Asthma is a common condition in the UK and about a third of women with asthma are obese. Obesity is a known risk factor for asthma attacks. It is recognised that two hormones, oestrogen and testosterone, play a key role in developing obesity-related asthma in women. But there is a lack of data on the effect on asthma attacks. There are several key points in a women’s life where their hormone levels may change; we will use these changes to investigate the effect on their number of asthma attacks. The first one is during pregnancy. It has been said for many years, by doctors to pregnant asthma patients, that in one third of pregnant women their asthma will worsen, one third will stay the same and one third will improve. We will establish if this remains true in modern times. The second time hormones change is when women use oral contraceptives. These have been shown to reduce asthma attacks but no one has looked specifically in women with obesity-related asthma, which this study will focus on. A third time hormones may change, is if women take hormone replacement therapy (HRT). Again, the effect on asthma attacks is understudied but due to knowledge of human biology is thought that it may be having considerable effects.
The aim of this study is to determine the effect of changes in hormones in women with asthma on the risk of asthma attacks, particularly focussing on obesity-related asthma. We will draw a cohort of adult women with asthma patients between 2004 and 2021. The exposure will be hormone changes, either pregnancy, use of oral contraceptive use, or hormone replace therapy. The outcome will be asthma attacks. These will be defined as either managed using oral corticosteroids from their GP, an A&E or hospital admission (HES), or death (ONS). We will assess the effect of each of these three periods of change on the risk of asthma attack in women with asthma. To do this we will use a self-controlled case series design and conditional Possion regression, this methodology implicitly removes time-invariant confounding, e.g. socioeconomic status and genetics. We will determine if associations between hormone changes and asthma attacks are modified by body mass index, changes in weight, type-2 inflammation or diabetes medications. The public health benefit is to provide additional and robust evidence regarding the use of these therapeutics (oral contraception and hormone replacement therapy) in asthma management.
Asthma attacks
Chloe Bloom - Chief Investigator - Imperial College London
Chloe Bloom - Corresponding Applicant - Imperial College London
Amir Reza Rafati Fard - Collaborator - Imperial College London
Bohee Lee - Collaborator - Imperial College London
Carlos Andres Valencia Hernandez - Collaborator - Imperial College London
Ernie Wong - Collaborator - Imperial College Healthcare NHS Trust
Mark Cunningham - Collaborator - Imperial College London
Tricia Tan - Collaborator - Imperial College London
HES Accident and Emergency;HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation;CPRD Aurum Pregnancy Register;CPRD GOLD Pregnancy Register