Study Reveals Reasons for Increased Hospital Readmission Rates in NMOSD

Newly published in the International Journal of MS Care, a retrospective study identified several characteristics that were associated with increased risk of hospital readmission among patients with neuromyelitis optica spectrum disorder (NMOSD), an aggressive central nervous system astrocytopathy.¹ These findings suggest that the development of treatment targeted toward such high-risk characteristics may result in reduced readmission and disease burden for patients with NMOSD.

Among 2447 weighted (unweighted, n = 1350) primary admissions with NMOSD, approximately 11.9% (95% CI, 10.6%-13.3%) of patients were readmitted to the hospital in 30 days of discharge (weighted, n = 292; unweighted, n = 169). Analysis of hospital readmission etiologies showed that the most common causes of readmissions were neurologic complications (50.2%), infectious (15.3%) and respiratory (6.0%) complications. Notably, investigators observed that the most common readmission diagnosis was NMOSD (25.6%).

“The primary cause of readmission seems to be neurologic, which in a condition like NMO in which attacks are devastating, is not necessarily surprising. Older age and infectious and respiratory complications as well seemed common, which can occur in prolonged hospital stays of patients accumulating disability. Plasma exchange paradoxically seemed to increase the odds of readmission,” senior author William Kilgo, MD, director of the neurology residency program and assistant professor of neurology at the University of South Alabama College of Medicine, told NeurologyLive®. "Does that mean we should not do plasma exchange? No, and I think that should be considered within the context that patients requiring plasma exchange are often having a severe relapse that may require further hospital care. Like all patient care scenarios, it comes down to the risk/benefit ratio for individual patients."

READ MORE: Significant Demographic and Clinical Differences Observed in Patterns Between NMOSD and MS

Investigators searched for hospital admissions for NMOSD in the United States using the 2017 Nationwide Readmissions Database of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality.² The primary outcome variable was the first nonelective readmission in 30 days of discharge from the hospitalization index. Using weighted admissions, investigators performed statistical testing on baseline patient and hospital characteristics which included age, sex, true cost of hospitalization, length of stay, weekend admission, insurance status, quartile of median household income, and All Patient Refined Diagnosis Related Groups.

In a multivariate logistic regression analysis, investigators observed that patients aged 65 to 74 years (OR, 1.954; P = .042) had an increased rate of readmission whileall other age groups had a similar rate of readmission. Compared with other comorbidities, researchers observed that sex had no effect on readmission odds for patients. Also, the only insurance status protective of readmission was private insurance (OR, 0.528; P <.001) compared with the population of patients with Medicaid. Additionally, authors noted that hospital teaching status impacted readmission odds, as both teaching metropolitan hospitals (OR, 0.535; P < .001) and nonmetropolitan hospitals (OR, 0.425; P = .042) were protective of readmission relative to nonteaching metropolitan hospitals.

Investigators observed that comorbidities such as respiratory failure (OR, 2.952; P < .001), peripheral vascular disease (OR, 2.401; P = .005), neurocognitive disorders (OR, 3.944; P < .001), and neurologic blindness (OR, 2.159; P < .007) were all shown to be predictive of readmission into the hospital. Notably, researchers observed that only lipid disorders resulted in decreased odds of hospital readmission (OR, 0.624; P = .016). In addition, IVIg and immunomodulatory infusions did not impact the odds of readmission compared with PLEX, which increased odds of readmission (OR, 1.483; P = .025).

Limitations of this analysis included the study design as authors noted that only correlation can be inferred, and no statement of causation can be made. The authors also noted that the database used stores only admission data, does not record emergency or urgent care after discharge or admitted to the hospital for observation, and does not include medications taken which may affect readmission rates. Additionally, the investigators noted misclassification bias in the study, since a small proportion of patients were readmitted with the diagnosis of MS. Also, other cofactors and synergistic roles between some risk factors were not explored, which may impact readmission rates.

"I believe this adds some context to potential causes of readmission for a rare disease, and hopefully we can be more predictive in the future of which patients may be at risk of readmission. Patients with NMO tend to end up in the hospital for relapses, and we should as always be diligent to minimize the potential for readmission to the hospital," Kilgo told. "Retrospective chart review or prospective institutional cohorts would be reasonable next steps as this project involved retrospective review of ICD-10 codes, which limits our ability to get more context for thought processes underlying readmission."

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REFERENCES
1. Padarti A, Amritphale A, Kilgo W. Hospital Readmission Rates in Patients With Neuromyelitis Optica Spectrum Disorder. Int J MS Care. 2023;25(5):221-225. doi:10.7224/1537-2073.2022-049
2. NRD Database Documentation. Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, Department of Health and Human Services. Last modified December 7, 2022. Accessed January 8, 2024. http://www.hcup-us.ahrq.gov/db/nation/nrd/nrddbdocumentation.jsp