Weather Variations and Hospital Admissions for Depressive Disorders: A Case Study in Hanoi

Studies from developed countries have shown season and weather influencing mood disorders, but it is not known whether such associations exist in tropical/subtropical lowand middle-income countries. This study from Vietnam examined the seasonal pattern of hospital admissions for depressive disorders andits relationship to daily weather variations, after stratifying for age, sex, and geographic area. Daily admission data from 2008 to 2012 were collected from Hanoi Mental Hospital in which 619 first-episode admissions for depressive disorders were diagnosed by the International Classification of Diseases 10 criteria for mood disorders (F30–F39). A negative binominal time series regression model for daily counts of eventswasestablished to analyze the relationship between weather variations, seasonality and daily hospital admissions for depressive disorders after adjusting for time trends. Our findings showed a general tendency for more admissionsin 2010 as well as between May and December, with a seasonal bi-annual high between May-June and NovemberDecember. Males were more affected by high ambient temperature and sunshinehours. Elevated ambient temperature was significantly related to increasing admissions RR=1.05 (1.01 – 1.09) over the same or following day. The relationship between hours of sunshine and the number of cases indicateda significant linear associationin menwhen the number of hours of sunlight per day was over each one hour RR=1.06 (1.02 – 1.11). High temperatures and high numbers of sunshine hours had a strong positive relationship to admission with a delay of 0–13 days. For these associations, men and ages below 40 years appeared more susceptible.