Prevalence of low Back pain among adolescents in relation to the weight of school bags

Table 4 Association between bag weight (as a percentage of body weight) and low back pain before and after adjusting for potential confounders

Bag weight (% of body weight)	Model 1 OR [95%CI]	Model 2 OR [95%CI]	Model 3 OR [95%CI]	Model 4 OR [95%CI]
< 7.3%	1.00 [Reference]	1.00 [Reference]	1.00 [Reference]	1.00 [Reference]
7.3 to < 11%	1.32 [0.96–1.82]	1.09 [0.78–1.52]	0.80 [0.56–1.15]	0.79 [0.55–1.14]
≥ 11%	1.49 [1.08–2.04]	1.25 [0.90–1.76]	0.85 [0. 59–1.24]	0.84 [0.58–1.23]
p-value	0.041	0.390	0.488	0.458

OR: odds ratio; Model 1: unadjusted; Model 2: adjusted for socio-demographic factors (gender, governorate, education of the father); Model 3: adjusted for variables in the Model 2 in addition to the perceived heaviness of school bags, number of days the students carry their bag to schools and number of bags taken to schools; Model 4: adjusted for variables in Model 3 in addition to smoking and hours per day spent on watching TV/using computer

ISSN: 1471-2474