Longitudinal evolution of cortical thickness signature reflecting Lewy body dementia in isolated REM sleep behavior disorder: a prospective cohort study

Table 4 Performance of cortical thickness signature scores with the hazard ratio for total conversion and sensitivity/specificity for differentiating dementia-first vs. motor-first conversion in iRBD

Total disease conversion in iRBD	Hazard ratio [95% Confidence interval]
MRI (DLB-pattern)	2.27 [0.70, 7.61]
MRI(Mean cortical thickness)	9.33 [1.16, 74.12]
¹⁸F-FP-CIT PET (posterior putamen SUVR < 0.65)	8.65 [2.54, 29.41]
Hyposmia (B-SIT)	4.38 [1.47, 13.08]
Objective motor examination*	2.89 [0.91, 9.18]

Dementia-first (n = 7) vs Parkinsonism-first (n = 10) among the converters	Overall discrimination
	Sensitivity (%)	Specificity (%)	Diagnostic accuracy (%)
MRI (DLB-pattern)	85.7	90	88.2
MRI (Mean cortical thickness)	85.7	0	35.3
¹⁸F-FP-CIT PET (posterior putamen SUVR < 0.65)	57.1	10	29.4
Hyposmia (B-SIT)	66.7	33.3	31.3
Objective motor examination*	85.7	30.0	58.2

*Objective motor examination was defined by UPDRS part III score > 3 excluding action tremor[1]
AD Alzheimer’s dementia, B-SIT Brief smell identification test, DLB Dementia with Lewy bodies, iRBD Idiopathic rapid-eye-movement sleep behavior disorder, SUVR Standardized uptake ratio
Sensitivity, specificity and diagnostic accuracy were calculated by detection of dementia-first converters among total converters as follows
a = number of dementia-first converters with positive biomarker
b = number of total dementia-converters
c = number of motor-first converters with negative biomarker
d = number of total motor-first converters
(a/b for sensitivity, c/d for specificity and (a + c)/(a + b + c + d) for diagnostic accuracy)

ISSN: 2047-9158