Applying UK real-world primary care data to predict asthma attacks in 3776 well-characterised children: a retrospective cohort study

Steve W Turner,Clare Murray,Annie Burden,David B Price,Mike Thomas

doi:10.1038/s41533-018-0095-5

Abstract

Current understanding of risk factors for asthma attacks in children is based on studies of small but well-characterised populations or pharmaco-epidemiology studies of large but poorly characterised populations. We describe an observational study of factors linked to future asthma attacks in large number of well-characterised children. From two UK primary care databases (Clinical Practice Research Datalink and Optimum Patient Care research Database), a cohort of children was identified with asthma aged 5–12 years and where data were available for ≥2 consecutive years. In the “baseline” year, predictors included treatment step, number of attacks, blood eosinophil count, peak flow and obesity. In the “outcome” year the number of attacks was determined and related to predictors. There were 3776 children, of whom 525 (14%) had ≥1 attack in the outcome year. The odds ratio (OR) for one attack was 3.7 (95% Confidence Interval (CI) 2.9, 4.8) for children with 1 attack in the baseline year and increased to 7.7 (95% CI 5.6, 10.7) for those with ≥2 attacks, relative to no attacks. Higher treatment step, younger age, lower respiratory tract infections, reduced peak flow and eosinophil count >400/μL were also associated with small increases in OR for an asthma attack during the outcome year. In this large population, several factors were associated with a future asthma attack, but a past history of attacks was most strongly associated with future attacks. Interventions aimed at reducing the risk for asthma attacks could use primary care records to identify children at risk for asthma attacks.

Highlights

There are one million children in the United Kingdom with asthma[1] and six times as many in the United States.[2]
Data from clinical trials where participants are well-characterised but relatively small in number find that risk factors for asthma attacks include a recent attack[8,9,10] and clinical measurements such as blood eosinophilia,[10] spirometry (forced expiratory volume in 1 s (FEV1))[11] and bronchial hyperreactivity.[10]
Asthma attacks are common in children and potentially preventable, and this study was designed to relate a comprehensive number of factors, which are readily available in primary care, to Number of future attacks

Summary

INTRODUCTION

There are one million children in the United Kingdom with asthma[1] and six times as many in the United States.[2]. Data collected in everyday clinical practice give the opportunity to study outcomes in many conditions.[16] Here we use a large dataset holding routinely acquired patient information to address the question “what factors available in primary care practice can be used to predict asthma attacks in children aged 5–12 years?” Predictive variables included oral corticosteroid treatment for a past attack (this was the definition of an asthma attack in the present study), current control, severity COPD chronic obstructive pulmonary disease step), age, sex, obesity, peak flow and blood eosinophilia The latter was included in light of evidence from children[17] and adults[18] that eosinophilia is predictive of future asthma attacks. The Global INitiative for Asthma (GINA) guideline does not recommend routine measurement of eosinophil count, it does identify eosinophilia as a risk factor for asthma attacks in children aged 6–11 years and adolescents.[6]

RESULTS

DISCUSSION

Findings

METHODS