Outcomes of combined fluticasone-propionate/salmeterol and budesonide/formoterol on adults with chronic asthma in a Singapore primary care setting – A retrospective study

Aim: In Singapore, patients can be prescribed single inhalers or combined inhaled corticosteroid and beta-blocker inhalers. Some patients are prescribed combination inhaler as studies showed those on combination had increased adherence and reduced moderate to severe asthma exacerbation. This study aims to evaluate the asthma outcomes, in terms of symptom control, assessed using Asthma Control Test (ACT), and exacerbation (emergency department referrals, oral Prednisolone and rescue therapy with short-acting beta-agonists) among the combined inhalers in Singapore (fluticasone-propionate/salmeterol evohaler and acuhaler form, and budesonide/formoterol). Methods: A retrospective cohort study was performed with data retrieved from 2018-2019. The study included patients aged above 21 who were on combined inhaler, had been managed by SingHealth Polyclinics, for at least one year, made at least two visits during the study period, with at least two asthma control test (ACT) scores. Dose was categorised into low, medium, and high based on guideline. Asthma control test score and exacerbation were used to evaluate treatment outcomes. Results: There were 2370 patients included in the cohort. Majority of the patients were females (59.7%), with a mean age of 61±15.6 years old. Fluticasone-propionate/salmeterol Evohaler was most commonly prescribed (56.7%) followed by budesonide/formoterol (33.6%). 81.3% of patients were on low-dosed inhaler. Patients in all groups had marginal increase in ACT from baseline (mean=21.0) to one year follow-up (mean=22.0) which was not significant. The number of emergency department referrals and oral Prednisolone dispensed were similar among the three groups (fluticasone-propionate/salmeterol, budesonide/formoterol or the control group of fluticasone only). Using logistic regression (adjusted for age, gender, ethnicity, marital status, and dose category), patients who were on budesonide/formoterol were 1.3 times more likely to require rescue therapy, when taking fluticasone-propionate/salmeterol as reference. Conclusion: Patients on budesonide/formoterol were more likely to be given treatment for exacerbation of asthma.