Epidemiology of mechanically ventilated patients treated in ICU and non-ICU settings in Japan: a retrospective database study

Abstract

Background: In most countries, patients receiving mechanical ventilation (MV) are treated in intensive care units (ICUs). However, in some countries, including Japan, many patients on MV are not treated in ICUs. There are insufficient epidemiological data on these patients. Here, we sought to describe the epidemiology of patients on MV in Japan by comparing and contrasting patients on MV treated in ICUs and in non-ICU settings. A preliminary comparison of patient outcomes between ICU and non-ICU patients was a secondary objective.

Methods: Data on adult patients receiving MV for at least 3 days in ICUs or non-ICU settings from April 2010 through March 2012 were obtained from the Quality Indicator/Improvement Project, a voluntary data-administration project covering more than 400 acute-care hospitals in Japan. We excluded patients with cancer-related diagnoses. Patient demographic data and the critical care provided were compared between groups.

Results: Over the study period, 17,775 patients on MV were treated only in non-ICU settings, whereas 20,516 patients were treated at least once in ICUs (46.4% vs. 53.6%). Average age was higher in non-ICU patients than in ICU patients (72.8 vs. 70.2, P < 0.001). Mean number of ventilation days was greater in non-ICU patients (11.7 vs. 9.5, P < 0.001). Hospital mortality was higher in non-ICU patients (41.4% vs. 38.8%, P < 0.001). Standard critical care (e.g., arterial line placement, enteral nutrition, and stress-ulcer prevention) was provided significantly less often in non-ICU patients. Multivariate analysis showed that ICU admission significantly decreased hospital mortality (adjusted odds ratio 0.713, 95% CI 0.676 to 0.753).

Conclusions: A large proportion of Japanese patients on MV were treated in non-ICU settings. Analysis of administrative data indicated preliminarily that hospital mortality rates in these patients were higher in non-ICU settings than in ICUs. Prospective analyses comparing non-ICU and ICU patients on MV by severity scoring are needed.

Keywords: ICU; Japan; Mechanically ventilated patient.

Fig. 1

The selection of patients. Among patients who received invasive mechanical ventilation (MV), those who were younger than 18 years, those who received MV for fewer than 3 days, those who stayed in hospital for more than 60 days, and those who had a major diagnosis of cancer were excluded; 17,775 patients were ventilated only in non-ICU settings

Fig. 2

a Number of patients treated in ICU and non-ICU setting. Nearly half of acute-phase patients on mechanical ventilation (MV) were treated in non-ICU settings. b Male versus female ratio of patients on MV treated in ICU and non-ICU settings

Fig. 3

Comparison of ICU and non-ICU patients. Non-ICU patients were significantly older. Ventilation period was longer in non-ICU and in-hospital mortality was higher in non-ICU patients, while hospital stay was significantly higher in ICU patients

Fig. 4

Treatments frequently applied to patients on mechanical ventilation (MV) in the ICU. Invasive lines were used in significantly fewer non-ICU patients than in ICU patients. There was significantly less use of catecholamines and renal replacement in non-ICU patients. There was shorter duration of enteral nutrition (EN) and less frequent use of stress-ulcer prophylaxis in the non-ICU group. CV, central vein; RRT, renal replacement therapy