Table 1 Characteristics of the 45,555 pre-adolescents included in the study population according to the main exposure status (screen-based activity) (11-year follow-up, The Danish National Birth Cohort, 1996–2003)
From: Spinal pain in pre-adolescence and the relation with screen time and physical activity behavior
| Â | Â | Average time spent on screen-based activity (h/day)a | |||
|---|---|---|---|---|---|
Characteristics | N | <  2 | 2 to < 4 | 4 to < 6 | ≥ 6 |
Totalb | 45,555 (100) | 10,104 (22.2) | 22,057 (48.4) | 9452 (20.8) | 3942 (8.7) |
Physical activity behavior | Â | Â | Â | Â | Â |
 Inactive | 5201 (11.4) | 753 (7.5) | 2251 (10.2) | 1366 (14.5) | 831 (21.6) |
 Lightly active | 20,436 (44.9) | 4186 (41.5) | 9730 (44.1) | 4544 (48.1) | 1973 (49.3) |
 Moderately active | 17,853 (39.2) | 4519 (44.7) | 9065 (41.1) | 3218 (34.1) | 1051 (26.7) |
 Vigorously active | 2065 (4.5) | 643 (6.4) | 1011 (4.6) | 324 (3.4) | 87 (2.2) |
Sex | Â | Â | Â | Â | Â |
 Boys | 21,711 (47.7) | 3686 (36.5) | 10,177 (46.1) | 5355 (56.7) | 2493 (63.2) |
 Girls | 23,844 (52.3) | 6418 (63.5) | 11,880 (53.9) | 4097 (43.4) | 1449 (36.8) |
Age | Â | Â | Â | Â | Â |
 11 years | 38,326 (84.1) | 8943 (88.5) | 18,784 (85.2) | 7599 (80.4) | 3000 (76.1) |
 12 years | 7229 (15.9) | 1161 (11.5) | 3273 (14.8) | 1853 (19.6) | 942 (23.9) |
Parental educational levelc | Â | Â | Â | Â | Â |
 High | 30,629 (67.2) | 7389 (73.1) | 14,994 (68.10) | 5987 (63.3) | 2259 (57.3) |
 Medium | 14,100 (31.0) | 2579 (25.5) | 6699 (30.4) | 3276 (34.7) | 1546 (39.2) |
 Low | 826 (1.8) | 136 (1.4) | 364 (1.7) | 189 (2.0) | 137 (3.5) |
Equivalised household incomec | Â | Â | Â | Â | Â |
 4th quartile (highest) | 16,333 (35.9) | 4082 (40.4) | 8095 (36.7) | 3055 (32.3) | 1101 (27.9) |
 3rd quartile | 14,011 (30.8) | 2996 (29.7) | 6848 (31.1) | 3010 (31.9) | 1157 (29.4) |
 2nd quartile | 10,225 (22.4) | 2006 (19.9) | 4836 (22.0) | 2259 (23.9) | 1124 (28.5) |
 1st quartile (lowest) | 4986 (11.0) | 1020 (10.1) | 2278 (10.3) | 1128 (12.0) | 560 (14.2) |
Family type | Â | Â | Â | Â | Â |
 Living with both parents | 35,638 (78.2) | 8110 (80.3) | 17,449 (79.1) | 7193 (76.1) | 2886 (73.2) |
 Not living with (both) parentsd | 9917 (21.8) | 1994 (19.7) | 4608 (20.9) | 2259 (23.9) | 1056 (26.8) |
Paritye | Â | Â | Â | Â | Â |
 Nulliparous | 21,976 (48.2) | 5498 (54.4) | 10,755 (48.6) | 4152 (43.9) | 1571 (39.9) |
 Parous | 23,579 (51.8) | 4606 (45.6) | 11,302 (51.4) | 5300 (56.1) | 2371 (60.2) |