Increased Incidence of Legionellosis after Improved Diagnostic Methods, New Zealand, 2000-2020.

Legionellosis, notably Legionnaires' disease, is recognized globally and in New Zealand (Aotearoa) as a major cause of community-acquired pneumonia. We analyzed the temporal, geographic, and demographic epidemiology and microbiology of Legionnaires' disease in New Zealand by using notification and laboratory-based surveillance data for 2000‒2020. We used Poisson regression models to estimate incidence rate ratios and 95% CIs to compare demographic and organism trends over 2 time periods (2000-2009 and 2010-2020). The mean annual incidence rate increased from 1.6 cases/100,000 population for 2000-2009 to 3.9 cases/100,000 population for 2010-2020. This increase corresponded with a change in diagnostic testing from predominantly serology with some culture to almost entirely molecular methods using PCR. There was also a marked shift in the identified dominant causative organism, from Legionella pneumophila to L. longbeachae. Surveillance for legionellosis could be further enhanced by greater use of molecular typing of isolates.

Retrofitting home insulation reduces incidence and severity of chronic respiratory disease.

To assess whether retrofitting home insulation can reduce the risk of respiratory disease incidence and exacerbation, a retrospective cohort study was undertaken using linked data from a national intervention program. The study population was made up of 1 004 795 residents from 205 001 New Zealand houses that received an insulation subsidy though a national Energy Efficiency and Conservation Authority program. A difference-in-difference model compared changes in the number of prescriptions dispensed for respiratory illness post- insulation to a control population over the same timeframe. New prescribing of chronic respiratory disease medication at follow-up was used to compare incidence risk ratios between intervention and control groups. Chronic respiratory disease incidence was significantly lower in the intervention group at follow-up: odds ratio 0.90 (95% CI: 0.86-0.94). There was also a 4% reduction in medication dispensed for treating exacerbations of chronic respiratory disease symptoms in the intervention group compared with the control group: relative rate ratio (RRR) 0.96 (95% CI: 0.96-0.97). There was no change in medication dispensed to prevent symptoms of chronic respiratory disease RRR: 1,00 (95% CI: 0.99-1.00). These findings support home insulation interventions as a means of improving respiratory health outcomes.

Evaluating a community-based public health intervention using a complex systems approach.

Background: This article outlines the methods being used to evaluate a community-based public health intervention. This evaluation approach recognizes that not only is the intervention, Healthy Families NZ, complex, but the social systems within which it is being implemented are complex. Methods: To address challenges related to complexity, we discuss three developing areas within evaluation theory and apply them to an evaluation case example. The example, Healthy Families NZ, aims to strengthen the prevention system in Aotearoa/New Zealand to prevent chronic disease in 10 different geographic areas. Central to the evaluation design is the comparative case method which recognizes that emergent outcomes are the result of 'configurations of causes'. 'Thick', mixed-data, case studies are developed, with each case considered a view of a complex system. Qualitative Comparative Analysis is the analytical approach used to systematically compare the cases over time. Conclusions: This article describes an approach to evaluating a community-based public health intervention that considers the social systems in which the initiative is being implemented to be complex. The evaluation case example provides a unique opportunity to operationalize and test these methods, while extending their more frequent use within other fields to the field of public health.

How has contraceptive provision at Family Planning clinics in Aotearoa New Zealand changed between 2009, 2014 and 2019: a cross-sectional analysis.

AIM: To investigate changes in contraceptive starts among Family Planning clients in 2009, 2014 and 2019. METHODS: National data of 75,825 contraceptive starts of clients at Family Planning clinics in New Zealand in 2009, 2014 and 2019 were analysed to measure changes in contraceptive starts across the three points in time. Data were analysed by age and ethnicity at each point in time, and by deprivation in 2019. RESULTS: After being adjusted for age and ethnicity, there was a significant decline in the proportion of starts for the combined oral contraceptive pill (43% to 23%), the progestogen-only pill (22% to 13%) and Depo Provera (15% to 12%) from 2009 to 2019. There was a significant increase in the proportion of starts for implants (0.7% to 22%) and intra-uterine contraception (19% to 30%). There were significant differences in contraceptive starts between ethnicities and levels of deprivation. CONCLUSIONS: There was an overarching trend of increasing long-acting reversible contraceptive (LARC) starts from 2009 to 2019 among Family Planning clients across all age groups and ethnicities. There were also differences in the types of contraceptive starts by ethnicity and deprivation. Information about contraceptive use and changes over time, by age and ethnicity, is essential for evidence-based policy, funding decisions and ensuring equitable access to contraception.

An empirical test of the biodiversity hypothesis: Exposure to plant diversity is associated with a reduced risk of childhood acute lymphoblastic leukemia.

The biodiversity hypothesis posits that declining biodiversity may be responsible, at least in part, for the global increase in immune diseases. However, few studies have been able to demonstrate a link between exposure to biodiversity and specific health outcomes. We test whether exposure to plant diversity protects against childhood acute lymphoblastic leukemia (ALL) by promoting immune maturation. Our sample consisted of all children born in New Zealand from 1998 to 2013 (n = 899,126; 264 ALL cases), which we followed from birth to age five. We calculated plant-diversity metrics using the Global Biodiversity Information Facility, which contains over two million geocoded plant records in New Zealand. Consistent with previous research, children who had always lived in an urban area, or who had an older mother, were at greater risk for ALL, whereas children with older siblings were at lower risk. In addition, we found that plant-diversity metrics based on the maximum number of plant genera a child was exposed to during the first two years of life were protective of ALL. Specifically, exposure to the highest tertile of plant diversity was associated with a reduction in ALL risk of 35% (95% CI: 11%-53%). Exposure to plant diversity, and associated microbial communities, may be a viable public-health intervention to reduce the risk of ALL and possibly other immune diseases.

Association between home insulation and hospital admission rates: retrospective cohort study using linked data from a national intervention programme.

OBJECTIVES: To investigate whether retrofitting insulation into homes can reduce cold associated hospital admission rates among residents and to identify whether the effect varies between different groups within the population and by type of insulation. DESIGN: A quasi-experimental retrospective cohort study using linked datasets to evaluate a national intervention programme. PARTICIPANTS: 994 317 residents of 204 405 houses who received an insulation subsidy through the Energy Efficiency and Conservation Authority Warm-up New Zealand: Heat Smart retrofit programme between July 2009 and June 2014. MAIN OUTCOME MEASURE: A difference-in-difference approach was used to compare the change in hospital admissions of the study population post-insulation with the change in hospital admissions of the control population that did not receive the intervention over the same two timeframes. Relative rate ratios were used to compare the two groups. RESULTS: 234 873 hospital admissions occurred during the study period. Hospital admission rates after the intervention increased in the intervention and control groups for all population categories and conditions with the exception of acute hospital admissions among Pacific Peoples (rate ratio 0.94, 95% confidence interval 0.90 to 0.98), asthma (0.92, 0.86 to 0.99), cardiovascular disease (0.90, 0.88 to 0.93), and ischaemic heart disease for adults older than 65 years (0.79, 0.74 to 0.84). Post-intervention increases were, however, significantly lower (11%) in the intervention group compared with the control group (relative rate ratio 0.89, 95% confidence interval 0.88 to 0.90), representing 9.26 (95% confidence interval 9.05 to 9.47) fewer hospital admissions per 1000 in the intervention population. Effects were more pronounced for respiratory disease (0.85, 0.81 to 0.90), asthma in all age groups (0.80, 0.70 to 0.90), and ischaemic heart disease in those older than 65 years (0.75, 0.66 to 0.83). CONCLUSION: This study showed that a national home insulation intervention was associated with reduced hospital admissions, supporting previous research, which found an improvement in self-reported health.

A cost effectiveness analysis of community water fluoridation in New Zealand.

AIM: The aim of the study was to use recent data to determine whether Community Water Fluoridation (CWF) remains a cost effective public health intervention in New Zealand, given a reduction in dental caries in all communities over time. METHOD: Local authorities that fluoridated their water supplies were asked to complete a questionnaire regarding fixed and variable costs incurred from CWF. Cost savings were calculated using data from the 2009 New Zealand Oral Health Survey. The cost effectiveness of CWF in conjunction with treatment per dmft/DMFT averted was compared to an alternative of treatment alone. Calculations were made for communities with populations of less than 5,000, 5,000 to 10,000, 10,001 to 50,000 and greater than 50,000. RESULTS: CWF was cost effective in all communities at base case. CWF remained cost effective for communities over 5,000 under all scenarios when sensitivity analysis was conducted. For communities under 5,000 the there was a positive net cost for CWF under certain scenarios. CONCLUSION: In this study, CWF was a cost effective public health intervention in New Zealand. For smaller communities cost effectiveness would be more dependent upon the population risk profile of the community.