Table 3.
Prevalence of LBP (95%CI) as a percentage of the total number of respondents (overall, per year level and gender), and evidence of linearity for trend over the year levels (overall and per gender).
| Lifetime | 12-Month | 1-Month | 1-Week | |
| First year | ||||
| Male | 47.6 (29.8–69.4) | 42.9(21.3–64.5) | 33.3 (12.7–53.9) | 19.0 (1.9–36.1) |
| Female | 61.0 (48.5–73.4) | 54.2 (41.5–76.9) | 30.5 (18.7–42.4) | 13.6 (4.8–22.3) |
| Overall | 57.5 (46.4–68.5) | 51.3(40.1–62.5) | 31.3 (20.9–41.7) | 15 (7.0–22.9) |
| Second year | ||||
| Male | 78.4 (64.9–91.8) | 70.3 (57.6–83.0) | 48.6 (32.3–64.9) | 35.1 (21.2–48.9) |
| Female | 66.7 (52.1–81.3) | 61.5 (46.4–76.6) | 51.3 (35.8–66.8) | 35.9 (21.0–50.8) |
| Overall | 72.4 (62.3–82.4) | 65.8 (55.1–76.5) | 50.0 (38.7–61.2) | 35.5(24.7–46.2) |
| Third year | ||||
| Male | 85.7 (39.4–100) | 85.7 (30.6–100) | 71.4 (12.9–87.0) | 57.1 (0.1–70.9) |
| Female | 63.0 (44.7–81.2) | 55.6 (36.8–74.3) | 33.4 (15.6–51.2) | 25.9 (9.4–42.4) |
| Overall | 67.6 (51.9–83.3) | 61.8 (45.5–83.9) | 41.2 (24.6–57.7) | 32.4 (48.1–16.7) |
| Fourth year | ||||
| Male | 75.0 (57.7–92.3) | 66.7 (47.8–85.5) | 45.8 (25.9–65.7) | 16.7 (1.8–31.6) |
| Female | 86.1 (74.7–97.4) | 83.3 (71.1–95.5) | 63.9 (48.2–79.5) | 41.7 (25.6–57.8) |
| Overall | 81.7 (71.9–91.5) | 76.7 (66.0–77.4) | 56.7 (44.2–69.2) | 31.7 (19.9–43.5) |
| Total sample | 69.2 (63.4–75.0) | 63.2 (57.1–69.3) | 44.4 (38.1–50.7) | 27.6 (21.9–33.2) |
| Chi Square (p value) describing linearity of trend | ||||
| • Overall | 7.9 (0.005) | 8.2 (0.004) | 7.1 (0.008) | 4.1 (0.04) |
| • Females | 5.1 (0.02) | 6.2 (0.01) | 7.1 (0.007) | 7.4 (0.006) |
| • Males | 2.7 (0.09) | 2.0 (0.15) | 0.7 (0.4) | 0.1 (0.7) |