Table 1.
Clinical and demographic characteristics of the participants
| Variable | All participants | Active tDCS | Sham tDCS | P-value* |
|---|---|---|---|---|
| Number (n) | 14 | 6 | 8 | |
| Gender (F/M)‡ | 11/3 | 5/1 | 6/2 | 1.00 |
| Hand dominance (right/left)‡ | 14/0 | 6/0 | 8/0 | 1.00 |
| Age (years) | ||||
| Mean ± standard deviation† | 71±7 | 72±6 | 71±8 | 0.56 |
| Range | 62–84 | 67–83 | 62–84 | |
| Baseline pain score (T1)† (average daily pain – pain logbook) | 4.3±2.9 | 6.3±3.1 | 2.7±1.4 | 0.10 |
| Etiology of pain | ||||
| Osteoarthritis | 4 | 3 | 1 | |
| Sprained shoulder | 1 | 1 | ||
| Chronic low back pain | 4 | 2 | 2 | |
| Cervical injury | 1 | 1 | ||
| Shoulder tendonitis | 1 | 1 | ||
| Polymyalgia rheumatica | 1 | 1 | ||
| Sciatica | 1 | 1 | ||
| Unspecific leg pain | 1 | 1 | ||
| Side of the most problematic pain (right/left)‡ | 8/6 | 4/2 | 4/4 | 0.41 |
| Duration of chronic pain | ||||
| Less than 2 years | 2 | 1 | 1 | |
| Between 2 and 10 years | 3 | 1 | 2 | |
| More than 10 years | 9 | 4 | 5 | |
| Mean ± standard deviation† | 20±18 | 26±24 | 15±11 | 0.48 |
| Baseline ISI score† | 14.9±5.2 | 15.0±6.4 | 14.9±4.7 | 0.39 |
| Baseline sleep efficacy (T1)† | 85.9±7.0 | 86.4±7.5 | 85.5±8.1 | 0.83 |
| Baseline quantity of nocturnal awakenings (T1)† | 53.9±28.4 | 50.2±32.3 | 56.6±27.1 | 0.90 |
| Duration of sleep complaints | ||||
| Less than 2 years | 2 | 1 | 1 | |
| Between 2 and 10 years | 5 | 1 | 4 | |
| More than 10 years | 7 | 4 | 3 | |
| Mean ± standard deviation† | 21±22 | 28±25 | 16±19 | 0.44 |
| Present medication | ||||
| Pregabalin | 2 | 1 | 1 | |
| Benzodiazepine | 4 | 3 | 1 | |
| NSAID | 3 | 1 | 2 | |
| Morphine | 1 | 1 | ||
| SNRI | 2 | 2 | ||
| Tricyclic antidepressant | 2 | 2 | ||
| Levothyroxine | 4 | 2 | 2 | |
| β-Blocker | 3 | 2 | 1 | |
| ASA | 2 | 1 | 1 | |
| PPI | 3 | 2 | 1 | |
| Statin | 5 | 2 | 3 | |
| ARB | 2 | 1 | 1 | |
| Thiazide diuretic | 1 | 1 | ||
| ACE inhibitor | 1 | 1 | ||
| Triptan | 1 | 1 | ||
| No medication | 2 | 1 | 1 | |
| Other health problem | ||||
| Myalgic encephalomyelitis | 1 | 1 | ||
| Myocardial ischemia | 1 | 1 | ||
| Hypercholesterolemia | 5 | 2 | 3 | |
| Angina pectoris | 1 | 1 | ||
| Hypertension | 4 | 2 | 2 | |
| Hypothyroidism | 4 | 2 | 2 | |
| No other health problem | 6 | 2 | 4 | |
Notes: Some participants had more than 1 health problem and medication; consequently, the total number of health problems and medications does not correspond to the total number of participants in each group.
P-value of the comparison between active tDCS group and sham tDCS group.
Fisher’s exact test.
Mann–Whitney test. Data presented as mean ± standard deviation or n.
Abbreviations: tDCS, transcranial direct current stimulation; F, female; M, male; ISI, Insomnia Severity Index; NSAID, nonsteroidal anti-inflammatory drug; SNRI, serotonin–norepinephrine reuptake inhibitor; ASA, acetylsalicylic acid; PPI, proton pump inhibitor; ARB, angiotensin II receptor blocker; ACE, angiotensin-converting enzyme; T1, 7-day baseline.