4th September 2015, Volume 128 Number 1421

Susan Bibby, Richard Milne, Richard Beasley

Bronchiectasis, a condition characterised by dilated, thick-walled bronchi, is associated with recurrent respiratory tract infection,1 chronic cough, sputum production, dyspnoea and progressive loss of lung function.2 Treatable, but rarely curable, management revolves around preventing or slowing progression by regular clearance of airway secretions and prompt treatment of lung infections.3 It places a large burden on the healthcare system, as it is a chronic disease that may require not only hospital admissions, but also frequent outpatient visits, physiotherapy, and antibiotic use.3

While there is a general belief that the incidence of bronchiectasis has fallen since the introduction of antibiotics, its prevalence in the US is reportedly increasing, with one study showing an annual increase of 8.7% from 2000 to 2007.4 This could represent a true increase in prevalence, and/or improved survival, and/or increased diagnosis due to more frequent use of high resolution computed tomography (HRCT).4 The true incidence and prevalence are likely to be underestimated due to under-diagnosis.3,5 There is also a wide variation in prevalence and incidence between and within populations.1,2

Bronchiectasis is considered a serious health issue for the indigenous and disadvantaged populations of the US, Australia and New Zealand.1,6 Prevalence rates are consistently higher for indigenous populations in all these countries: 52 per 100,000 overall in the US, but 1,100–2,000 per 100,000 in southwest Alaskan native children;7 and 1,470 per 100,000 in Australian Aboriginal children.5 Another study estimated the point prevalence of bronchiectasis solely in Auckland (in 1998–2000) as 17 per 100,000; further breakdown by ethnicity gave values of 24 per 100,000 for Māori and 53 per 100,000 for Pacific children, compared to 4 per 100,000 for Europeans.8

Another New Zealand study also reported that the incidence of bronchiectasis varies with ethnicity: a rate of 3.7 per 100,000 children per year in 2001–2, breakdown by ethnicity of 17.8 for Pacific peoples, 4.8 for Māori and 1.5 per 100,000 per year for the European population.1

The main purpose of this study was to analyse national hospital admissions for bronchiectasis over a recent 5-year period, in order to estimate the burden of moderate or severe bronchiectasis, and the distribution by age, ethnicity, socio- economic status, geographical location and other variables. A secondary purpose was to estimate the budget impact of these admissions.

Methods

A nation-wide data set of anonymised publicly funded hospital admissions with a principal clinical diagnosis of bronchiectasis (ICD10 J47; which includes bronchiolectasis but excludes cystic fibrosis and congenital and tubercular bronchiectasis) was obtained from the Ministry of Health, for the period July 1, 2008 to June 30, 2013 (financial years (FY) 2008/09 to 2012/13). Admissions with a length of stay >89 days were excluded in an attempt to avoid biasing the mean costs and the average length of stay (LOS). The data included age, sex, prioritised ethnicity, District Health Board (DHB), length of stay, deprivation index (NZDep06), patient complication and morbidity level (PCCL), Australian Refined Diagnosis Related Group (AR-DRG) version 6.0, case weight and seasonality.

Multiple ethnic groups were prioritised using the following hierarchy: Māori; Pacific; European/Other. Population denominators were obtained from the 2013 census (Statistics NZ). An index admission in 2012/13 was defined as an admission for a patient who had not been admitted over the previous 4 years—which in some cases might have been a re-admission from earlier years. The time to a repeat admission was defined as the number of days from the date of discharge from an admission to the date of the next admission, excluding same day readmissions and transfers between hospitals. Age-adjustment by sex and ethnicity was by the direct method, with ‘male’ and ‘European/other’ as the references. Age-standardisation was not attempted for DHBs because of the small numbers of admissions.

Australian Refined Diagnosis Related Groups (AR-DRGs) are a patient classification system used by the New Zealand Ministry of Health to structure episodes of care into groups that are clinically similar both in terms of patient characteristics and health interventions, and that are therefore anticipated to consume comparable levels of hospital resources.

The ‘NZDep’ is a small, geographical area-based index of socioeconomic deprivation calculated from each 5-yearly census based on the following variables: income; employment; communication; transportation support; educational and other qualifications; home ownership and household crowding. It is arranged in 10 (approximately equal) deciles, with ‘1’ representing the least disadvantaged and ‘10’ representing the most disadvantaged. Higher decile groups tend to have higher proportions of Māori and Pacific peoples. Individuals were assigned a domicile code based on their home address at the time of admission, which was then mapped to the NZDep for 2006 (NZDep06).9

Admission costs were estimated using admission-specific diagnosis related group (DRG) cost weights applied to financial year 2012/13, multiplied by the mean national price for all types of hospital admission (NZ4614; NZ Ministry of Health). These costs take into account resource consumption, which reflects the intensity of care and length of stay. More detailed costings could be obtained hospital by hospital, but that would be beyond the scope of this study.

No attempt was made to obtain numbers of patient presentations or costs for Outpatient Clinic or Emergency Department visits because this information is not specific to the indications under study.

Analyses were conducted using Stata v.12 and a spreadsheet.

Results

Admissions by age, ethnicity and socioeconomic status

There were 5,519 admissions with a principal diagnosis of bronchiectasis in financial years 2008/09 to 2012/13. Twenty-five admissions had a length of stay greater than 89 days, leaving 5,494 admissions for analysis. The annual number of admissions was stable across the 5-year period, despite an ageing population, with a mean of 1,100 admissions per annum.

By age group, admissions had a double peak which centred on children less than 15 years of age and older adults. Admission rates for children were markedly higher for Māori and Pacific peoples than for European/other children. Adult admission rates for older adults were higher for women than men, and also for Māori and Pacific than for European/others (Figure 1).

Figure 1: Admission rates by age group, sex and ethnicity in FY 2008/09 to 2012/13

1ab

The average length of stay did not differ statistically across the 3 main ethnic groups (Table 1).

Table 1: Average length of stay in FY 2008–2012 by ethnic group 

 

Number of admissions

ALOS in days (±95% CI)

Māori

1,448

5.78 (5.51, 6.05)

Pacific

1,095

5.60 (5.26, 5.94)

European/Other

2,951

5.50 (5.25, 5.74)

Total

5,494

5.59 (5.43, 5.76)

ALOS = average length of stay

Admissions varied substantially with the level of socioeconomic deprivation. The total number of admissions for those patients residing in NZDep06 decile 10 was approximately five-fold higher than those in decile 1: when broken down by ethnicity, this was largely accounted for by the proportions of admissions for Māori/Pacific peoples increasing steeply with socioeconomic deprivation (Figure 2).

 Figure 2: Admissions in FY 2008–2012 by ethnicity and socioeconomic deprivation

c 

Age adjusted mean admission rates over the 5-year period were 38% higher for women than men; and 4.9-fold higher for Māori and 9.1-fold higher for Pacific peoples than for European/other ethnicities (Table 2). The overall crude rate was 25.7 and age-adjusted rate 20.4 admissions per 100,000 population.

Table 2: Admission rates by sex and by the major ethnic groups in FY 2012/13 

 

Number

Crude ratea

Age adjusted rate

Rate ratiob

By sex

Females

3,402

30.9

23.5

1.38

Males

2,092

20.2

17.0

1.00

Total

5,494

25.7

20.4

 

By ethnicity

Māori

1,448

51.2

54.3

4.93

Pacific

1,095

78.4

100.0

9.09

European/other

2,951

17.2

11.0

1.00

Total

5,494

25.7

20.4

 

aPer 100,000 population
bRelative to males or relative to European/Other (age adjusted) 

Admissions by DHB

Admissions were distributed unevenly across the 20 DHBs(Table 3).

 Table 3: Hospital admissions in FY 2008/09 to 2012/13 by DHB

c 

Re-admissions

In the 12-month period July 1, 2012 to June 30, 2013 there were 1,172 admissions, 227 re-admissions (19%) within 90 days, and 115 re-admissions within 30 days. Over the entire 5-year study period, the 30 day re-admission rate was 12.4%, and 2,364 patients out of 5,494 (43%) were re-admitted within 12 months: the time to re-admission of those 43% is shown in Figure 3. Time to re-admission was independent of ethnicity and socioeconomic deprivation.

Figure 3: Time to readmission for patients who were readmitted within 12 months of discharge 

c 

Season of admissions

Hospital admissions were more common in winter and spring than summer or autumn (Figure 4).

 Figure 4: Season of admissions for bronchiectasis

c 

Budget impact

Over the 5-year period there were 5,494 admissions at an estimated cost of NZD 25.6 million. There was no evidence of a statistically significant difference in mean cost across years (Table 4). In financial year 2012/13, the mean cost per admission for bronchiectasis was NZD 4,555, and the total cost was NZD 5.34M. Corresponding to admissions, most of the cost was for the elderly, with NZD 0.95 million (18%) for children and youth less than 20 years of age and a disproportionally high cost for Māori children (Figure 5).

Table 4: Admissions and their estimated budget impact in FY 2008/09 to 2012/13 

Financial year

Admissions

Mean cost (±95% CI)

Total cost ($m)

2008/09

1,028

4,616 (4,486, 4,745)

4.74

2009/10

1,078

4,714 (4,589, 4,838)

5.08

2010/11

1,083

4,618 (4,495, 4,741)

5.00

2011/12

1,133

4,806 (4,686, 4,926)

5.45

2012/13

1,172

4,555 (4,442, 4,668)

5.34

Total

5,494

4,662 (4,637, 4,686)

25.61

 All costs are in 2012/13 New Zealand dollars (NZD) 

 Figure 5: Budget impact by age and ethnicity in FY 2012/13 (NZD)

c 

Discussion

This analysis shows that there is a substantial burden of bronchiectasis in New Zealand occurring from hospital admissions for moderate to severe exacerbations. There is a double peak of hospital admissions for bronchiectasis by age, occurring in children less than 10 years of age, and the over-65s, with adult admissions being higher for women than men, higher in Māori and Pacific communities, and increasing with the standard index of socioeconomic deprivation.

After adjustment for age, admission rates are raised by 5-fold in Māori and by 9- fold for Pacific populations compared to others. Previous reports also highlight the difference in rates of hospital admissions for bronchiectasis between ethnic groups: admissions in 2003–2005 were 3.6 times higher for Māori compared to non-Māori, with the difference rising with age from double the rate for the paediatric population to nearly 6 times the rate at ages 45–64 years.6 The high prevalence in Māori and Pacific communities is likely to be related, at least in part, to socioeconomic deprivation: here, we found that admission rates increased markedly with decreasing socioeconomic status, as also found previously in studies that focused on the wider Auckland area,8,10 which has the highest rate of admissions in the country. In a retrospective study of adults hospitalised with bronchiectasis in Middlemore Hospital during 2002,10 27% were Māori and 41% Pacific peoples. Another study, of paediatric outpatients with bronchiectasis in Auckland, showed that 25% of outpatient visits were by Māori and 55% were by Pacific patients.8 This contrasts with the census population of this area, where only 18% and 17% of children were Māori and Pacific respectively.8 Similarly to our national data, these studies show admission rates in Auckland also increasing with decreasing socioeconomic status: 77% of adult inpatients10 and 67% of paediatric outpatients8 lived in areas categorised as the 30% most deprived in New Zealand, where just 49% of adults reportedly reside.10 Substandard housing, malnutrition, barriers to medical care and inadequate education are all likely to impact on the occurrence and outcome of bronchiectasis.6 Low immunisation rates in these communities may also be a factor, as infant vaccination against diseases such as whooping cough are important in childhood prevention.6 In New Zealand, half of the cases in children and adults with a known aetiology were caused by childhood infection,8,10 underlying the importance of prompt treatment of respiratory infections. Vaccinations against influenza and pneumococcal diseases are also important parts of the management of bronchiectasis.6

The rate of admissions in different DHBs varied substantially, with Counties Manukau having much a higher admission rate than other DHBs, and thus the highest 5-year cost. With the exception of Canterbury, those DHBs with the highest rates generally had the highest proportions of Māori and Pacific peoples admitted. The overall percentage of cases which were in people of Maori and Pacific Island decent, 40%, is over twice that reported in the last census (19.6%).

The impact of sex on adult admissions seen here has been noted previously: an analysis of Medicare beneficiaries in the US showed that women 65–85 years had a prevalence 1.3 to 1.6-fold higher than men of the same age group.4 At Middlemore Hospital, 59% of patients admitted with bronchiectasis were women, despite an almost equal male/female balance in census data for Counties Manukau DHB.10 Bronchiectasis was reported in 1994 to be the 6th most common cause of death for Pacific women over 65 years of age, but was not listed in the top eight causes for men of the same age and ethnic group; it did however have almost equal ranking as a cause of admissions.11 The imbalance between the sexes in our study is unlikely to be due to relative longevity because age-specific admission rates were higher for women 40–80 years of age.

The estimated costs corresponding to admissions reported in this analysis are likely to be a gross underestimate of the real disease burden. Admissions with other principal diagnoses, such as chronic obstructive pulmonary disease (COPD), asthma or pneumonia, that could have been due to, complicated and/or prolonged by a comorbidity of bronchiectasis were excluded from the analysis, as we did not assess admissions in which bronchiectasis was a secondary diagnosis. However, we suspect that bronchiectasis may be a contributing factor in other respiratory admissions, as previous studies have reported comorbidities in 80% of adults admitted with bronchiectasis (most commonly COPD or asthma),10 while 37% of children with bronchiectasis had a clinical history of asthma.8

Hospital admission is an indicator of disease severity,12 with prior research showing that 21% of adults admitted with bronchiectasis died within 12 months of admission: that study, on adult inpatients over a 12-month period, showed a readmission rate of 46%.10 Here we found a similar rate of 43% having a repeat admission within 12 months of the index admission over this 5-year period. We did not find ethnic or socioeconomic differences in the time to readmission. Other predictors of disease prevalence thus presumably influence the reports of different mortality rates in different ethnic groups (in 2000–2004 the overall mortality rate from bronchiectasis was 6.7 times higher in Māori than Non- Māori).6

Bronchiectasis also comprises a costly respiratory disease, with 1,172 hospital admissions in 2012/13, costing the DHBs an estimated NZD 5.34 million (giving a mean cost per admission for bronchiectasis of $4,555). This figure is likely to be an underestimate, as it was based on casemix cost weights rather than detailed patient-level assessment. This estimate is also conservative due to the exclusion of outpatient and GP appointments, emergency care, community pharmaceuticals and admissions with a length of stay greater than 90 days. These will all contribute to care of these patients, but were outside the scope of this study. Non-medical costs also include disability care and loss of earnings by patients. In the US, it was estimated that total medical-care expenditures for the year 2001 were on average $5,681 higher for those individuals with bronchiectasis than without.13 While the annual cost is much less than that due to COPD in New Zealand,14 community interventions to prevent or treat bronchiectasis and reduce admissions could have an important impact on the healthcare budget. The disproportionately high cost for Māori children that we see here is also a concern.

Interventions that may help reduce the burden of bronchiectasis include increasing immunisation rates;6 improvements in housing (overcrowding has been shown to increase risk of other diseases in New Zealand15); treatment of exacerbations with antibiotics—IV when indicated, and long-term when appropriate3—and sputum clearance techniques.3 Novel medical therapies are now also becoming available, such as long term humidification therapy, which may also help decrease the frequency and duration of exacerbations; although this study did not separate bronchiectasis from COPD.16

In conclusion, hospital admissions for bronchiectasis peak in both the young and the older adult by age, and are concentrated in socioeconomically disadvantaged Māori and Pacific peoples. Admissions are more common for women than for men, and for colder months of the year: and they incur a high cost. Effective community interventions that are targeted to disadvantaged communities, high-risk ethnic groups and perhaps tailored to season could greatly reduce the human and economic burden of respiratory illness.

Summary

Bronchiectasis is a chronic lung condition, usually caused by damage to the lungs from a serious childhood infection, and leading to in recurrent lung infections. Here we show that there is a significant burden for New Zealanders and the New Zealand health system due to bronchiectasis. People admitted to hospital due to this condition are much more likely to be of Maori and Pacific descent, and more likely to be young children and elderly people, from low socioeconomic areas. There is a seasonal variation, suggesting that the cold and damp in winter and spring makes this condition more likely to flare up. We recommend that further research is done into why this disease is more common in these populations, and what can be done to better treat and prevent it.

Abstract

Aim

To investigate hospital admissions for non-cystic fibrosis bronchiectasis during July 1, 2008 to June 30, 2013; and to describe their distribution and annual cost in New Zealand.

Method

Admissions with a principal diagnosis of bronchiectasis (ICD10 J47), excluding cystic fibrosis, and length of stay <90 days were analysed by age, sex, ethnicity, socioeconomic deprivation, DHB, re-admissions and seasonality.

Results

There were 5,494 admissions with a mean annual rate of 25.7 (age adjusted rate 20.4) per 100,000. Admission rates peaked in childhood and in the elderly, and increased steeply with socioeconomic deprivation. Age-adjusted rates were 38% higher for women, 4.9-fold higher for Māori and 9.1-fold higher for Pacific peoples. Counties Manukau had the highest unadjusted rate for any DHB (49.4 per 100,000). The overall 30 day readmission rate was 12.4%. Admissions peaked in winter and spring. The estimated cost in financial year 2012/13 was NZD 5.34M.

Conclusion

Hospital admissions for bronchiectasis are concentrated in socioeconomically disadvantaged young and elderly Māori and Pacific peoples; are more common in winter and spring, and incur a high annual cost. Evidence- based interventions to reduce the disproportionate burden of bronchiectasis in Māori and Pacific children and the elderly is a public health priority.

Author Information

Susan Bibby, Senior Medical Research Fellow, Medical Research Institute of New Zealand, Wellington, New Zealand; Richard J Milne, Hon. Associate Professor, University of Auckland; Richard Beasley, Director, Medical Research Institute of New Zealand.

Correspondence

Susan Bibby, Medical Research Institute of New Zealand

Correspondence Email

sue.bibby@mrinz.ac.nz

Competing Interests

Fisher & Paykel Healthcare Ltd. provided funding to XXX for this study but had no input into the design, analyses, interpretation or write up.

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