How to make adjustments of underreporting of suicide by place, gender, and age in China?

Purpose Underreporting of suicide is a worldwide problem. In particular, the national suicide rates published by the Chinese Ministry of Health (“MOH”) could be severely underreported. Validity of the assumption of evenly underreported of suicide by place (city/rural), gender, and age in China has been evaluated and some possible adjustments to the underreporting have been suggested. Methods Mortality rates from the MOH from 2002 to 2016 were extracted. Due to zero undetermined deaths, accidental deaths (weighted by causes of death) were used to evaluate underreported suicides. 53% of drownings, 11% of falls, 11% of poisonings, and 7% of other accidents were assumed as underreported suicides. Negative binomial regressions were used to calculate the rate ratios of the underreported suicides compared to suicides. Negative binomial regressions were also used to calculate the annual percentage changes of different mortality rates. Results Suicides of rural males could most likely be underreported (49%; 95% CI 39–61%), but suicides of rural females would least likely (30%; 95% CI 24–38%). Suicides of people aged 15–24 years and 75 years and above could more likely to be underreported than other ages. After adding the underreported suicides, declining trends of the national suicide rates had been eased. Conclusions People who lack social connection could have a high possibility of underreporting suicide. However, when rural females died of unnatural causes, their parents or even the whole village tended to quest for their intents, thus rural females had a lower possibility of underreporting suicide.