Daily communication of corrected mortality estimates in Spain during the second wave of the COVID-19 pandemic

ABSTRACT

Introduction: MoMo monitors and communicates daily mortality in Spain, however, the delay in the notifi- cation of deaths biases downwards the estimates from MoMo. Objective: this study evaluates five methods that correct for the effect of notification delays on daily excess mortality estimates during the second wave of the COVID-19 pandemic. Methods: 1) estimates for the excess mortality in Spain were published daily and gathered within 01/09/2020-25/12/2020. 2) adjusted excess mortality estimates were computed by applying five different models that correct for the delay in the notification of deaths. 3) these corrections were evaluated using the mean absolute error (MAE) and the root mean square error (RMSE). Results: the delay in the notification implied that the cumulative excess mortality estimates from MoMo during the second wave were, on average, 87% of their definitive values. The quadratic and cubic regression models raised them to 98%, on average. Using quadratic regressions reduced the RMSE and the MAE of MoMo's estimates in 6 and 13%, respectively. Conclusion: to improve the daily estimates from MoMo for the cumulative excess of deaths, it is recommended to use quadratic regressions to correct the effect of the notification delay.