BackgroundLongitudinal predictors of persistent poor asthma control in severe asthma (SA) cohort remain scarce. The predictive value of the asthma severity scoring system (ASSESS) and their validation in the SA cohort outside the original study and in the Asian population is unknown. ObjectiveTo determine the 5-year longitudinal outcome of SA patients and validate the use of ASSESS score in predicting future outcomes in SA. MethodsProspective longitudinal observational study of patients with severe asthma (SA) attending the multidisciplinary specialist SA clinic from 2011 to 2021. The number of exacerbations and asthma control tests (ACT) were recorded yearly for 5 consecutive years. ASSESS score was computed at baseline, and the area under the receiving operating characteristics curve (AUC) for predicting persistent poor asthma control was generated. ResultsOf the 489 patients recruited into the study, 306 patients with 5-year follow-up data were analyzed. Seventy-three percent had Type-2 inflammation (T2) with increased overall exacerbations over 5 years (rate ratio (RR) 2.55, 95% CI 1.31-4.96, p=0.006) relative to non-T2 SA. In the multivariate model, bronchiectasis, gastroesophageal reflux disease (GERD) and ACT<20, were significantly associated with persistent poor asthma control over 5 -years. ASSESS scores were good at predicting persistent poor asthma control with an AUC of 0.71 (95% CI 0.57-0.84). ConclusionBronchiectasis and GERD are predictors for persistent poor asthma control and targeted traits for precision medicine in SA. The ASSESS score has a good prediction for persistent poor asthma control over 5 years.