Association between pm2.5 concentrations and hospitalization cases for schizophrenia and mood disorders in Ho Chi Minh city, Vietnam from 2019 to 2020

Abstract

The evidence for adverse effects of ambient particulate matter pollution on mental and behavioral disorders (MBDs) is limited. Until now, few epidemiological studies have focused on this field, especially in developing countries. With the changes in concentrations and sources of air pollution over the past decade in Vietnam lead to high levels of air pollutants, especially particulate matters including PM2.5. Therefore, it is worthwhile to investigate the acute effects of outdoor air pollution on MBDs. However, no Vietnamese study has looked into the short-term effect of PM2.5 on hospitalization for MBDs.

To examine the association between PM2.5 and the cases for total MBDs, Schizophrenia and Mood disorder from June 2019 to December 2020 at Ho Chi Minh City Mental health hospital. A quasi-Poisson time series regression model was used to determine the association between PM2.5 exposure and daily hospital admission for all-cause mental disorders and two specific disorders including Schizophrenia and Mood disorder. A natural cubic regression smooth function was adopted to filter out long term trends and seasonality and stratified analyses were also performed by age, gender and season. Besides, to estimate the delayed effect, we examined the association in distributed lag models when lag terms were modelled one at a time (from lag0 to lag7). We select the most optimal model based on the Q-AIC criterion (Akaike Information Criterion).

In total, 3,513 hospital admissions for MBDs were collected from HCMC Mental health hospital in 2019-2020. The number of hospital admissions of Schizophrenia was nearly four times of Mood disorder (1,724 vs 447 admissions, respectively). Data from monitoring stations suggested that the daily concentration of PM2.5 ranged from 8.7 to 66.0 μg/m3 with a mean of 25.6 μg/m3. Results revealed that each 10 μg/m3 increase in PM2.5 at lag 7 for MBDs and Schizophrenia corresponded to an increase of 1.25 (95%CI: 1.03 – 1.52), 1.45 (95%CI: 1.12-1.89) in daily hospital admission among the elderly, respectively.

Our study demonstrated that the elderly in HCMC have an increased risk of MBDs admissions due to the high level of PM2.5 concentration in the city's ambient air. These findings have provided evidence for building public health policies to prevent and minimize the adverse health effects of air pollution on the elderly.