Time trends in 30 day case-fatality following hospitalisation for asthma in adults in Scotland: a retrospective cohort study from 1981 to 2009.

BACKGROUND

The risk of case-fatality following hospitalisation for asthma has not been well characterised. We describe trends in 30 day case-fatality following hospitalisation for asthma in adults in Scotland from 1981 to 2009.

METHODS

Using the Scottish Morbidity Record Scheme (SMR01) with all asthma hospitalisations for adults (≥18 years) with ICD9 493 and ICD10 J45-J46 in the principal diagnostic position at discharge (1981-2009). These data were linked to mortality data from the General Register Office for Scotland (GROS), with asthma case-fatality defined as death within 30 days of asthma admission (in or out of hospital). Logistic regression was used to explore the impact of age, sex, previous asthma admission (in the 12 months prior to hospitalisation), socioeconomic deprivation, year of admission and co-morbidity on 30-day case-fatality.

RESULTS

There were a total of 116,457 asthma hospitalisations; a total of 1000 (0.9%) hospitalisations resulted in a post-admission death (within 30 days of admission). Odds ratios for unadjusted and adjusted case-fatality showed a decreased risk of case-fatality from the mid-1990s onwards when compared to case-fatality in 1981. Advancing age and co-morbid diagnoses of respiratory failure, cancer, renal failure, cor pulmonale, coronary heart disease and respiratory infection were associated with increased likelihood of death.

CONCLUSIONS

30 day case-fatality has declined over the last three decades, comparable to case-fatality reported in other parts of the U.K. This decline may be in part due to improved guidelines, protocols and disease management for asthma over the last 30 years. The likelihood of death 30 days following an asthma admission increased with age group and was associated with respiratory failure, renal failure and cancer.