Ten-year longitudinal study of factors influencing nocturnal asthma symptoms among Asian patients in primary care.
BACKGROUND
Nocturnal asthma symptoms result in poor quality of life and morbidity.


OBJECTIVE
This study primarily examines key factors predicting and mitigating nocturnal symptom risks among asthma patients, who were enrolled into a Singapore publicly funded asthma care programme. It also studies the association between nocturnal symptoms and medication changes as the secondary outcome.


METHODS
A longitudinal study was conducted on 939 multi-racial Asian patients with persistent asthma. Patient clinical and therapeutic data were retrieved retrospectively from the programme's database established in 2004. Association between nocturnal symptoms (defined as night-time cough, wheeze and breathlessness at least twice monthly) and each categorical predictor was tested. The generalised linear mixed-effects model (GLIMM) was used to model the primary and secondary outcomes.


RESULTS
Having nocturnal asthma symptoms was significantly associated with the number of days with breathlessness, off usual activities and off work, and asthma severity at baseline (all P values <0.05). The asthma action plan (AAP) status is significantly associated with nocturnal symptoms after adjusting for race, age and smoking status at baseline (odds ratio (OR)=0.49 (updated asthma action plan versus none), OR=0.37 (been-on plan versus none)). The risks of nocturnal asthma symptoms increased over time for those with allergic rhinitis (OR=1.52) and reduced with subsequent visits (OR=0.91). Nocturnal symptoms increased the odds (OR=2.87) of switching from inhaled corticosteroid (ICS) to combination medications (ICS-LABA (long-acting β2-agonist)).


CONCLUSIONS
The risks of having nocturnal symptoms were primarily associated with those with allergic rhinitis. An increase in patients' nocturnal symptoms was also predictive of the switching from ICS medications to combination formulations by their physicians.
Department of Research, SingHealth Polyclinics, Singapore, Singapore.|Centre of Quantitative Medicine, Duke-NUS Graduate Medical School, Singapore, Singapore.
Ngiap Chuan
NC
Tan
Centre of Quantitative Medicine, Duke-NUS Graduate Medical School, Singapore, Singapore.
Nivedita V
NV
Nadkarni
Centre of Quantitative Medicine, Duke-NUS Graduate Medical School, Singapore, Singapore.
Weng Kit
WK
Lye
Department of Research, SingHealth Polyclinics, Singapore, Singapore.
Usha
U
Sankari
Health Services and Systems Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore.
van Hai
vH
Nguyen
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D058666:Adrenergic beta-2 Receptor Agonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D044466:Asian People; D001249:Asthma / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D003371:Cough / Q000209:etiology / Q000503:physiopathology*; D057915:Drug Substitution; D004359:Drug Therapy, Combination; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D012135:Respiratory Sounds / Q000209:etiology / Q000503:physiopathology*; D012189:Retrospective Studies; D065631:Rhinitis, Allergic / Q000150:complications; D012846:Singapore; D013997:Time Factors; D055815:Young Adult
D000305:Adrenal Cortex Hormones; D058666:Adrenergic beta-2 Receptor Agonists; D018927:Anti-Asthmatic Agents