Lurie Center for Autism

Randomized controlled trials, placebo effect, sampling bias, and evidence-based medicine are terms often used by researchers. Understanding the definitions of these terms may help individuals with autism spectrum disorders and their families better evaluate proposed treatments for ASD.

Why Is Evidence-Based Research Important in Autism?

Parents often question why doctors and other healthcare providers use phrases such as “randomized controlled trials,” “controlled trials,” “placebo” and “evidence-based medicine” when discussing treatments for patients with autism spectrum disorders. As with all medical conditions, research studies need to be done to find scientific evidence to prove that therapies, supplements and medications used for autism are safe and make any real difference in the patients’ functioning that could not be accounted for by other interventions or treatments. We will define some of the above terms in this section and explain their importance for parents who may find themselves sifting through many proposed treatments and cures for autism.

Controlled Trials and Randomized Controlled Trials

A study that is a controlled trial includes patients or subjects who are getting a treatment and those who are not. A randomized controlled trial (RCT) is a specific type of scientific study in which subjects are randomly – meaning by chance alone – assigned to receive the experimental treatment (the treatment group) or to have the usual care, or no intervention (the control group). After randomization, the two groups of subjects are followed in exactly the same way, and the only differences between the care, procedures and tests they receive are the treatments being compared. RCTs avoid sampling bias, where portions of a population are more or less likely to be included. This would result in a situation in which all types of participants are not equally represented. The RCT has been shown to be very reliable and is believed to be the best at discerning real improvements. Autism is a relatively new field in the history of medicine and many commonly used treatments have not yet been tested in RCTs, in order to establish their safety and effectiveness.

Placebo Effect

In studies of medications and supplements, the participants taking an inactive substance (placebo) that appears similar to the study medication or supplement, can often improve as much as the subjects who are taking the real treatment. There is a significant placebo effect that has been shown in autism. Researchers think that the expectancy for improvement in children with developmental problems, day to day fluctuations in functioning that occur in developmental disabilities no matter what, and participation effects such as changes in caregiver behavior while an individual is enrolled in a study all contribute to the placebo effect. The placebo effect suggests that, in families with autism, nonverbal communication may occur to a greater extent than we realize.

  1. Siegel M and Beaulieu AA. (2012) Psychotropic medications in children with autism spectrum disorders: A systematic review and synthesis for evidence-based practice. Journal of Autism and Developmental Disorders 42:1592-1605. See discussion.
  2. Sandler A. (2005) Placebo effects in developmental disabilities: Implications for research and practice. Mental Retardation and Developmental Disabilities 11:164-170.

Evidence-Based Medicine

Evidence-based medicine (EBM) has been described as the wise use of the best currently available scientific research (the evidence) in making decisions about the care of individual patients. Official recommendations about screening tests for disease, and treatment of conditions and illnesses, result from considering all the data from well-designed studies (usually from randomized controlled trials). Evidence-based medicine integrates clinical expertise with research evidence and patient values. Evidence is the tool with which a doctor can assess the risks and benefits of treatments (including lack of treatment) and diagnostic tests. This helps medical providers understand whether or not a treatment will do more good than harm for an individual patient, and whether it has been proven to change the course of a disease or disorder. The use of evidence can help patients and families, with their doctors, to make the best informed decisions to guide their care. In the long run evidence can improve health care and lower its cost by avoiding unnecessary or ineffective treatments.

  1. Atkins D, Best D, Briss PA, et al. (2004) Grading quality of evidence and strength of recommendations. British Medical Journal 328:1490.