Asthma patients in SG show poor inhaler adherence, good disease control

Adherence to inhaler therapy among adult asthma patients in Singapore is intermediate or poor, reports a study, noting the importance of targeted interventions.

“This study provides insights into inhaler adherence among local adult asthma patients, identifying distinct adherence patterns and recognizing potential complacency issues associated with traditional adherence assessments,” the researchers said.

“The identification of diverse patterns of non-compliance underscores the need for tailored strategies in clinical management,” they added.

Ninety-nine patients from a specialist outpatient clinic met the eligibility criteria for this cross-sectional study and completed the Test of Adherence to Inhalers (TAI) questionnaire.

The researchers then collected data on asthma control test scores, medication possession ratio, and healthcare utilization. They also examined the associations between adherence, patient characteristics, and clinical outcomes via statistical analyses.

Of the patients, 68.7 percent demonstrated either poor (n=45) or intermediate (n=23) adherence, with younger patients showing poorer adherence. [Singapore Med J 2026;67:30-36]

Different patterns of non-compliance were observed. For instance, 19 patients with poor adherence (38.8 percent) exhibited deliberate non-compliance, while three with good adherence (7.3 percent) displayed unconscious non-compliance.

Unexpectedly, patients who had intermediate or poor adherence often demonstrated good asthma control, indicating potential challenges in outcome-based adherence assessments.

Hospital visit

In the past 12 months, a relatively higher but statistically non-significant proportion of patients with poor adherence experienced at least one hospitalization or emergency department (ED) visit due to asthma (42.4 percent with poor adherence vs 35.5 percent with good adherence) or at least one asthma exacerbation that required the use of oral corticosteroids (64.4 percent vs 48.4 percent).

“Our study revealed that more than half of the recruited subjects demonstrated intermediate or poor adherence, which is in line with findings from Ethiopia, Bangladesh, and Malaysia,” the researchers said. “Tailored strategies may be essential for different patterns of non-compliance.” [Asthma Res Pract 2017;3:7; J Asthma 2021;58:1229-1236; Asthma Res Pract 2022;8:1]

The finding of good asthma control among non-compliant patients suggests possible complacency, overtreatment, or inadequate awareness of asthma symptoms, which may lead to overestimation of control, with the latter supporting the current literature review by the researchers.

“Bereznicki [and colleagues] found that almost half of the Australian population … over-reported well-controlled asthma using validated tools, and this was consistent with the findings of a large multinational observational study, where a significant proportion of the participants tended to overestimate their asthma control,” they said. [Asthma Res Pract 2022;8:1; NPJ Prim Care Respir Med 2014;24:14009]

 “Similarly, a large European study by Kritikos [and colleagues] found that most of the participants rated their asthma as well-controlled using validated tools, although close to half had required steroid bursts within the last year, and almost a quarter had visited the ED,” they added. [NPJ Prim Care Respir Med 2019;29:1-9]

Interventions

The researchers also listed several evidence-based interventions to improve inhaler adherence among asthma patients. These included shared decision-making in selecting medications and dosages, inhaler reminders, and a once-daily prescription of low-dose inhaled corticosteroids. [Am J Respir Crit Care Med 2010;181:566-577; J Allergy Clin Immunol 2014;134:1260-1268.e3; Lancet Respir Med 2015;3:210-219]

“Inhaler therapy … remains the cornerstone of treatment in asthma management,” the researchers said. “Adherence to inhaler therapy is therefore imperative for controlling asthma symptoms and preventing asthma exacerbations.”