Table 1.
Differences between the two subgroups: demographic and polysomnographic parameters
| All patients | Group 1 | Group 2 | P-values | ||
|---|---|---|---|---|---|
| Number of patients | n (%) | 66 (100) | 59 (89.4) | 7 (10.6) | |
| Sex (male/female) | n (%) | 21 (31.8)/45 (68.2) | 4 (6.1)/3 (4.5) | 18 (27.3)/41 (62.1) | 0.162 |
| Age (years) | Mean ± SD | 43.6±10.0 | 43.3±10.2 | 46.4±6.6 | 0.431 |
| Min–max | 20–66 | 20–66 | 38–57 | ||
| Range 25%–75% | 38.75–49.0 | 38.5–49.0 | 41.5–51.0 | ||
| EDSS | Mean ± SD | 2.7±1.8 | 2.4±1.5 | 4.9±1.5 | 0.023 |
| Range 25%–75% | 1.5–3.6 | 1.6–3.0 | 2.5–7.0 | ||
| Disease-modifying therapy | n (%) | 50 (75.8) | 44 (66.7) | 6 (9.1) | * |
| Glatiramer acetate | n (%) | 24 (36.4) | 20 (30.3) | 4 (6.1) | |
| Interferon | n (%) | 22 (33.3) | 21 (31.8) | 1 (1.5) | |
| Immunoglobulins | n (%) | 1 (1.5) | 0 (0.0) | 1 (1.5) | |
| Mitoxantrone | n (%) | 2 (3.0) | 2 (3.0) | 0 (0.0) | |
| Natalizumab | n (%) | 1 (1.5) | 1 (1.5) | 0 (0.0) | |
| Cortisone** | n (%) | 2 (3.0) | 2 (3.0) | 0 (0.0) | |
| No therapy | n (%) | 14 (21.2) | 13 (19.7) | 1 (1.5) | |
| Disease course | * | ||||
| RRMS | n (%) | 46 (69.7) | 42 (63.6) | 4 (6.1) | |
| SPMS | n (%) | 16 (24.2) | 13 (19.7) | 3 (4.5) | |
| PPMS | n (%) | 4 (6.1) | 4 (6.1) | 0 (0.0) | |
| PLMI (per hour of sleep) | Mean ± SD | 23.1±29.8 | 18.3±22.8 | 63.5±49.4 | 0.008 |
| Range 25%–75% | 2.3–36.0 | 2.0–28.4 | 11.5–121.3 | ||
| REM-PLMI (per hour of REM sleep) | Mean ± SD | 6.0±18.5 | 1.5±2.6 | 44.5±41.2 | <0.0001 |
| Range 25%–75% | 0.0–3.7 | 0.0–1.8 | 13.8–69.0 | ||
| PLM arousal index (per hour of sleep) | Mean ± SD | 2.7±4.2 | 2.3±3.9 | 6.6±5.1 | 0.030 |
| Range 25%–75% | 0.2–3.6 | 0.2–1.9 | 0.8–12.7 | ||
| Sleep efficiency (% TST/TiB) | Mean ± SD | 74.8±14.9 | 74.0±15.5 | 82.3±4.7 | 0.151 |
| Range 25%–75% | 67.1–85.3 | 64.2–85.1 | 77.6–85.7 | ||
| NREM 1+2 (%/TiB) | Mean ± SD | 51.2±12.2 | 50.9±12.6 | 54.2±7.1 | 0.539 |
| Range 25%–75% | 43.6–62.5 | 41.6–62.5 | 48.2–62.6 | ||
| NREM 3+4 (%/TiB) | Mean ± SD | 13.9±12.0 | 14.0±6.6 | 13.4±9.7 | 0.958 |
| Range 25%–75% | 6.6–18.8 | 12.3–18.5 | 4.1–23.8 | ||
| REM (%/TiB) | Mean ± SD | 14.3±7.4 | 14.0±7.6 | 16.2±5.8 | 0.338 |
| Range 25%–75% | 10.6–17.5 | 10.5–17.0 | 11.8–21.7 | ||
| Sleep latency (minutes) | Mean ± SD | 31.9±35.7 | 33.4±11.0 | 19.3±13.0 | 0.307 |
| Range 25%–75% | 12.5–41.0 | 37.4–42.0 | 9.6–42.0 | ||
| Number of awakenings | Mean ± SD | 26.7±12.4 | 26.9±18.0 | 24.4±17.0 | 0.827 |
| Range 25%–75% | 18.0–32.0 | 12.7–32.0 | 10.2–34.0 | ||
| Wake after sleep onset (minutes) | Mean ± SD | 83.8±57.3 | 86.4±43.0 | 61.9±36.0 | 0.539 |
| Range 25%–75% | 43.0–120.0 | 59.7–128.0 | 22.2–80.0 |
Notes:
Due to the small sample size in the different subgroups and because of different disease-modifying therapies and different disease courses, a statistical analysis of the difference between different disease courses and different disease-modifying therapies was not possible.
One patient with intrathecal application of triamcinolone acetonide and one patient with repetitive use of pulse therapy with methylprednisolone. Group 1, patients with REM-PLMI <10 per hour; Group 2, patients with REM-PLMI ≥10 per hour. P-values given in bold demonstrate a significant difference between the two subgroups.
Abbreviations: SD, standard deviation; min, minimum; max, maximum; EDSS, expanded disability status scale; RRMS, relapsing–remitting multiple sclerosis; SPMS, secondary progressive multiple sclerosis; PPMS, primary progressive multiple sclerosis; PLMI, periodic limb movement index; REM-PLMI, PLMI during REM sleep; REM, rapid eye movement; TST, total sleep time; TiB, time spent in bed; NREM, nonrapid eye movement.