Subcutaneous Allergen Immunotherapy for Allergic Disease

Examining Efficacy, Safety and Cost-Effectiveness of Current and Novel Formulations

Linda Cox; Moisés Calderón; Oliver Pfaar

Disclosures

Immunotherapy. 2012;4(6):601-616. 

In This Article

Cost–effectiveness of SCIT Compared With Pharmacotherapy Alone

Allergic conditions represent some of most common, chronic and costly diseases seen in westernized societies. In the USA, more than 50 million US residents are affected by an allergic disease. It is estimated that the cost of allergic disease to the US healthcare system is in excess of US$18 billion annually.[79] The majority of these costs are attributable to asthma and AR.

Asthma is the leading chronic illness of children in the USA. With a prevalence of approximately 8%, asthma currently affects over 7 million children and 16 million adults in the USA.[203] Total US direct medical care costs for asthma in 2010 were estimated at $15.6–18 billion.[80,203] The burden of asthma, in terms of direct medical costs, is substantially borne by the US public healthcare system: Medicaid, a government insurer that provides healthcare coverage for low-income individuals, covered 30% of the US adult asthma population, whereas only 10% of the general population was covered by Medicaid.[80]

In 2005, approximately 7.3% of the US population (22 million people) reported experiencing AR-related symptoms, visiting a physician or obtaining a prescription drug to treat AR.[204] Direct medical expenses for AR nearly doubled in the 5 year period from 2000 to 2005, from $6.1 billion to $11.2 billion (all in 2005 US dollars and exclusive of costs for over-the-counter medications).[204] Outpatient visits account for approximately one-third (36%) of AR-related direct costs and prescription medications account for nearly the entire remainder (59%).[81] Allergen immunotherapy accounts for a small percentage (~2%) of AR-related costs, probably because only a small percentage of allergic patients (~5%) are prescribed this treatment in Europe and the USA.[82] Inconvenience caused by the necessity for this treatment to be administered in a medical facility is the most likely reason for the low use of SCIT. SCIT's potential to alter the course of allergic disease, thereby reducing the need for long-term treatment in contrast to symptomatic drug treatment, which only temporarily relieves allergy symptoms, suggests that the clinical benefits of SIT may lead to economic benefits. This premise was confirmed in a review of allergen immunotherapy pharmacoeconomics, which found that SCIT was associated with substantial healthcare cost savings.[83] In a prospective 6 year study of 30 adults with Parietaria pollen-induced rhinitis and asthma randomly assigned to 3 years of SCIT plus standard drug treatment or standard drug treatment alone, there was a significant progressive reduction in cost associated with SCIT beginning in the third year of treatment.[84] Annual costs were 80% lower in the SCIT group at the end of the study, 3 years after discontinuation of treatment.

Two large-scale, retrospective, US-based studies have examined whether SCIT confers economic benefits among children with AR.[85,86] In the first, researchers conducted a 7 year (1997–2004) retrospective claims analysis of 354 Florida Medicaid-enrolled children with newly diagnosed AR to examine short-term (6 month) pre-SIT versus post-SIT healthcare costs.[86] There were significant reductions in the use of outpatient (p < 0.001), pharmacy (p < 0.001) and inpatient (p = 0.02) services in the 6 months after termination of SCIT compared with the 6 months preceding SCIT initiation. This reduction in healthcare utilization resulted in a 6 month, per-patient, total weighted cost saving of $401.

In the second study, these investigators examined 10 years (1997–2007) of Florida Medicaid data to compare healthcare costs between children with newly diagnosed AR who subsequently received SIT versus a control group of patients who did not receive SCIT.[85] Patients were matched by age at first AR diagnosis, sex, race/ethnicity and diagnosis of asthma, conjunctivitis and atopic dermatitis. Children with AR who received SCIT had significantly lower 18 month, median, per-patient total healthcare costs (33%; $3247 vs 4872), outpatient costs (29%; $1829 vs 2594) and pharmacy costs (16%; $1108 vs 1316) compared with matched controls (p < 0.001 for all). The differences in outpatient, pharmacy and total healthcare costs were significant (p < 0.001) within 3 months of SIT imitation, and increased through to the study end.

A similar retrospective (1997–2008), matched cohort, claims analysis of adults (>18 years) with newly diagnosed AR with and without allergic conjunctivitis demonstrated similar findings in terms of cost savings with SCIT.[87] At 18 months, there were significant cost reductions for inpatient ($10,352 vs 14,796; p = 0.003), outpatient ($2668 vs 4101; p < 0.0001), pharmacy ($5636 vs 6321; p < 0.0001) and total healthcare ($10,626 vs 17,912; p < 0.0001) services in the SCIT-treated patients versus the non-SCIT group. The total healthcare cost savings were realized within 3 months of SCIT initiation and resulted in an 18 month mean per-patient total cost saving of 41% ($7286 divided by 17,912).

Collectively, these studies provide considerable support for the cost–effectiveness of SIT compared with pharmacotherapy alone during the treatment. This effect is even greater when one considers the persistent clinical benefits of SIT after discontinuation of treatment, an effect not seen with pharmacotherapy.[53,88]

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