Drug Overdose Deaths Exceeded Forecast During Early Pandemic

Abigail R. Cartus, PhD

Drug overdose deaths in 2020 exceeded experts’ model forecasts, according to new US data which sought to interpret the impact of the COVID-19 pandemic and national response on rising rates of fatal overdoses.

The findings specifically showed that the rate of US overdoses may have stabilized after a spike in March 2020, at the beginning of significant COVID-19 case outbreaks and public health response.

Led by Abigail R. Cartus, PhD, of the Department of Epidemiology at Brown University School of Public Health, investigators sought to estimate the proportion of fatal drug overdoses to occur in the final 43 weeks of 2020 against time series forecasts informed by national historic trends. As they noted, significantly reported deaths from overdose during 2020 coincided with the pandemic—but was proceeded by already increasing trends in overdose deaths through 2019.

The team’s cross-sectional analysis included data from the Centers for Disease Control and Prevention (CDC) National Vital Statistics System weekly, model-based count of provisional overdose deaths.

Estimates were derived from February 9, 2016 through March 7, 2020 to create an overdose death forecast for the remaining 43 weeks of that year. Parameters of the used forecasting model included factors for autoregression, differencing, and moving averages.

Cartus and colleagues observed 363,086 overdose deaths in the US from 2016 to 2020; approximately one-fourth (n = 91,799 [25%]) occurred in 2020. Their model-based estimates showed fatal overdoses steadily increased through 2019—from 4694 in February 2016 to 5592 in December 2019. It then increased substantially in the spring of 2020 before subsequently decreasing—from 9883 in May to 6467 in September.

Forecasted deaths did not substantially increase nor decrease from the December 2019 level of fatal overdoses. In fact, the model’s forecast of 65,042 deaths in the latter 43 weeks of 2020 was 12% less than the observed rate of 72,643. Plausible forecast scenarios set the range of difference for overdose deaths from no difference to 28% greater than observed rates.

“Our forecasts represent a counterfactual scenario in which overdose deaths stabilized at a high level from March to December 2020,” investigators wrote. “Although overdose mortality steadily increased throughout 2019, our model’s forecast did not yield a continued secular increase through 2020.”

Though it’s impossible to know what the trend in US overdose deaths would be had the pandemic never occurred, the investigators concluded COVID-19’s beginning in the US was likely associated with increased overdose mortality in 2020.

“This study’s results are consistent with the emerging consensus that the COVID-19 pandemic was associated with increased overdose mortality in 2020,” they wrote. “Our findings further underscore the importance of swiftly controlling transmission of infectious diseases to minimize disruptions to treatment of substance use disorders and access to harm reduction services.”

The study, “Forecasted and Observed Drug Overdose Deaths in the US During the COVID-19 Pandemic in 2020,” was published online in JAMA Network Open.