Table 1. Case–Control Studies and Genetic Epidemiological Studies Assessing Family History of Postural Tremor or ET as a Risk Factor for PD.
| Authors | Methodology/Study Design | PD Patients |
Controls |
OR (95% CI) or HR (95% CI) | p-Value |
| n (% with postural tremor) | n (% with postural tremor) | ||||
| Marttila et al.24 | Population-based case–control study | 444 (5.8%) | 444 (8.1%) | 0.71 (0.41–1.22) | 0.188 |
| Lang et al.25 | Hospital-based case–control study | 159 (17%) | 104 (5.8%) | 3.34 (1.25–9.41) | 0.007 |
| Marttila and Rinne26 | Hospital-based case study | 52 (2.03%) (All early onset PD) | No control group (expected frequency 1.67%) | – | |
| Cleeves et al.15 | Hospital-based case–control study | 100 (15%) | 100 (6%) | 2.80 (1.03–7.45) | 0.036 |
| Semchuk et al., 1993, 199527, 28 | Population-based case–control study | 125 (?) | 250 (?) | 2.37 (1.20–4.69) | <0.05 |
| 1.37 (0.67–2.80) after multivariate analysis | n.s. | ||||
| Morano et al.29 | Hospital-based case–control study | 74 (14.9%) | 148 (4.7%) | 3.52 (1.19–10.62) | 0.009 |
| Vieregge et al.30 | Hospital-based case–control study | 66 (13.6%) | 72 (4.2%) | 3.62 (0.84–17.86) | 0.049 |
| Jankovic et al.31 | Hospital-based family study | 1874 parents and siblings or 391 PD patients (5.1%) | 448 parents and siblings or 104 controls (2.2%) | 2.37 (1.19–4.86) | 0.008 |
| De Michele et al.32 | Hospital-based case–control study | 100 (17%) | 200 (5.5%) (1 spouse and 1 neurological control for each PD case) | 3.1 (1.5–6.3) | 0.002 |
| De Michele et al.33 | Hospital-based case–control study | 116 (16.4%) | 232 (5.6%) (1 spouse and 1 neurological control for each PD case) | 3.30 (1.48–7.41) | 0.001 |
| Taylor et al.34 | Hospital-based case–control study | 140 (11.2%) | 147 (3.4%) | 3.97 (1.17–13.50) | 0.007 |
| Zorzon et al.35 | Hospital-based case–control study | 136 (6.6%) | 272 (1.1%) | 10.8 (2.6–43.7) | 0.002 |
| Kang et al.36 | Population-based cases study | 162 (15.4%) | – | – | – |
| Rocca et al.37 | Population-based family study | 981 first-degree relatives of 162 PD patients | 838 first-degree relatives of 147 controls (3.5%) | ||
| Total series 4.8% | 1.51 (0.95–2.41) | 0.158 | |||
| PD onset ≤66 years 5.8% | 2.24 (1.26–3.98) | 0.006 | |||
| Rocca et al.37 | Hospital-based family study | 2684 first-degree relatives of 411 PD patients | 838 first-degree relatives of 147 controls (3.5%) | ||
| Total series 5.92% | |||||
| PD onset ≤57 years 7.3% | 1.96 (1.35–2.86) | 0.0004 | |||
| Spanaki and Plaitakis38 | Population-based case–control study | 303 (8.6%) | 249 (3.2%) | 2.83 (1.19–6.92) | 0.015 |
| Spanaki and Plaitakis38 | Population-based family study | 1483 first-degree relatives of 303 PD patients (2.8%) | 1315 first-degree relatives of 249 controls (0.80%) | 1.75–7.77 | 0.0001 |
| Costello et al.39 | Population-based family study | 2980 first-degree relatives of 372 PD patients | 2981 first-degree relatives of 404 controls (1.0%) | ||
| Total series 1.5% | 1.44 (0.90–2.29) | 0.13 | |||
| Relatives of tremor-dominant case 1.7% | 1.69 (0.90–2.88) | 0.05 | |||
| Relatives of younger case 1.4% | 2.03 (0.93–4.44) | 0.08 |
Abbreviations: CI, confidence interval; ET, essential tremor; HR, hazard ratio; n.s., not significant; OR, odds ratio; PD, Parkinson's disease