Forecasting emergency admissions due to respiratory diseases in high variability scenarios using time series: A case study in Chile.

Respiratory diseases are ranked in the top ten group of the most frequent illness in the globe. Emergency admissions are proof of this issue, especially in the winter season. For this study, the city of Santiago de Chile was chosen because of the high variability of the time series for admissions, the quality of data collected in the governmental repository DEIS (selected period: 2014-2018), and the poor ventilation conditions of the city, which in winter contributes to increase the pollution level, and therefore, respiratory emergency admissions. Different forecasting models were reviewed using the Akaike Information Criteria (AIC) with other error estimators, such as the Root Mean Square Error (RMSE), for selecting the best approach. At the end, Seasonal Autoregressive Integrated Moving Average (SARIMA) model, with parameters (p,d,q)(P,D,Q)s=(2,1,3)(3,0,2)7, was selected. The Mean Average Percentage Error (MAPE) for this model was 7.81%. After selection, an investigation of its performance was made using a cross-validation through a rolling window analysis, forecasting up to 30 days ahead (testing period of one year). The results showed that error do not exceed a MAPE of 20%. This allows taking better resource managing decisions in real scenarios: reactive staff hiring is avoided given the reduction of uncertainty for the medium term forecast, which translates into lower costs. Finally, a methodology for the selection of forecasting models is proposed, which includes other constraints from resource management, as well as the different impacts for social well-being.