Implementation of guidelines in real-world UK asthma management

Background: Current asthma guidelines suggest use of add-on therapy (i.e. leukotriene receptor antagonists (LTRAs), theophylline (theo), oral beta₂-agonists) in patients whose asthma control remains inadequate despite daily high-dose inhaled corticosteroid (hdICS) and long-acting beta₂-agonist (LABA) therapy.

Objectives: To evaluate the proportion of patients on daily hdICS/LABA therapy experiencing exacerbations (1, 2 and ≥3 exacerbations annually), but who have not received a trial of additional add-on therapy.

Methods: Retrospective study using the General Practice Research Database (GPRD) to identify inadequately controlled hdICS/LABA patients (average ICS daily dose of ≥800mcg beclometasone dipropionate equivalent in the prior year and ≥1 LABA prescription in the prior 2 years) and the proportion prescribed appropriate “additional add-on therapy” (namely ≥1 month of: LTRA, or theo, or oral beta₂-agonists ever). We used a history of exacerbations (1, 2, ≥3 exacerbations) as evidence of poor control. High risk patients were those with ≥2 exacerbations in the prior year, detected using a composite measure based on the American Thoracic Society / European Respiratory Society exacerbation definition, namely records of: acute oral steroid prescriptions, hospital admissions and Accident & Emergency attendance for asthma.

Results:  Of 96,964 asthma patients in the dataset, 21,994 (23%) were prescribed hdICS+LABA. Of these, 17,971 (82%) had never received additional add-on therapy.  Although patients experiencing exacerbations were more likely to have been prescribed additional add-on therapy (p<0.001), 15% of those on hdICS/LABA alone had had 2 or more exacerbations in the past year.

Number of exacerbations in prior year	n	HDICS+LABA + NO additional add-on	HDICS+LABA + Additional add-on
0 exacerbations	14,375	12,257 (85%)	2,118 (15%)
1 exacerbation	3,744	2,995 (80%)	749 (20%)
2 exacerbations	1,584	1,153 (73%)	431 (27%)
≥3 exacerbations	2,291	1,566 (68%)	725 (32%)

Conclusions: The low prescribing of additional add-on therapy among hdICS/LABA patients with inadequate control and at high risk of exacerbations (many of whom should be receiving specialist input) suggests limited implementation of asthma guidelines and potential sub-optimal asthma management in UK primary care.