Dementia and Risk of 30–Day Readmission in Older Adults After Discharge From Acute Care Hospitals

Nobuo Sakata, MD, MPH; Yasuyuki Okumura, PhD; Kiyohide Fushimi, MD, PhD; Miharu Nakanishi, RN, PSW, PhD; Asao Ogawa, MD, PhD

Disclosures

J Am Geriatr Soc. 2018;66(5):871-878. 

In This Article

Abstract and Introduction

Abstract

Objectives To assess the association between dementia and risk of hospital readmission and to evaluate whether the effect of dementia on hospital readmission varies according to primary diagnosis.

Design Retrospective cohort study.

Setting Nationwide discharge database of acute care hospitals in Japan.

Participants Individuals aged 65 and older diagnosed with one of the 30 most common diagnoses and discharged from 987 hospitals between April 2014 and September 2015 (N = 1,834,378).

Measurements The primary outcome was unplanned hospital readmission within 30 days. Poisson generalized estimating equation models were fitted to assess the risks of readmission for individuals with and without dementia, using primary diagnosis as a possible effect modifier and clinical factors as potential confounders.

Results The overall prevalence of dementia was 14.7% and varied according to primary diagnosis, ranging from 3.0% in individuals with prostate cancer to 69.4% in those with aspiration pneumonia. Overall, individuals with dementia had a higher risk of hospital readmission (8.3%) than those without (4.1%) (adjusted risk ratio (aRR])=1.46, 95% confidence interval (CI)=1.44–1.49), although diagnostic category substantially modified the relationship between dementia and hospital readmission. For hip fracture, dementia was associated with greater risk of hospital readmission (adjusted risk 11.5% vs 7.9%; aRR=1.46; 95% CI=1.28–1.68); this risk was attenuated for cholecystitis (adjusted risk 12.8% vs 12.4%; aRR=1.03; 95% CI=0.90–1.18).

Conclusion Risk of hospital readmission associated with dementia varied according to primary diagnosis. Healthcare providers could enforce interventions to minimize readmission by focusing on comorbid conditions in individuals with dementia and specific primary diagnoses that increase their risk of readmission.

Introduction

In acute care hospitals, 25% of admitted older adults have dementia and greater risk of negative events such as emergence delirium and in–hospital falls than those without dementia.[1–3] Consequently, individuals with dementia are likely to have poorer outcomes in acute care settings such as long hospital stays and greater in–hospital mortality than those without.[2,4,5] In addition to these outcomes during the hospital stay, early hospital readmission after discharge is a critical outcome for individuals with dementia and society.

To the best of our knowledge, 8 studies have been published regarding the effect of dementia on early hospital readmission—a critical outcome in acute care settings—but previous studies have produced conflicting findings.[2,6–12] For example, one study found that the risk of readmission was 27% higher in individuals with dementia than in those without, whereas another study reported that the risk of readmission was 9% lower in individuals with dementia.[2,8] This discrepancy could be attributable to differences in composition of primary diagnoses between these study populations. Such heterogeneity in study populations may mask the extent and direction of the true association between dementia and readmission. One study found that the risk of readmission in individuals admitted because of injuries was lower in those with dementia than in those without, although this pattern was not consistent across injury type.[8] No study has formally evaluated whether the effect of dementia on hospital readmission differs according to primary diagnosis.

In addition, previous studies had important limitations that could have led to an over– or underestimation and an imprecise estimation of the true association between dementia and readmission. First, most previous studies did not adjust for important clinical factors such as baseline mobility and severity of disease, which are considered to be associated with risk of hospital readmission.[2,6–9,12] Second, three prior studies were conducted in single institutions, which might limit the generalizability of the results obtained.[2,10,12] Furthermore, two studies were had small sample sizes.[6,12] Thus, further studies are required to confirm the relationship between dementia and hospital readmission.

A better understanding of the relationship between dementia and readmission could facilitate more appropriate discharge planning. In particular, identification of diagnostic subgroups of individuals with dementia who are at risk of readmission is needed to optimize use of medical resources. Therefore, we aimed to assess the association between dementia and risk of hospital readmission, accounting for primary diagnosis as a possible effect modifier.

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