Epidemiology and direct health care costs of hospitalised legionellosis in New Zealand, 2000-2020.

BACKGROUND: Legionellosis is a collective term used for disease caused by Legionella species which result in community and hospital acquired pneumonia worldwide. The aim of this analysis was to describe the epidemiology of legionellosis hospitalisations in Aotearoa New Zealand (NZ) over a 21-year period and quantify the health care costs. METHOD: This study combined national legionellosis notification and hospital discharge data that were linked via the National Health Index (NHI) to provide a more complete dataset of hospitalised cases. The direct cost of hospital care was estimated by multiplying the diagnosis-related group cost-weight by the national price and inflating to 2020/2021 values. RESULTS: There were 1479 records matched across notifications and discharge databases, including 990 with principal and 489 with additional diagnosis of legionellosis. Incidence rose to an average of 143 cases per annum for 2016-2020, a rate of 3·2/100,000. The median LOS was 6 days (IQR 4-13·5) with direct costs of $2·1 million per annum over that period. Rates were highest in those aged 65 years and above, male, and of European/Other ethnicity. Hospitalisations showed a peak in spring and summer. CONCLUSION: The rate of hospitalised legionellosis in New Zealand rose from 2000 to 2015, largely reflecting improved diagnosis. This preventable disease results in substantial health care costs. Greater efforts are needed to identify and control sources of exposure. Surveillance could be improved by routine integration of notification and hospital discharge data.

Beyond muddy waters: Three Waters reforms required to future-proof water service delivery and protect public health in Aotearoa New Zealand.

A 2016 drinking water-related campylobacteriosis outbreak in Aotearoa New Zealand made much of an entire town sick leading to reforms colloquially called "Three Waters", which aims to improve the management and delivery of waste, storm and drinking water systems. Public discourse on the Three Waters reforms has been dominated by anti-co-governance rhetoric, concerns around privatisation and loss of local control and alternative less comprehensive reform models. This debate has drowned out the fundamental problem statement justifying the reforms, that is, the management of drinking water resources is currently: 1) demonstrably inadequate to protect public health and promote health equity; and 2) economically inefficient. We discuss four areas where the proposed Three Waters reforms are likely to address current and future challenges and improve public health. We conclude by outlining four areas of remaining contention.

Nitrate contamination in drinking water and colorectal cancer: Exposure assessment and estimated health burden in New Zealand.

BACKGROUND: Epidemiological evidence in multiple jurisdictions has shown an association between nitrate exposure in drinking water and an increased risk of colorectal cancer (CRC). OBJECTIVE: We aimed to review the extent of nitrate contamination in New Zealand drinking water and estimate the health and financial burden of nitrate-attributable CRC. METHODS: We collated data on nitrate concentrations in drinking water for an estimated 85% of the New Zealand population (∼4 million people) who were on registered supplies. We estimated nitrate levels for the remaining population (∼600,000 people) based on samples from 371 unregistered (private) supplies. We used the effective rate ratio from previous epidemiological studies to estimate CRC cases and deaths attributable to nitrate in drinking water. RESULTS: Three-quarters of New Zealanders are on water supplies with less than 1 mg/L NO3-N. The population weighted average for nitrate exposure for people on registered supplies was 0.49 mg/L NO3-N with 1.91% (95%CI 0.49, 3.30) of CRC cases attributable to nitrates. This correlates to 49.7 cases per year (95%CI 14.9, 101.5) at a cost of 21.3 million USD (95% 6.4, 43.5 million USD). When combining registered and unregistered supplies, we estimated 3.26% (95%CI 0.84, 5.57) of CRC cases were attributable to nitrates, resulting in 100 cases (95%CI 25.7, 171.3) and 41 deaths (95%CI 10.5, 69.7) at a cost of 43.2 million USD (95%CI 10.9, 73.4). CONCLUSION: A substantial minority of New Zealanders are exposed to high or unknown levels of nitrates in their drinking water. Given the international epidemiological studies showing an association between cancer and nitrate ingestion from drinking water, this exposure may cause an important burden of preventable CRC cases, deaths, and economic costs. We consider there is sufficient evidence to justify a review of drinking water standards. Protecting public health adds to the strong environmental arguments to improve water management in New Zealand.

Home modifications to prevent home fall injuries in houses with Maori occupants (MHIPI): a randomised controlled trial.

BACKGROUND: As with many Indigenous populations internationally, Maori in New Zealand suffer health inequity. We aimed to assess the rate of fall injuries at home with and without home modifications in houses with Maori occupants. METHODS: We did a single-blind randomised controlled trial in the Wellington and Taranaki regions of New Zealand and enrolled owner-occupied households with at least one Maori occupant. Only households who stated they intended to live at that address for the subsequent 3 years were eligible for participation. We randomly assigned (1:1) households to either the intervention group, who received home modifications (handrails for outside steps and internal stairs, grab rails for bathrooms, outside lighting, repairs to window catches, high-visibility and slip-resistant edging for outside steps, fixing of lifted edges of carpets and mats, non-slip bath mats, and slip-resistant surfacing for outside areas such as decks) immediately, or the control group, who received the modifications 3 years later. Data on home injuries were obtained from the Accident Compensation Corporation and coded by study team members, who were masked to study group allocation. The primary outcome was the rate of medically treated fall injuries at home per household per year, analysed according to intention to treat. This Maori Home Injury Prevention Intervention (MHIPI) trial is now completed, and is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12613000148774. FINDINGS: Between Sept 3, 2013, and Oct 1, 2014, 824 households were assessed for eligibility and 254 were enrolled, of which 126 (50%) were assigned to the intervention group and 128 (50%) were assigned to the control group. After adjustment for previous falls and geographical region, there was an estimated 31% reduction in the rate of fall injuries at home per year exposed to the intervention compared with households in the control group (adjusted relative rate 0·69 [95% CI 0·47-1·00]). INTERPRETATION: Low-cost home modifications and repairs can be an effective means to reduce injury disparities. The high prevalence of modifiable safety issues in Maori homes merits considerable policy and community effort. FUNDING: Health Research Council of New Zealand.

Bumper issue of COVID-19 pandemic studies of relevance to Aotearoa New Zealand.

In response to the COVID-19 pandemic, Aotearoa New Zealand adopted a clear 'elimination strategy', which has (up to June 2021) been very successful in both health and economic terms compared to other OECD countries. Nevertheless, the pandemic response has still been a very major shock to the New Zealand health system. This issue of the New Zealand Medical Journal has 14 new pandemic-related articles. Some of this work can help inform vaccination prioritisation decisions and inform preparations of primary and secondary care services and social services for any future raising of levels in the pandemic Alert Level system. Particularly strong themes are around the value (and challenges) of telehealth services, and also the need for responses throughout the health system to ensure health equity and support for the most vulnerable citizens.

Early diagnosis of acute rheumatic fever and rheumatic heart disease as part of a secondary prevention strategy: Narrative review.

Acute rheumatic fever (ARF) and its sequela rheumatic heart disease (RHD) remain significant causes of morbidity and mortality. In New Zealand, ARF almost exclusively affects Indigenous Maori and Pacific children. This narrative review aims to present secondary interventions to improve early and accurate diagnosis of ARF and RHD, in order to minimise disease progression in New Zealand. Medline, EMBASE and Scopus databases were searched as well as other electronic publications. Included were 56 publications from 1980 onwards. Diagnosing ARF and RHD as early as possible is central to reducing disease progression. Recent identification of specific ARF biomarkers offer the opportunity to aid initial diagnosis and portable echocardiography has the potential to detect undiagnosed RHD in high-risk areas. However, further research into the benefits and risks to children with subclinical RHD is necessary, as well as an economic evaluation.

Environmental burden of disease from unsafe and substandard housing, New Zealand, 2010-2017.

OBJECTIVE: To assess the burden of disease related to unsafe and substandard housing conditions in New Zealand from 2010 to 2017. METHODS: We focused on substandard housing conditions most relevant for New Zealand homes: crowding, cold, damp or mould, and injury hazards linked to falls. We estimated the population attributable fraction using existing estimates of the population exposed and exposure-response relationships of health disorders associated with each housing condition. We used government hospitalization data, no-fault accident insurance claims and mortality data to estimate the annual disease burden from the most severe cases, as well as the resulting costs to the public sector in New Zealand dollars (NZ$). Using value of a statistical life measures, we estimated the indirect cost of deaths. FINDINGS: We estimated that illnesses attributable to household crowding accounted for 806 nights in hospital annually; cold homes for 1834 hospital nights; and dampness and mould for 36 649 hospital nights. Home injury hazards resulted in 115 555 annual accident claims. We estimated that direct public sector costs attributable to these housing conditions were approximately NZ$ 141 million (100 million United States dollars, US$) annually. We also estimated a total of 229 deaths annually attributable to adverse housing and the costs to society from these deaths at around NZ$ 1 billion (US$ 715 million). CONCLUSION: Of the conditions assessed in this study, damp and mouldy housing accounted for a substantial proportion of the burden of disease in New Zealand. Improving people's living conditions could substantially reduce total hospitalization costs and potentially improve quality of life.

Rising Ethnic Inequalities in Acute Rheumatic Fever and Rheumatic Heart Disease, New Zealand, 2000-2018.

We describe trends in acute rheumatic fever (ARF), rheumatic heart disease (RHD), and RHD deaths among population groups in New Zealand. We analyzed initial primary ARF and RHD hospitalizations during 2000-2018 and RHD mortality rates during 2000-2016. We found elevated rates of initial ARF hospitalizations for persons of Maori (adjusted rate ratio [aRR] 11.8, 95% CI 10.0-14.0) and Pacific Islander (aRR 23.6, 95% CI 19.9-27.9) ethnicity compared with persons of European/other ethnicity. We also noted higher rates of initial RHD hospitalization for Maori (aRR 3.2, 95% CI 2.9-3.5) and Pacific Islander (aRR 4.6, 95% CI 4.2-5.1) groups and RHD deaths among these groups (Maori aRR 12.3, 95% CI 10.3-14.6, and Pacific Islanders aRR 11.2, 95% CI 9.1-13.8). Rates also were higher in socioeconomically disadvantaged neighborhoods. To curb high rates of ARF and RHD, New Zealand must address increasing social and ethnic inequalities.

The economic and health burdens of diseases caused by group A Streptococcus in New Zealand.

OBJECTIVES: In preparation for the future arrival of a group A Streptococcus (GAS) vaccine, this study estimated the economic and health burdens of GAS diseases in New Zealand (NZ). METHODS: The annual incidence of GAS diseases was based on extrapolation of the average number of primary healthcare episodes managed each year in general practices (2014-2016) and on the average number of hospitalizations occurring each year (2005-2014). Disease incidence was multiplied by the average cost of diagnosing and managing an episode of disease at each level of care to estimate the annual economic burden. RESULTS: GAS affected 1.5% of the population each year, resulting in an economic burden of 29.2 million NZ dollars (2015 prices) and inflicting a health burden of 2373 disability-adjusted life years (DALYs). Children <5 years of age were the most likely age group to present for GAS-related healthcare. Presentations for superficial throat and skin infections (predominantly pharyngitis and impetigo) were more common than other GAS diseases. Cellulitis contributed the most to the total economic and health burdens. Invasive and immune-mediated diseases disproportionately contributed to the total economic and health burdens relative to their frequency of occurrence. CONCLUSION: Preventing GAS diseases would have substantial economic and health benefits in NZ and globally.

Estimation of the burden of leptospirosis in New Zealand.

BACKGROUND: Human leptospirosis mainly affects people in close occupational contact with domestic livestock and their products in New Zealand. The disease has an unquantified impact on both human health and animal production in the country. This study aimed to estimate the burden of leptospirosis in terms of disability-adjusted life years (DALYs) and cost associated with loss due to absence from work, treatment of disease, animal production loss and cost of vaccination. METHODS: Previously published studies of abattoir workers farmers, and veterinarians, reporting annual risks of influenza-like illness attributable to Leptospira infection, were used to estimate the expected number of cases in a year. The cost of lost animal production was based on results of observational studies in beef cattle, sheep and deer conducted in New Zealand. RESULTS: Expected median annual number of severe and mild cases of human leptospirosis was 2,025 (95% probability interval [95% PI] 1,138-3,422). Median annual DALYs were 0.42 (95% PI: 0.06-2.40) per 100,000 people for the entire population, and 15.82 (95% PI: 2.09-90.80) per 100,000 people working in at-risk occupations (i.e. abattoir workers, farmers and veterinarians). Human infection resulted in a median cost of 4.42 (95% PI: 2.04-8.62) million US dollars (USD) due to absence from work and disease treatment. Median production loss cost in beef cattle, sheep and deer was USD 7.92 (95% PI: 3.75-15.48) million, while median vaccination cost in cattle, (including dairy), sheep and deer was USD 6.15 (95% PI: 5.30-7.03) million. Total annual cost of leptospirosis plus vaccination was USD 18.80 (95% PI: 13.47-27.15) million, equivalent to USD 440,000 (95% PI: 320,000-640,000) per 100,000 people. CONCLUSION: This study provides an estimate of the disease burden and cost of leptospirosis in New Zealand that could support occupational health authorities and livestock industries in assessing interventions for this disease.

An economic case for a vaccine to prevent group A streptococcus skin infections.

BACKGROUND: Group A streptococcus (GAS) causes an exceptionally diverse range of diseases, raising questions about the optimal product characteristics of a commercially viable vaccine. The objectives of this study were to (1) estimate the current health and economic burdens caused by 24 diseases attributable to GAS each year in Australia and (2) use these estimates to explore the value of a GAS vaccine for different clinical indications, age schedules, and population groups. METHODS: For objective 1, we estimated the population heath and economic burdens by synthesising data from administrative databases, nationally representative surveys, literature reviews, public reimbursement schedules, and expert opinion. For objective 2, we modelled the prospective lifetime burden of GAS for all infants from birth, for children from 5 years of age, and for adults from 65 years of age. A vaccine was assumed to reduce each GAS disease by 70% for a period of 10 years, and the difference in outcomes between vaccinated and non-vaccinated cohorts were used to calculate the cost-effective value of vaccination. RESULTS: The annual health and economic burdens of GAS diseases totalled 23,528 disability-adjusted life years and AU$185.1 million in healthcare costs respectively; approximately half of each measure was due to cellulitis, followed by other skin infections and throat infections. Reducing the incidence of throat infections, skin infections, and cellulitis in non-Indigenous cohorts resulted in 30%, 33%, and 28% of the total vaccine value for an infant schedule (cost-effective vaccine price AU$260 per course); 47%, 26%, and 22% of the value for a child schedule (AU$289); and 2%, 15% and 74% for an adult schedule (AU$489). CONCLUSIONS: A vaccine that prevents GAS cellulitis and other skin infections, in addition to throat infections, would maximise its value and commercial viability, with a cost-effective price in line with other recently-licensed and funded vaccines in Australia.

Economic evaluation of border closure for a generic severe pandemic threat using New Zealand Treasury methods.

OBJECTIVE: To perform a comprehensive economic evaluation of border closure for an island nation in the face of severe pandemic scenarios. METHODS: The costing tool developed by the New Zealand (NZ) Treasury (CBAx) was used for the analyses. Pandemic scenarios were as per previous work;1 epidemiological data were from past New Zealand influenza pandemics. RESULTS: The net present value of successful border closure was NZ$7.86 billion for Scenario A (half the mortality rate of the 1918 influenza pandemic) and $144 billion for preventing a more severe pandemic (10 times the mortality of scenario A). Cost-utility analyses found border closure was relatively cost-effective, at $14,400 per QALY gained in Scenario A, and cost-saving for Scenario B (taking the societal perspective). CONCLUSIONS: This work quantifies the economic benefits and costs from border closure for New Zealand under specific assumptions in a generic but severe pandemic threat (e.g. influenza, synthetic bioweapon). Preparing for such a pandemic response seems wise for an island nation, although successful border closure may only be feasible if planned well ahead. Implications for public health: Policy makers responsible for generic pandemic planning should explore how border closure could be implemented, including practical and legal frameworks.

Primary prevention of rheumatic fever in the 21st century: evaluation of a national programme.

Background: Acute rheumatic fever (ARF) has largely disappeared from high-income countries. However, in New Zealand (NZ) rates remain high in indigenous (Maori) and Pacific populations. In 2011, NZ launched an intensive and unparalleled primary Rheumatic Fever Prevention Programme (RFPP). We evaluated the impact of the school-based sore throat service component of the RFPP. Methods: The evaluation used national trends of all-age first episode ARF hospitalisation rates before (2009-11) and after (2012-16) implementation of the RFPP. A retrospective cohort study compared first-episode ARF incidence during time-not-exposed (23 093 207 person-days) and time-exposed (68 465 350 person-days) with a school-based sore throat service among children aged 5-12 years from 2012 to 2016. Results: Following implementation of the RFPP, the national ARF incidence rate declined by 28% from 4.0 per 100 000 [95% confidence interval (CI) 3.5-4.6] at baseline (2009-11) to 2.9 per 100 000 by 2016 (95% CI 2.4-3.4, P <0.01). The school-based sore throat service effectiveness overall was 23% [95% CI -6%-44%; rate ratio (RR) 0.77, 95% CI 0.56-1.06]. Effectiveness was greater in one high-risk region with high coverage (46%, 95% CI 16%-66%; RR 0.54, 95% CI 0.34-0.84). Conclusions: Population-based primary prevention of ARF through sore throat management may be effective in well-resourced settings like NZ where high-risk populations are geographically concentrated. Where high-risk populations are dispersed, a school-based primary prevention approach appears ineffective and is expensive.

Risk of rehospitalisation and death for vulnerable New Zealand children.

OBJECTIVES: There is considerable need to improve the effectiveness of healthcare to reduce morbidity and mortality. Child hospitalisations are influenced by determinants of health, including the home environment. Our aims were: (1) To investigate whether children hospitalised with potentially avoidable conditions thought to be associated with the home have an increased risk of rehospitalisation and death, (2) To investigate whether children hospitalised with particular subgroups of potentially avoidable conditions have an increased risk of rehospitalisation and death, (3) To assess the usefulness of these subgroups for identifying at-risk children. DESIGN: We used four existing groups of potentially avoidable conditions developed based on expert opinion: 1. the potentially avoidable hospitalisations (PAH) group, associated with social/environmental conditions, 2. the potentially avoidable hospitalisations attributable (at least in part) to the home environment (PAHHE) group, 3. the crowding group, and 4. the Ministry of Health (MoH) group. We analysed national New Zealand hospital discharge data (2000-2014). Rehospitalisation and death were described using Kaplan-Meier curves. Group effectiveness for identifying at-risk children was assessed using Cox proportional hazard models with children hospitalised for non-PAH conditions as comparison. RESULTS: In total, 1425085 hospital admissions occurred, for 683115 unique children. Rehospitalisation was relatively common (71.0%). Death was rare (0.6%). All groups performed moderately well identifying at-risk children. Children with PAH have increased risk of rehospitalisation (adjusted HR (aHR):2.30-3.60) and death (aHR:3.07-10.44). PAH group had highest sensitivity (75.1%). The MoH group has the highest positive predictive value (rehospitalisation: 86.2%, death: 2.5%). CONCLUSIONS: Children in the MoH group are very likely to benefit from housing interventions. Rehospitalisation and early mortality are useful assessment measures. Rehospitalisation exerts a considerable burden, and child deaths are catastrophic.