Vital Sign Instability Near Discharge Tied to Poor Outcomes

Veronica Hackethal, MD

August 22, 2016

Vital sign instability within 24 hours of hospital discharge is linked to almost 40% increased likelihood of death or readmission within 30 days, according to a study published online August 8 in the Journal of General Internal Medicine.

The study is the first to evaluate the links among vital sign instability within 24 hours of discharge, 30-day mortality, and readmission in a general population of adults hospitalized for a variety of medical conditions, according to the authors.

"Simply put, vital signs are still vital," write Oanh Kieu Nguyen, MD, MAS, from the University of Texas Southwestern Medical Center, Dallas, and colleagues.

"[O]ur findings suggest that providers should pay close attention to patients' vital signs in the 24 hours prior to contemplating discharge, and not just the very last set, which may be subject to measurement bias favoring discharge," they add.

Recent decades have witnessed a dramatic decrease in hospital length of stay, raising the question of whether some patients are discharged prematurely. Early discharge has been linked to higher mortality and readmission rates. Evaluating vital signs for instability within 24 hours of discharge may be a reasonable and straightforward way to improve safety, yet little evidence exists on this issue.

The observational study included medical records data on 32,835 adults hospitalized for a variety of reasons between November 2009 and October 2010 at six hospitals in the Dallas–Fort Worth, Texas, area. Researchers evaluated vital sign instability within 24 hours of discharge, defined as: temperature ≥37.8°C, heart rate ≥100 beats per minute, respiratory rate >24 breaths per minute, systolic blood pressure ≤90 mm Hg, or oxygen saturation <90%.

They adjusted results for six factors of poor prognosis, including severity on admission, comorbidities, and hospital complications.

Almost one in five individuals included in the study (18.7%) were discharged with one or more vital sign instability.

Among those without any instabilities, 12.8% died or were readmitted within 30 days of discharge compared with 16.9% with one instability, 21.2% with two instabilities, and 26.0% with three or more instabilities (P < 001).

After adjusting for other factors, those with one or more instability had a 36% higher chance of death or readmission compared with those with no instabilities (risk adjusted odds ratio [AOR], 1.36; 95% CI, 1.26 - 1.48). When analyzed separately, the risk for death was more strongly associated with having one or more vital sign instability near discharge (AOR, 2.36; 95% CI, 1.97 - 2.83) than was 30-day readmission (AOR, 1.36; 95% CI, 1.26 - 1.47) compared with no instabilities.

Moreover, risk for death or readmission increased with increasing number of vital sign instabilities. The relationship was especially strong for death, which doubled, tripled, and quadrupled for each additional instability.

As a diagnostic test for adverse events, analyses found that vital sign instability may be better for predicting death than readmission within 30 days. Among those with two or more vital sign instabilities, the positive likelihood ratio for death within 30 days was 3.0 compared with 1.5 for readmission.

The authors suggest that discharge guidelines should include vital sign criteria. Patients with at least one instability should be discharged with caution, and providers should weigh the risks and benefits for extending hospitalization for such patients. Those with two or more instabilities should probably stay in the hospital, although the study could not evaluate whether extending hospitalization would improve clinical stabilization. The authors note that more research is needed on this issue.

They conclude: "Further attention is needed toward developing evidence-based discharge criteria and interventions to optimize post-discharge patient safety."

The study was funded by the Agency for Healthcare Research and Quality UT Southwestern Center for Patient-centered Outcomes Research and the Commonwealth Foundation. The authors have disclosed no relevant financial relationships.

J Gen Intern Med. Published online August 8, 2016. Abstract

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