ASH adult - single mapNurse listening to heart

ASH adult - double map

Ambulatory sensitive hospitalisations (ASH) are mostly acute admissions that are considered potentially reducible through prophylactic or therapeutic interventions deliverable in a primary care setting[1].

In New Zealand, ASH accounted for around a fifth of all acute and arranged medical and surgical discharges in 2011–12. However, determining the reasons for high or low ASH rates is complex, as it is in part a whole-of-system measure. It has been suggested that admission rates can serve as proxy markers for primary care access and quality, with high admission rates indicating difficulty in accessing care in a timely fashion, poor care coordination or care continuity, or structural constraints such as limited supply of primary care workers[2]. This indicator can also highlight variation between different population groups that will assist with district health board (DHB) planning to reduce disparities.

Data for this Atlas were drawn from the National Minimum Dataset and present overall acute and arranged admissions and overall ASH rates by DHB. Data for conditions contributing the most to ASH rates in adults (15–74 years) are presented. These conditions were selected with the assistance of an expert advisory group as being conditions possibly amenable to primary care interventions. The conditions selected were: angina/chest pain, asthma, cellulitis/skin infections, congestive heart failure, epilepsy, gastroenteritis and pneumonia.

There is considerable debate about the appropriateness of the term ASH and its definition. While ASH rates have traditionally tended to focus on primary care provision (particularly in general practice), it is important to remain aware that many other aspects of the health care system – hospital supply and configuration, emergency care department management, community care provision etc – can have an effect on ASH.

For these reasons, both the Ministry of Health ASH and a modified version of ASH are presented. ‘Modified ASH’ removes filters and exclusions normally applied to ASH data and presents all ASH admissions, including emergency department admissions and non-casemix events. Weighting was not applied as presenting all events was thought most relevant - the relative preventability of any ASH event warrants consideration. To view methodology click here. Modified ASH is intended to highlight the impact these filters have on ASH rates and promote the concept of ‘hospitalisations for whole system sensitive conditions’.

It is important to note the deliberate use of the word ‘sensitive’ in the title of ASH – not all these admissions would be preventable even in a perfect health system. Moreover, many ‘unplanned’ admissions are planned in the acute sense by the primary care clinician, and are not ‘avoidable’ given current health service resources, and the psycho-social circumstances of patients and their families.

It is also important to think clearly about the focus of any apparently preventable admission. Angina is an example where ‘preventability’ could refer to acute primary care interventions, such as a decision to seek an opinion or not, or much longer-term public health measures, such as smoking cessation legislation.

For all of the conditions in the Atlas, many of the admissions are warranted using present health system conditions. Hence, zero is not the sought target.

It has been suggested that to interpret ASH analyses, the preventability of classes of admission through access to specific primary care interventions should be considered, rather than individual failures to prevent admissions of an individual.

Key messages:

Age had a significant impact on admissions for some conditions: angina, congestive heart failure and pneumonia increased significantly with each age band, whilst gastroenteritis admissions were significantly higher in the oldest age group. Age had no apparent effect on admissions for asthma or epilepsy.

Māori and Pacific peoples had significantly higher admissions for asthma, congestive heart failure, epilepsy, pneumonia and cellulitis/skin infections. Admissions due to gastroenteritis were significantly lower for Asian peoples.

Two- to three-fold variations between DHBs were reported for angina/chest pain, asthma, cellulitis/skin infections and congestive heart failure.

In reporting these rates, the intention is not to prevent all admissions but to question:

  • How might high rates of admissions be affected by more intensive support for primary care management?
  • How do health literacy, service provision, primary care access and prevention programmes impact on admission rates?

Recommended reading

Baird J, Smith P. 2011. A short report on integrated care initiatives in selected New Zealand Health Networks. URL:

Basu A, Brinson D. 2008. The effectiveness of interventions for reducing ambulatory sensitive hospitalisations: a systematic review (Vol 1). University of Canterbury: Health Services Assessment Collaboration.

Kruzikas D et al. 2004. Preventable Hospitalizations: A Window into Primary and Preventive Care. HCUP Fact Book 5, 0056.

Purdy, S. (2010). Avoiding hospital admissions. What does the research evidence say? The King's Fund.



  1.  Jackson, G. and M. Tobias, Potentially avoidable hospitalisations in New Zealand, 1989-98. Aust N Z J Public Health, 2001. 25(3): p. 212-21.
  2.  Kruzikas, D., et al. Preventable Hospitalizations: A Window Into Primary and Preventive Care. HCUP Fact Book, 2004. 5, 0056.

Last updated 13/10/2016