Cost-benefit analysis of first-generation antihistamines in the treatment of allergic rhinitis

Background: The majority of individuals with allergic rhinitis in the US take first-generation antihistamines (FGAs). Although FGAs have been proven effective in alleviating allergic rhinitis symptoms, they have been associated with an increased risk of motor vehicle, aviation and occupational injuries and deaths, reduced productivity and impaired learning. Objective: The objective of this analysis was to quantify the total costs and benefits of FGA use in the US from the societal perspective. Methods: We used a decision-analytic model to quantify the annual societal costs and benefits of treatment with FGAs compared with the hypothetical alternative of no treatment for the population of individuals with allergic rhinitis and taking FGAs in the US in 2001. The benefit associated with FGA use was estimated using the willingness-to-pay framework and projected to the US population using published estimates of the prevalence of allergic rhinitis. The costs of FGA-associated sedation included lost productivity and the direct and indirect cost of unintentional injuries (including motor vehicle, occupational, public and home injuries and fatalities). The incidence of injuries and fatalities associated with FGA use was estimated using the risk of injury attributable to the sedatory effects of FGAs in the allergic rhinitis population. To evaluate uncertainty in the model assumptions, a probabilistic sensitivity analysis was conducted using Bayesian second-order Monte Carlo simulation. Costs and benefits are expressed in 2001 US dollars, using a 3% discount rate. Results: Based on current utilisation, the total societal benefit (95% credible interval) associated with the use of FGAs for the treatment of allergic rhinitis was $US7.7 billion ($US1.3 billion to $US21 billion). The societal cost of purchasing FGAs was only $US697 million. However, the societal cost of FGA-associated sedation was $US11.3 billion ($US2.4 billion to $US50.8 billion). The annual societal net benefit of FGA use for the treatment of allergic rhinitis in the US was -$US4.2 billion (-$US36 billion to +$US0.296 billion). The net benefit was negative in 97% of the 10 000 Monte Carlo simulations. Conclusions: The societal benefits of FGA use in alleviating the symptoms of allergic rhinitis are significant. However, based on the assumptions, probability distributions and parameter estimate ranges used in the current model, it is very likely that the costs associated with sedation exceed the benefits of FGA use in the US. The cost of FGA-associated sedation is comparable to estimates of the cost of all medical care expenditures on respiratory conditions in the US ($US12.1 billion to $US31.3 billion) [1996 values] and provides compelling evidence of the economic burden of sedation associated with FGA use.