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A recent study showed that a short self-screening questionnaire boasted high sensitivity and specificity for identifying psychosis among patients with Parkinson disease.
Vindhya Koneru, MD
Credit: Houston Methodist Hospital
In a recent study published in Movement Disorders, the Self-Administered Screening Questionnaire for PD-Associated Psychosis (SASPAP) demonstrated high precision in identifying psychosis in patients with Parkinson disease (PD) compared with gold standard assessment.1 These findings provide evidence to validate the 4-question self-administered screening questionnaire as a high accuracy tool at visit intake for better screening of PD psychosis.
Among 250 patients with PD, both the SASPAP and Parkinson's Disease Psychosis Scale (PDPS)2 showed positive results for current psychosis in approximately one-third of the participants, with SASPAP identifying 33.6% (n = 83) and PDPS identifying 32.0% (n = 80). In 2 patients with a PDPS score of 0, psychosis was diagnosed in an interview, leading the “true” count of PD psychosis to be 32.8% (n = 82). Notably, the SASPAP showed a sensitivity of 87.8% (95% CI, 78.7–93.9), and a specificity of 92.3% (95% CI, 87.1–95.8) compared with the gold standard assessment, defined as PDPS/interview.
Conducted by lead author Vindhya Koneru, MD, movement disorders fellow at Houston Methodist Hospital, and colleagues, a committee of 2 neurologists, a psychiatrist, a patient, and patient advocate developed the questionnaire. The questionnaire went through several rounds of revisions, including patient β-testing, where it was then provided to patients with PD at the Methodist Hospital Movement Disorders Clinic, and separately to their caregivers at intake. PD specialists administered the PDPS and a general psychosis interview, without knowing the screening questionnaire responses, and compared with the SASPAP questionnaire.
In the responses from SASPAP, 13 (5.2%) resulted as false positives commonly because of misinterpretation of symptoms (n = 7), hallucinations had resolved more than 1 month before evaluation (n = 5), or language barrier (n = 1). Comparing 143 questionnaires with separate patient and caregiver responses, authors observed substantial agreement (Cohen’s κ coefficient = 0.65). Only 10 out of 143 (6.9%) caregivers thought the patient had psychosis when the patient themselves did not. Among these patients, the caregivers reported psychosis for illusions (n = 6), sense of presence (n = 4), hallucinations (n = 3), and delusions (n = 4). Only 7 of these 10 patients classified as having current psychosis per PDPS/interview and 13 (9.1%) of them thought they had psychosis when their caregivers did not.
For psychosis risk factors, investigators observed a lifetime incidence of psychosis in 98 participants (39.2%). Among these patients, authors reported a history of any REM sleep behavior disorder (RBD) in 41 patients (41.8%), constipation in 70 (71.4%), orthostatic hypotension in 45 (45.9%), falls in 42 (42.8%), and dementia in 34 (34.6%). Noteworthy, RBD, constipation, falls, and dementia had a significant association with the history of psychosis. Additionally, current use of dopamine agonists correlated the most with the current psychosis (OR, 1.8, P = 0.04, Pearson R = 0.12, P = 0.06), and istradefylline (OR, 3.58, P = 0.08, Pearson R = 0.14, P = 0.03).
All told, the study faced potential biases in psychosis associations because of chart review data collection. To mitigate potential bias, the authors considered "ever having psychosis" for associated conditions instead of "current psychosis" to account for improvements following intervention. In this analysis, investigators focused on current psychosis rather than analysis of current PD medications because of challenges in accurately assessing medications at psychosis onset. Overall, researchers acknowledged the limitations of determining current psychosis in a cross-sectional assessment, as patients with prior psychosis often undergo changes in medications.
