Patient deterioration
The goal of this Atlas domain is to identify whether there is wide variation in rates of patient deterioration, which may highlight areas for further local investigation and improvement.
About the patient deterioration Atlas domain
The national patient deterioration programme is a five-year plan to reduce harm from failures to recognise or respond to acute physical deterioration in adults admitted to Aotearoa New Zealand hospitals. Such patients may suffer acute physical deterioration at any point during a hospital stay with many showing signs of instability for some time before events such as cardiac arrest or admission to an intensive care unit (ICU) occur. There are often opportunities to intervene to prevent serious harm if deterioration is detected early.
The patient deterioration domain of the Atlas of Healthcare Variation focuses on patients who deteriorate to the point of needing ICU admission. This is because individual data is not currently collected from the ward environment on patients who do not require ICU admission, as they are detected earlier. We acknowledge there are limitations of focusing on ICU admission.
This Atlas domain reports data from the Australian and New Zealand Intensive Care Society (ANZICS) adult patient database, to which 15 district health boards (DHBs) with an ICU contribute data. The domain presents data for DHBs whose ICU has explicitly given permission for data to be included.
Patient deterioration
- Emergency ICU admissions from the ward varied by DHB, from 2.1 to 11.0 per 1,000 hospital admissions in 2018.
- The average length of stay following an emergency ICU admission from the ward is 20 hours longer than other ICU admissions.
- Twenty-one percent of patients admitted to ICU as an emergency from the ward received invasive ventilation.
- The severity of illness on ICU admission varied 1.4-fold between DHBs.
- There were no consistent significant differences in mortality rates between DHBs over the last three years.
- There was wide variation between DHBs in the percentage of patients discharged after-hours, from 8.6 percent to 30.3 percent of discharges.
Note: the denominator used to estimate rates for Auckland’s cardiovascular ICU was different to the method applied for other units. This difference means, for this indicator, cardiovascular ICU should not be compared with other units. For the full description view the methodology (PDF 221 KB)
On average, 5.9 per 1,000 hospital admissions resulted in an emergency admission to ICU from the ward. This varied widely from 2.1 to 11.0 per 1,000 admissions.
Rates of emergency admission to ICU were significantly higher for Māori than for those of Other ethnicity.
Those in the youngest and oldest age bands were significantly less likely to be admitted to ICU as an emergency, while those aged 65–74 years had the highest rate of admission.
Emergency ICU admissions from the ward, by age group and ethnicity, per 1,000 admissions (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 3.7 | 3.5 | 2.0 | 3.2 (2.9–3.5) |
| 45–64 | 7.8 | 7.9 | 6.6 | 8.1 (7.6–8.7) |
| 65–74 | 8.0 | 7.1 | 7.1 | 8.7 (8.0–9.4) |
| 75–84 | 10.2 | 8.5 | 5.8 | 7.0 (6.4–7.7) |
| 85 and over | < 10 | < 10 | 1.8 | 2.0 (1.6–2.6) |
| Total | 6.0 (5.4–6.6) | 5.7 (4.9–6.5) | 4.7 (4.4–4.9) | 5.9 (5.6–6.1) |
Average length of stay following emergency admission to ICU from the ward is 20 hours longer than other ICU admissions
- People admitted to ICU as an emergency from the ward stayed on average 89 hours in 2018. This was 20 hours longer than other ICU admissions.
- Some DHBs had a consistently higher average length of stay over 2014–18.
- Those aged 65–74 years stayed significantly longer than those in all other age groups.
- Average length of stay for emergency admissions varied over 2.5-fold between DHBs.
- The Other ethnic group had a significantly longer average length of stay than all other groups.
Average length of stay in hours for emergency admissions to ICU, by age group and ethnicity (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 91.3 | 64.2 | 86.1 | 85.2 (84.3–86.1) |
| 45–64 | 72.8 | 85.0 | 94.4 | 88.7 (88.0–89.3) |
| 65–74 | 79.2 | 61.8 | 92.4 | 104.4 (103.5–105.3) |
| 75–84 | 86.5 | 72.8 | 75.6 | 76.0 (75.2–76.9) |
| 85 and over | < 10 | < 10 | 56.9 | 59.1 (57.4–60.9) |
| Total | 80.6 (79.7–81.5) | 73.8 (72.6–75.0) | 87.0 (86.5–87.5) | 88.6 (88.2–89.0) |
Twenty-one percent of patients received invasive ventilation following emergency admission to ICU from the ward
- This indicator shows the percentage of patients who received invasive ventilation. Invasive ventilation includes any form of positive pressure ventilation delivered through an artificial airway such as oral or nasal endotracheal tube or a tracheostomy.
- On average, 21 percent of people received invasive ventilation following emergency admission to ICU, with rates significantly lower in those aged 85 years and over.
- From 2014 to 2018, there was a significant reduction in the percentage of patients who received invasive ventilation following emergency admission to ICU.
Percentage of patients receiving invasive ventilation following emergency admission to ICU, by age group and ethnicity (2017–18)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 26.6 | 28.2 | 23.4 | 24.0 (20.5–28.0) |
| 46–64 | 23.5 | 31.1 | 24.4 | 24.4 (22.0–27.0) |
| 65–74 | 22.5 | 17.6 | 27.6 | 25.6 (22.7–28.8) |
| 75–84 | 18.5 | 29.4 | 19.3 | 19.2 (16.1–22.6) |
| 85 and over | < 10 | < 10 | 10.8 | 9.6 (5.4–15.9) |
| Total | 23.6 (20.0–27.7) | 27.5 (22.3–33.5) | 23.4 (21.6–25.3) | 23.2 (21.8–24.7) |
The severity of illness on emergency admission to ICU varied between DHBs
- Illness severity is measured using the APACHE III score. This calculates a patient’s risk of death using physiological parameters such as age. Scores range from 0 (no risk) to 299 (very high risk). It partially explains why scores increase with age regardless of pathology.
- In 2018, the mean score for illness severity was 63, ranging between 52 and 75.
- The mean score increased with age, peaking at 75–84 years.
- There has been no significant change in APACHE III score since 2014.
Mean APACHE III score for emergency admissions to ICU, by age group and ethnicity (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 46.9 | 52.7 | 48.2 | 48.5 (47.9–49.2) |
| 45–64 | 61.6 | 59.7 | 57.8 | 59.5 (59.0–60.0) |
| 65–74 | 72.5 | 78.8 | 69.2 | 70.1 (69.4–70.8) |
| 75–84 | 76.1 | 76.3 | 72.2 | 72.3 (71.5–73.1) |
| 85 and over | < 10 | < 10 | 71.0 | 73.2 (71.2–75.1) |
| Total | 60.9 (60.1–61.7) | 62.8 (61.7–63.9) | 63.5 (63.1–63.9) | 62.9 (62.6–63.2) |
Around 11 percent of emergency admissions to ICU from the ward resulted in death
- Mortality rates did not vary significantly in 2017–18, nor did any DHBs have consistently significantly higher rates in 2016 –18.
- There are signs of a downward trend in mortality rates for Māori between 2014 and 2018 but this is not yet significant.
- Mortality was significantly lower in those aged 18–44 years and significantly higher in the oldest age group (75 and over).
Percentage of emergency admissions to ICU resulting in death, by age group and ethnicity (2017–18)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 5.6 | 10.8 | 6.3 | 7.0 (5.2–9.3) |
| 45–64 | 9.5 | 13.5 | 11.1 | 11.4 (9.8–13.2) |
| 65–74 | 11.6 | < 10 | 15.2 | 14.5 (12.4–16.9) |
| 75–84 | 14.9 | < 10 | 16.7 | 16.0 (13.3–19.1) |
| 85 and over | < 10 | < 10 | 14.3 | 12.6 (7.7–19.4) |
| Total | 9.4 (7.2–12.0) | 12.0 (8.8–16.0) | 13.1 (11.8–14.5) | 12.4 (11.4–13.5) |
The average ICU length of stay for all admissions was 68 hours
- On average, ICU length of stay was 68 hours. This remained consistent over 2014–18, with some DHBs consistently having shorter or longer stays. The variation between DHBs was greater than 2.6-fold.
- Those aged 85 years and over tended to stay for a shorter time than those aged under 85 years.
On average 5 percent of people were re-admitted to ICU during their hospital stay
- The rate of re-admission varied more than 2.3-fold between DHBs.
- The youngest and oldest age categories were significantly less likely to be re-admitted than those aged 45–84 years.
A total of 2,400 patients were discharged after-hours (6pm–6am) in 2018
- There was wide variation between DHBs, with between 9 percent and 30 percent of all discharges being after-hours.
- On average, after-hours discharges represented 18.5 percent of all discharges and did not significantly change over 2016–18. However, since 2014 there has been a statistically significant increase in the percentage of after-hours discharges.
What questions might the data prompt?
- How do similar DHBs compare?
- Are rates increasing or decreasing over time?
- Why do rates vary between DHBs? How much can be explained by differences in patient population?
- What is the impact of ICU capacity on the rate of emergency admissions to ICU?
- How do these rates over time reflect changes in population health status?
- ANZICS adult patient database: https://www.anzics.com.au/adult-patient-database-apd/
- Gantner D, Farley K, Bailey M, et al. 2014. Mortality related to after-hours discharge from intensive care in Australia and New Zealand, 2005–12. Intensive Care Med 40(10): 1528–35.
Patients who deteriorate in smaller ('secondary') hospitals are often transferred to larger ('tertiary') hospitals with more ICU resource. As such, patients in tertiary hospital ICUs will include those who may have deteriorated in that hospital or been transferred as an emergency from a secondary hospital. The data set does not discriminate between these patient groups.
It is important to note that some ICUs have high dependency units (HDUs) attached. There will be a proportion of patients who may be suitable for HDU but not for ICU and this may affect APACHE III scoring. Units that have an HDU may be able to admit patients earlier in their course of deterioration. Earlier admission may result in less severe APACHE III scores than those admitted late but they may have similar outcomes. This bias is due to APACHE III scoring only looking at the first 24 hours.
Although some variation between ICUs is due to factors outside the scope of the Commission’s patient deterioration programme (such as the balance between elective and emergency admissions, ICU bed availability and 'secondary' vs 'tertiary' level ICUs), the focus on patients admitted to ICU in an emergency from the ward may provide information as to when deterioration was detected and whether appropriate actions were taken in a timely manner.
We were not able to find a reliable measure of ICU occupancy, which can also alter the threshold for admission; this is best explored using local data and should include staff availability.
The data will not reflect patients in whom deterioration was detected early and managed appropriately and so ICU admission was never required. Similarly, patients who deteriorated but died before reaching ICU will not be represented in this data set.
Key findings
- Emergency ICU admissions from the ward varied by DHB, from 2.1 to 11.0 per 1,000 hospital admissions in 2018.
- The average length of stay following an emergency ICU admission from the ward is 20 hours longer than other ICU admissions.
- Twenty-one percent of patients admitted to ICU as an emergency from the ward received invasive ventilation.
- The severity of illness on ICU admission varied 1.4-fold between DHBs.
- There were no consistent significant differences in mortality rates between DHBs over the last three years.
- There was wide variation between DHBs in the percentage of patients discharged after-hours, from 8.6 percent to 30.3 percent of discharges.
Note: the denominator used to estimate rates for Auckland’s cardiovascular ICU was different to the method applied for other units. This difference means, for this indicator, cardiovascular ICU should not be compared with other units. For the full description view the methodology (PDF 221 KB)
On average, 5.9 per 1,000 hospital admissions resulted in an emergency admission to ICU from the ward. This varied widely from 2.1 to 11.0 per 1,000 admissions.
Rates of emergency admission to ICU were significantly higher for Māori than for those of Other ethnicity.
Those in the youngest and oldest age bands were significantly less likely to be admitted to ICU as an emergency, while those aged 65–74 years had the highest rate of admission.
Emergency ICU admissions from the ward, by age group and ethnicity, per 1,000 admissions (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 3.7 | 3.5 | 2.0 | 3.2 (2.9–3.5) |
| 45–64 | 7.8 | 7.9 | 6.6 | 8.1 (7.6–8.7) |
| 65–74 | 8.0 | 7.1 | 7.1 | 8.7 (8.0–9.4) |
| 75–84 | 10.2 | 8.5 | 5.8 | 7.0 (6.4–7.7) |
| 85 and over | < 10 | < 10 | 1.8 | 2.0 (1.6–2.6) |
| Total | 6.0 (5.4–6.6) | 5.7 (4.9–6.5) | 4.7 (4.4–4.9) | 5.9 (5.6–6.1) |
Average length of stay following emergency admission to ICU from the ward is 20 hours longer than other ICU admissions
- People admitted to ICU as an emergency from the ward stayed on average 89 hours in 2018. This was 20 hours longer than other ICU admissions.
- Some DHBs had a consistently higher average length of stay over 2014–18.
- Those aged 65–74 years stayed significantly longer than those in all other age groups.
- Average length of stay for emergency admissions varied over 2.5-fold between DHBs.
- The Other ethnic group had a significantly longer average length of stay than all other groups.
Average length of stay in hours for emergency admissions to ICU, by age group and ethnicity (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 91.3 | 64.2 | 86.1 | 85.2 (84.3–86.1) |
| 45–64 | 72.8 | 85.0 | 94.4 | 88.7 (88.0–89.3) |
| 65–74 | 79.2 | 61.8 | 92.4 | 104.4 (103.5–105.3) |
| 75–84 | 86.5 | 72.8 | 75.6 | 76.0 (75.2–76.9) |
| 85 and over | < 10 | < 10 | 56.9 | 59.1 (57.4–60.9) |
| Total | 80.6 (79.7–81.5) | 73.8 (72.6–75.0) | 87.0 (86.5–87.5) | 88.6 (88.2–89.0) |
Twenty-one percent of patients received invasive ventilation following emergency admission to ICU from the ward
- This indicator shows the percentage of patients who received invasive ventilation. Invasive ventilation includes any form of positive pressure ventilation delivered through an artificial airway such as oral or nasal endotracheal tube or a tracheostomy.
- On average, 21 percent of people received invasive ventilation following emergency admission to ICU, with rates significantly lower in those aged 85 years and over.
- From 2014 to 2018, there was a significant reduction in the percentage of patients who received invasive ventilation following emergency admission to ICU.
Percentage of patients receiving invasive ventilation following emergency admission to ICU, by age group and ethnicity (2017–18)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 26.6 | 28.2 | 23.4 | 24.0 (20.5–28.0) |
| 46–64 | 23.5 | 31.1 | 24.4 | 24.4 (22.0–27.0) |
| 65–74 | 22.5 | 17.6 | 27.6 | 25.6 (22.7–28.8) |
| 75–84 | 18.5 | 29.4 | 19.3 | 19.2 (16.1–22.6) |
| 85 and over | < 10 | < 10 | 10.8 | 9.6 (5.4–15.9) |
| Total | 23.6 (20.0–27.7) | 27.5 (22.3–33.5) | 23.4 (21.6–25.3) | 23.2 (21.8–24.7) |
The severity of illness on emergency admission to ICU varied between DHBs
- Illness severity is measured using the APACHE III score. This calculates a patient’s risk of death using physiological parameters such as age. Scores range from 0 (no risk) to 299 (very high risk). It partially explains why scores increase with age regardless of pathology.
- In 2018, the mean score for illness severity was 63, ranging between 52 and 75.
- The mean score increased with age, peaking at 75–84 years.
- There has been no significant change in APACHE III score since 2014.
Mean APACHE III score for emergency admissions to ICU, by age group and ethnicity (2018)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 46.9 | 52.7 | 48.2 | 48.5 (47.9–49.2) |
| 45–64 | 61.6 | 59.7 | 57.8 | 59.5 (59.0–60.0) |
| 65–74 | 72.5 | 78.8 | 69.2 | 70.1 (69.4–70.8) |
| 75–84 | 76.1 | 76.3 | 72.2 | 72.3 (71.5–73.1) |
| 85 and over | < 10 | < 10 | 71.0 | 73.2 (71.2–75.1) |
| Total | 60.9 (60.1–61.7) | 62.8 (61.7–63.9) | 63.5 (63.1–63.9) | 62.9 (62.6–63.2) |
Around 11 percent of emergency admissions to ICU from the ward resulted in death
- Mortality rates did not vary significantly in 2017–18, nor did any DHBs have consistently significantly higher rates in 2016 –18.
- There are signs of a downward trend in mortality rates for Māori between 2014 and 2018 but this is not yet significant.
- Mortality was significantly lower in those aged 18–44 years and significantly higher in the oldest age group (75 and over).
Percentage of emergency admissions to ICU resulting in death, by age group and ethnicity (2017–18)
| Age group (years) | Ethnicity | |||
| Māori | Pacific peoples | Other | Total | |
| 18–44 | 5.6 | 10.8 | 6.3 | 7.0 (5.2–9.3) |
| 45–64 | 9.5 | 13.5 | 11.1 | 11.4 (9.8–13.2) |
| 65–74 | 11.6 | < 10 | 15.2 | 14.5 (12.4–16.9) |
| 75–84 | 14.9 | < 10 | 16.7 | 16.0 (13.3–19.1) |
| 85 and over | < 10 | < 10 | 14.3 | 12.6 (7.7–19.4) |
| Total | 9.4 (7.2–12.0) | 12.0 (8.8–16.0) | 13.1 (11.8–14.5) | 12.4 (11.4–13.5) |
The average ICU length of stay for all admissions was 68 hours
- On average, ICU length of stay was 68 hours. This remained consistent over 2014–18, with some DHBs consistently having shorter or longer stays. The variation between DHBs was greater than 2.6-fold.
- Those aged 85 years and over tended to stay for a shorter time than those aged under 85 years.
On average 5 percent of people were re-admitted to ICU during their hospital stay
- The rate of re-admission varied more than 2.3-fold between DHBs.
- The youngest and oldest age categories were significantly less likely to be re-admitted than those aged 45–84 years.
A total of 2,400 patients were discharged after-hours (6pm–6am) in 2018
- There was wide variation between DHBs, with between 9 percent and 30 percent of all discharges being after-hours.
- On average, after-hours discharges represented 18.5 percent of all discharges and did not significantly change over 2016–18. However, since 2014 there has been a statistically significant increase in the percentage of after-hours discharges.
What questions might the data prompt?
- How do similar DHBs compare?
- Are rates increasing or decreasing over time?
- Why do rates vary between DHBs? How much can be explained by differences in patient population?
- What is the impact of ICU capacity on the rate of emergency admissions to ICU?
- How do these rates over time reflect changes in population health status?
Recommended reading
- ANZICS adult patient database: https://www.anzics.com.au/adult-patient-database-apd/
- Gantner D, Farley K, Bailey M, et al. 2014. Mortality related to after-hours discharge from intensive care in Australia and New Zealand, 2005–12. Intensive Care Med 40(10): 1528–35.
Method and limitations
Patients who deteriorate in smaller ('secondary') hospitals are often transferred to larger ('tertiary') hospitals with more ICU resource. As such, patients in tertiary hospital ICUs will include those who may have deteriorated in that hospital or been transferred as an emergency from a secondary hospital. The data set does not discriminate between these patient groups.
It is important to note that some ICUs have high dependency units (HDUs) attached. There will be a proportion of patients who may be suitable for HDU but not for ICU and this may affect APACHE III scoring. Units that have an HDU may be able to admit patients earlier in their course of deterioration. Earlier admission may result in less severe APACHE III scores than those admitted late but they may have similar outcomes. This bias is due to APACHE III scoring only looking at the first 24 hours.
Although some variation between ICUs is due to factors outside the scope of the Commission’s patient deterioration programme (such as the balance between elective and emergency admissions, ICU bed availability and 'secondary' vs 'tertiary' level ICUs), the focus on patients admitted to ICU in an emergency from the ward may provide information as to when deterioration was detected and whether appropriate actions were taken in a timely manner.
We were not able to find a reliable measure of ICU occupancy, which can also alter the threshold for admission; this is best explored using local data and should include staff availability.
The data will not reflect patients in whom deterioration was detected early and managed appropriately and so ICU admission was never required. Similarly, patients who deteriorated but died before reaching ICU will not be represented in this data set.
Published: 29 Oct 2021
Modified: 10 Mar 2026
