • May be due to difference in exposure and outcome definition • Repeated their method on our data and found no association

17. Discussion • Future studies • Employ continuous glucose monitoring to fully understand the complexities of corticosteroid usage, the glycemic response and clinical outcomes in this group of people • Study the association between metabolic syndrome and clinical outcomes and how much glycemic status contributes to that association

18. Disclosure The authors do not have conflicts of interest to report. This study was funded by a Marshfield Clinic Research Foundation resident research grant.