Is the BTS/SIGN guideline confusing? A retrospective database analysis of asthma therapy

BACKGROUND: The British guideline on the management of asthma produced by the British Thoracic Society (BTS) and the Scottish Intercollegiate Guidelines Network (SIGN) describes five steps for the management of chronic asthma. Combination therapy of a long-acting β(2)-agonist (LABA) and an inhaled corticosteroid (ICS) is recommended as first-line therapy at step 3, although the dose of ICS at which to add a LABA is subject to debate. AIMS: To classify the inhaled therapy prescribed to patients with asthma in NHS Forth Valley according to two interpretations of the BTS/SIGN guideline and to evaluate the use of combination therapy in this population. METHODS: A retrospective analysis including patients from 46 general practitioner surgeries was conducted. Patients with physician-diagnosed asthma were classified according to the BTS/SIGN guideline based on treatment prescribed during 2008. Patient characteristics were evaluated for the overall step classification, and specifically for therapy in step 3. RESULTS: 12,319 patients were included. Guideline interpretation resulted in a shift of 9.2% of patients (receiving medium-dose ICS alone) between steps 2 and 3. The largest proportion of patients (32.3%) was classified at step 4. Age, sex, smoking status, chronic obstructive pulmonary disease co-morbidity, and utilisation of short-acting β(2)-agonists and oral corticosteroids all correlated with step; however, no differences in these characteristics were evident between low-dose combination therapy and medium-dose ICS alone at step 3. CONCLUSIONS: Further studies are needed to evaluate prescribing decisions in asthma. Guideline recommendations regarding the use of ICS dose escalation versus combination therapy need to be clarified relative to the published evidence.