The adverse effect of ambient temperature on respiratory deaths in a high population density area: the case of Malta.

BACKGROUND: The effect of ambient temperature on respiratory mortality has been consistently observed throughout the world under different climate change scenarios. Countries experiencing greater inter-annual variability in winter temperatures (and may not be lowest winter temperatures) have greater excess winter mortality compared to countries with colder winters. This study investigates the association between temperature and respiratory deaths in Malta which has one of the highest population densities in the world with a climate that is very hot in summer and mild in winter. METHODS: Daily number of respiratory deaths (7679 deaths) and meteorological data (daily average temperature, daily average humidity) were obtained from January 1992 to December 2017. The hot and cold effects were estimated at different temperatures using distributed lag non-linear models (DLNM) with a Poisson distribution, controlling for time trend, relative humidity and holidays. The reference temperature (MMT) for the minimum response-exposure relationship was estimated and the harvesting effects of daily temperature (0-27 lag days) were investigated for daily respiratory mortality. Effects were also explored for different age groups, gender and time periods. RESULTS: Cooler temperatures (8-15 °C) were significantly related to higher respiratory mortality. At 8.9 °C (1st percentile), the overall effect of daily mean temperature was related to respiratory deaths (RR 2.24, 95%CI 1.10-4.54). These effects were also found for males (95%CI 1.06-7.77) and males across different age groups (Males Over 65 years: RR 4.85, 95%CI 2.02-11.63 vs Males between 16 and 64 years: RR 5.00, 95%CI 2.08-12.03) but not for females. Interestingly, colder temperatures were related to respiratory deaths in the earliest time period (1992-2000), however, no strong cold effect was observed for later periods (2000-2017). In contrast, no heat effect was observed during the study period and across other groups. CONCLUSIONS: The higher risk for cold-related respiratory mortality observed in this study could be due to greater inter-annual variability in winter temperatures which needs further exploration after adjusting for potential physical and socio-demographic attributes. The study provides useful evidence for policymakers to improve local warning systems, adaptation, and intervention strategies to reduce the impact of cold temperatures.

Assessing evidence for seasonality of hospital admissions for schizophrenia in Queensland, Australia: a time series observational study.

Most evidence on seasonal admission patterns for schizophrenia derives from the Northern Hemisphere with results from the Southern Hemisphere less documented. This study examines seasonal patterns in hospital admissions due to schizophrenia in Queensland, Australia, a large area that has a range of different climatic features. Daily hospital admissions data for people with the primary diagnosis of schizophrenia were collected from Queensland Health Department for the period from January 1996 to December 2015. A generalised linear regression model with Quasi-Poisson distribution was used to assess seasonal admission patterns across different climatic regions. The evidence for seasonality was also explored in subgroups that had different socio-demographic characteristics or history of prior hospitalisation for psychiatric disorders. Overall, a significant winter pattern (RR 1.05, 95%CI 1.01-1.13) was found with a peak in August (RR 1.08, 95%CI 1.03-1.17) in temperate Southeast Queensland. However, the hot humid North and Far North Queensland showed a peak in October (RR 1.10, 95%CI 1.02-1.22). Males (RR 1.11, 95%CI 1.07-1.14), people aged 40-59 years old (RR 1.10, 95%CI 1.05-1.15) and those who had never married (RR 1.09, 95%CI 1.06-1.12), were Australian by birth (RR 1.07, 95%CI 1.04-1.10) or were unemployed (RR 1.13, 95%CI 1.09-1.18) had significantly higher risk for hospital admissions, particularly during the winter months. The seasonal admission pattern for schizophrenia did not change significantly according to admission status and history of outpatient or community psychiatric treatment. The study found some evidence for seasonality of hospital admissions for schizophrenia that differed from northern tropical to southern temperate regions of Queensland.

Immediate and delayed effects of climatic factors on hospital admissions for schizophrenia in Queensland Australia: A time series analysis.

BACKGROUND: Evidence of immediate and delayed effects of climatic drivers on hospital admissions for schizophrenia is limited and inconsistent. We aimed to assess the association between climatic factors and daily hospital admissions for schizophrenia in Queensland, Australia. METHODS: Daily hospital admissions for schizophrenia from January 1, 1996 to December 31, 2015 in all private and public hospitals of Queensland were obtained from Queensland Health. The association between climatic factors and hospital admissions for schizophrenia were analysed using Generalised Linear Models with Poisson distribution (GLM) and Distributed Lag non-linear Models (DLNM) across different climatic zones. RESULTS: In South East Queensland, only daily mean temperature showed an immediate negative effect on schizophrenia admissions (RR 0.93, 95%CI 0.90-0.98, p value < 0.001). For other regions, the adverse effect of temperature on hospital admissions was not significant, however, relative humidity (North: RR 1.01, 95%CI 1.00-1.02, p = 0.05) and air pressure (North: RR 1.03, 95%CI 1.00-1.05, p = 0.04; South West: RR 1.01, 95%CI 1.00-1.02, p = 0.05) had an immediate and positive effect on hospital admissions. Moreover, climatic factors had some delayed effects on schizophrenia admissions in different regions of Queensland, i.e. temperature over 0-4 lag days (South East: RR 0.97, 95%CI 0.94-0.98, p = 0.05; South West: RR 0.96, 95%CI 0.94-0.98, p = 0.01), relative humidity over 0-7 lag days (North: RR 0.95, 95%CI 0.92-0.98, p = 0.01; Central: RR 1.02, 95%CI 1.00-1.03, p = 0.05) and rainfall over 0-21 lag days (North: RR 1.03, 95%CI 1.01-1.04, p = 0.01). Meta-analysis showed significant pooled delayed effects of temperature (0-15 days lag: RR 0.95, 95% CI 0.93-0.98, p value < 0.001), relative humidity (0-7 days: RR 0.96, 95%CI 0.92-0.99, p < 0.001); rainfall (0-21 lag days: RR 1.03, 95%CI 1.01-1.04, p < 0.001) and air pressure (0-7 days lag: RR 1.02, 95%CI 1.00-1.04, p < 0.001) on schizophrenia admissions in Queensland. DISCUSSION: As this is the largest study from Australia and also internationally to extensively examine both short term and delayed association between climatic factors and daily admissions for schizophrenia, the results of the study indicate that climate plays an important role in the sudden exacerbation of acute episodes of schizophrenia. Thus, preventive measures could be taken to reduce the severity of symptoms as well as hospital admissions due to schizophrenia during vulnerable periods.

Seasonality and schizophrenia: a comprehensive overview of the seasonal pattern of hospital admissions and potential drivers.

Schizophrenia is a severe neuropsychiatric disorder with heterogeneous aetiology mostly affecting younger people and causing immense disability. Seasonal patterns may be observed in schizophrenia hospital admissions with possible association with changing climatic parameters and socio-demographic characteristics. This study critically reviewed studies that have assessed seasonal variations of hospital admissions for schizophrenia and/or explored an association with climate parameters and/or other potential factors. Following PRISMA guidelines, a systematic literature search was conducted using electronic databases (e.g. MEDLINE, Science Direct, PsycINFO, Pub Med) from inception to February 29, 2020. Thirty five papers were identified, of which only six (17.1%) examined evidence for a seasonal pattern or monthly excess of hospital admissions and the remaining twenty nine (82.9%) assessed climatic and socio-demographic attributes relating to the seasonal pattern or increased hospitalisation for schizophrenia. While most studies reported a summer peak in hospital admission rates, other studies reported a winter peak. Most of the evidence indicated that higher temperatures (> 28 °C) were positively correlated with schizophrenia admission rates. The individual effects of other climatic parameters (e.g. relative humidity, rainfall, atmospheric pressure, sunlight) were less frequently assessed. Males, people of 21-60 years old, and those married were more vulnerable to climatic variability specifically to higher temperatures. Further studies using large sample sizes, analysis of a wide range of interacting environmental variables and sophisticated statistical approaches are needed to better understand the underlying mechanisms involved. This will also provide more reliable statistical evidence that will help in the prevention and better management of cases.