Table. Baseline Characteristics of the Patients.
| Characteristic | Patients, No. (%) | |
|---|---|---|
| Device (n = 272) | Control (n = 278) | |
| Age, mean (SD), y | 43 (11) | 44 (10) |
| Sex | ||
| Female | 116 (43) | 107 (38) |
| Male | 156 (57) | 171 (62) |
| BMI, mean (SD) | 26 (4) | 26 (4) |
| Smoking history | 173 (64) | 175 (63) |
| Medical historya | ||
| Musculoskeletal | 95 (35)b | 91 (33)c |
| Head and neck | 62 (23)b | 54 (20)c |
| Gastrointestinal | 53 (20)d | 59 (21)b |
| Cardiovascular | 49 (18)b | 48 (17)b |
| Genitourinary | 39 (14)b | 35 (13)b |
| Skin | 29 (11)b | 30 (11)b |
| Respiratory | 28 (10)b | 44 (16)b |
| Visual analogue scale for leg paine | 81 (15) | 81 (15) |
| Oswestry Disability Index scoref | 59 (12) | 58 (14) |
| SF-36 component summary score, mean (SD)g | ||
| Physical | 29 (6) | 29 (6) |
| Mental | 40 (13) | 41 (13) |
| Index level | ||
| L2-L3 | 2 (1) | 1 (<1) |
| L3-L4 | 8 (3) | 5 (2) |
| L4-L5 | 123 (45) | 101 (36) |
| L5-S1 | 139 (51) | 171 (62) |
| Disc height, mean (SD), mm | 8.9 (2.1) | 8.9 (2.2) |
| Spondylolisthesis (grade I) | 6 (2) | 8 (3) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); SF-36, 36-Item Short-Form General Health Survey.
a
Medical history variables reported with frequency of 10% or more in either group.
b
Data from 2 patients not reported.
c
Data from 1 patient not reported.
d
Data from 3 patients not reported.
e
Scores on the visual analogue scale range from 0 to 100, with higher scores indicating more severe pain.
f
Scores on the Oswestry Disability Index range from 0 to 100, with higher scores indicating more severe disability.
g
Physical Component Summary and Mental Component Summary scores from the SF-36 scale range from 0 to 100, with higher scores indicating better health-related quality of life.