The POSI validation information
The Parent’s Observations of Social Interactions (POSI) is a 7-item screening instrument for Autism Spectrum Disorders (ASD). The POSI was the outgrowth of a group of clinicians and research colleagues supported by a small grant from the Boston Autism Consortium. The group was generated and led by Dr. Alice Carter and consisted in addition of Marilyn Augustyn, Elizabeth Caronna, Alison Schonwald, Chris Sheldrick, and Ellen Perrin. The group met for several months to generate, format, and pilot test the questions that eventually became the seven-item POSI.
Initial validation was conducted by Nicola Smith, R. Christopher Sheldrick, and Ellen C. Perrin (see Smith, N, Sheldrick, R.C., Perrin, E.C. (2012). An abbreviated screening instrument for Autism Spectrum Disorders. Infant Ment. Health J. doi: 10.1002/imhj.21356). This publication reported on two sub-studies, 1) in a sub-specialty setting and 2) in separate mixed sub-specialty/primary care settings. In the first sample, parents of 213 children aged 18-48 months who presented to a developmental clinic for diagnostic evaluation completed a clinical intake questionnaire that included the POSI and the Modified Checklist for Autism in Toddlers (M-CHAT) checklist. POSI and MCHAT scores were compared to results of the full clinical evaluation to derive scoring thresholds for the POSI and to assess the sensitivity and specificity of both instruments. In the second sample, 235 parents of children aged 16-36 months were enrolled from a combination of primary care and subspecialty settings. They completed the POSI, M-CHAT, and a report of their child’s diagnoses. POSI and M-CHAT scores were compared to reported diagnoses to assess validity. In both studies, the POSI’s internal reliability was high and sensitivity of the POSI compared favorably to that of the M-CHAT. More children scored positive on the POSI than on the MCHAT, and best evidence from population samples suggests that the MCHAT is more specific than the POSI. For a more comprehensive view of the research on the M-CHAT, please see their website at mchatscreen.com.
POSI at a glance
Domain:
- Development (Risk for ASD)
Age range:
- 16 months, 0 days- 35 months, 31 days
- The POSI is on the top of the back side of the 18, 24, and 30 month Age-Specific SWYC Form
Scoring:
- Score each of the seven questions. Each question is assigned either a “1” or a “0”. If the parent selects one or more responses that fall in the last three columns, the question is scored as “1”; otherwise, it is scored as “0” (see image below).
- For items where parents have selected multiple responses for a single question (i.e., multiple responses in each row):
- Choose the more concerning answer (i.e., lower-functioning behavior) farthest to the right.
- If the parent has selected multiple answers in the last three columns for one item, assign only one point for the item.
- Missing items count as zero.
- Since there are seven questions total, there is a maximum of seven potential points.
- A result of three or more points in the last three columns indicates that a child is “at risk” and needs further evaluation or investigation.
The authors of the POSI acknowledge the extensive research done by the authors of the M-CHAT in the identification of autism spectrum disorder, which has significantly informed our work.