PhD ThesisAsthma and Chronic Obstructive Pulmonary Disease (COPD) are two of the most
common chronic respiratory diseases causing a major burden of ill health to
populations across the world. Respiratory medication prescribing can be used as an
indicator of air pollution effect on asthma and COPD, capturing patients with any
severity of disease from mild to severe. In contrast, the traditional indicators of
asthma exacerbation, such as hospital admissions and emergency room visits, only
capture events of patients who suffer severe symptoms.
In this study, I aimed to develop statistical models for assessing the spatiotemporal
patterns of salbutamol prescribing in relation to air quality, in a primary
health care setting. Salbutamol represents 93% of short-acting β2-agonists, which
are prescribed for quick-relief of symptoms and acute exacerbations to individuals
that suffer from asthma or COPD. I analysed salbutamol medication (approximately
67 billion Average-Daily-Quantities) prescribed by 64 GP practices in Newcastle and
North Tyneside Primary Care Trusts, Northeast England, in 2002-2006. I used a
mixed-effects model suitable for data that are not independent in time or space.
My study found ambient Particulate Matter (PM10) concentrations to have a
significant relationship to salbutamol prescribing in primary care. An increase of
10μg/m3 in ambient PM10 concentrations was associated with an increase of 1% in
salbutamol prescribing. Income deprivation and average age of patients registered
per practice also had a significant relationship with salbutamol prescribing. The
findings showed that the variation of salbutamol prescribing was subject not only to
health needs caused by deprivation and air quality, but also random effects that
were practice specific, such as facilities within the practice or experience and
prescribing pattern of practitioners. Overall, the findings demonstrated that
respiratory prescribing in primary care can be used as indicator of air pollution
effect on asthma and COPD, increasing the scope of its use for health surveillance
in the future.Colt Foundatio