Appendix D.

Mental Health Classification of Studies

MH Classification	Author	Study Measures Relating to Review Aims: Description Extracted from Individual Papers	Measurement Scales Selected	Measurement Scales excluded
Positive Mental Health	Pajareya and Nopmaneejumruslers (2019)	Primary Outcome The Functional Emotional Assessment Scale (FEAS) (child behaviours) - to measure changes in children's functional development. A 15-min videotaped child–parent interaction was collected for each child. Each parent was asked to play with their child as they normally would at home using a standard set of toys (including symbolic, tactile and movement play materials). Secondary Outcome Functional Emotional Developmental Questionnaire (FEDQ) - The questionnaire was related to Greenspan's Six Functional Development Levels (FDL): 1) shared attention and regulation; 2) engagement and relating; 3) purposeful emotional interaction; 4) social problem solving; 5) creating ideas; and 6) thinking logically. The difference between the increments determined the clinical progression.	FEAS scoring reported did not include sub-scales so the summary score is used in the meta-analysis. The score is interpreted as having positive directionality FEDQ scoring reported did not include sub-scales so the summary score is used in the meta-analysis. The score is interpreted as having positive directionality	No sub-scales were excluded No sub-scales were excluded
Positive Mental Health	Solomon et al. (2014)	Primary Outcome The Functional Emotional Assessment Scale – is a video assessment of a child's interactional/ social functioning. The FEAS has 6 sections and 34 items based on Greenspan's 6 functional developmental levels (FDLs), 33 which progress from simple attention (FDL 1) and engagement (FDL 2) to 2-way purposeful reciprocal exchanges (FDL 3), to problem solving gestures (FDL 4), and then to the consistent use of words (FDL 5) leading to rich pretend play, emotional thinking, and complex interaction (FDL 6). Items are rated as 0 (not at all or very brief), 1 (present some of the time, observed several times), or 2 (consistently present, observed many times). Ratings were summed to compute scores. Higher raw scale scores indicate greater social–emotional development. Items are rated as 0 (not at all or very brief), 1 (present some of the time, observed several times), or 2 (consistently present, observed many times). Ratings were summed to compute scores. Higher raw scale scores indicate greater social–emotional development. Parent child free play with toys in the home was video recorded for 15 min at pre- and post-assessment and coded by raters blind to group allocation and assessment time. Child Behaviour Rating Scale (CBRS) - The CBRS is composed of 7 items, which assesses 2 interactive style dimensions for children: Attention (4 items, a 5 .88 at baseline and .89 at follow-up) and Initiation (3 items, a 5 .70 at baseline and .83 at follow-up).	FEAS scoring reported did not include sub-scales so the summary score is used in the meta-analysis. The score is interpreted as having positive directionality. CBRS measure selected and both subscales are used: Attention Initiation	No sub-scales were excluded No sub-scales were excluded
Positive Mental Health	Pilarz (2009)	Primary Outcome The Functional Emotional Assessment Scale (FEAS) - The FEAS assesses children whose developmental age is between 7 months and 4 years, who are at risk or have problems in the development of attachment, regulation, social engagement, play interactions and emotional functioning. The FEAS focuses on the dynamic interaction between caregiver-child. The FEAS provides a formal system of coding child and caregiver's behaviours using the six developmental levels of the DIR/Floortime Model.	FEAS measure selected but only the ‘total sub-scale’ is used in the meta-analysis. The score is interpreted as having positive directionality.	FEAS subscales excluded: Subscale 1 - Attachment Subscale 2 - Regulation Subscale 3 - Social engagement Subscale 4 - Play interactions Subscale 5 - Emotional functioning
Positive Mental Health Outcomes	Doernberg, et al. (2021)	Primary Outcome The Kusche Affective Inventory Revised (KAI-R) - a child interview-based measure used to directly evaluate children's emotional understanding abilities. Two sections: 1) their ability to generate lists of feelings and describe emotional experiences of simple and complex emotions, while defining more complex emotions, and 2. their ability to understand the emotional states of self and other). (For the emotional experience section, children were asked to generate a list of as many positive and negative feelings that they could without a time limit, and up to three prompts of “Any more?” by the researcher. A total frequency score was then calculated for positive emotions, negative emotions, and total number of emotions. Responses were coded only if they qualified as valid positive/negative emotions per the manual (Greenberg et al., 1995). Each child was next asked to provide examples of times when he/she had felt 10 specific emotions, ranging from simple to complex: happy, sad, angry, scared, love, proud, guilty, jealous, anxious, and lonely (e.g., “Tell me about a time when you felt happy?”). If a child had difficulty providing an example for a particular emotion, he/she was asked to give an example of a time when someone else felt that emotion (Greenberg et al., 1995). Responses were coded on a 4-point developmental scale according to the manual (Greenberg et al., 1995). A sum score was calculated for the child's ability to appropriately describe an emotional experience (sum of all coded responses across the 10 different emotions based on the 4-point scale). Additionally, a sum score was calculated for the child's quality in defining a more complex emotion (sum of all coded responses across the five latter complex emotions— proud, guilty, jealous, anxious, and lonely—based on a 0–2 scale from Greenberg et al., 1995). For the understanding of emotional states of self and other section of the KAI-R, children were asked to provide cues used to recognise emotional states in themselves and others. The children were asked about five emotional states: happy, sad, scared, angry, and love (e.g., for self: “How do you know when you are feeling happy?”, for other: “How do you know when other people are feeling happy?). The responses were coded in accordance with the cognitive developmental framework of Carroll and Steward (1984), on a 4-point developmental scale according to the manual (Greenberg et al., 1995). The scores for each of the five emotions for self and other were summed to provide two total scores of understanding of emotional states of self, and understanding of emotional states of other.	KAIR measure selected but only the following sub-scales are used: Total positive affect (coded as positive mental health) This scale consists of counts of positive feelings and is interpreted as having positive directionality.	KAIR excluded Scales: Total affect Total appropriate Total quality Total understanding of self Total understanding of other
Negative Mental Health	Doernberg, et al. (2021)	Primary Outcome The Kusche Affective Inventory Revised (KAI-R) -	KAIR measure selected but only the following was sub-scales used: Total negative affect (coded as negative mental health). The scale consists of counts of negative feelings and is interpreted as having positive directionality.	KAIR excluded Scales: Total affect Total appropriate Total quality Total understanding of self Total understanding of other
Negative Mental Health	Corbett, et al. (2017)	Primary Outcome STAI-C. The STAI-C is a questionnaire - The scale is based on the original STAI, modified for children, and has been used to measure anxiety in numerous previous intervention studies. The inventory measures state (current) and trait (persistent) anxiety. Alpha reliability of the STAI-C is high, ranging from 0.78 to 0.91 (Muris 2002). Test–retest reliability for STAI-C Trait is higher (0.65–0.71) than the test–retest reliability for STAI-C State (0.31–0.41), but this is valid, as the STAI-C State is intended to measure a transient state (Julian, 2011). Furthermore, STAI-C effectively distinguishes between those with and without anxiety disorders (Seligman et al., 2004) and correlates with other measures of anxiety (Spielberger & Edwards, , 1973).	STAIC measure selected and both subscales are used: Trait anxiety State anxiety This scale expresses negative emotions and is interpreted as having negative directionality or lower scores imply less anxiety	No subscales were excluded
Negative Mental Health	Ioannou, et al., (2020)	Primary Outcome State-Trait Anxiety Inventory for Children - The STAIC is a self-report questionnaire aimed to measure both State (current) and Trait (enduring) anxiety (Spielberger et al., 1983). It has been utilised among both TD youth (e.g., Muris & Merckelbach, 1998) and youth with ASD (Lanni et al., 2012; Park et al., 2013; Simon & Corbett, 2013). Alpha reliability ranges from 0.78 to 0.91; test–retest reliability for the STAIC-Trait is 0.65–0.71 (Julian, 2011). Participants in the EXP and WLC groups were administered the STAIC after the PIP.	STAIC measure selected and both subscales are used: Trait anxiety State anxiety This scale expresses negative emotions and is interpreted as having negative directionality or lower scores imply less anxiety	No subscales were excluded
Negative Mental Health	Rezaei et al. (2018)	Primary Outcome Aberrant Behavior Checklist (ABC): The checklist includes 58 questions designed to assess the presence and severity of maladaptive behaviors in people with developmental disabilities. This tool evaluates five categories of behavioural disorders, three of which are the main defects in autism: lethargy, stereotypical behaviour, and inappropriate speech, with the other two being related to hyperactivity/restlessness and irritability.	ABC measure selected but only the following subscales were used: hyperactivity/restlessness Irritability The scale expresses negative emotions and is interpreted as having negative directionality or lower score imply less hyperactivity/restlessness and irritability,	ABC subscales excluded: Lethargy Stereotypical behaviour Inappropriate speech
Umar to decide the categorisation of the attachment outcome variable (According to the attachment scales that the authors used)	Siller et al., (2014)	Primary Outcome The Proximity and Contact Seeking Behaviors (PCSB) Scale “The PCSB evaluates the intensity of a child's effort to regain contact with, or proximity to, their mother. Higher PCSB scores indicate that the child took initiative in achieving contact, where lower scores indicate the child made no effort to make contact with their mother (p.1725)”. The Avoidant Behaviors (AB) Scale “The AB evaluates the intensity and duration of the child's avoidance toward their mother. Lowest AB scores indicate that the child did not greet his/her mother upon reunion despite the mother's attempts at interaction, where higher scores indicate that the child did not display avoidant behaviors toward his/her mother. Please note that both measures were scored so that higher numbers represent stronger signs of attachment (p.1725)”. Observed Attachment Behaviours (mean of PCSB and AB) The authors created a global measure of observed attachment behaviours, which was computed as the average of children's PCSB and AB scores. Higher means represent stronger signs of attachment. Maternal Perceptions of Child Attachment questionnaire (MPCA;Hoppes and Harris 1990). “This parent-report measure consists of 23 items rated on a 5-point rating scale, ranging from frequently (1) to never (5). High scores indicate maternal perceptions of strong child attachment (p.1725)”.	PCSB measure did not include sub-scales so the total score is used in the meta-analysis. PCSB total score is interpreted as higher numbers represent stronger signs of attachment. AB measure did not include sub-scales so the total score is used in the meta-analysis. AB total score is interpreted as higher numbers represent stronger signs of attachment. Observed Attachment Behaviour measure did not include any subscales as it is created as the sum of PCSB and AB measures. Therefore, the total score in this scale is interpreted as higher means represent stronger signs of attachment. MPCA measure did not include sub-scales so the total score is used in the meta-analysis. MPCA total score is interpreted as higher numbers represent stronger signs of attachment.	No subscales were excluded
Negative Mental Health	Schottelkorb et al. (2020)	Primary Outcome Child Behavior Checklist (CBCL) - The CBCLs for children ages 1 to 5 and 6 to 18 are instruments of the Achenbach System of Empirically Based Assessment. Both measures are used for examining emotional and behavioral problems as well as adaptive functioning of children as rated by parents/guardians. In our study, parents rated the items on the CBCL on a 3-point Likert-type scale ranging from 0 (not true) to 2 (very true or often true). The instruments are designed to evaluate child behaviors across three domains—externalizing, internalizing, and total behavior problems—using various subscales. Due to the varied ages of participants in this study, the two different CBCL versions were used. Because the two versions offer differing subscales, we focused on comparing pre-post data from those subscales that were consistent across the two types: Attention Problems, Aggressive Behavior, and Externalizing Problems. Scoring procedures for the CBCL involve calculating T scores and percentiles for each subscale. T scores between 60 and 63 are considered borderline, suggesting an area of concern, and T scores higher than 63 are considered clinical. Both versions of the CBCL (1–5 and 6–18) are reliable (test-retest coefficients between .68 and .92) and valid for identifying individuals with internalizing and externalising behaviours (Achenbach & Rescorla, 2001).	CBCL measure selected but only the following subscale was used: externalising problems The scale expresses negative emotions and is interpreted as having negative directionality or lower score imply less externalising problems	CBCL subscales excluded: Attention Problems Aggressive Behaviour
Negative Mental Health	Duifhuis et al. (2017)	Secondary Outcome Child Behavior Checklist (CBCL) - behavioral problems were measured using parents’ ratings on the Dutch translation of the Child Behavior Checklist (CBCL). This is a widely used standardised questionnaire for those aged either 1 − 5 or 6–18 years (Achenbach & Rescorla 2000). The CBCL is a parent rating scale which measures children's general problem behavior and internalizing and externalizing behavior, while more specific problem behaviors are assessed with supplementary scales. In the analyses of this study, three major scales in the CBCL were focused on: The total scale, externalizing behavior, and internalizing behavior. Cut-off scores for clinically elevated symptoms are based on T-scores ≥ 68 (Achenbach ∧ Rescorla 2000). Internal consistencies (Cronbach's Alpha) for the Dutch version were found to be >0.90 (Verhulst et al., 1996).	CBCL measure selected and the following subscales were used: Externalising behaviour Internalising behaviour High scores are indicators of negative mental health so the scale is interpreted as having positive directionality	CBCL subscales excluded: Total scale