Shaw 2007.

Methods	Randomised, single‐blind controlled trial comparing exacerbation frequency and corticosteroid dosage in people whose asthma management was based on measurements of FeNO to a control group where management was based on the British Thoracic Society and Scottish Intercollegiate Guidelines Network treatment guidelines. Stratified by baseline sputum eosinophil count, baseline rescue steroid course in last year. The participants were blinded to which group they were randomised to. At completion, the participants were asked to record which randomisation group they thought they had been assigned to. There were 15 dropouts, 6 in FeNO group and 9 in control group. The study ran for 12 months, and the participants were assessed 10 times
Participants	900 adults were contacted from general‐practice registers, of which 118 were randomised. FeNO group N = 58; median age 50 (range 20 to 75), 27 males, 31 females. Control group N = 60; median age 52 (range 24 to 81), 27 males, 33 females. Attending a general practice in Leicester, UK. Inclusion: > 18 years old, diagnosis of asthma and at least 1 prescription for anti‐asthma medication in the past 12 months. Exclusion: Current smokers, past smoking history of > 10 pack‐years, or physician determines that they are poorly compliant
Interventions	Participants were seen at baseline, 2 weeks, month: 1, 2, 3, 4, 6, 8, 10, and 12. FEV1, FeNO, and Juniper asthma control score (JACS) were undertaken at each visit. Methacholine challenge for sputum induction was undertaken at initial visit, 6 months, and at completion of 12 months. In control group: Treatment was doubled if JACS > 1.57, and treatment halved if JACS < 1.57 for 2 consecutive months. In FeNO group: When FeNO > 26 ppb, ICS was increased. If < 16 ppb, or < 26 ppb on 2 separate occasions, treatment was decreased
Outcomes	Primary outcome: Number of exacerbations. Secondary outcome: Total ICS dose
Notes	Funding: This study was supported by a grant from Asthma UK
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information provided in published article
Allocation concealment (selection bias)	Low risk	Randomisation was done by an independent individual using minimisation method, stratified by baseline sputum eosinophil count, FeNO and rescue steroid courses in the last year
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Single blind. Participants were assessed at completion of study regarding the group they thought they were assigned to, 49% were unsure of which group they were assigned. 33% correctly identified their group, and 18% incorrectly identified their group
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Assessment of asthma control was made by investigators who were blinded to the participant's randomisation group. A separate unblinded physician communicated to the patient the correct treatment decision
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing outcome data
Selective reporting (reporting bias)	Unclear risk	Insufficient information
Other bias	Low risk	Measurement of FeNO was successful on every occasion