Reply to ADOS-2 and Comparison score (CSS)

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[quote=Anonymous]

Let’s break this down step-by-step to clarify how the ADOS-2 Module 3 overall total (Social Affect + Restricted Repetitive Behaviors, or SA + RRB) is converted to a Calibrated Severity Score (CSS), and what that score means.
Conversion of Overall Total to CSS
The ADOS-2 Module 3 assesses verbally fluent children or young adolescents, typically aged 4 to 16, using 14 scored items across two domains: Social Affect (SA) and Restricted Repetitive Behaviors (RRB). Each item is scored from 0 to 2 or 0 to 3 (with 3s often collapsed to 2s in scoring), but not all items contribute to the algorithm total. The algorithm selects specific items—usually around 10 to 12 of the 14—depending on the revised scoring rules. The maximum raw total score for SA + RRB in Module 3 is indeed 28 if every algorithm item maxes out at 2, though in practice, the range is typically lower due to item selection and individual variation.
This raw total (SA + RRB) isn’t directly converted to the CSS using a simple formula or universal chart. Instead, the conversion depends on the child’s age and language level, which are used to calibrate the score against a reference population. The process was developed by researchers like Gotham, Pickles, and Lord (2009) to make severity comparable across different ADOS modules and developmental stages. They divided participants into age-language cells (e.g., 4-5 years with fluent speech, 6-8 years, etc.) and mapped raw totals to a 1-10 CSS scale based on percentiles within those cells. Scores of 1-3 generally align with minimal-to-no autism symptoms, 4-5 with mild-to-moderate (often autism spectrum), and 6-10 with moderate-to-severe (often autism classification).
Unfortunately, there’s no publicly available, universal chart linking every possible raw total (0-28) to a CSS because the exact mapping varies by age-language group and is proprietary to the ADOS-2 manual. Clinicians use lookup tables provided in the ADOS-2 manual after calculating the raw SA + RRB total. For example, a raw total of 10 might map to a CSS of 4 for a 5-year-old but a CSS of 6 for a 10-year-old, reflecting how symptom severity is interpreted relative to developmental expectations. Without the manual, you can’t pinpoint the exact conversion, but the CSS always ranges from 1 to 10, not 0 to 10 as you mentioned—1 is the minimum, indicating little evidence of ASD.
Interpreting the Comparison Score (CSS)
The CSS, sometimes called the Comparison Score in Modules 1-3, reflects the severity of autism-specific symptoms relative to other children with ASD of the same age and language ability. It’s not a direct measure of overall functioning (like IQ or adaptive skills) but focuses on core ASD traits: social communication difficulties and repetitive behaviors.
Low CSS (1-3): Little to no evidence of ASD. These scores typically fall below the autism spectrum cutoff.
Moderate CSS (4-5): Suggests mild-to-moderate ASD symptoms, often corresponding to an “autism spectrum” classification rather than full “autism.”
High CSS (6-10): Indicates moderate-to-severe ASD symptoms, with 9 or 10 reflecting the most pronounced difficulties relative to peers with ASD. A 9 or 10 means the individual’s raw total fell in the top ~20% of autism-classified scores for their age-language group.
Does a high CSS (like 9 or 10) mean Level 3 ASD? Not necessarily. The DSM-5 uses Levels 1, 2, and 3 to describe support needs (Level 1 = mild, Level 3 = severe), which consider broader factors like communication, adaptive functioning, and behavioral challenges—not just ADOS-2 observations. A CSS of 9 or 10 signals severe ASD symptoms during the assessment (e.g., minimal social reciprocity, intense repetitive behaviors), but it doesn’t automatically translate to Level 3. Someone with a CSS of 10 could be Level 1 if they manage well with support outside the test setting, or Level 3 if they also have significant intellectual or behavioral challenges. The CSS informs diagnosis and severity within the ADOS context, but clinicians integrate it with other data (e.g., ADI-R, adaptive assessments) to assign a DSM-5 level.
Why It’s Confusing
The lack of a simple, public chart stems from the calibration process being tailored to age and language, and the ADOS-2 being a clinical tool with protected scoring details. The shift from a raw maximum of 28 to a 1-10 scale also feels non-intuitive without seeing the data-driven mapping. If you’re working with a specific ADOS-2 report, the clinician should provide the raw total, CSS, and interpretation based on the manual’s tables.
In short: Yes, the raw total tops out around 28, gets calibrated to a 1-10 CSS based on age and language, and a high score like 9 or 10 means more severe ASD symptoms—but it’s just one piece of the puzzle, not a direct ticket to Level 3. For precise conversion, you’d need the ADOS-2 manual or a clinician’s breakdown.[/quote]

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