title: Evaluation of the asthma control test: a reliable determinant of disease stability and a predictor of future exacerbations.
abstract: OBJECTIVE
  This study assessed the asthma control test (ACT) cut-off values for asthma control according to the Global Initiative for Asthma guideline in adults and the effectiveness of ACT scores in predicting exacerbations and serial changes in ACT scores over time in relation to treatment decisions.
  
  
  METHODS
  Subjects completed ACT together with same-day spirometry and fractional concentration of exhaled nitric oxide (FeNO) measurement at baseline and at 3 months. Physicians, blinded to the ACT scores and FeNO values, assessed the patient's asthma control in the past month and adjusted the asthma medications according to management guidelines. Asthma exacerbations and urgent health-care utilization (HCU) at 6 months were recorded.
  
  
  RESULTS
  Three hundred seventy-nine (120 men) asthmatics completed the study. The ACT cut-off for uncontrolled and partly controlled asthma were ≤19 (sensitivity 0.74, specificity 0.67, % correctly classified 69.5) and ≤22, respectively (sensitivity 0.73, specificity 0.71, % correctly classified 72.1). Baseline ACT score had an odds ratio of 2.34 (95% confidence interval: 1.48-3.69) and 2.66 (1.70-4.18) for urgent HCU and exacerbations, respectively, at 6 months (P < 0.0001). However, baseline FeNO and spirometry values had no association with urgent HCU and exacerbations. The 3-month ACT score of ≤20 correlated best with step-up of asthma medications (sensitivity 0.65, specificity 0.81, % correctly classified 72.8). For serial changes of ACT scores over 3 months, the cut-off value was best at ≤3 for treatment decisions with low sensitivity (0.23) and % correctly classified (57.3%) values.
  
  
  CONCLUSIONS
  Single measurement of ACT is useful for assessing asthma control, prediction of exacerbation and changes in treatment decisions.
authors: Departments of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong. fannyko@cuhk.edu.hk
authors: Fanny W S
authors: FW
authors: Ko
authors: David S C
authors: DS
authors: Hui
authors: Ting-Fan
authors: TF
authors: Leung
authors: Hong-Yin
authors: HY
authors: Chu
authors: Gary W K
authors: GW
authors: Wong
authors: Alvin H M
authors: AH
authors: Tung
authors: Jenny C N
authors: JC
authors: Ngai
authors: Susanna S S
authors: SS
authors: Ng
authors: Christopher K W
authors: CK
authors: Lai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology*; D001944:Breath Tests / Q000379:methods; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D011237:Predictive Value of Tests; D011788:Quality of Life; D012372:ROC Curve; D012008:Recurrence; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013147:Spirometry / Q000379:methods; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D009569:Nitric Oxide