Cost-Effectiveness Analysis of Wait Time Reduction for Intensive Behavioral Intervention in Ontario

Background:  In Ontario, the Autism Intervention Program funds intensive behavioral intervention (IBI) for children severely affected by autism spectrum disorder (ASD). Accessing IBI before age four is associated with significantly better outcomes compared with later access; however, the average wait time (WT) for this program is 2.7 years. There have been no analyses modeling the lifetime cost-effectiveness of reducing the WT for IBI.

Objectives:  The objective of this study was to perform a cost-effectiveness analysis (CEA) comparing WT reduction and elimination to the current status quo over the lifetime from both provincial government and societal perspectives.

Methods:  Published wait list statistics were used to calculate the average IBI starting age for the current WT, reduced WT (halved), and eliminated WT. CEA model inputs were derived from published literature. The target population was children diagnosed with severe ASD. The outcome modeled was independence measured in dependency-free life years (DFLYs) to age 65. To derive this, the mean expected IQ was modeled for each comparator based on probability of early (< age 4) or late (4 or older) access to IBI. Probabilities of having an IQ in the normal (70+) or intellectual disability range (< 70) were calculated. Each IQ stratum was assigned a probability of achieving an Independent (60 DFLYs), Semi-Dependent (30 DFLYs) or Dependent (0 DFLYs) outcome. Costs were determined for both provincial government and societal perspectives and were taken from government publications. Parameters were inputted into a decision analytic model, with an annual discount rate of 3% applied to costs and DFLYs. Incremental cost-effectiveness ratios (ICERs) were determined for each strategy from both perspectives. One-way and probabilistic sensitivity analyses were performed to assess the impact of uncertainty in the model.

Results: From the provincial government perspective, eliminated wait time dominated the other two strategies, generating the most DFLYs for $6,500 less per individual to age 65 than current wait time and $2,700 less than the reduced wait time. From the societal perspective, eliminated wait time again dominated the other strategies, generating the most DFLYs with lifetime savings of $38,000 per individual compared with current wait time and $16,200 in savings compared with reduced wait time. From both perspectives, ICER outputs were most sensitive to uncertainty in the probability of achieving a post-treatment IQ score greater than 70 and the probability of an Independent outcome when post-treatment IQ was greater than 70. Probabilistic sensitivity analyses comparing the eliminated to reduced WT strategies from both perspectives each showed a 57% probability of a positive ICER (increased costs and DFLYs), with a 21% probability of cost-savings and increased DFLYs.  

Conclusions:  The results suggest that an investment to eliminate wait times could produce eventual cost-savings as well as improved independence. Funding expanded program capacity would optimize the likelihood of positive outcomes, improve future independence, and lessen the lifetime cost burden from provincial and societal perspectives.