To the Editors:
Asthma is an important disorder worldwide, as a major cause of hospital admissions, medical consultations, prescriptions and impaired quality of life. The precise causes of asthma, although largely unknown, are multifactorial and involve a complex interaction of genetic and environmental factors.
Although hospital admission rates are often increased for people in lower socioeconomic groups [1], little has been reported specifically for serious asthma (i.e. prolonged admissions and/or death within 30 days). Evidence about the effects of air pollutants on the occurrence of serious asthma is also unclear [2].
We aimed to establish the hospital admission rate and case fatality for serious asthma, and whether admissions are associated more strongly with social deprivation or air pollutants.
We used medical record linkage of inpatient data from the Patient Episode Database for Wales (PEDW) and mortality data from the National Health Service (NHS) Welsh Administrative Register. PEDW covers inpatient admissions to all NHS hospitals across 22 local health authorities in Wales, UK (population three million) and has been used as the basis of many previous published studies.
We included all emergency admissions from April 1, 1999 to March 31, 2007 where asthma (ICD-10 codes J45 and J46) was the principal diagnosis at discharge. Patients of all ages with admissions lasting ≥3 days, or who died (from any cause) within 30 days, were classified as “serious” cases. We included all first “serious” admissions during the study period, and subsequent serious admissions providing they occurred >30 days after the preceding serious admission.
We measured social deprivation and its seven domains using the Welsh Index of Multiple Deprivation 2005 [3]. Social deprivation scores were assigned to 1,896 lower super output areas (LSOAs) across Wales (average LSOA population 1,560) [3]. The LSOAs were ranked according to …
