Table 3.
Studies investigating phenoconversion in cohorts of patients with iRBD.
| References | Study sample | PSG | Overall follow-up of the study | Conversion risk | Phenoconversion | Prevalence of MSA in converters (%) |
|---|---|---|---|---|---|---|
| Fantini et al. (56) | 24 (75.0% males) |
Yes | 26.3 months (SD 5.0) |
3 (12.5%) patients converted at follow-up | n = 2 PD | 0.0 |
| Boot et al. (57) | 44 (77.3% males) |
No | 46 months (IQR 31–47) |
15 (34.1%) patients evolved into neurodegenerative disease Median time between onset of dream-enactment behaviour and diagnosis of MCI/PD = 20.7 years |
n = 1 PD n = 14 MCI |
0.0 |
| Wing et al. (58) | 91 (82.4% males) |
Yes | 5.6 years (SD 3.3) |
19 (20.9%) patients evolved into neurodegenerative disease The estimated 5 and 9 year risks of any neurodegenerative disorder for the overall study cohort were 8.5% and 38.1%. |
n = 8 PD n = 8 AD n = 1 DLB n = 2 vascular dementia |
0.0 |
| Schenck et al. (43) | 26 (100% males) |
Yes | 16 years | 21 (80.8%) patients who were initially diagnosed with iRBD eventually developed parkinsonism/dementia Mean time to conversion = 14.2 ± 6.2 years (range: 5–29 years) |
n = 13 PD n = 3 DLB n = 2 MSA n = 1 dementia (unspecified); n = 2, clinically diagnosed AD with autopsy-confirmed combined AD + Lewy body disease pathology. |
9.5 |
| Arnulf et al. (59) | 69 (81.2% males) |
Yes | 3 years (range: 1–15) |
16 (23.2%) converted into neurodegenerative disorders Median time from RBD onset to parkinsonism/dementia = 16 years |
n = 6 parkinsonism n = 6 dementia n = 2 dementia plus parkinsonism n = 2 MSA |
12.5 |
| Mahlknecht et al. (60) | 34 (85.3% males) |
Yes | 4.9 years (SD 0.3) |
9 (26.5%) patients with iRBD developed Lewy body disease Mean interval from iRBD diagnosis to conversion = 5.5 ± 4.7 years |
n = 6 PD n = 3 DLB |
0.0 |
| Fernández-Arcos et al. (53) | 203 (79.8% males) |
Yes | 5.0 years (range: 0.1–17) |
69 (34.0%) received a diagnosis of defined neurodegenerative syndrome after a median follow-up of 5 years |
n = 22 PD n = 32 DLB n = 2 MSA n = 13 MCI |
2.9 |
| Youn et al. (61) | 84 (69.1% males) |
Yes | 4.1 years (SD 2.1, range 1.0–10.3) |
18 (21.4%) patients developed neurodegenerative disorders The estimated risk of developing neurodegenerative diseases was 9% at 3, 18% at 6 and 35% at 6 years from the diagnosis of iRBD, respectively. |
n = 9 PD n = 4 DLB n = 1 MSA n = 3 AD n = 1 spinocerebellar ataxia |
5.6 |
| Li et al. (62) | 43 patients (79.1% males) |
Yes | 5 years | 18 (41.9%) developed neurodegenerative synucleinopathy diseases Median interval from the estimated onset of iRBD symptoms to conversion = 10.5 years |
n = 9 PD n = 2 DLB n = 3 MSA n = 4 PD/MCI |
16.7 |
| Zhou et al. (63) | 179 patients (79.1% males) |
Yes | 5.8 ± 4.3 years | 50 (27.9%) patients developed neurodegenerative diseases Median time of conversion to neurodegenerative diseases = 9 years from RBD onset, 3.1 years from RBD diagnosis |
n = 27 PD n = 7 DLB n = 2 MSA n = 14 AD |
4.0 |
| Fereshtehnejad et al. (48) | 154 patients | Yes | 8.2 years (SD 9.0) |
55 (36%) converted to an overt neurodegenerative syndrome Mean interval between baseline evaluation and phenoconversion = 4.6 ± 2.5 years |
n = 25 PD n = 4 MSA n = 26 dementia |
7.3 |
| Postuma et al. (54) (IRBDSG*) | 279 (79.6% males) |
Yes | 3.8 years (SD 1.4) | 93 (33.3%) developed a neurodegenerative disease Risk of neurodegenerative disease was 15% after 2 years, 25% after 3, 36% after 4, and 41% after 5 years Mean interval between baseline and disease diagnosis = 2.5 ± 1.7 years |
n = 39 PD n = 7 MSA n = 47 dementia (n = 28 probable DLB) |
7.5 |
| Postuma et al. (55) (IRBDSG*) | 1,280 patients (82.5% males) |
Yes | 3.6 years (max 19) | 352 (27.5%) converted to an overt neurodegenerative syndrome Phenoconversion rate of 6.25% per year (10.6% after 2 years, 17.9% after 3 years, 31.3% after 5 years, 51.4% after 8 years, 60.2% after 10 years, and 73.5% after 12 years) Mean interval between baseline evaluation and phenoconversion was 4.6 ± 3.5 years |
n = 199 parkinsonism (16 probable MSA) n = 153 dementia first. | 4.6 |
These prevalence rates were calculated from raw data, when not available in the studies.
AD, Alzheimer's disease; DLB, dementia with Lewy bodies; IRBDSG
*
International REM Sleep Behaviour Disorder Study Group; n = sample; PD, Parkinson's disease; PSG, polysomnography; MCI, mild cognitive impairment; MSA, multiple system atrophy; SD, standard deviation.