Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 https://doi.org/10.1186/s12888-021-03330-y RESEARCH ARTICLE Open Access Functioning assessment short test (FAST): validity and reliability in adults with Autism Spectrum Disorder Laura Gisbert-Gustemps1,2,3,4*† , Jorge Lugo-Marín1,4*†, Imanol Setien Ramos2, Gemma Español Martín1,2,3, Eduard Vieta5, C. Mar Bonnín5 and Josep Antoni Ramos Quiroga1,2,3,4 Abstract Background: The assessment of functional impairment is crucial both for the diagnosis and the therapeutic approach to autism spectrum disorder (ASD). The purpose of the present study was to evaluate whether the FAST is a reliable and valid tool to assess functional impairment in adults with Level 1 ASD and to study the differences in psychosocial functioning between younger and older adults with ASD. Methods: A case–control study was carried out in a sample of 150 participants, 71 adults with Level 1 ASD, and 79 adults without psychiatric history records. Results: Results showed good psychometric properties in terms of validity and reliability. Cronbach’s alpha for the total scale was .91 and the area under the curve was .98. The study also showed that adults with ASD present different profiles of functional impairment depending on their age: while younger patients present greater impairment in autonomy, older patients show more difficulties in interpersonal relationships. Conclusions: Our results support the use of the FAST in the evaluation of adaptive functioning in adults with Level 1 ASD. Keywords: Autism Spectrum quotient, Adult, Functioning, Validity, Reliability, Factor analysis Background The severity of ASD can vary greatly and is based on Autism spectrum disorder (ASD) is a neurodevelopmen- the degree to which social communication, insistence on tal condition with a prevalence of up to 1 out of 54 the sameness of activities and surroundings, and repeti- children and it is characterized by early onset of social- tive patterns of behavior affect the daily functioning of communication difficulties and repetitive or stereotypical the individual [2]. The term “spectrum” refers to the behaviors [1]. According to the Diagnostic and Statistical wide range of symptoms, skills, and levels of disability Manual of Mental Disorders, Fifth Edition Disorders in functioning that can occur in people with ASD. In (DSM-5) criteria, these symptoms cause “clinically sig- fact, adult outcomes are diverse from individuals who nificant impairment in social, occupational, and other remain non-verbal to those able to work and live fields of current functioning” [2]. independently [3]. One of the main therapeutic objectives for individuals with ASD is autonomy in adulthood [4]. Thus, a useful and easy-to-use tool for the assessment of the subject’s * Correspondence: lgisbert@vhebron.net; jlugo@vhebron.net † functional state is urgently needed to guide the thera- Laura Gisbert-Gustemps and Jorge Lugo-Marín share first authorship. 1 Department of Psychiatry, Universitari Vall d’Hebron Hospital, Barcelona, peutic effort to obtain the best results. Catalonia, Spain Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 2 of 8 The assessment of functional impairment, including appropriate either due to their length, missing areas of different areas of a person’s life, such as education, fam- evaluation in a person’s life and not having validation in ily, social life, working life, leisure and free time [5], is ASD population. Finally, in ASD and other neurodeve- crucial both for the diagnosis and the therapeutic lopmental disorders such as ADHD [21, 22] instruments approach to ASD. ASD has been widely studied in like the Sheehan’s Disability Scale (SDS) [23] are being children, but the quantity and quality of adult research used because of its easy application despite not having is scarce [6, 7]. Valid, reliable, and sensitive outcome sufficient psychometric properties. measures, which are fundamental for the development According to this, efforts are needed to adapt the of an evidence-based for clinical effectiveness, are also existing instruments and/or develop and evaluate new lacking [8]. To date, the little existing evidence points to ones for assessing specific or related outcomes in a poor psychosocial outcome for adults with ASD, even adult individuals with ASD. Low cost, valid, and not in the less severe group [4]. time-consuming measures are needed to facilitate Also, the different stages of adulthood have been stud- research and monitoring of patients outcome. The ied in relation to the trajectory of people with ASD in Functioning Assessment Short Test (FAST) [24] was different areas of adaptive functioning [9, 10]. However, created in order to evaluate functional impairment in there have been conducted very few studies that have patients with mental health difficulties. It is a short directly compared the different stages of adult life in the (6 min to apply) and simple interview-administered ASD population. Lever et al. [11] studied the prevalence instrument which evaluates different domains of func- of psychiatric disorders in young, middle and older tioning regarding the last 15 days before assessment. adults, finding a higher level of psychopathology in The higher the score greater difficulties functioning young and middle-aged adults when compared to older and greater severity [24]. adults. These differences throughout adult life can be Results of previous studies using the FAST showed reflected in different levels of functionality, being able to optimal validity and reliability properties in patients establish different trajectory profiles according to the suffering from different mental health conditions. For adult stage. Regarding levels of functionality adaptative instance, in patients with bipolar disorder, high internal behavior measures, particularly daily living skills, have consistency for the overall scale (Cronbach’s alpha of been the variables most closely correlated with outcome .909) as well as for all its domains have been found [24] . in people with ASD [12] and evidence supports that are In another study with patients with first psychotic not fully accounted for by differences in cognitive ability episodes [25], an internal consistency level of .88 at [13]. The curvilinear association between full-scale baseline, .89 six months later, and .94 one year later have intelligence quotient (IQ) and adaptive behavior found been reported. Recently different severity gradations in in the study by Chatham et al. [14] suggests that IQ does first-episode of non-affective psychosis patients have not fully explain adaptive behavior difficulties among been stablished using this test [26]. The FAST also individuals with ASD, particularly at high IQs where showed good psychometric properties and could detect the association between IQ and adaptive behavior is functional differences between patients with a diagnosis attenuated. of schizophrenia and healthy subjects [27]. Finally, To assess functioning in ASD population, the Vineland Rotger et al. [5] obtained good psychometric properties, Adaptive Behavior Scales, Second Edition (VABS-II) [15] in terms of reliability and validity, in the measure of the and the Adaptive Behavior Assessment System, Second functional level of adults with ADHD. Edition (ABAS-II) [16] are widely used. The VABS-II is Hence, the purpose of the present study is to evaluate the leading instrument for supporting the diagnosis of whether the FAST could be a reliable and valid tool to intellectual and developmental disabilities and the assess the functional outcome in adults with ASD in an ABAS-II is a checklist of a broad range of skill areas re- outpatient clinical setting and to study the differences in lated to development, behavior, and cognitive abilities. psychosocial functioning between younger and older Although they are extensively used, they present some adults with ASD. disadvantages, such as their length, making them diffi- cult to apply routinely in a medical setting; moreover, they might not be reliable to assess functioning in people Method with ASD who do not present intellectual disability. This is an observational case-control study. The study Other measures used to evaluate functionality like The took place in two hospitals from the mental health World Health Organization Disability Assessment network of Catalonian Health Institute: Vall d’Hebron Schedule II (WHO-DAS II) [17], the SF-36 Health Sur- Hospital and Barcelona Clinic Hospital. The time vey (SF-36) [18], the Global Assessment of Functioning window was set in one year and comprised from Scale [19] or the Independent Living Scales [20], are not January 2019 to January 2020. Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 3 of 8 Participants point visual analog scale. Clinicians are recommended to A sample of participants with ASD was recruited from pay special attention to patients who score 5 or higher the monitored population within the Comprehensive on any of the three scales because such high scores are Care Program for Autism Spectrum Disorder (PAITEA), associated with significant functional impairment. The from the Vall d’Hebron Hospital’s Psychiatry Depart- SDS has shown good validity and reliability in Spanish ment. All participants were diagnosed using the Autism clinical population [30]. Diagnostic Observational Schedule-2 [28] by trained clinicians (L.GG and J.L.M). Inclusion criteria included: Statistical analyses 1) being aged between 18 and 65 years; 2) diagnosis of To study the normality of the FAST variables, Shapiro– ASD according to DSM-5 diagnostic criteria [2]. Wilk coefficient was applied. The results showed significant Respondents’ language and cognitive barriers and ASD deviations from normality, precluding the use of parametric levels 2 and 3 were considered as exclusion criteria [2]. tests. The reliability coefficient (Cronbach’s alpha) was used The nonclinical control group (NC) was recruited at the to examine the internal consistency of the FAST items in Barcelona Clinic Hospital’s Bipolar and Depressive each domain and the full scale. Cronbach’s alpha measures Disorders Unit [29]. NC inclusion criteria were (1) age were considered minimally acceptable if α = .65, acceptable between 18 and 65 years, (2) no current or past psychi- if α = .7, and optimal if α = .8 [31]. Spearman’s correlation atric history as collected from medical records, and (3) coefficient was calculated to examine the correlations be- non-reported history of family psychiatric disorder. tween the FAST and the SDS scores. To explore intergroup differences between ASD versus controls and between Assessment younger ASD adults (18–25 years) versus older ASD adults After informing the participants and obtaining their (= > 26 years), nonparametric tests (U Mann-Whitney test) written consent, the investigator recorded demographic for each FAST domain were conducted. A confirmatory (age and gender) and clinical variables (psychiatric diag- factor analysis (CFA) with the original six-factor structure nosis history, if any) and administered the FAST scale of the FAST was studied. When evaluating the fit of the [24]. The FAST is an interviewer-administered instru- CFA and stability models to the data, the root mean square ment, designed to be used by a trained clinician. The error of approximation (RMSEA) and comparative fit index evaluation time-window refers to the last two weeks. (CFI) were used. RMSEA values below .06 indicate a good The areas evaluated with the FAST are six, including: 1) fit to the data and CFI values close to .95 are acceptable Autonomy, related to the ability of living on their own, [32]. The optimal cut-off point of the measure was analyzed taking care of themselves (physical appearance, hygiene by the area under the ROC curve (AUC). The AUC values …); 2) Occupational functioning, capacity to get and were considered minimally acceptable when lower than .7, keep a paid job and being efficient at it, working in the acceptable when between .7 and .8, optimal when between field in which the patient was educated, and earning .8 and .9, and excellent when above .9 [33]. Data analyses according to the level of his/her position; 3) Cognitive were carried out with the statistical package IBM SPSS 19.0 functioning, being able to concentrate while reading or and AMOS 26.0 for Windows. The alpha level was set at watching a movie, solve problems, remember simple p < .05. data and learn new information; 4) Financial issues, be- ing capable to manage their own finances; 5) Interper- Results sonal relationships, refers to the capacity of keeping The total sample consisted of 150 participants: 71 adults friendships, getting well with family, involvement in so- with a diagnosis of ASD level 1 (43 male, 28 female), cial activities, sexual relations, and being able to express and 79 adults without psychiatric history records (51 and defend own interests; 6) Leisure Time, capacity to female, 28 male). The mean age in the ASD group exercise and enjoy a hobby. Items (24 in total) are rated was 30.03 years (SD = 12, range 18–61), and 39.54 on a 4-point scale, ranging from 0 (no difficulty) to 3 years (SD = 11, range 19–55) in the healthy control (severe difficulty). All scores are added to obtain a global group (Z = − 5.02, p < 0.001). The estimated time to punctuation for which high scores indicate poorer func- complete the FAST was approximately 8 min. tioning [24]. Additionally, the Sheehan’s Disability Scale (SDS) [23] Internal consistency was also administered. It is a three-item instrument Cronbach’s alpha showed excellent value for the widely used in clinical settings, which measures the se- FAST total score (α = .97) in the total sample of verity of disability in three inter-related domains: work, participants, and also for the ASD group (α = .91), family life/home responsibilities, and social/leisure whereas acceptable values were found for the NC activities. The patient rates the extent to which responsi- group (α = .76). Table 1 shows internal consistency bilities are impaired by his or her symptoms on a 10- results for each FAST subscale. Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 4 of 8 Table 1 Internal consistency (Cronbach’s alpha) for all FAST subscales and Total score Total sample (n = 150) ASD (n = 71) NC (n = 79) FAST Total score (24 items) 0.97 0.91 0.76 Autonomy (4 items) 0.92 0.85 0.02 Occupational functioning (5 items) 0.91 0.80 0.91 Cognitive functioning (5 items) 0.90 0.82 0.42 Financial issues (2 items) 0.95 0.93 0.88 Interpersonal relationships (6 items) 0.94 0.82 0.54 Leisure (2 items) 0.56 0.48 0.18 Convergent validity (Fig. 1). The RMSEA value was .104, (90% CI [.94, .11]; Spearman’s correlations analyses were conducted to p = .00), which is below the acceptable threshold, whereas study convergence between the FAST total score with the CFI value was .90, indicating poor model fit. the SDS scores. Results showed significant small to moderate correlations with each of three SDS do- ROC curve mains: Work (r = .54, p < .001), Social Life (r = .27, The AUC was .98, 95% CI [0.96, 1] which, being close to p = .02), and Family Life (r = .31, p = .01). FAST Occu- 1, indicates excellent discriminant capacity. A total pational Functioning also showed a moderate correl- FAST score above 12 reached best sensitivity (96%) and ation with SDS Work domain (r = .61, p < .001); specificity (94%) scores. Positive and negative predictive FAST Interpersonal Relationships correlated with the values were .96 and .94, respectively. Figure 2 shows the SDS Social domain (r = .46, p < .001); and the FAST ROC curve for the FAST total score comparing the ASD Family Life item (Item 20) correlated with the SDS and NC groups. Family Life domain (r = .68; p < .001). Discussion Intergroup mean differences The main goal of this study was to analyze the psycho- Table 2 shows the results of the intergroup mean differ- metric properties of the FAST scale for the first time in ences analysis. The ASD group showed significantly ASD population using a sample of patients with ASD higher scores in the FAST total score (Z = − 10.23, p < and non-clinical individuals. Results showed good psy- 0.001), and in all the subscales when compared to NC chometric properties in terms of validity and reliability. participants. When compared by age, younger ASD Cronbach’s alpha for the total scale was .91 and the area adults showed significantly lower scores in the FAST under the curve was .98. Moreover the ASD group Autonomy subscale (Z = − 2.31, p = .02), whereas older showed significantly higher scores in the FAST total ASD adults showed significantly lower scores in the score (Z = − 10.23, p < 0.001), and in all the subscales FAST Interpersonal Relationships subscale (Z = − 2.27, when compared to NC participants. p = .02). No significant differences in the FAST total A good functional outcome of people with autism is score were found between age groups (Table 3). the main objective for professionals, families, and the in- dividuals themselves, but there is no agreement about Confirmatory factor analysis the instrument to measure it in adults with ASD [34]. At The study of the internal structure of the FAST deter- present, there are some limitations to evaluate function- mined a poor model fit to the original six-factor structure ing in autistic people due to methodological issues, Table 2 Intergroup mean differences (sd) between ASD and NC participants ASD (n = 71) NC (n = 79) U Mann-Whitney (Z) FAST Total score 40 (13.55) 4.24 (4.63) −10.23* Autonomy 6.08 (3.4) 0.27 (0.63) −10.27* Occupational functioning 8.59 (3.84) 0.85 (2.56) −9.57* Cognitive functioning 7.62 (3.58) 1.11 (1.27) −9.75* Financial issues 2.83 (2.14) 0.2 (.81) −8.5* Interpersonal relationships 11.77 (4.4) 1.11 (1.58) −10.25* Leisure 3.08 (1.51) 0.7 (1.1) −8.35* *p < .05 Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 5 of 8 Table 3 Intergroup mean differences (sd) between ASD younger vs. older adults ASD younger adults ASD older adults U Mann-Whitney (Z) (n = 40) (n = 31) FAST Total score 39.33 (12.12) 40.84 (15.36) −.87 Autonomy 6.93 (3.21) 5 (3.39) −2.31* Occupational functioning 8.3 (3.23) 8.97 (4.54) −1.22 Cognitive functioning 7.23 (2.90) 8.13 (4.3) −.84 Financial issues 3.03 (2.06) 2.58 (2.26) −.90 Interpersonal relationships 10.9 (4.24) 12.9 (4.41) −2.25* Leisure 2.95 (1.34) 3.26 (1.71) −.93 *p < .05 particularly related to the wide heterogeneity in the Regarding the psychometric properties of the FAST cohorts studied and the variability in the measures scale, promising results were found in terms of validity used, which have led to inconsistent and sometimes and reliability, very similar to those obtained in bipolar contradictory research findings [4]. Thus more re- disorder [24], schizophrenia [25], first psychotic episodes search is needed in this field. [27], and ADHD [5]. Thus our results support the use of Fig. 1 Factor structure of the FAST, including factor correlation and factor loadings (N = 150; all subjects) Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 6 of 8 those obtained in previous studies regarding bipolar [24] and ADHD populations [5]. The study of the scale’s discriminant capacity also indicates that a score above 12 achieves the best balance between sensitivity (96%) and specificity (94%). Factor analysis showed poor model fit to the six-factor model pro- posed in the original validation [24]. This may be due to a small sample size. All items showed strong cor- relations with high factor loadings, except for Items 8 (Charge according to your position) and 24 (Having a hobby). Further studies should reconsider the original six-factor model when using the FAST in ASD population. In accordance with previous studies [4, 34], our re- Fig. 2 Receiver operating characteristic (ROC) curves illustrating the sults indicate poorer functional outcomes for adult ability of the total FAST scale to identify any ASD cases at alternative people with ASD compared to NC. Most studies of cut-oFf points. N = 150 (ASD vs NC) adults with ASD suggest that prognosis, as assessed by objective measures of social outcome (e.g., inde- pendence, employment, social relationships), is poor [4]. Considering the age group differences, the youn- the FAST in the evaluation of adaptive functioning in ger people showed more difficulties in the autonomy adults with ASD level 1. Moreover, the FAST can be domain. This may be explained by the fact that the very useful in clinical settings because it is short and sample of younger adults still lived with their parents, very easy to apply. The instrument has been translated compromising their possibilities of developing the to English and validated in different languages, including self-care necessary skills, as their relatives compensate French [35], Portuguese [36], and Italian [37], among for their difficulties, which leads to these younger others. ASD adults’ low motivation to perform these tasks by The analysis of the FAST’s internal consistency with themselves. On the other hand, older ASD adults Cronbach’s alpha showed good consistency between the show poorer interpersonal relationships, which might different responses and, therefore, between the scale’s be due to constant pressure to “fit in” with the items. An excellent alpha index of .91 was found for the demands of a society that fails to understand their ASD group, while an acceptable value, .76, was found for needs or difficulties [38]. Their inability to meet these the NC group. This may be because the NC is more het- demands may lead to stress and anxiety and progres- erogeneous than the ASD group, thus providing different sive isolation [39]. The older they get, the more social functioning profiles and, therefore, a lower consistency contacts center around special interests and skills, between items. rather than involving close, spontaneous friendships Concerning concurrent validity, modest positive cor- [40]. relations between the FAST total score and scores in each of the three SDS domains were observed. Similar Limitations results were obtained in a previous validation of the The findings of this study should be interpreted with FAST for ADHD population [5], where the SDS was caution, considering some limitations that have been also used to examine convergent validity. In both identified. First, given that patients and controls were cases, the modest correlation obtained could be re- not matched by gender, the number of males in the lated to the low similarity between the two measures ASD group is much higher than in the NC group. This in the number of items (the SDS with only 3 items is due to a higher prevalence of ASD in male population and the FAST with 24). In any case, when directly [41]. Further studies should address gender differences comparing specific social- and family-related items in the adaptive functioning of adults with ASD levels. with SDS subareas, higher convergence values were Also, in relation to age, the older ASD group comprised found. a wide range of ages (26–65 years). Considering the great Furthermore, we analyzed the scale’s discriminant variability that can occur throughout the different stages capacity between patients and controls using the diag- of adult life (middle adult vs. older adult), future studies nostic performance or ROC curve. The AUC was .98 should explore these differences with greater accuracy. which, being very close to 1, indicates an excellent Finally, the FAST might not be appropriate for ASD pa- discriminant capacity. These results are in line with tients of Levels 2 and 3 due to the content of the items Gisbert-Gustemps et al. BMC Psychiatry (2021) 21:321 Page 7 of 8 examined. Moreover, differences in cognitive domains Competing interests (e.g., executive function), as well as adaptive functioning The author LGG received travel awards for taking part in psychiatric meetings from Shire in the last 3 years. in our sample could not be reported as many of the par- The author EV has received grants and served as consultant, advisor or CME ticipants lacked this information. Future research could speaker for the following entities (unrelated to the present work): AB-Biotics, be conducted in order to adapt some items regarding Abbott, Allergan, Angelini, Dainippon Sumitomo Pharma, Ferrer, Gedeon Richter, Janssen, Lundbeck, Otsuka, Sage, Sanofi-Aventis, and Takeda. these variables and thus making the FAST more suitable The author JA.R.Q was on the speakers’ bureau and/or acted as consultant for the entire ASD spectrum. Among others, items like for Eli-Lilly, Janssen-Cilag, Novartis, Shire, Takeda, Bial, Shionogui, Lundbeck, support needs, communication skills, and cognitive and Almirall, Braingaze, Sincrolab, Medice and Rubió in the last 5 years. He also received travel awards (air tickets + hotel) for taking part in psychiatric behavioral difficulties could be taken into account. meetings from Janssen-Cilag, Rubió, Shire, Takeda, Shionogui, Bial, Medice and Eli- Lilly. The Department of Psychiatry chaired by him received unrestricted educational and research support from the following companies Conclusions in the last 5 years: Eli-Lilly, Lundbeck, Janssen- Cilag, Actelion, Shire, Ferrer, Despite the limitations, these preliminary results point Oryzon, Roche, Psious, and Rubió. out that the FAST scale presents adequate psychometric The authors JLM, ISR, GEM and CMB declare no conflict of interest. properties in terms of validity and reliability, suggesting Author details that it could be an adequate tool to measure of the func- 1 Department of Psychiatry, Universitari Vall d’Hebron Hospital, Barcelona, tioning in adults with ASD level 1. It shows a strong Catalonia, Spain. 2Group of Psychiatry, Mental Health and Addictions, Vall d’Hebron Research Institute (VHIR), Barcelona, Catalonia, Spain. 3Department discriminant capacity between ASD and nonclinical sub- of Psychiatry and Forensic Medicine, Universitat Autònoma de Barcelona, jects. Due to its characteristics, the scale is a feasible Barcelona, Spain. 4Biomedical Network Research Centre on Mental Health measure in healthcare settings, at least to assess patients (CIBERSAM), Madrid, Spain. 5Bipolar and Depressive Disorders Unit, Hospital Clinic, Institute of Neurosciences, University of Barcelona, IDIBAPS, CIBERSAM, with ASD level 1. The study also showed that adults Barcelona, Spain. with ASD present different profiles of functional impair- ment depending on their age: while younger patients Received: 6 December 2020 Accepted: 8 June 2021 present greater impairment in autonomy, older patients show more difficulties in interpersonal relationships. References Acknowledgments 1. Maenner MJ, Shaw KA, Baio J. 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