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The asthma domain of the Atlas of Healthcare Variation gives clinicians, patients and providers an overview of asthma admission rates and medicine use by district health board (DHB). To increase diagnostic certainty and reduce the contribution from chronic obstructive pulmonary disease (COPD), only data for adults aged less 50 years are included.

Detailed information on the indicators, data sources, definitions, ages and rationale can be found in the methodology.

Update 2016 data

(Data updated June 2018)

Key messages

  • Admission rates in young children are many fold higher than in older children (10–14 years) and adults.
  • Admissions for Pacific peoples and Māori are proportionally higher than European/Other.
  • Fourteen percent of people had a readmission within 3 months and 17 percent had a readmission between three months and one year.
  • Thirty six percent of people admitted with asthma were not regularly dispensed an inhaled corticosteroid (ICS) in the year after admission.
  • Eighty three percent of people admitted did not receive a funded influenza vaccine in the year after admission.
  • In the community, 20 percent of those regularly dispensed a short-acting beta agonist (SABA) in two or more quarters in a year, were not dispensed any preventer medication in the year, and 32 percent regularly dispensed a SABA were not regularly dispensed a preventer.

Key findings

Pacific and Māori children are more likely to be admitted than European/Other
  • On average, 5.4 per 1000 children (~5,000) are admitted one or more times with a primary diagnosis of asthma each year. Rates varied three-fold between DHBs.
  • The proportion of Pacific children (10.4/1000) admitted was statistically significantly higher than for European/Other children (4.2/1000). Māori (6.6/1000) were not statistically higher than European/Other children. This result is a decrease from previous reporting for the year 2014 in which Māori rates (7.3/1000) were significantly higher than European/Other rates.
  • Younger children (aged 0 to 4 years) had the highest rate of admission.
  • Boys (aged 0–14) were more likely to be admitted than girls.
Pacific and Māori adults (aged 15 to 49 years) are more likely to be admitted with asthma than European/Other
  • On average 0.9 per 1000 adults are admitted one or more times in a year with a primary diagnosis of asthma. This varied three-fold between DHBs.
  • Pacific people and Māori had approximately three times the admission rate of European/Other.
  • Females had twice as many admissions compared to males.
At all ages, on average 14 percent of those admitted with asthma had a second admission within 90 days
  • A high rate of admissions within 90 days of discharge, suggests there may be room for improvement in discharge planning or continuity of care.
  • There was limited variation between DHBs.
Seventeen percent of people admitted had at least two admissions between 91–365 days of each other
  • High readmission rates within 3 months to 1 year post-discharge highlight the potential for community follow-up of people admitted with asthma.
Thirty six percent of people admitted with asthma were not regularly dispensed an inhaled corticosteroid (ICS) in the year after admission
  • It is recommended[1] that all people admitted with asthma should regularly receive an ICS following admission. High rates not on a regular ICS in the year post-discharge raise questions as to why this might be. Is there potential to improve ongoing management?
  • On average, 36 percent of people aged 5 to 49 years admitted with a primary diagnosis of asthma did not receive an ICS in two or more quarters in the year after admission. This did not vary widely between DHBs.
  • Pacific peoples were significantly less likely to receive a regular ICS than European/Other.
  • Children aged 0–4 years were not included in indicators looking at medication use as they are a unique group. Not all will respond to ICS therapy and of those who do, only some will have asthma at school age or as an adult.
Eighty three percent of those aged 0–49 years did not receive a funded influenza vaccine in the year after admission
  • Those who have a hospital admission for asthma are recommended to receive regular ICS therapy to manage their asthma. Influenza vaccine is also considered part of their preventive care. PHARMAC funds the influenza vaccine for this group.
  • Overall, the percent of those hospitalised with asthma receiving the influenza vaccine was low and ranged from 13–28 percent of those admitted with a primary diagnosis of asthma.
  • Māori (86 percent) and Pacific peoples (85 percent) were less likely to receive an influenza vaccine compared to European/Other (81 percent).
  • Influenza vaccination was significantly lower in those aged 0–4 years (only 12 percent received it), compared to all other ages.
  • Influenza vaccines that are administered in hospital, self-funded or funded by another third party won’t be included here. It is expected that self-funded/alternately funded is likely to biased towards working age groups. It is considered that these exclusions are unlikely to explain the entire treatment gap.
These indicators look at those in the general population who had a community dispensing of a reliever (short-acting beta agonist, SABA) inhaler and a preventer (inhaled corticosteroid or other) in a year
  • Children aged 0–4 years were not included in indicators looking at medication use as they are a unique group. Not all will respond to ICS therapy and of those who do, only some will have asthma at school age or as an adult.
  • The data presented do not allow for analysis of patients’ condition or their need for treatment. This means it is not possible to assess the appropriateness, or otherwise, of prescribing. However, wide variation at the population level, both between DHBs and by age or ethnic group is a starting point for asking whether the variation looks appropriate or if there are people who may benefit from preventer medication.
20 percent of those regularly dispensed SABA medication were not dispensed any preventer medication
  • It is recommended[1] that good control of asthma shows little use of SABA (reliever) medication. Preventer (ICS or other preventer) should be introduced if people are using their reliever two or more times in a week.
  • This indicator shows that 20 percent of those dispensed SABA in two or more quarters in a year, were not dispensed any preventer medication in the year.
  • Pacific people (22 percent) were significantly less likely to receive preventer medication than Māori (20 percent) or European/Other (20 percent).
  • Those aged 5–9 years also received significantly less preventer than all other age groups.
  • There was limited variation between DHBs.
32 percent of people regularly dispensed SABA medication were not regularly dispensed a preventer medication
  • Good control of asthma should show little use of relievers and regular use of preventers[1].
  • This indicator shows that 32 percent of people regularly dispensed SABA in two or more quarters in a year, were not also regularly dispensed a preventer (in two or more quarters in a year).
  • There was no significant variation by ethnicity. Preventer use was significantly lower in those aged 5-9 years at 60 percent, compared with 71 percent of those aged 24–49 years. This did not vary widely by DHB.

What questions might these data prompt?

  • Why do some DHBs have consistently lower or higher rates than the national mean?
  • Does this variation reflect differences in patient population or are there other factors?
  • How do DHBs with similar populations compare?
  • At the practice level, how many practices have a mechanism to check which of their patients have had an asthma admission and follow-up if they have not rebooked within a certain period?
The rates of medication use including ICS and influenza vaccine in the year after discharge raise questions as to why this might be
  • What proportion of those not receiving an ICS were readmitted?
  • What do patients understand with regards to the use of ICS and reliever medication?
  • How much of the gap can be explained by medication dispensing that is not captured, for example, prior to admission, free samples or oral steroids?

Background

Asthma is a chronic condition affecting the airways. Internationally, New Zealand has a high prevalence of asthma, with one in seven children (14 percent) aged 2–14 years (114,000 children) and one in eight adults (12 percent, 459,000 adults) reporting taking current asthma medication[2]. OECD statistics indicate New Zealand has one of the highest hospital admission rates for asthma of OECD countries.

The report The Impact On Respiratory Disease In New Zealand 2016 (2016) presents data on asthma mortality rates[3]. In 2013, 70 people died from asthma. Between 2006–11, asthma mortality was highest in people aged 65 and over, and higher in women than in men. Asthma mortality rates were highest for Māori and Pacific peoples, with rates 5.1 and 4.6 times higher than rates for those of Other ethnicity. 

There were socio-economic differences in asthma mortality, with higher deprivation (quintile 9 and 10) rates being 3.7 times higher than the least deprived (quintile 1 and 2). 

Data sources and method

The Atlas draws on existing national data collections held by the Ministry of Health, including the National Minimum Dataset (NMDS) and the Pharmaceutical Collection.

The indicators looking at admissions combines data for emergency department attendances meeting the three-hour rule and for hospital admissions. This is because different DHBs handle emergency department attendances differently. For more information, see the methodology.

Due to the uncertainty of diagnosing asthma in children under five years, ‘wheeze’ as an alternate diagnosis was included in the indicator reporting hospital admissions in children. Further analysis in the methodology demonstrates higher use of this code in the 0–4-year age group and significant variation between DHBs in the use of ‘wheeze’ as a diagnosis. 

The methodology is provided here.

Further information


References
  1. Beasley R, Hancox RJ, Harwood M et al. Asthma and Respiratory Foundation NZ adult asthma guidelines: a quick reference guide. 2016. NZ Med J 129 (1445). URL: http://www.nzasthmaguidelines.co.nz/uploads/8/3/0/1/83014052/adult_asthma_guidelines.pdf.
  2. Ministry of Health. 2017. Annual Data Explorer 2016/17: New Zealand Health Survey. URL: https://minhealthnz.shinyapps.io/nz-health-survey-2016-17-annual-update (accessed 6 November 2018).
  3. Telfar Barnard L, Zhang J. 2017. The impact of respiratory disease in New Zealand: 2016 update. Wellington: The Asthma Foundation. https://www.asthmafoundation.org.nz/research/the-impact-of-respiratory-disease-in-new-zealand-2016-update (accessed 6 November 2018).

Last updated 09/11/2018