Impact of prior authorization for asthma medications on the use of emergency health services: a retrospective cohort study among newly diagnosed patients with asthma.
BACKGROUND
A prior authorization process to limit the nonoptimal use of medications combining inhaled corticosteroids and long-acting bronchodilators was introduced in the province of Québec, Canada, on October 1, 2003.


OBJECTIVE
We assessed the impact of this administrative measure on the rate of asthma-related emergency department (ED) visits and hospitalizations.


METHODS
A retrospective cohort study was conducted using Régie de l'assurance maladie du Québec administrative databases. We identified all persons aged 6 to 44 years with an incident asthma diagnosis in the 2-year periods preceding (October 1, 2001-September 30, 2003) and following (October 1, 2003-September 30, 2005) the introduction of the process. Children aged < or = 5 years at the time of the first encountered diagnosis were excluded because it is difficult to make an objective asthma diagnosis until 6 years of age. People aged > or = 45 years at the time of the first encountered diagnosis were also excluded to avoid the inclusion of persons who might also have had chronic obstructive pulmonary disease. Two groups were created based on their prescription drug insurance (private or public). Publicly insured persons were considered exposed to the process while privately insured persons were considered not exposed. Cox proportional hazards regression was used to assess, for each insurance group, the hazard ratio (HR) for an asthma-related first hospitalization or ED visit between the 2 periods. The use of medication, quality of life, and visits to physicians' offices were not considered in the analysis. The interaction between group and period was assessed to test whether the change in risk between the preprocess and postprocess periods differed by insurance group; statistical models were adjusted for sex, age, region, presence of a comorbidity other than asthma, and discipline of diagnosing physician.


RESULTS
There were 47,579 publicly insured persons and 93,177 privately insured persons with incident asthma during the study period. The risk of an asthma-related first hospitalization or ED visit remained unchanged in the 2 periods evaluated among both the publicly insured (adjusted HR, 0.95 [95% CI, 0.88-1.03]) and the privately insured (adjusted HR, 1.03 [95% CI, 0.96-1.03]). The change in risk between the preprocess and postprocess periods was not significantly different between insurance groups.


CONCLUSIONS
The prior authorization process introduced to limit the nonoptimal use of combination products (formoterol/budesonide and salmeterol/fluticasone) had no apparent impact on first asthma-related hospitalization or ED visit in these patients newly diagnosed with asthma who were covered by Québec's public prescription drug insurance plan.
Guénette
Line
L
Direction Scientifique du Suivi et de L'usage Optimal, Conseil du Médicament du Québec, Québec City, Québec, Canada. line.guenette@msss.gouv.qc.ca
Gaudet
Michel
M
D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D002648:Child; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D004632:Emergency Medical Services; D006760:Hospitalization; D006801:Humans; D007356:Insurance, Pharmaceutical Services; D012189:Retrospective Studies