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National Collaborating Centre for Women’s and Children’s Health (UK). Autism: Recognition, Referral and Diagnosis of Children and Young People on the Autism Spectrum. London: RCOG Press; 2011 Sep. (NICE Clinical Guidelines, No. 128.)

7Assessment of coexisting conditions

Introduction

This chapter focuses on the coexisting conditions that any healthcare professional should think about when a child or young person is undergoing an autism diagnostic assessment.

There are a number of disorders or diagnoses that co-occur in autism at higher than expected rates and these are referred to as coexisting conditions. This differentiates them from other common health problems and conditions that affect other children and young people. They may also, in some instances, be regarded as risk factors (see Chapter 4, Following referral) and may also be differential diagnosis (see chapter 6, Differential diagnosis). The reasons why some disorders co-occur more commonly in people with autism is not well understood.

Coexisting conditions may either be treatable in their own right or may influence the long-term outcome for the child or young person. When there is a focus on the diagnosis of autism, it is possible to neglect other diagnosable conditions. The most important coexisting conditions are those that occur most frequently, have a high impact on present quality of life, or may impact on the future development of the child or young person.

Clinical question

Which are the common coexisting conditions that should be considered as part of assessment?

7.1. Overview of the evidence

A list of possible coexisting conditions and symptoms to include in the review was agreed with the guideline development group (GDG).

In total, 38 studies were included in the review. All of the studies were uncontrolled observational in design and were graded as very low quality. The studies were carried out in Brazil,150 Canada,151 Czech Republic,152 Finland,153;154 France,155157 Italy,158160 Israel,161 Netherlands,162 Japan,163;164 Portugal,165 Sweden,166 the UK,167171 the USA,172185 Turkey186 and Venezuela.187 One study was conducted in both Europe and the USA.188

One study included children of preschool age179 and three studies included primary school age children.158;177;184 No study included children of secondary school age only. Seven studies included mixed preschool and primary school age children;151;156;166;167;172;185;187 13 studies included mixed primary and secondary school age children;150;154;155;157;159;162;165;168;171;174176;178 and 12 studies included all age groups.152;153;160;161;164;169;170;173;180;182;183;186 Two studies included adults (age over 19 years).181;188 Age was not reported in the remaining studies.

Only one study reported mean intelligence quotient (IQ) scores but the proportion of children with intellectual disability was not reported.178 Fourteen studies reported the proportion of children with intellectual disability but no separate outcome was provided for each IQ group.152;153;156;157;163;165;168;169;176;181;184186;188 One study only included children with intellectual disability160 while three studies excluded children with intellectual disability.151;154;166 Intellectual ability was not reported in the remaining studies.

Details of the individual studies are presented in evidence tables (see Appendix H, Tables of included studies).

Given the number of coexisting conditions reported in the evidence tables, the evidence statements only summarise the data for the most common conditions.

7.2. Evidence profiles

Table 7.1 summarises the data for each common coexisting condition in children and young people with autism and table 7.2 summarises the data for children and young people with autism spectrum disorders (ASD). The data for autism has been separated from the data for ASD as it was expected that some coexisting conditions would have different prevalence rates for each category and so it would not be appropriate to pool these data.

Table 7.1. Prevalence of each coexisting condition in children or young people with autism.

Table 7.1

Prevalence of each coexisting condition in children or young people with autism.

Table 7.2. Prevalence of each coexisting condition in children with ASD.

Table 7.2

Prevalence of each coexisting condition in children with ASD.

7.3. Evidence statements

Evidence for autism

All evidence was graded as very low quality.

Mental and behaviour disorders

Prevalence data for 12 conditions were identified: ADHD, adjustment disorder, an aggression problem, anxiety, an attention problem, bipolar disorder, depression, emotionally reactivity, OCD, ODD, self-injurious behaviour and somatic complaints syndrome. Only studies examining the prevalence of the most common conditions are reported here.

The pooled prevalence of ADHD was 41% (95% confidence interval [CI] 21, 63). The prevalence for self-injurious behaviour was 49%, for anxiety 62%, for ODD 7%, for OCD 37%, for depression 13% and for seizures 18%.

Neurodevelopmental conditions

Prevalence data for three conditions were identified: language problems, intellectual disability, regression and restricted interest. Only studies examining the prevalence of intellectual disability are reported here.

The pooled prevalence for intellectual disability was 76% (95% CI 61, 89).

Medical or neurological conditions

Prevalence data for 15 conditions were identified: auditory deficits; epilepsy; gastrointestinal problems; chromosomal abnormalities; congenital disorder; genetic disorder; motor impairment; obesity (body mass index more than [BMI] 95th centile); perinatal condition; sleep problem; vision deficits; cerebral palsy; seizures; hydrocephalus and meningitis. Only studies examining the prevalence of cerebral palsy, sleep problems, gastrointestinal problems, epilepsy, motor problems, vision deficits and auditory deficits are reported here.

The pooled prevalence of cerebral palsy was 5% (95% CI 4, 6), for sleep problems it was 37% (95% CI 11, 68), for epilepsy it was 24% (95% CI 8, 46), for vision deficits it was 7% (95% CI 0, 26) and for auditory deficits was 3% (95% CI 0, 9). The prevalence for motor problems and gastrointestinal problems was 13% and 3% respectively.

Evidence for ASD

Mental and behavioural disorders

Prevalence data was identified for 13 conditions: ADHD; adjustment/reactive attachment/post-traumatic stress disorder; anxiety; behaviour problem; bipolar disorder; conduct disorder; depression; mutism; OCD; oppositional defiant disorder (ODD); psychotic disorder; tic; and Tourette syndrome. Only studies examining the prevalence of ADHD, anxiety, ODD, tic, OCD, depression, Tourette syndrome and conduct disorder are reported here.

The pooled prevalence in children with ASD for the different conditions was:

  • ADHD: 45% (95% CI 24, 67)
  • anxiety: 27% (95% CI 10, 49)
  • ODD: 23% (95% CI 6, 47)
  • tics: 19% (95% CI 2, 47)
  • OCD: 8% (95% CI 2, 17)
  • depression: 9% (95% CI 3, 19)
  • Tourette syndrome: 12% (95% CI 2, 28)
  • conduct disorder: 3% (95% CI 0, 9).

Neurodevelopmental conditions

Prevalence data were identified for four conditions: communication disorders; language problem; intellectual disability; and regression. Only the nine studies examining the prevalence of intellectual disability are reported here.

The pooled prevalence for intellectual disability was 65% (95% CI 38, 87).

Medical or neurological conditions

Prevalence data were identified for 17 conditions: cerebral palsy; hydrocephalus; asthma; auditory deficits; chromosomal abnormalities; congenital disorder; epilepsy; seizures; febrile convulsions; gastrointestinal problems; genetic disorder; mitochondrial respiratory chain disorder; motor impairment; obesity (BMI more than the 95th centile); sleep problem; vision deficits; and elimination disorder. Only studies examining the prevalence of cerebral palsy, epilepsy, seizures, gastrointestinal problems, sleep problem, motor problem, vision deficits and auditory deficits are reported here.

The pooled prevalence for the conditions was:

  • cerebral palsy: 5% (95% CI 1, 13)
  • sleep problems: 61% (95% CI 31, 88)
  • epilepsy: 15% (95% CI 7, 26)
  • seizures: 5% (95% CI 2, 69)
  • motor problems: 25% (95% CI 0, 75)
  • vision deficits: 6% (95% CI 0, 21)
  • auditory deficits: 8% (95% CI 1, 20).

The prevalence for gastrointestinal problems was 62%.

7.4. Evidence to recommendations

Relative value placed on the outcomes considered

The GDG agreed specific criteria for whether a disease or symptom should be considered a coexisting condition with autism. The conditions listed had to have at least one of the following characteristics:

  • a documented prevalence rate of the condition in children and young people with autism higher than that for the general population
  • likely to benefit from appropriate intervention(s)
  • likely to have an important impact on quality of life.

The GDG also considered the ease of diagnosis, defined as diagnostic accuracy, and the cost effectiveness of treatment of the condition if identified.

Trade-off between clinical benefits and harms

The identification of important coexisting conditions was of clinical benefit because it may affect how a child is cared for in all aspects of the diagnostic process and subsequent management and support. Systematic enquiry into coexisting conditions should be part of any clinical assessment of a child or young person with suspected or confirmed autism because there are various known conditions associated with autism that, if not recognised, can impact on the welfare of the child or young person. Identification of other disorders in a child with suspected or confirmed autism contributes to an understanding of the individual’s profile of strengths and weaknesses and informs intervention. Some conditions require specific medical intervention or modification of the overall treatment strategy. It might also lead to the identification of other family members with the condition and have implications for genetic counselling.

The available evidence shows that a wide range of disorders and symptoms can co-occur in children and young people with autism. The GDG took into consideration the possible harm associated with assessing a child or young person for coexisting conditions, which includes prolonging the autism-specific diagnostic assessment. Looking for coexisting conditions in addition to autism could cause distress to the child or young person and to their parents or carers. In all stages of the autism pathway, the risk of such difficulties can be alleviated by good communication and close involvement of the child or young person and their parents or carers in the process. The GDG considered that, overall, the potential benefits of early identification of coexisting conditions outweigh the possible harms.

Trade-off between net health benefits and resource use

Clinical assessment to find evidence of a coexisting condition may significantly increase the time required for a clinical assessment of a child or young person with suspected autism. Given the possible benefits of recognising coexisting conditions, the GDG considered this likely to be a cost-effective use of a healthcare professional’s time. However, additional assessments for coexisting conditions is only cost effective if the additional cost (including assessments undertaken on individuals who turn out not to have the condition) can be justified by the health benefit of early identification and management. No evidence to support or refute the cost effectiveness of early identification of coexisting conditions was identified.

However, the GDG’s consensus was that use of healthcare resources to look for rare conditions in individuals without clinical manifestations to suggest their presence could not be justified. Furthermore, assessing a child or young person for coexisting conditions for which no useful treatment existed should not be undertaken since there is no health improvement from such an assessment. All the conditions on the list of coexisting conditions agreed by the GDG are important because either there are specific treatments of proven efficacy or they require support and management with clinically important benefits to the individual. The GDG considered that identifying important coexisting conditions and undertaking further assessments of these conditions on the basis of clinical judgement was likely to be a cost-effective use of NHS resources.

Quality of evidence

Where there were multiple studies identified for one condition or symptom, the prevalence estimates vary widely. This reflects both differences in the populations studied and variation in the ways in which coexisting conditions were identified. The evidence on prevalence summarised in the literature is highly variable and is not exhaustive.

There were insufficient studies overall and a lack of replication of findings across studies, as well as under-reporting of important coexisting conditions. The GDG was unable to judge how comparable the studies were with each other and whether they reflected usual clinical practice in the UK. In certain cases (for example intellectual disability) the pooled prevalence statistic was in conflict with the clinical experience of GDG members, although in this particular case they also noted that the confidence intervals for all children with ASD (as opposed to autism) were wide and therefore that the true value would lie within this range.

Other considerations

The term used for a condition in the table is taken directly from the literature except where the GDG considered a more generic term was appropriate. For example, ‘mood disorder’ is an interpretation by the GDG of the evidence for depression and genetic disorders instead of genetic abnormalities. The terms ‘seizure’ and ‘epilepsy’ are also used here, although other terms are used in the studies.

The consensus of the GDG was that, when assessing a child or young person with suspected or confirmed autism, the healthcare professional should always consider the possibility of a coexisting condition and should undertake an appropriate systematic clinical enquiry with this in mind. This should identify the presenting problem and any relevant history.

The GDG noted that the communication difficulties associated with autism might increase the risk of coexisting conditions going undetected. For example, functional mental health difficulties might be overlooked. The GDG recommended that particular attention be given to information from other sources (including direct observation of the child or young person) and in different settings.

The GDG was aware that healthcare professionals have raised the possibility of eating disorders being a coexisting condition with autism, but at the current time the evidence is not strong enough and the clinical view within the GDG was that this should not be listed as a coexisting condition that should be systematically looked for.

Recommendations

NumberRecommendation
54Consider whether the child or young person may have any of the following as a coexisting condition, and if suspected carry out appropriate assessments and referrals:
Copyright © 2011, National Collaborating Centre for Women’s and Children’s Health.

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Cover of Autism
Autism: Recognition, Referral and Diagnosis of Children and Young People on the Autism Spectrum.
NICE Clinical Guidelines, No. 128.
National Collaborating Centre for Women’s and Children’s Health (UK).
London: RCOG Press; 2011 Sep.

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