Population Based Autism Screening Program Using MCHAT

Background: A previous study carried out by the Institute of Health CarlosIII of Spain proved a significant delay in obtaining an ASD diagnosis by Spanish families. The mean age at which the sample of 646families received an ASD diagnosis was 4.72years (SD 3.54years) -current children age was 14years-. Results showed that a part of this diagnosis delay was due to the inefficacy of primary health care services (basically paediatricians) to detect ASD and to make the specific referrals. This was the main reason to pilot an AutismScreeningProgram in the Spanish public HealthSystem that covers 100% of the general population using the MCHAT/Spanish version previously validated

Objectives:

To estimate the cost of the instauration and application of and AutismScreeningProgram in the general population.

To detect children with PDD before 30months and apply them a specialised intervention at a very early age that improves their prognosis.

To reduce the uncertainty and stress of the families that spend a mean of two years seeking for a definitive diagnosis since their first worries appeared.

To inform and improve awareness about ASD in Primary Care Services (through workshops for paediatricians and nurses).

Methods:

Population: 9883 children of a selected area of Madrid from (1st April2006 and 31st May2008) that attend to two compulsory paediatricians visits: vaccination  at 18months (N=7024) and general follow-up at 24months (N=5728). 

Procedure:

1. Handing over of the MCHAT questionnaire and the informed consent to the families with a possibility given to the medical professional (blind to the MCHAT result) to mark the questionnaire in the case of a personal suspect. 

2. Telephone interview to the families of the positive cases following the flow-chart format for the exploration of each failed item (Robins, 2001).

3. Referral to the Childhood Psychiatry Unit for the specialised evaluation of the confirmed positives cases (ADOS-G, ADI-R, MERRIL PALMER –R, VINELAND, Mac Arthur and SCQ).

4. Referral to Early Intervention Programs of those cases finally diagnosed with ASD, SLI, developmental delays, etc.

5. Search of “false negatives” though a randomized sampling selection of negative cases in which a telephone interview exploring each DSM-IV-TR criteria for AutisticDisorder was carried out.

Results: Global response rate (total of children): 2909/9883=29.43%
Total questionnaires received: 3341 (1880 from 18 months visit and 1461 from 24 months visit)
Response rate at 18months visit= 1880/7024 (26.76%)
Response rate at 24months visit =1461/5728 (25.50)
Positive cases in the questionnaire that follows to the second step of the a telephone interview=537
Positive cases confirmed after the telephone interview =55
Evaluated cases=43
ASD cases=10 (the rest were SLI or global developmental delay) False negative found cases= 1 (Asperger Syndrome)

Prevalence: 3.8 per 1000

Conclusions:   It is possible to reduce time needed to obtain a diagnosis of autism, to involve children earlier in intervention programs and to reduce family stress, however, it is not clear thus far if these population programs are effective in terms of their economical costs and if they are able to detect at that age less severe forms of ASD as Asperger Syndrome. Nevertheless we must to have into account the limits of our results due to the partial participation rate.