Recruitment is perhaps the most challenging part of a clinical research study and this phase II study will provide important information about the feasibility of recruiting to a full scale clinical trial. Inadequate recruitment is known to have a significant impact on the scientific and financial viability of RCTs. RCTs are widely accepted as the gold standard for the assessment of the safety and
efficacy of healthcare interventions. Successful patient recruitment and retention in clinical trials is known to be one of the most difficult aspects to complete in RCTs (McDonald et al., 2006). It has been reported that difficulties with recruitment can disrupt the timetable for a research project, preoccupy staff, reduce the ability of a therapeutic study to detect treatment differences and, ultimately, result in a trial being abandoned (Ashery & McAuliffe, 1992). Increasing participation in clinical research has become a key area within the National Health Service (NHS) to facilitate evidence-based policy, improve health outcomes and reduce health inequality (Watson and Torgerson, 2006).
There are multiple factors that have shown to influence recruitment rates to RCTs, such as greater age, male gender, non-white race, urban residence, low educational status, unemployed or low occupational status, low family income, smokers, recent illness or poor present health, high use of medical care (Armstrong et al, 1992). There are also reports that locations such as large cities have a factor that influence recruitment, with possible suggestions for lower recruitment rates such as varied ethnic population (individuals who are traditionally more difficult to engage in medical research), higher population mobility (individuals potentially missing invitations or reminders to participate) and more university hospitals (creating research fatigue as individuals are repeatedly approached to participate in research) (Gilbert et al., 2012) Additionally, Marcus and Schütz (2005) observed that research volunteers were more extroverted, more open to experience and more
narcissistic than non-volunteers, suggesting that personality traits could also be an influence to participation in research.
Adults with ASD can be a ‘hard-to reach’ population for researchers (Beadle-Brown et al., 2012). Howlin (2005) noted that the unique social-communicative profile associated with the autism spectrum is that some adults with ASD are reluctant to engage with new people and experiences or to disclose personal information that affects their willingness to participate in research. In addition, our study had a stringent inclusion and exclusion criteria, excluding individuals younger than 18 years of age and over the age of 35, who suffered from migraines (research by Sullivan and colleagues, (2014) has shown that the presence of migraines in ASD and sensory hyperactivity in the children are significantly linked), have ever suffered from epilepsy, febrile convulsions in infancy, had recurrent fainting spells or are on medications or psychoactive drugs that can lower seizure threshold (multiple studies have shown that up to 29% of individuals with ASD have
epilepsy; Tuchman, Rapin and Shunnar, 1991; McDermott et al., 2005; Amiet et al., 2008; Bolton et al., 2011; Cuccaro et al., 2012; Woolfenden et al., 2012; Viscidi et al., 2013), have a family history of epilepsy (Sundelin et al., 2016 reported that family members of an individuals with epilepsy are also at an increased risk) and suffer from any major mood disorders (research showing that up to 38% of individuals with ASD have a comorbidity of depression and up to 21.4% have a
comorbidity of bipolar disorder; Lainhart, 1999; Vannucchi et al., 2014). Therefore, not only did we have to contend with the recruitment issues faced elsewhere, but with additional set of issues
associated with our stringent inclusion and exclusion criteria.
After two years (first year without NHS ethics), and contacting 116 individuals with HFA, we were able to recruit 25 participants with HFA into the study (21.55% recruitment rate). Recruitment of
individuals with HFA started in February 2017, an initial planning stage involving co-investigator (CM) identifying potential participants to be recruited to the study. HFA participants were recruited from service users of the Adult Autism Service of NHS Greater Glasgow and Clyde. A total of 25 typically developed controls were recruited from the students of the University of Glasgow and the general population. Eligible individuals meeting the inclusion/exclusion criteria were randomly allocated using a computerised program to allocate randomly participants to which stimulation condition they would receive first (anodal, cathodal, sham). The random allocation sequence and participant enrolment was done by the lead researcher.
Invitation to participate in the study was mailed to a participant by the medical secretary in January 2018. Three hundred and fifty information packs were sent out over three identification rounds. The information packs comprised an invitation to participate in the study, a letter from the potential participant’s therapist, psychiatrist or psychologist, a participant information sheet, the WMQ and a FREEPOST envelope. In order to prevent identification of numerous potentially ineligible
participants, co-investigator (CM) used the inclusion and exclusion criteria (although final
assessment of eligibility into the study was made by the researcher (AH) after informed consent). It was explained to potential participants that on the back of the participant information sheet, a tear off slip was provided in which they could complete, to indicate they were interested in taking part in the study. Potential participants replied to the invitation to the study by FREEPOST using the self-addressed envelope provided, indicating whether they would like to meet the researcher to find out more about the study. If the potential participant was not interested in taking part in the full study, they were invited to complete the WMQ and return in the FREEPOST envelope.
Where an individual was interested in finding out more about a study the chief investigator (AH) then made first contact with the individual arranged to meet with them at a convenient time and location to the individual to discuss the study and answer any questions they had. Participants were invited to identify a place to meet. At the time of the first meeting with the potential participant, the researcher discussed what would be involved in participation in the research study. The researcher also read through the information sheet with the potential participant and the potential participant was invited to ask any questions. When the potential participant was satisfied that all their questions had been adequately answered, they were invited to choose whether or not they would like to participate.
The participant was given every opportunity to clarify points they did not understand and, if necessary ask for more information. The participant was given sufficient time to consider the information sheets provided and if necessary, schedule another meeting. If the individual was willing to participate they provided informed consent. It was emphasised that the participant may withdraw their consent to participate at any time without loss of benefits to which they otherwise would be entitled. On completion of informed consent participants were screened for eligibility. Individuals who chose to take part in the research study were asked to complete a written consent form. The chief investigator and the participant signed and dated the consent form to confirm that consent has been obtained. The participant received one original consent form, the second original was kept with the chief investigator. Only after an individual had consented to participate would screening data be collected.
Typically developed controls were recruited from the students of the University of Glasgow and the general population by adverts detailing the purpose and duration of the experiment. Posters were posted around the university campus and on an online data base hosting psychological experiments. The majority of the typically developed controls had already been recruited through the previous ethics approved by the College of Science and Engineering (reference number 300160040) of the University of Glasgow on the 5th of January 2017, which follows the exact same ethical and experimental protocol.
Eligibility of participants was based on the following inclusion and exclusion criteria
Inclusion criteria:
1. Males 2. Aged 18+
3. Clinical diagnosis of ASD (for the HFA group only) 4. Met the ADOS criteria for ASD (for the HFA group only) 5. Right handed
6. Speaks English fluently
7. Normal vision or corrected to normal 8. Passing tDCS safety screening
Exclusion criteria:
1. Participants younger than 18
2. Participants who do not understand verbal or written English (i.e. would be in need of translators)
3. Participants that have ever suffered from epilepsy, febrile convulsions in infancy or had recurrent fainting spells
4. Has a family history of epilepsy 5. Suffer from any major mood disorders
6. Has a Heart pacemaker, Cochlear implant, Medication pump, Surgical clips 7. Drank more than 3 units of alcohol in the last 24 hours
8. Suffered from migraines
9. Metal in the head, implanted brain medical devices. 10. Have undergone a neurosurgical procedure
11. Had more than one cup of coffee, or other sources of caffeine in the last hour 12. Taking any prescribed or over the counter medication that might affect tDCS
13. Medications or psychoactive drugs that can lower seizure threshold [imipramine, amitriptyline, doxepine, nortriptyline, maprotiline, chlorpromazine, clozapine, foscarnet, ganciclovir, ritonavir, amphetamines, cocaine, (MDMA, ecstasy), phencyclidine (PCP, angel dust), ketamine, gamma-hydroxybutyrate (GHB), alcohol, theophylline].
14. Withdrawal from alcohol, barbiturates, benzodiazepines, meprobamate, chloral hydrate.