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

Abstract

Abstract 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 for this program is 2.7 years. There have been no analyses modeling lifetime cost-effectiveness of wait time reduction for IBI. OBJECTIVES: 1) Model the change in starting age for IBI with halved and eliminated wait times; 2) Perform a cost-effectiveness analysis (CEA) comparing wait time reduction and elimination to the current status quo from both provincial government and societal perspectives. DESIGN/METHODS: Published wait list statistics were used to calculate average starting age for IBI for current wait time, wait time halved, and wait time eliminated. 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, 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. IQ strata were assigned probabilities of achieving an Independent (60 DFLYs), Semi-Dependent (30 DFLYs) or Dependent (0 DFLYs) outcome. Costs were determined from provincial government and societal perspectives. 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. One-way and probabilistic sensitivity analyses were performed to assess the impact of model uncertainty. RESULTS: Average starting ages for IBI were determined to be 5.24 years for current wait time, 3.89 years for wait time halved, and 2.71 years for wait time eliminated. From the provincial government perspective, eliminated wait time was the dominant strategy, generating the most DFLYs for $6,500 less per individual than current wait time. From the societal perspective, eliminated wait time again dominated the other strategies, with lifetime savings of $38,000 per individual compared with current wait time. ICERs were most sensitive to uncertainty associated with probability of having an IQ greater than 70 and probability of achieving an independent outcome when IQ was greater than 70. CONCLUSION: The results suggest that funding expanded program capacity would optimize the likelihood of positive IBI outcomes, improve future independence, and lessen the cost burden from provincial and societal perspectives.