Asthma management in pregnancy

Abstract

Background: Asthma is common during pregnancy, however research is limited regarding the extent and timing of changes in asthma management associated with pregnancy.

Objective: To determine the prevalence of asthma during pregnancy and identify changes in treatment and asthma exacerbation rates associated with pregnancy, while controlling for seasonal influences.

Methods: Pregnant women with asthma were identified from the UK General Practice Research Database between 2000 and 2008. For each woman asthma medication prescribed during the study period was identified; for each product combination the British Thoracic Society medication-defined asthma treatment step was identified. Asthma exacerbations were identified during pregnancy and in the corresponding 12 months prior. Analyses of changes in asthma treatment and exacerbation rates during pregnancy relative to the corresponding period 12 months prior, to control for seasonality, were stratified by trimester and asthma treatment intensity level.

Results: The prevalence of treated asthma in pregnancies resulting in a delivery was 8.3%. From 14,141 pregnancies, in 12,828 women with asthma, 68.4% received prescriptions for a short-acting β2-agonist and 41.2% for inhaled corticosteroids; 76.5% were managed with asthma treatment Step 1 or 2. Poor persistence to inhaled corticosteroids, defined as a gap of up to 60 days between prescriptions, was common. In 45.0% of pregnancies, an increase in average treatment step was observed whereas in 25.6% the treatment step decreased. Treatment intensity remained the same in 29.5% of pregnancies. Exacerbations occurred in 4.8% of pregnancies compared to 5.9% in the same season the year before (p<0.001).

Conclusion: Exacerbation rates during pregnancy were slightly lower than in the year before. However, treatment patterns and exacerbation rates in this study suggest asthma control during pregnancy is variable, and women may require close monitoring especially in those with evidence of poor control before pregnancy.

Figure 1. Example scenario for extracts of patients’ mapped prescription records and the allocated corresponding treatment steps.

Figure 2. Identifying eligible pregnancies in females with asthma.

Figure 3. Change in average British Thoracic Society (BTS) asthma treatment step.

The percentage of deliveries in which the average BTS asthma treatment step increased, decreased or remained unchanged compared with the calendar period 12 months prior stratified by pregnancy trimester.

Figure 4. Exacerbations during pregnancy.

Stacked bars showing the percentage of deliveries where the mother had ≥1 exacerbation during pregnancy (right hand side) and in the corresponding time period the year before pregnancy (left hand side) stratified by pregnancy trimester and asthma treatment intensity level.^* *Asthma treatment intensity level: mild = average step≤1, moderate = average step>1 and ≤2, considerable to severe = average step>2 Definite exacerbation = a medical code for an asthma exacerbation or asthma attack or an asthma diagnosis code recorded on the same date as a hospitalisation or accident and emergency visit; probable exacerbation = a prescription for short-term oral corticosteroid treatment with a record of asthma (but not explicitly an exacerbation) on the same date the prescription was issued; possible exacerbation = a prescription for short-term oral corticosteroid treatment with no record of the indication for treatment.