Predicting suicide rates during the COVID-19 pandemic using a pre-pandemic death rate model

In 1952, the psychiatrist Erwin Stengel hypothesized that suicide becomes rarer in times when the value of life within a society is lower, when death is more common. In Canada, suicide rates and death rates present with consistent seasonality between years, fluctuating inversely with one another. However, the typical pre-pandemic seasonality seen in death rates was broken during the first year of the COVID-19 pandemic, as a consequence of inordinate deaths occurring at an odd time of year. This offers a unique opportunity to observe whether suicide rates were inversely disrupted. The present study models weekly Canadian suicide rates using death rates, from time series data spanning 2010 to 2019. Results indicate that suicide rates decrease on average by 0.27 standard deviations per 1 standard deviation increase in the death rate. This model is then used to predict 2020 suicide rates, using 2020 death rates. Predictions account for 11.6% of the variation in actual 2020 suicide rates. Overall, results are interpreted as being favorable towards Stengel’s theory. As alternative interpretation, we suggest that each non-suicide-related death removes a potential suicide from the population. Thus the death rate censors the suicide rate. We conclude that the process co-generating suicide and death rates pre-pandemic was maintained during the pandemic in 2020.