Table 4.

Risk ratio of LBP occurring in each year level compared with the first year students (RR = 1)

Year Level	Prevalence	Overall Risk Ratio (95%CI)	Gender-specific Risk Ratios (95%CI)
			Female	Male
Fourth Year Students	Lifetime	1.4 (1.1–1.8)++	1.4 (1.1–1.8)++	1.6 (0.9–2.6)
	12-month	1.5 (1.2–1.9)++	2.1 (1.3–3.3)++	1.6 (0.9–2.7)
	1-month	1.8 (1.2–2.7)++	1.5 (1.2–2.0)++	1.4 (0.6–2.9)
	1-week	2.1 (1.1–4.0)++	1.4 (1.1–1.8)++	0.9 (0.2–3.1)
Third Year Students	Lifetime	1.2 (0.9–1.6)	1.0 (0.7–1.5)	1.8 (1.0–3.1)*
	12-month	1.2 (0.9–1.7)	1.0 (0.7–1.5)	2.0 (1.1–3.6)++
	1-month	1.3 (0.8–2.2)	1.1 (0.6–2.1)	2.1 (1.0–4.6)*
	1-week	2.2 (1.1–4.4)++	1.1 (0.8–4.7)	3.0 (1.0–8.9)*
Second Year Students	Lifetime	1.3 (1.0–1.6)*	1.1 (0.8–1.5)	1.6 (1.0–2.7)*
	12-month	1.3 (1.0–1.7)*	1.1 (0.8–1.6)	1.6 (1.0–2.8)*
	1-month	1.6 (1.0–2.4)*	1.7 (1.0–2.7)*	1.5 (0.7–2.9)
	1-week	3.1 (1.4–7.3)++	2.6 (1.2–5.7)++	1.8 (0.7–4.9)