0626 Impact of Washout Timing of Psychotropic Medications on the MSLT

Abstract Introduction While highly reproducible in narcolepsy type 1, MSLT results are more variable in other CNS hypersomnolence disorders. Use of psychotropic medications is a known contributor to MSLT validity given the high comorbidity of psychiatric illness in patients with hypersomnolence disorders. We leveraged a large MSLT database to study the impact of timing of washout of psychotropic medications with known REM-suppressing effects on MSLT results. Methods This was a retrospective analysis of MSLTs performed 2012-2023 at Cleveland Clinic. Medication groups studied included selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and tricyclic antidepressants (TCAs). Date of last dose prior to MSLT was collected and categorized as ≤14 days or >14 days prior to MSLT. Multivariable adjusted regression analyses (linear and logistic) adjusting for age, sex, and BMI were conducted to evaluate the influence of a late washout (ie ≤14 days prior to MSLT) on recording ≥2 sleep onset REM periods (SOREMPs) and on recording a mean sleep latency (MSL) < 8 minutes. Results 180 unique MSLTs were analyzed. Of these, 80 patients had recorded use of SSRIs, SNRIs, and/or TCAs leading up to the MSLT, and 63 of these 80 patients used such a medication ≤14 days before the MSLT. Seven of 80 patients (8.8%) had ≥2 SOREMPs, and 27 (33.8%) had MSL < 8 minutes. Logistic regression analysis showed a negative correlation between a late washout and obtaining ≥2 SOREMPs (OR 0.05, p< 0.01), but no significant correlation with obtaining MSL < 8 minutes (p=0.07). Linear regression analysis similarly showed a negative correlation between a late washout and obtaining ≥2 SOREMPs (coefficient -0.77, p>0.001) but no significant correlation with obtaining MSL < 8 minutes. Conclusion These findings underscore the importance of appropriately timed REM suppressant washout prior to MSLT to optimize test validity. Further analyses will examine the effects of other CNS-active medication classes in a larger cohort of patients. Support (if any) NIH grant R21HL170206