Persistent Diagnostic Disagreement Among Individuals With Functional Movement Disorders

Diagnostic agreement influences treatment outcomes, but studies on persistent diagnostic disagreement (PDD) in functional movement disorder (FMD) are lacking. The authors propose a definition for PDD and identified associated factors in a clinical cohort of patients with FMD.

The authors retrospectively reviewed clinical data of 158 FMD patients seen in an integrated movement disorders program from July 2019 to December 2021. Patients self-reported diagnostic agreement before an initial assessment (as disagree, unsure, or agree). PDD status was determined by a specialist assessment on the basis of observable behaviors. Exploratory logistic regression and a least absolute shrinkage and selection operator (LASSO) model were used to examine associations of demographic and clinical features with PDD. Alignment between referring clinician impressions and patient self-reports was also evaluated.

Of 158 patients, 116 had complete data for both baseline self-reports and specialist PDD determination. Forty-seven patients (41%) were classified as having PDD. PDD was observed for 52% (N=15 of 29) of those who self-reported disagreement, 71% (N=17 of 24) who self-reported ambivalence, and 24% (N=15 of 63) who self-reported agreement. Variables associated with PDD included low agency, cluster B traits, lower readiness to change, inability to notice symptom variability, and lower self-reported agreement; only low agency was retained in the LASSO analysis. Among 78 patients with complete data including referring physician impressions, concordance with patient self-reported disagreement was low (weighted κ=0.21, p<0.001).

PDD was common in FMD, was not accurately identified by referral impressions or patients' self-reports, and may be linked to modifiable psychological processes.