Table 1
Summary of previous studies reporting tremor prevalence.
| Variable | Rajput et al. 1991 | Hughes et al. 1993 | Louis et al. 2001 | Gigante et. al. 2014 | Pasquini et al. 2018 |
|---|---|---|---|---|---|
| Study design | Longitudinal, neuropathological | Longitudinal, neuropathological | Cross-sectional, clinical | Cross-sectional, clinical | Longitudinal, clinical |
| Disease duration (years) | NR | 13.1 ± 6.3 | 7.9 ± 5.1 | 5.2 ± 3.8 | 2.56 ± 0.56 |
| Tremor assessment method | Visual inspection | PDSBB form | WHIGET Tremor Rating Scale | UPDRS | MDS-UPDRS |
| Sample size | 30 | 100 | 197 | 237 | 378 |
| Any tremor prevalence | NR | 69% | NR | NR | 87.8% |
| Rest tremor prevalence | 100% | NR | NR | 83.12% | 69.6% |
| Action tremor prevalence | NR | NR | 93.4% | 46% | NR |
| Postural tremor prevalence | NR | NR | NR | NR | 52.1% |
| Kinetic tremor prevalence | NR | NR | NR | NR | 51.6% |
[i] Legend: Not reported (NR), Unified Parkinson Disease Rating Scale (UPDRS), Washington Heights-Inwood Genetic Study of ET (WHIGET), Parkinson’s Disease Society Brain Bank (PDSB). The study by Pasquini et. al. used the Parkinson Progression Marker Initiative (PPMI) data and also reported on prevalence of difference tremor types at 2-years follow-up as following: any tremor 83.9%, rest tremor 67.9%, postural tremor 49.5%, and kinetic tremor 46.8%.
Table 2
Summary of relevant demographics and clinical features of the PPMI, BioFIND and PDBP cohorts.
| Variable | PPMI (n = 423) | BioFIND (n = 118) | PDBP (n = 874) |
|---|---|---|---|
| Gender (Male/Female) | 146/277 | 62.7% | 563/319 |
| Age (mean ± standard deviation) | 61.6 ± 9.7 | 68.0 ± 6.5 | 64.3 ± 9.1 |
| Disease duration | 5.85 ± 7.5 | 8.5 ± 3.2 | 7.2 ± 7.5* |
| % on Dopamine Treatment | 0 | 100% | 90.8% |
[i] Legend: Parkinson Progression Marker Initiative (PPMI), The Fox Investigation for New Discovery of Biomarkers (BioFIND) and Parkinson’s Disease Biomarkers Program (PDBP). * this value was taken from original description of the PDBP cohort for 449 Parkinson’s disease subjects.
Figure 1
Average prevalence of different tremor types and their combinations across baseline data of the PPMI, BioFIND and PDBP cohorts. Parkinson Progression Marker Initiative (PPMI), The Fox Investigation for New Discovery of Biomarkers (BioFIND) and Parkinson’s Disease Biomarkers Program (PDBP). Size of the circles are not indicative of the prevalence magnitude.
Table 3
Distribution of prevalence of different types and combinations of tremor in baseline data of each of three cohorts.
| Tremor Type | PPMI (n = 423) | BioFIND (n = 118) | PDBP (n = 874) |
|---|---|---|---|
| Rest tremor | 290 (68.6%) | 75 (63.6%) | 459 (52.0%) |
| Pure rest tremor | 87 (20.6%) | 15 (12.7%) | 104 (11.8%) |
| Action tremor | 156 (36.9%) | 46 (39.0%) | 316 (35.8%) |
| Pure action tremor | 40 (9.5%) | 10 (8.5%) | 87 (9.9%) |
| Postural tremor | 223 (52.7) | 69 (58.5%) | 412 (46.7%) |
| Pure Postural tremor | 18 (4.3%) | 8 (6.8%) | 31 (3.5%) |
| Kinetic tremor | 217 (51.3%) | 61 (51.7%) | 463 (52.5%) |
| Pure kinetic tremor | 23 (5.4%) | 6 (5.1%) | 86 (9.8%) |
| No tremor | 52 (12.3%) | 19 (16.1%) | 211 (23.9%) |
| Any tremor | 371 (87.7%) | 99 (83.9%) | 663 (75.2%) |
| All tremor | 116 (27.4%) | 36 (30.5%) | 229 (26.0%) |
[i] Legend: Parkinson Progression Marker Initiative (PPMI), Fox Investigation for New Discovery of Biomarkers (BioFIND), Parkinson’s Disease Biomarkers Program (PDBP).
Table 4
Distribution of perception of tremor in each of three cohorts.
| Variable | PPMI (n = 422) | BioFIND (n = 118) | PDBP (n = 826) |
|---|---|---|---|
| No tremor | 59 (14.0%) | 24 (20.3%) | 183 (22.1%) |
| Subtle tremor | 282 (66.8%) | 59 (50.0%) | 380 (46.0%) |
| Mild tremor | 73 (17.3%) | 30 (25.4) | 189 (22.9%) |
| Moderate tremor | 7 (1.7%) | 4 (3.4%) | 62 (7.5%) |
| Severe | 1 (0.2%) | 1 (0.8%) | 12 (1.5%) |
[i] Legend: Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) item 2.10.
Figure 2
Changes in different tremor types and their combinations from off-state to on-state in the BioFIND cohort. Fox Investigation for New Discovery of Biomarkers (BioFIND). On-state data were obtained from the baseline visit; off-state data were obtained by the follow-up visit (14 days after the baseline). * p < 0.05, Chi-Square test.