Study Population and Sociodemographic Characteristics

The study cohort, sociodemographic characteristics and cooperation rates of the patients and physicians have been previously reported [24]. Briefly, 1400 patients and 599 physicians were included in the survey. The mean patient age was 34 ± 8.9 years, and 52% were male. The mean physician age was 43 ± 9.4 years, and 53% were male. Approximately 64% of physicians practised at treatment facilities in a large city or metropolitan area.

Cooperation Rates

The cooperation rates have been previously reported [24]. Briefly, 400–2000 invitations were sent to patients in each country, with 200 patients from each country completing the survey, totalling 1400 patients. The overall patient cooperation rate was 77%. For the physician survey, 1300–2600 invitations were sent to each country (excluding Vietnam), with 100 completed surveys per country, totalling 599 physicians. The overall physician cooperation rate was 6%.

Patient-Reported Treatment Patterns

In the overall cohort, 82% of patients (1108/1354) reported having ever received treatment with a daily controller inhaler for regular dosing. Additionally, 75%, 85% and 92% of patients among those with mild, moderate and severe asthma, respectively, reported having ever received treatment with a daily controller inhaler. The proportion of patients reporting that they had ever received treatment with a daily controller inhaler differed significantly across the surveyed countries (P < 0.0001) and asthma severities (P < 0.0001) (Table 1).

Table 1 Patient responses on treatment patterns by location and asthma severity

Among the patients prescribed inhaled relievers with or without a separate daily controller inhaler, 38% used an inhaled reliever at least once daily for quick symptom relief. The frequency with which patients used an inhaled reliever for quick symptom relief varied significantly across the surveyed countries (P < 0.001) and asthma severities (P < 0.0001). Among those prescribed a daily controller inhaler with or without a separate inhaled reliever, 88% used the daily controller inhaler for quick symptom relief instead of inhaled relievers. The proportion of patients using daily controller inhalers instead of inhaled relievers for quick symptom relief differed significantly across the surveyed countries (P < 0.01) and asthma severities (P < 0.05) (Table 1).

Eighty-one percent of the patients (1083/1329) were aware of the maintenance and reliever therapy (MART) approach, with significant variations observed across the surveyed countries (P < 0.0001). Approximately 84% (897/1066) of patients reported having been prescribed MART, of whom 830 (93%) were administered a separate inhaled reliever, with significant variations observed across the surveyed countries (P < 0.01). Eighty-five percent of the patients (698/820) reported requesting a separate inhaled reliever. Based on patient perception, the primary reason for MART prescription was ease of management compared with previous treatments (52%), followed by perceived MART effectiveness (48%).

Treatment Adherence

Among 848 patients prescribed daily controller inhalers with or without separate inhaled relievers, 432 patients (51%) reported adherence to the prescribed daily controller inhaler, with utilisation at least once daily (Fig. 1a). Regular controller inhaler use differed significantly across the surveyed countries (P < 0.001) and asthma severities (P < 0.0001) (Table 1).

Fig. 1

Adherence to daily controller inhalers reported by a patients and b physicians. aOverall cohort includes patients with asthma of unknown severity. GP general practitioner

Overall, physicians reported that 73% of patients with moderate or severe asthma or asthma of fluctuating severity adhered to their prescribed regular medication (Fig. 1b, Table S1), with similar rates reported by pulmonologists and primary care physicians (77% and 72%, respectively) (Fig. 1b).

Treatment Nonadherence

Erratic nonadherence (primary definition) to inhalers was reported by 55% (462/845) of patients prescribed controller inhalers with or without inhaled relievers, with its prevalence increasing with worsening asthma severity (Fig. 2a, Table S1). Additionally, 30% of patients (354/1192) reported forgetting to use at least half of their inhalers in the past week. The proportion of patients forgetting to use inhalers over the past week differed significantly across the surveyed countries (P < 0.01) and asthma severities (P < 0.0001) (Table S1).

Fig. 2

Treatment nonadherence: a Erratic nonadherence (primary definition) and b nonerratic nonadherence. aOverall cohort includes patients with asthma of unknown severity

Nonerratic nonadherence to inhalers was reported by 49% (415/847) of patients prescribed daily controller inhalers with or without separate inhaled relievers, showing a decreasing trend with increasing asthma severity (59%, 48% and 26% of patients among those with mild, moderate and severe asthma, respectively) (Fig. 2b, Table 1).

Regression Analysis

Regression analyses were conducted to determine patient characteristics that predict poor adherence to controller medications. These analyses included patient-reported erratic and nonerratic nonadherence as well as a separate set of analyses focusing solely on patient-reported erratic nonadherence.

Erratic and Nonerratic Nonadherence

Approximately 80% (653/820) of patients reported both erratic nonadherence (primary definition) and nonerratic nonadherence. The proportions of adherent/nonadherent patients were similar when adjusted for age, sex, asthma severity and treatment type (Table S1). The pseudo-R2 value indicated that the variables in the model explained only 5% of the variation in nonadherence. Only current inhaled reliever used was a significant predictor of poor adherence to the controller inhaler (P = 0.04) (Fig. 3).

Fig. 3

Forest plot showing odds ratios for poor adherence to controller inhalers with various patient-reported variables. A total of 820 patients were included in the analysis, of whom 653 reported erratic nonadherence (primary definition) and nonerratic nonadherence. Pseudo-R2 was 5%; 95% CIs are shown in parentheses. Only patients reporting controller inhaler use were included; those reporting only inhaled reliever use were excluded. CI confidence interval; ICS inhaled corticosteroids; LABA long-acting beta-agonists; LAMA long-acting muscarinic antagonists; MART maintenance and reliever therapy; OR odds ratio; R coefficient of determination; SABA short-acting beta-agonists

Sensitivity analysis 1 was conducted to examine patient-reported erratic nonadherence (sensitivity definition 1) and nonerratic nonadherence. Accordingly, 66% (539/820) of patients were nonadherent to daily controller inhaler use. The pseudo-R2 value indicated that the variables in this model explained only 4% of the variation in nonadherence. Household smoking status was a borderline predictor of nonadherence (P = 0.05), whereas current asthma severity was a significant predictor (P = 0.03) (Table S2).

Erratic Nonadherence

Approximately 54% (445/819) of patients showed erratic nonadherence (primary definition). The pseudo-R2 value indicated that the variables in the model explained 7% of the variance in nonadherence. Age, household smoking status, treatment regimen and current inhaled reliever used were significant predictors of nonadherence (P < 0.05). Regression analyses using sensitivity definitions of erratic nonadherence are summarised in Table S3.

Adherence to AAPs

Overall, 69% of physicians reported that they often or always provide patients with an AAP. However, 47% of physicians reported that patients ‘sometimes’, ‘rarely’ or ‘never’ adhered to the AAP. Additionally, 95% of patients (93%, 96% and 95% among those with mild, moderate and severe asthma, respectively) reported discussing the AAP with their physicians during or after consultations. However, 39% of patients reported that their physicians ‘sometimes’, ‘rarely’ or ‘never’ followed up on the progress of the AAP; this rate declined in patients with increasing asthma severity (48%, 37% and 17% among those with mild, moderate and severe asthma, respectively). The responses to the survey questions regarding adherence to AAPs varied significantly across the surveyed countries (P < 0.0001) and asthma severities (P < 0.05) (Fig. 4, Table S4).

Fig. 4

Adherence to the asthma action plan in the overall cohort

Asthma Treatment Monitoring

Overall, 48% of patients tracked their dosing using the controller inhaler’s dose counter, 39% recorded usage in a diary or journal and 37% discussed dosing and usage during regular follow-up visits (these categories were not mutually exclusive); the rates among patients with severe asthma were 55%, 60% and 44%, respectively (Table S5).

To estimate patient use and treatment adherence, 80%, 58% and 57% of physicians relied on patient self-reporting, prescription records and review of notes related to past prescriptions, respectively (these categories were not mutually exclusive). Among these methods, physicians rated patient self-reporting (24%), direct adherence monitoring (20%) and checking of prescription records (19%) as the most reliable. The responses to survey questions regarding asthma treatment monitoring varied significantly (P < 0.05) across the surveyed countries (Table S5).