This present study found that the 7-day in-hospital mortality was 2.80% among medical patients admitted from the ED. We established a mortality prediction score at the initial admission using the Barthel index score, presence of cancer and metastasis, admission diagnoses of pneumonia and sepsis, and triage score at arrival at the ED. Scores of ≥ 4 had NPVs of up to 99% and could be used for exclusion screening. By contrast, scores of ≥ 6 had specificity of 89% and PPV of 10.55%, which could cover most of the frail patients.
To manage the mortality outcomes of patients admitted to general medical wards is never easy for hospitalists, although some mortality cannot be avoided. In particular, for patients admitted for unplanned causes leading to ED visits, it is difficult to stratify those who have a high risk for potential death at initial admission. Although prediction scores of NEWS  or clinical alert system  have been developed, the indications of the two scores are mostly regarding the change of vital signs and ensuing critical status that is not strange to initiate intensive care. However, to predict the targeted risk group before they exhibit unstable vital signs is important, for it would allow us to prepare further discussions regarding intensive care and prognosis explanations. By using the prediction score developed and validated in the present study with a large-scale sample, we could stratify the patients easily into three subgroups: low risk for prediction scores of < 4, intermediate risk for scores of 4–6, and high risk for scores of ≥ 6. Those with scores of < 4 can be excluded from the alarm status, and those with scores of ≥ 6 probably need intensive treatment.
The prediction score showed a high AUROC of 0.819 and a hazard ratio of 1.659 (95% C.I.: 1.55–1.76 per 1 point increment) in the derivation cohort to predict in-hospital mortality within 7 days; the results were similar in the validation group. This score is the first mortality prediction score developed from general medical hospitalized patients and could be applied broadly. However, because the score element is relatively non-specific to diseases, the sensitivity and specificity are not > 90%. Therefore, the score can be used in clinical practice to detect fragile patients at initial admission, but final judgement must be reserved for inpatient physicians.
Among the prediction model, the Barthel index, which measures performance in activities of daily living, can be used to represent general condition and disease severity, and it is one of the important factors in prognosis prediction. For patients with chronic illness, the Barthel index result can be affected by patients’ frailty [11, 12] and disability, which correlate with mortality . On the other hand, it could be the severity of the acute illness which is responsible for the admission. Although we did not discriminate the influence proportions of the Barthel index by acute or chronic illness, it affected the 7-day mortality, with the highest beta coefficient of 2.38 in the multivariable analysis. It might be more easily applied generally at initial admission.
The presence of underlying active cancer and metastatic status are both important predictors for in-hospital mortality due to their immune-compromised status . The effect of cancer on a patient’s outcome has been proven in critical care [15, 16]. However, whether patients have cancer with or without metastasis may provide little insight on the poor prognosis, and as high as 25% of terminal cancer patients receive vasopressors in the dying process . Therefore, hospitalists need to hold family meetings to explain and discuss treatment plans for shared decision making on cancer patients with high prediction scores .
In contrast to a chronic illness such as cancer, triage on arrival to ED could be used as an initial summary index for acute status. The triage index is the five-level Taiwan Triage and Acuity Scale (TTAS) computerized system implemented nationally since 2010 . The triage index includes changes in vital signs, organ failure and acute problems needing immediate treatment . Triage level 1 at the ED has been classified as an impact factor in the prediction score in the present study. In addition, admission diagnoses including sepsis and pneumonia are responsible for acute illness and associated with 7-day in-hospital mortality. Sepsis is a high-mortality syndrome caused by severe infection with or without organ failure. In-hospital mortality could be as high 17% for patients with sepsis and 26% for those with severe sepsis . Both factors (triage at the ED and admission diagnosis) represent acute changes for admitted patients. However, age was statistically significant only in the univariable analysis and not significant in the multivariable Cox analysis, possibly because its effect was erased by other co-morbidity and performance statuses.
This study had several limitations. First, we did not record initial vital signs, laboratory results in the original study design of clinical analysis. In addition, pre-hospital changes in the medical condition or Barthel index were not recorded, so their roles in in-hospital mortality prediction require further study. In addition, patients enrolled in this study may have been more severely ill, and a higher proportion may have had cancer, because the present study was conducted in a tertiary referral center. Third, this study was performed in Taiwan, so whether the results can be generalized to other ethnic groups and areas should be validated.