Table 1 Details of diagnostic and/or evaluation tools used in studies included in this review

DSM

Diagnostic

The "DSM," a reference work on mental health and brain-related illnesses and problems is written, edited, reviewed, and published by the American Psychiatric Association (APA) [1, 2, 6, 9, 39, 45, 73, 74, 88, 91]. It offers concise, in-depth descriptions of illnesses relating to the brain and mental health. Additionally, it describes and illustrates the symptoms and indicators of such illnesses and identifies the severity level of ASD. The latest edition of this reference book is the 5^th edition (DSM-5).

CARS

Diagnostic

The CARS [74] is a 15-item observation-based rating scale that is intended to distinguish autistic children from those who are experiencing developmental delays without showing any signs of autism. The CARS is designed to be utilized by highly skilled raters as part of a broader multi-method approach that also includes behavioral observations, interviews with main caregivers, an evaluation of intellectual functioning, and a thorough developmental and family history [74]. According to a seven-point rating scale (1, 1.5, 2…4), each of the 15 items is classified from "within normal limits for that age," which is coded as one, to "severely abnormal for that age," which is coded as four [75]. The ratings for each of the 15 elements are added up to create a final score. CARS overall scores vary from a low of 15 (all items within normal limits) to a high of 60 (all things highly aberrant). In 2010 Schopler and colleagues published the Second Edition (CARS2) [76].

GARS

Diagnostic

A common diagnostic technique for determining if a person has ASD is the GARS (Gilliam Autism Rating Scale). It was created by James E. Gilliam and is intended to help educators, psychologists, and doctors recognize and diagnose ASD [32].

Three sub-scales make up the 56 items that make up the GARS:

Stereotyped Behaviors: This subscale focuses on the stereotyped and repetitive behaviors that are frequently seen in people with ASD. It evaluates the existence and intensity of actions including body swaying, echolalia, and hand flapping.

Communication: The individual's verbal and nonverbal communication skills are evaluated by this sub-scale. It evaluates skills in social language, expressive language, and receptive language, among other areas.

Social Interaction: This sub-scale focuses at the person's social interaction abilities and any deficiencies brought on by an ASD diagnosis. It evaluates actions pertaining to interpersonal interactions with peers, social responsiveness, and social play.

The GARS is seen to be an important diagnostic tool for ASD, especially when used in conjunction with other evaluation tools and clinical judgment. It offers a systematic method for assessing ASD-related behaviors and aids doctors in determining the severity of symptoms across different domains.

VABS

Diagnostic

The VABS is a thorough adaptive behavior assessment that produces composite standard scores in three domains: communication, daily living skills, and socialization [86]. The Adaptive Behavior Composite score (ABC), which combines the three core domain scores, is calculated. Items are rated on a 3-point scale as 0 (never), 1 (sometimes), and 2 (usually) doing a behavior. Items are arranged in a developmental sequence within each subdomain. The Receptive, Expressive, and Written subdomains of the Communication domain evaluate the behaviors required to interact with others vocally and in writing. The Personal, Domestic, and Community subdomains of the Daily Living Skills domain examine the behaviors required to be self-sufficient in personal care, housekeeping, and community functioning. Its latest edition was published in 2016 (VABS-3) [86].

ISAA

Diagnostic

The National Institute for the Empowerment of Persons with Intellectual Disabilities, Government of India, created the ISAA screening tool to aid in the early detection of autism. In order to diagnose autism, the ISAA, an objective assessment instrument for people with autism, employs observation, clinical behavior evaluation, testing via contact with the individual, as well as information from parents or other caregivers. The ISAA comprises of 40 items, each of which is graded on a range of 1 to 5 (always). Six domains—social interaction and reciprocity, emotional response, language and communication, behavior patterns, cognitive component, and sensory aspects—are used to categorize the 40 items that make up the ISAA [14].

ATEC

Measuring changes in severity of ASD in response to a treatment

The ATEC is a questionnaire that caretakers administer to track changes in ASD severity in response to therapy. Four subscale scores are presented along with a total score. The first three subscales' questions are graded on a 0–2 scale. Health/Physical/Behavior, the fourth subscale, is graded on a 0–3 point scale.

Speech/Language/Communication, the first subscale, has 14 items with a score range of 0–28. Participants can score between 0 and 40 on the 20 items that make up the Sociability subscale. With 18 items and a score range of 0–36, the third subscale measures sensory and cognitive awareness. Finally, there are 25 items on the Health/Physical/Behavior subscale. The total score, which varies from 0–179 points, is determined by adding the results from each subscale. Lower scores reflect less severe ASD symptoms [68].

CGI

Evaluating the severity and improvement of psychiatric diseases

To evaluate the severity and improvement of psychiatric diseases, the rating scales CGI-I (Clinical Global Impressions-Improvement) and CGI-S (Clinical Global Impressions-Severity) are often used in clinical research and treatment. Based on observations and interactions with the patient, they offer a clinician's subjective assessment. The CGI-I is used to determine how much a patient's condition has changed or improved from its initial (pre-treatment) state. The CGI-S is a tool used to evaluate the severity of a disease in a patient at a certain period. It offers a general assessment of the patient's discomfort, functional impairment, and symptom severity. The CGI-S aids physicians in determining the severity of a patient's symptoms by giving a picture of the patient's present clinical condition. These rating scales are frequently employed in clinical trials and academic research projects to evaluate the effectiveness of the therapeutic intervention and to offer a standardized assessment of symptom intensity and improvement [36].

PDDBI

Evaluating the severity and improvement of ASD

ASD and other pervasive developmental disorders are evaluated and measured using the PDDBI, a commonly used assessment instrument. The PDDBI is made up of two primary parts:

The PDD Behavior Inventory measures problematic patterns of behavior that are frequently seen in people with pervasive developmental disorders. It contains things that cover a range of topics, including aberrant behavior, social interaction, and communication. The inventory gives details on how frequently, severely, and appropriately these behaviors occur.

The PDD Screening Test is a screening instrument used to find people who may be at risk of a pervasive developmental disorder. It consists of items that can only be evaluated in two ways: either they are there or they are not, giving a rapid screening evaluation. From infants to adults, the PDDBI may be used to evaluate people of various ages. Caretakers, parents, or experts who are acquainted with the person's conduct frequently complete it.

To compare a person's behavior to that of those who are ordinarily developing or people who have pervasive developmental disorders, the PDDBI offers standardized scores and profiles. It can help in diagnosis, planning treatments, and tracking development over time [75].

EOWPVT

Evaluation of expressive vocabulary level

A standardized assessment instrument called the EOWPVT is used to evaluate people's expressive vocabulary levels. It is frequently used to assess language abilities, particularly expressive language abilities, in clinical, educational, and research settings.

In the EOWPVT, candidates are shown a sequence of images and asked to verbally describe the term or concept that each image represents. Various semantic categories are covered by the test, including objects, actions, and properties. The individual's remarks are noted and given an accuracy rating.

Raw scores, standard scores, percentile ranks, and age equivalents are just a few of the scores that the EOWPVT offers. These results aid in evaluating a person's expressive vocabulary abilities against those of their classmates and in spotting possible language problems. Individuals of all ages, from infants to adults, are eligible to take the exam. It can be given by qualified experts with standardized testing experience, such as speech-language pathologists, psychologists, or educators [30].

ROWPVT

Evaluation of receptive vocabulary skills

The ROWPVT is a test that measures a test-taker's ability to properly match verbalized words to their matching images, and it may be used to evaluate receptive vocabulary skills in children as well as adults. These terms cover things, behaviors, and/or ideas that people frequently encounter. The EOWPVT is frequently combined with this kind of measurement.

FIM

Evaluation of functional abilities

The Functional Independence Measure (FIM) and WeeFIM (Functional Independence Measure for Children) are evaluation instruments for assessing the independence and functional abilities of people with a range of disorders, including Autism Spectrum Disorder (ASD). They offer a systematic assessment of a person's level of functional mobility and independence with regard to ADLs.

FIM: The FIM is a popular evaluation instrument for determining an individual's degree of independence in ADL. Self-care, sphincter control, transfers, locomotion, communication, and social cognition are among the six areas represented by its 18 items. Each item is given a rating on a 7-point scale, with 1 being the highest level of support and 7 being the lowest. The FIM offers a thorough assessment of a person's functional condition, which can aid with treatment planning and track advancement over time.

Functioning Independence Measure for Children, or WeeFIM:

A modified version of the FIM called the WeeFIM was created especially for kids, including those with developmental problems like ASD. It evaluates one's functional capacities in the areas of mobility, cognition, and self-care. The WeeFIM consists of 18 questions that assess a range of independent skills, including problem-solving, eating, dressing, bathing, and transferring. Each item is scored on a 7-point scale, same as the FIM. The WeeFIM helps with treatment planning and goal-setting by providing useful data on a child's functional skills [35, 57].

Stanford Binet Knowledge

Evaluation of intelligence

The Stanford-Binet test is a well-known instrument for measuring intelligence. It may be used to assess cognitive capacities in both adults and children. It is neither intended nor especially developed for the diagnosis or evaluation of ASD.

Verbal reasoning, non-verbal reasoning, memory, and mathematical reasoning are all comprehensively assessed by the Stanford-Binet exam. It evaluates abilities like verbal comprehension, visual-spatial processing, and problem-solving. A sequence of exercises and questions make up the exam, which gauges a person's cognitive ability throughout a variety of ages.

The Stanford-Binet exam can reveal important details about a person's cognitive profile, but it's important to remember that ASD is a complex neurodevelopmental disease that includes a variety of symptoms and difficulties beyond just cognitive ability.