Reassessing AIMS Scale for Tardive Dyskinesia in Age of Approved Treatments

AUGUST 20, 2018
Kenneth Bender, PharmD, MA
The recently released consensus statement from the Tardive Dyskinesia Assessment Workshop indicates that the Abnormal Involuntary Movement Scale (AIMS) remains a valid measure for assessing tardive dyskinesia (TD); however, they suggest alternative analyses of the AIMS data to better gauge the effectiveness of clinical interventions.

The invitational workshop, sponsored by the manufacturer of 1 of the 2 vesicular monoamine transporter 2 (VMAT2) inhibitors now approved by the US Food and Drug Administration (FDA) for the treatment of TD, convened a working group of 7 psychiatrists with clinical practice and research focus in psychopharmacology and drug safety, and 1 neurologist specializing in movement disorders.

With the new availability of approved treatments for TD, after what the statement describes as a "historical absence," workshop attendees discussed the AIMS as an assessment tool, considered the challenges in translating the scoring data from clinical intervention trials to clinical practice, and proposed different methods for reporting AIMS data in clinically relevant terms.

"The availability of novel treatments and the current resurgence of interest in TD are encouraging and potentially transformative for individuals affected by [the condition]," explained lead author John Kane, MD, department of psychiatry, The Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, New York, and colleagues.  "However, available treatments do not eliminate the need for careful assessment of involuntary movements and preventative efforts."

The consensus statement emphasizes that the AIMS is an instrument for measuring the anatomic distribution and severity of abnormal movements; however, it does not provide criteria to diagnose TD. Diagnosis is based on multiple considerations, including clinical presentation, medication history, and the process of ruling out of other diagnostic possibilities. Kane and colleagues also point out that there are other standardized instruments developed to aid diagnosis of TD in clinical research, including the Schooler-Kane criteria developed in 1982 by Kane with Nina Schooler, PhD (then at the National Institutes of Mental Health).

The use of mean changes in the AIMS total score to gauge treatment response in clinical trials presents one of the challenges in applying trial results to clinical practice, according to the working group members. They noted this measure is confounded by newly emergent cases that produce no change in total AIMS score from baseline, and find that it can be obfuscated by inappropriate mathematical approaches and analyses. Possible solutions include reporting individual item scores in addition to the AIMS total score, and utilizing blinded central raters who view standardized video recordings or 2-way live examinations and follow protocol-defined rating procedures.

Although a minimal clinically important difference (MCID) in score change would be useful to inform TD assessment and intervention, the working group members acknowledged that there is no MCID for the AIMS yet established in TD. After performing their own assessments from historical data, they suggest that an MCID may correspond to a change of 2 or 3 points in the AIMS total score. The members are currently working on a further analysis of this finding.

Furthermore, the working group members note that analysis of AIMS data for response—generally considered as 30% to 50% reduction in AIMS total score—is used to reflect how many subjects in a clinical trial meet "response" threshold; but, it does not reflect symptom resolution or predict future symptom severity. The reporting of the analyses as an odds ratio or number needed to treat for complete response could help clinicians interpret these data, they suggest.

The Working Group confirmed that AIMS is useful for assessing symptoms of TD, but not for diagnosis, nor for gauging the related impaired functioning. "Patients do experience varying levels of impairment in subjective well-being, quality of life, and functionality due to TD," they indicate.

"Scales that measure such impairment are currently missing but urgently needed, and to achieve complete recovery from TD, such measures are needed to complement AIMS score assessment," Kane and colleagues conclude.

The consensus statement from the Tardive Dyskinesia Assessment Workshop was published in the May/June issue of the Journal of Clinical Psychiatry.

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