Association between daily ambient temperature and drug overdose in Tokyo: a time-series study

The association between hot days and substance-related suicides: a time-stratified case-crossover analysis in British Columbia, Canada

BACKGROUND

Hot weather can negatively impact mental health and increase the risk of suicide. The relationship between heat and risk of suicide is not fully understood, and varies geographically across regions with differing climates, cultures, and socio-economic factors. The objective of this study was to investigate the relationship between hot summer days and suicides in British Columbia, Canada (BC).

METHODS

A time-stratified case-crossover design was used to estimate the relationship between hot days (exposure) and suicide (outcome), considering same-day and two-day mean temperature. Conditional logistic regression was used to estimate the odds ratio (OR) for the association between hot days and suicides for three outcomes including: (1) suicide attempts by self-poisoning extracted from BC Drug and Poison Information Centre (DPIC) database (2012-2023); (2) completed suicides by self-poisoning extracted from BC vital statistics (2004-2023); and (3) completed suicides by violent methods extracted from BC vital statistics (2004-2023). Analyses were stratified by sex, age, ecological region, substance types used in self-poisonings, and by methods of violent suicide.

RESULTS

There were 9,599 suicide attempts via self-poisoning and 2,571 suicide deaths included in this study. Overall, hot days were associated with increased odds of self-poisoning suicide attempts and deaths, but not with suicide deaths via violent methods. The odds ratio [95% confidence interval] for suicide attempts via self-poisoning on hot days was 1.19 [1.11, 1.29], and 1.48 [1.12, 1.95] for suicide deaths. There was no effect of hot days on suicide deaths by violent methods. The associations varied by day of exposure, sex, age groups, and geography. The effect of hot days was greatest for suicide attempts and deaths involving opioids and elevated for suicide attempts involving opioid and analgesia combinations, analgesics alone, and alcohol.

CONCLUSIONS

The risk of suicide via self-poisoning was increased on hot summer days in BC, Canada. However, the relationship was influenced by other factors that vary among individuals and geographies. Policy decisions and future research for suicide-prevention during hot weather should consider sub-population susceptibility.

Extreme ambient temperature and emergency healthcare service utilization due to substance use disorders: a systematic review and meta-analysis

To synthesize the association between extreme ambient temperatures and the utilization of emergency healthcare services for substance use disorder (SUD). We performed a systematic literature review of original research published between 2000 and 2023 using five databases (PubMed, Embase, CINAHL, WoS, and Scopus) for literature search, and assessed study quality and risk of bias. A random-effects meta-analysis was conducted to calculate the odds ratios (OR) for SUD-related emergency healthcare service utilization during periods of extremely high or low ambient temperatures. Of 709 articles screened, eight studies met the eligibility criteria. Six studies focused on emergency department (ED) visits, while two examined on-site emergency care utilization. The risk of SUD-related ED visits was significantly higher when the mean ambient temperature was in the top 5% of the temperature distribution range (pooled OR = 1.11, 95% confidence interval [CI]: 1.07, 1.15). Conversely, the risk of SUD-related ED visits was lower when the mean temperature was in the bottom 5% of the distribution (pooled OR = 0.94, 95% CI: 0.89, 0.99). Our review showed the extremely high ambient temperature is associated with higher risk of SUD-related emergency healthcare service utilization. However, given the high heterogeneity observed across studies, these results should be interpreted with caution. Differences in study design, population characteristics, geographic region, and substance type may have contributed to this heterogeneity. Despite these differences, this finding highlights the importance of considering environmental factors in the management and prevention of SUD-related health issues.

Effects of apparent temperature on daily outpatient and inpatient visits for cause-specific respiratory diseases in Ganzhou, China: a time series study

BACKGROUND

Non-optimum temperatures are associated with increased risk of respiratory diseases, but the effects of apparent temperature (AT) on respiratory diseases remain to be investigated.

METHODS

Using daily data from 2016 to 2020 in Ganzhou, a large city in southern China, we analyzed the impact of AT on outpatient and inpatient visits for respiratory diseases. We considered total respiratory diseases and five subtypes (influenza and pneumonia, upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), asthma and chronic obstructive pulmonary disease [COPD]). Our analysis employed a distributed lag nonlinear model (DLNM) combined with a generalized additive model (GAM).

RESULTS

We recorded 94,952 outpatients and 72,410 inpatients for respiratory diseases. We found AT significantly non-linearly associated with daily outpatient and inpatient visits for total respiratory diseases, influenza and pneumonia, and URTI, primarily during comfortable AT levels, while it was exclusively related with daily inpatient visits for LRTI and COPD. Moderate heat (32.1 °C, the 75.0th centile) was observed with a significant effect on both daily outpatient and inpatient visits for total respiratory diseases at a relative risk of 1.561 (1.161, 2.098) and 1.276 (1.027, 1.585), respectively (both P < 0.05), while the results of inpatients became insignificant with the adjustment for CO and O3. The attributable fractions in outpatients and inpatients were as follows: total respiratory diseases (24.43% and 18.69%), influenza and pneumonia (31.54% and 17.33%), URTI (23.03% and 32.91%), LRTI (37.49% and 30.00%), asthma (9.83% and 3.39%), and COPD (30.67% and 10.65%). Stratified analyses showed that children ≤5 years old were more susceptible to moderate heat than older participants.

CONCLUSIONS

In conclusion, our results indicated moderate heat increase the risk of daily outpatient and inpatient visits for respiratory diseases, especially among children under the age of 5.