Is the ratio of inhaled corticosteroid to bronchodilator a good indicator of the quality of asthma prescribing? Cross sectional study linking prescribing data to data on admissions

Abstract

Objective-To investigate the ratio of inhaled corticosteroid to bronchodilator as a measure of the quality of asthma prescribing by general practitioners.Design-Ecological cross sectional study linking general practitioner asthma prescribing with hospital admission data and a measure of deprivation.Subjects-11 family health services authorities in the West Midlands region and 99 general practices in North Staffordshire.Main outcome measures-Hospital admission rates for asthma; the ratio of inhaled corticosteroid to bronchodilator; and Townsend deprivation scores.Results-No overall significant correlation was found between admission rates for asthma and corticosteroid:bronchodilator ratios for family health services authorities (Spearman's rs = -0.109, P = 0.750) or general practices (rs = -0.084, P = 0.407). In deprived family health services authority areas and general practices an inverse non-significant correlation existed between admission rates for asthma and corticosteroid:bronchodilator ratios (rs = -0.300, P = 0.624; rs = -0.218, P = 0.136). In contrast, in more affluent areas and general practices a positive non-significant correlation existed between admission rates and corticosteroid:bronchodilator ratios (rs = 0.371, P = 0.468; rs = 0.038, P = 0.792).Conclusion-Although the corticosteroid:bronchodilator ratio may be a valid indicator of the quality of prescribing for individual patients with asthma, caution should be applied in interpreting aggregated ratios. Differences in the severity of asthma or the prevalence of chronic obstructive pulmonary disease may explain inconsistent associations between admission rates for asthma and corticosteroid:bronchodilator ratios in family health services authorities and general practices with different deprivation scores. IntroductionThe ratio of inhaled corticosteroid to bronchodilator is a potential indicator of the quality of prescribing for asthma at aggregated family health services authority and general practice level.' A higher ratio reflects greater prescribing of inhaled corticosteroids relative to bronchodilators, a feature regarded as good practice.2 Nevertheless, few studies have validated the corticosteroid:bronchodilator ratio as an indicator of good quality prescribing because of the paucity of asthma outcome measures. At aggregated level, hospital admission rates for asthma are the only available outcome measure of asthma morbidity.At practice level two recent studies in the United Kingdom have found an association between hospital admission rates for asthma and corticosteroid:bronchodilator ratios.3 4 Both showed that practices with

Patterns of respiratory drug use in the Lombardy region of Italy, 1995–1997

“…As Tamblyn and his colleagues reported, drug dispensing databases may represent one of the most accurate means of determining drugs dispensed to individuals [23]. Moreover, if the database accounts for drug use of the entire population under study, this may be an extremely useful instrument for health research [24,29,30]. A limitation of the study is also its originality, the classification of severity of use, which was generated taking into account the international guidelines for chronic airflow limitations.…”

What can PACT tell us about prescribing in general practice?

“…Much of the research in this subject has tried to validate indicators by examining their association with other process measures. For example, several researchers have looked at the association between the ratio of inhaled corticosteroids to inhaled bronchodilators and admission rates for asthma 11 12 13. The next step in this research will be to validate the indicators against better quality measures.…”

Arzneimittelverordnungsstudien Zielsetzung und Ergebnisse

“…Nachdem initiale Untersuchungen in Groß-britannien gezeigt hatten, dass ein hö-herer Anteil inhalativer Glukokortikoide in der Therapie von Patienten mit Asthma bronchiale mit weniger Hospitalisierungen verbunden war [23], wurde ein höherer Anteil inhalativer Glukokortikoide entsprechend als Zeichen einer guten Verordnungspraxis gewertet. Um diese Annahme zu überprüfen, untersuchten Shelley et al die Qualität der medikamentösen Therapie des Asthma bronchiale in der allgemeinmedizinischen Praxis anhand des Verhältnisses der Verschreibungen inhalativer Kortikosteroide zu derjenigen bronchodilatierender Arzneimittel [24]. Sie fanden jedoch, dass der variierende Schweregrad des Asthma bronchiale, der Anteil von Patienten mit chronisch obstruktiver Bronchitis und andere individuelle Gegebenheiten die Interpretation dieses Indikators erschweren.…”