Using the Spanish Version of MCHAT in a Population Based Autism Screening Program

Background:

Early detection of autism has clear positive effects on prognosis, but a significant delay in obtaining an ASD diagnosis is found in Spain. For these reasons the University of Salamanca and the Institute of Health Carlos III carried out the Spanish validation of MCHAT and developed a population based screening for ASD in the public Health.

Objectives:

1. To check out if the population screening for ASD can work in the public Health System.
   
2. To instruct paediatricians of Primary Care Services, and to improve their awareness about ASD.
   
3. To improve coordination among health, social, and educational services.
   
4. To reduce the delay in the detection, diagnosis procedure, and treatment for children with ASD, and to reduce the family stress.
   
5. To estimate the incidence of ASD in the studied population
   

Methods:

Period: From September 2005 to December 2008
Place: Provinces of Salamanca and Zamora (Spain)
Population: 12.952 children in Salamanca and 5.761 children in Zamora that come up one of the to two compulsory paediatricians visits: vaccination at 18months and general follow-up at 24months. 
Procedure:
1. Handing over of the MCHAT questionnaire and the informed consent to the families when they attend to the paediatrician with a child 18 months and 24 months old.
2. Telephone interview in positive cases following the flow-chart format for exploration of each failed item (Robins, 2001).
3. Referral to the Childhood Unit of the University of Salamanca for a specialised evaluation of the confirmed positives cases (ADOS-G, ADI-R, MERRIL PALMER –R, VINELAND).
4. Search of “false negatives” through a randomized sampling selection of negative cases. A telephone interview exploring each DSM-IV-TR criteria for Autistic Disorder was carried out for each selected child.
5. Referral to the public Early Intervention Program of those cases finally diagnosed with ASD, SLI, developmental delays, etc.

Results:

Global response rate (total of children): 5726/18713=30.59%
Total questionnaires received: 5726 (1827 at 18 months visit in Salamanca and 1281 at 18 months visit in Zamora; and 1504 at  24 months visit in Salamanca and 1114 at 24 months visit in Zamora).
Response rate in Salamanca = 3331/12952 (25.71%)
Response rate in Zamora = 2395/5761 (41.57%)
Positive cases in the questionnaire that follows to the second step of the telephone interview=794
Positive cases confirmed after telephone interview =35
Evaluated cases=35
   1. Salamanca cases: ASD=5; SLI=3; Developmental delay=11; False positive=5.
   2. Zamora cases: ASD=4; SLI=2; Global developmental delay=5)

Prevalence: 1.6 per 1000

Conclusions:

The population screening program for ASD, using the Spanish version of MCHAT, showed that services coordination is possible. Also it is proved that a reduction of diagnosis delay in the public health system is possible. The study gives support that paediatricians can be involved in a detection program if they have available information and reliable resources. Nevertheless, we must to have into account the limits of our results, due to the low participation rate, and the high number of positive cases in the questionnaire, prior to the phone interview. These aspects suggest that a reform in the screening program could be necessary.