Dementia Linked With Worse Outcomes in Patients With COPD, Study Says

A recent study published in the International Journal of Chronic Obstructive Pulmonary Disease found that patients with dementia had a greater risk of worse outcomes when admitted to the hospital for chronic obstructive pulmonary disease (COPD) exacerbations.

The aim of this study was to assess the affect of coexisting dementia on inpatient mortality and length of stay (LOS) in patients with COPD admitted US hospitals.

The researchers used hospital discharge records from 2011-2015 from the National Inpatient Sample (NIS) database, part of the Healthcare Cost and Utilization Project, for the analysis. The all-payer database contains records on impatient utilization, charges, quality, and outcomes. This database lacked unique patient identifiable details, which means that all admissions, including readmissions, were treated as separate cases.

The database used both the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) from 2011-2015 and the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) in 2015. A coexisting diagnosis of dementia was categorized using these classifications.

The population for this study were all aged 41 years and older. Patients were included if they had been admitted to the hospital between January 1, 2011 and December 31, 2015, with a primary diagnosis of acute exacerbation of COPD according to ICD codes.

The researchers analyzed outcome measures that included LOS, calculated by subtracting the day of admission from the discharge date, and inpatient deaths. Some covariates that were accounted for included age, gender, comorbidity, race, year of admission and primary payer.

Comorbidity was analyzed using the Charlson comorbidity index, which give scores if the following conditions are present: COPD, dementia, rheumatological disease, renal disease, diabetes, congestive cardiac failure, liver disease, hemiplegia/paraplegia, malignancy, AIDS/HIV, or metastatic solid tumor. For this study, COPD and dementia were excluded from the comorbidity index to avoid over adjusting.

All continuous variables were represented with median and interquartile range (IQR) whereas categorical data were represented as frequency and percentages. Logistic regression analysis was used to assess inpatient deaths in patients with an exacerbation of COPD with coexisting dementia compared with those without dementia. Cox proportional hazard regression analysis was used to assess the affect of cognitive impairment on impatient deaths.

A total of 576,381 patients were identified for this study after excluding patients who were aged 40 years old and younger and/or had missing values. The prevalence of diagnosed dementia in these admitted patients with COPD exacerbations was 6.1%. The median (IQR) age of COPD patients with dementia was 82 (76-87) years vs 68 (59-77) years for patients without dementia.

Patients with COPD and dementia had a higher proportion of comorbidities. COPD patients with coexisting dementia reported respiratory compromise less often but of those who did, there were no significant differences in receiving noninvasive ventilation (NIV) or mechanical ventilation.

A total of 6413 (1.1%) of inpatient deaths in patients with COPD occurred during the study period. The total of inpatient deaths was significantly greater in patients with dementia compared with those without dementia (COPD with dementia vs COPD without dementia: 581 (1.6%) vs 5832 (1.1%), respectively).

Patients with COPD and dementia who were in the youngest age category, aged 41 to 64 years, had a significantly increased risk of inpatient death compared with patients without dementia (adjusted odds ratio, 1.75; 95% CI, 1.04-2.92; P = .03). There were no significant differences in the older age strata.

Patients with COPD and dementia admitted to the hospital with COPD exacerbations had a significantly greater death rate within 4 days compared with patients without dementia (HR, 1.79; 95% CI, 1.58-2.04 vs HR, 1.23; 95% CI, 1.08-1.41). From 5 days on, the mortality rate was lower, which indicated that patients admitted with COPD exacerbations with coexisting dementia were less likely to die during the rest of their hospital stay (HR, 1.09; 95% CI, 0.98-1.23).

The median LOS for patients with COPD and dementia was longer than the LOS of those without dementia (median [IQR] LOS with dementia vs without dementia: 4 [3-6] vs 3 [2-5]). Discharge rate was significantly lower for patients with dementia.

There were some limitations to this study. The NIS database did not have unique identifiers for patients which meant that readmissions could not be explored. This could mean that a group could have had more readmissions that would be included in the study. Mortality could only be assessed using in-hospital mortality, as patients were not tracked after discharge. Because of this, 30-day mortality could not be tracked, and the study may have underestimated mortality. There are also limitations to clinical coding, and it was previously highlighted that dementia is underdiagnosed in patients with COPD.

The use of ICD classification alone may lead to misidentification of some acute exacerbation cases, which makes it possible that the difference in observed outcomes was underestimated. Some prognostic factors of COPD, such as smoking, lung function, and severity of dementia, were not available in the database. The exclusion of cases with missing values may introduce a bias into the results of the study. The lack of reliable data on medications meant that their associations with mortality and LOS could not be tracked.

The researchers concluded that identifying pre-existing dementia in patients with COPD exacerbation and using pre-emptive strategies may improve inpatient mortality and LOS.

“Clinicians should be alert to developing a more tailored care plan for this subpopulation, taking into account patients’ specific dementia care needs and considering involvement of dementia specialist teams,” they wrote.

Reference

Gupta A, McKeever TM, Hutchinson JP, Bolton CE. Impact of coexisting dementia on inpatient outcomes for patients admitted with a COPD exacerbation. Int J Chron Obstruct Pulmon Dis. 2022;17:535-544. doi:10.2147/COPD.S345751