The rise and fall of excess winter mortality in New Zealand from 1876 to 2020.

Excess winter mortality (EWM) has been used as a measure of how well populations and policy moderate the health effects of cold weather. We aimed to investigate long-term changes in the EWM of Aotearoa New Zealand (NZ), and potential drivers of change, and to test for structural breaks in trends. We calculated NZ EWM indices from 1876 (4,698 deaths) to 2020 (33,310 deaths), total and by age-group and sex, comparing deaths from June to September (the coldest months) to deaths from February to May and October to January. The mean age and sex-standardised EWM Index (EWMI) for the full study period, excluding 1918, was 1.22. However, mean EWMI increased from 1.20 for 1886 to 1917, to 1.34 for the 1920s, then reduced over time to 1.14 in the 2010s, with excess winter deaths averaging 4.5% of annual deaths (1,450 deaths per year) in the 2010s, compared to 7.9% in the 1920s. Children under 5 years transitioned from a summer to winter excess between 1886 and 1911. Otherwise, the EWMI age-distribution was J-shaped in all time periods. Structural break testing showed the 1918 influenza pandemic strain had a significant impact on trends in winter and non-winter mortality and winter excess for subsequent decades. It was not possible to attribute the post-1918 reduction in EWM to any single factor among improved living standards, reduced severe respiratory infections, or climate change.

Novel use of three administrative datasets to establish a cohort for environmental health research.

BACKGROUND: In recent years publications have called for increased use of administrative data for research; predicted that use would rise; and discussed possible ethical parameters for that use. This paper describes the novel combination of three administrative datasets to create a population cohort for environmental health research, and investigates the potential use of a national health register as a total population denominator. METHODS: We matched a national health register (the New Zealand national health index or NHI) to Quotable Value New Zealand Ltd (QV) nationwide residential dwelling data, and to hospital admissions data, to create a national matched cohort with health outcomes for the period 2000 - 2006. We then compared population distribution and hospitalisation rates by gender, age, ethnic group and Census Area Unit-based socio-economic deprivation index across the Census, NHI and matched cohort populations. RESULTS: The NHI population was 23% larger than the Census. Differences between the NHI and Census were most marked in those aged over 90 years; with ethnicity unknown or an unassigned Census area unit; and in Asian Peoples aged under 30 years. The match rate between QV and NHI data was 70%. There were further differences between the NHI and matched cohort populations, particularly for rural areas and older age groups. Compared to Census-based rates, NHI and cohort-based hospitalisation rates were higher in those aged 75 and over, differed by ethnicity, and had less socio-economic gradient. CONCLUSIONS: The NHI was larger than the Census due to record duplication and entries for people residing overseas remaining on file under New Zealand addresses. NHI and QV matching was incomplete due to NHI address data being poor quality or not suitable for matching. To better approximate true hospitalisation rates, studies using the NHI as a cohort should exclude those aged over 90 years; or with ethnic group or Census area unit unknown. Cohort hospitalisation rates should also be adjusted for differences from the Census, particularly the lower hospitalisation rates for those aged 75 and over, and other differences by age, ethnic group and socio-economic deprivation.

Problematic Social Media Use and Its Relationship with Depression or Anxiety: A Systematic Review.

There has been a notable increase in social media and Internet use over recent decades, not only for social interaction or entertainment, but also for working and meeting tools, as seen during the COVID-19 pandemic. A relationship between this usage and the development of mental illness is frequently hypothesized, but a few studies have empirical findings. This study is a systematic review of the relationship between social media use and depression or anxiety. Our Medline search yielded 1,747 papers. Our study found a strong and often bidirectional relationship between social media use and depression or anxiety. This relationship was frequently related to problematic social media use. No definite linear relationship was found between time spent using social media and depressive or anxious symptoms, but usually, the longer the time spent in that activity, the worse the outcomes. Factors related to problematic social media use were often different for men and women. Other variables may also play a role, such as nighttime-specific use, emotional involvement, and whether the individual behaves as an active or passive user. Evidence from this review provides a solid base for recommending cautious use of social media. Intense use and unhealthy habits, evidenced by addiction symptoms, may be problematic in less resilient individuals.

Liquid-Immersion Reprocessing Effects on Filtration Efficiency of 'Single-Use' Commercial Medical Face Masks.

PURPOSE: Medical masks have inferior filtration efficiency and fit to filtering facepiece respirators (FFRs) but are widely used in healthcare and the community. These masks are intended for disposal after use but in the event of mask shortage re-use after reprocessing may be an option. We investigated eight reprocessing methods that each involved washing or soaking in liquid, are likely to eliminate respiratory viruses, and are safe and available in most community and healthcare settings. METHODS: Three brands of EN 14683 standards-compliant commercial medical mask were each reprocessed 10 times by one of eight methods. We measured filtration efficiency for poly-dispersed sodium chloride particles and pressure differential. RESULTS: Compared with new medical masks, reprocessed masks had significantly reduced filtration efficiency. The reduction was mild-moderate (6.5-25.8%) after warm water wash, hot water soak or boiling water soak; and moderate-large (24.1-51.5%) after detergent, soap or laundry machine wash, or bleach soak. There were mixed and minor changes in pressure differential. Most reprocessed standards-compliant masks had better filtration efficiency than new non-standard commercial masks and then cotton and cotton-polyester mix fabric samples, even triple-layered fabrics. CONCLUSIONS: High-quality commercial medical masks reprocessed 10 times by water immersion methods had better filtration efficiency than new non-standard masks and washable fabrics. These findings have particular relevance for community and low-resource healthcare settings.

Indoor air quality, largely neglected and in urgent need of a refresh.

Nil.

COVID-19 outbreaks in Aotearoa New Zealand: urgent action is required to address systematic causes and consequences of border failures.

Between August and November 2020, Aotearoa New Zealand experienced eight known failures of the COVID-19 border control system. Multiple introductions of this highly transmissible virus into New Zealand's almost completely susceptible population present a high risk of uncontrollable spread, threatening New Zealand's elimination strategy. In this editorial, we propose that, although steps are being taken reactively in response to these known breaches, systematic underestimation of risk across the pandemic response makes future failures inevitable. We present an epidemiological framework for identifying and addressing risk, giving examples of actions that can be taken to reduce the probability of further outbreaks and enable New Zealand to benefit from sustained elimination of COVID-19.

Time for time off? Secondary public holiday shows minimal net hospitalisation benefit.

BACKGROUND: We aimed to use New Zealand's Anzac Day to test the public health effect of secondary public holidays; and to use weekly hospitalisation counts to identify which dates were more health suitable for a potential new public holiday. METHODS: We conducted a retrospective population cohort study of hospital admissions in New Zealand between 23 April and 27 May 1988-2018. We compared acute and arranged hospitalisation and mortality rates in holiday (Anzac Day Monday to Friday) and non-holiday (Anzac Day Saturday or Sunday) years, for mid-week holidays and long weekends; and measured total weekly average acute and arranged hospitalisation counts. RESULTS: Hospitalisation rates were lower in holiday years than non-holiday years (rate ratio (RR) 0.96, 95% CI 0.95 to 0.96, p<0.001), with fewer arranged admissions (RR 0.93, 95% CI 0.93 to 0.94, p<0.001), but no significant difference for acute admissions (RR 1.00, 95% CI 0.99 to 1.00, p=0.087). Holiday year acute admission rates were lower than non-holiday years for children aged 0-4 years, but higher for adults aged 15-44 years. Holidays reduced arranged admissions most in children and areas of higher socioeconomic deprivation. There was no significant difference for mortality. Average weekly acute hospitalisations were higher than arranged admissions between 10 June and 7 October. CONCLUSION: Secondary holidays do not reduce deaths; or acute hospital admissions except in the holiday week; and may delay elective treatment. However, if New Zealand is to add a new public holiday, it would have least detrimental health effect scheduled between 10 June and 7 October.

Renting Poorer Housing: Ecological Relationships Between Tenure, Dwelling Condition, and Income and Housing-Sensitive Hospitalizations in a Developed Country.

BACKGROUND: Previous research has shown two-way associations between rental tenure, poorer housing quality, and health outcomes, but little research has looked at relative housing contributions to health outcomes. AIMS: We investigated whether tenure and/or dwelling condition were associated with housing-sensitive hospitalizations and whether any association differed by income. METHOD: Using a data set of housing characteristics matched to hospitalization records, rental tenure data, and income quintiles, we modeled differences in housing-sensitive hospitalization rates by ecological-level tenure and housing condition, controlling for age-group and mean temperatures. RESULTS: There were clear associations between income, tenure, and house condition, and winter-associated hospitalization risk. In the adjusted model, the largest risk differences were associated with neighborhoods with low income (risk ratio [RR] = 1.48) and high rental tenure (RR = 1.41). There was a nonsignificant difference for housing condition (RR = 1.04). DISCUSSION: Rental tenure and poor housing condition were risks for housing-sensitive hospitalization, but the association with income was stronger. Higher income households may be better able to offset quality and tenure-related health risks. This research illustrates the inverse housing law: Those most vulnerable, with most need for good-quality housing, are least likely to have it. Income inequity is inbuilt in tenure, quality, and health burden relationships. CONCLUSION: These findings suggest that measures to address health inequities should include improvements to both tenure security and housing quality, particularly in low-income areas. However, policymakers aiming to reduce overall hospitalization rates should focus their efforts on reducing fuel poverty and improving the affordability of quality housing.

Evidence base for a housing warrant of fitness.

Substandard housing is a major public health issue in New Zealand. Approximately, two-thirds of the housing stock is uninsulated and many homes are inadequately heated, with an average indoor temperature of 14.5°C. Cold, damp, and mouldy housing results in poor health; each year, respiratory hospital admissions are 74% higher during winter, and excess winter mortality is 20% higher than other seasons. The relationship between injury and housing conditions is also well established. Each year, 500,000 New Zealanders suffer falls requiring medical treatment in their homes. As a step towards improving the quality of existing housing, an evidence-based warrant of fitness has been developed. This article outlines the evidence base to each criterion in the warrant of fitness. We conclude that introducing and properly enforcing a housing warrant of fitness will ensure that basic minimum standards are met, which could mitigate the disease burdens and injuries associated with, or caused, by poorer quality housing. In addition, there are potential fiscal and economic advantages of the scheme, including reduced hospitalisations and increased productivity.

Why don't owners improve their homes? Results from a survey following a housing warrant-of-fitness assessment for health and safety.

OBJECTIVE: To assess homeowners' intentions to make voluntary improvements to their homes following a warrant-of-fitness (WOF) assessment to highlight health and safety issues. METHODS: We recruited 83 homeowners, including nine landlords, in Taranaki, New Zealand, who agreed to have a WOF assessment carried out on their homes. We interviewed 40 of the homeowners to ascertain what improvements they planned to make, and barriers to improving their homes. RESULTS: Of the 83 properties, 76 (92%) failed the WOF. Of the 40 interview participants, 31 (76%) had addressed or planned to address at least one of the identified issues with the home. Participants were least likely to address identified issues with security stays on windows, and absence of ground vapour barrier. Reasons for not addressing identified issues included cost, and a belief that making the improvement would not benefit health and safety. CONCLUSIONS: Information about housing defects appears insufficient to encourage people to make improvements to their homes to meet a specified health and safety standard. Implications for public health: Better understanding of how particular housing defects pose a risk for health and safety, and provision of funding support in some cases, may encourage people to invest in safer, healthier homes.

Impact of improved insulation and heating on mortality risk of older cohort members with prior cardiovascular or respiratory hospitalisations.

OBJECTIVES: We carried out an evaluation of a large-scale New Zealand retrofit programme using administrative data that provided the statistical power to assess the effect of insulation and/or heating retrofits on cardiovascular and respiratory-related mortality in people aged 65 and over with prior respiratory or circulatory hospitalisations. DESIGN: Quasi-experimental cohort study based on administrative data. SETTING: New Zealand. PARTICIPANTS: From a larger study cohort of over 900 000 people, we selected two subcohorts: 3287 people who were aged 65 and over and had experienced pretreatment period cardiovascular-related hospitalisation (ICD-10 chapter 9), and 1561 people aged 65 and over who had experienced pretreatment respiratory-related hospitalisation (ICD-10 chapter 10). INTERVENTIONS: Treatment group individuals lived in a home that received insulation and/or heating retrofits under the Warm Up New Zealand: Heat Smart programme. Control group individuals lived in a home that was matched to a treatment home based on physical characteristics and location. PRIMARY AND SECONDARY OUTCOME MEASURES: HR for all-cause mortality for treatment with insulation, heating, or insulation and heating relative to control group. RESULTS: People with pretreatment circulatory hospitalisation who occupied a household that received only insulation had an HR for all-cause mortality of 0.673 (95% CI 0.535 to 0.847) (p<0.001) relative to control group members. Individuals with a pretreatment respiratory hospitalisation who occupied a household that received only an insulation retrofit had an HR for all-cause mortality of 0.830 (95% CI 0.655 to 1.051) (p=0.122) relative to control group members. There was no evidence of an additional benefit from receiving heating. CONCLUSIONS: We interpret the hazard rate observed for cardiovascular subcohort individuals who received insulation as evidence of a protective effect, reducing the risk of mortality for vulnerable older adults. There is suggestive evidence of a protective effect of insulation for the respiratory subcohort.

Modelled seasonal influenza mortality shows marked differences in risk by age, sex, ethnicity and socioeconomic position in New Zealand.

OBJECTIVES: Influenza is responsible for a large number of deaths which can only be estimated using modelling methods. Such methods have rarely been applied to describe the major socio-demographic characteristics of this disease burden. METHODS: We used quasi Poisson regression models with weekly counts of deaths and isolates of influenza A, B and respiratory syncytial virus for the period 1994 to 2008. RESULTS: The estimated average mortality rate was 13.5 per 100,000 people which was 1.8% of all deaths in New Zealand. Influenza mortality differed markedly by age, sex, ethnicity and socioeconomic position. Relatively vulnerable groups were males aged 65-79 years (Rate ratio (RR) = 1.9, 95% CI: 1.9, 1.9 compared with females), Maori (RR = 3.6, 95% CI: 3.6, 3.7 compared with European/Others aged 65-79 years), Pacific (RR = 2.4, 95% CI: 2.4, 2.4 compared with European/Others aged 65-79 years) and those living in the most deprived areas (RR = 1.8, 95% CI: 1.3, 2.4) for New Zealand Deprivation (NZDep) 9&10 (the most deprived) compared with NZDep 1&2 (the least deprived). CONCLUSIONS: These results support targeting influenza vaccination and other interventions to the most vulnerable groups, in particular Maori and Pacific people and men aged 65-79 years and those living in the most deprived areas.

Measuring the Effect of Housing Quality Interventions: The Case of the New Zealand "Rental Warrant of Fitness".

In New Zealand, as in many other countries, housing in the private-rental sector is in worse condition than in the owner-occupier housing sector. New Zealand residential buildings have no inspection regime after original construction signoff. Laws and regulations mandating standards for existing residential housing are outdated and spread over a range of instruments. Policies to improve standards in existing housing have been notoriously difficult to implement. In this methods paper, we describe the development and implementation of a rental Warrant of Fitness (WoF) intended to address these problems. Dwellings must pass each of 29 criteria for habitability, insulation, heating, ventilation, safety, amenities, and basic structural soundness to reach the WoF minimum standard. The WoF's development was based on two decades of research on the impact of housing quality on health and wellbeing, and strongly influenced by the UK Housing Health and Safety Rating System and US federal government housing standards. Criteria were field-tested across a range of dwelling types and sizes, cities, and climate zones. The implementation stage of our WoF research consists of a non-random controlled quasi-experimental study in which we work with two city-level local government councils to implement the rental WoF, recruiting adjoining council areas as controls, and measuring changes in health, economic, and social outcomes.

Estimating the contribution of influenza to hospitalisations in New Zealand from 1994 to 2008.

BACKGROUND: Influenza has a substantially but poorly measured impact on population health. Estimating its true contribution to hospitalisations remains a challenge. METHODS: We used simple and comprehensive negative binomial regression models with weekly counts of hospitalisations and isolates of influenza A, B and respiratory syncytial virus for the period 1994- 2008. RESULTS: The estimated annual national average number of hospitalisations attributable to influenza was 822.1(95% CI: 815.3, 828.9) for pneumonia and influenza, 1861.3 (95% CI: 1842.9, 1879.7) for respiratory illness, 12.1 (95% CI: 2.6, 21.6) for circulatory illness, 2260.0 (95% CI: 2212.2, 2307.8) for all medical illness and 2419.9 (95% CI: 2356.4, 2483.4) for all causes. The contribution of influenza to total hospitalisations was about nine times larger than indicated by routine discharge data. New Zealanders 80 years of age and older had the highest annual excess rates of influenza-related hospitalisations (327.8 per 100,000); followed by infants under 1 year (244.5 per 100,000). Estimated influenza hospitalisation rates were also markedly higher in Pacific (83.3 per 100,000) and Maori (80.0 per 100,000) compared with European/Others (58.1 per 100,000). Respiratory illness was the major contributor to all cause hospitalisations attributed to influenza accounting for 77%. Influenza hospitalisations included only a negligible contribution from circulatory illness. CONCLUSION: These findings support efforts to reduce the impact of influenza, particularly for the most vulnerable population groups highlighted here. Analysis of the cost-effectiveness of such interventions needs to consider these higher modelled estimates of disease impact.