Cost-Effectiveness Analysis Comparing Pre-Diagnosis Autism Spectrum Disorder-Targeted Intervention with Ontario's Autism Intervention Program

Background:  Sequential wait times for diagnosis and intervention can negatively impact outcomes in autism spectrum disorder (ASD). New service delivery models propose providing ASD-targeted interventions to young children who show signs of ASD before a diagnosis. One such intervention is the Early Start Denver Model (ESDM), which has shown efficacy in children with ASD as young as 15 months. There are no studies examining the cost-effectiveness of pre-diagnosis ASD-targeted intervention models.

Objectives: We performed a cost-effectiveness analysis comparing the costs and dependency-free life years (DFLYs) generated by comparing pre-diagnosis intensive ESDM (ESDM-I) and pre-diagnosis parent-delivered ESDM (ESDM-PD) to the Ontario Status Quo (SQ).

Methods: The analysis took a time horizon to age 65 using both provincial government and societal perspectives. Published literature was used to derive estimates of effectiveness. The mean expected IQ was determined for each intervention profile. Probabilities of having an IQ in the typical (>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 using the budget of an ESDM pilot project and government publications. A discount rate of 3% was applied to costs and effects occurring more than one year in the future. An incremental cost-effectiveness ratio (ICER) was calculated. One-way and probabilistic sensitivity analyses were performed to assess the impact of uncertainty in the model.

Results:  From a provincial perspective, the ESDM-PD resulted in a savings of nearly $9,000 per person to age 65 compared to SQ, and generated 0.17 additional DFLYs. The ICER for ESDM-I compared to SQ was $23,000 per DFLY gained, and the ICER for ESDM-I compared to SQ was $58,000 per DFLY gained. One-way sensitivity analyses showed the model was most sensitive to uncertainty in predicting functional outcomes from IQ. From a societal perspective, the ESDM-I was the dominant strategy, producing more DFLYs for a lower cost than ESDM-PD or SQ. The societal model was most sensitive to uncertainty in predicted functional outcomes and caregiver costs. Probabilistic sensitivity analyses for both provincial and societal models showed considerable uncertainty in the effectiveness estimates of the interventions.

Conclusions:  Pre-diagnosis ASD-targeted intervention may be associated with cost savings from both provincial and societal perspectives compared to current Ontario service models; however, predicted gains in independence based on increased IQ remain low with all programs. Caregiver costs were a significant driver in cost-effectiveness estimates. There was a high degree of uncertainty in the effectiveness of pre-diagnosis intervention, suggesting that further study on the effectiveness of these models is necessary to produce more accurate cost-effectiveness estimates.