BackgroundThe association between the weight of school bag and Low Back Pain (LBP) amongst students remains under intense debate worldwide. This study aimed to estimate the prevalence of LBP amongst public high school students (14 to 19 years) in Kuwait and to investigate the association between LBP and the weight of school bags.MethodsAn analytical cross-sectional study using multistage cluster random sampling with probability proportional to size was conducted on a total of 950 public high school students from all governorates. Data on LBP were collected through face-to-face interviews using a structured questionnaire. A 0–10 Numeric Pain Rating Scale was used to rate the intensity of LBP. The students’ height and weight in addition to the weight of their school bags were measured using appropriate weight and height scales. Logistic regression was used to investigate the association between the weight of school bags and LBP while adjusting for potential confounders.ResultsThe estimated lifetime, 6-month, and 1-month prevalence of LBP were 70.3% (95% CI: 67.30–73.21%), 49.1% (95% CI: 45.83–52.28%), and 30.8% (95% CI: 27.81–33.78%) respectively, with significantly higher prevalence amongst females compared to males (p < 0.001). The absolute weight of school bag was not significantly associated with LBP neither in univariable nor multivariable analysis. The relative weight of school bag (as a percentage of the body weight) was significantly associated with LBP in univariable analysis but not in multivariable analysis. The perceived heaviness of school bag, however, was found to be significantly associated with LBP throughout the analysis (p < 0.001).ConclusionIn conclusion, LBP amongst high school students in Kuwait seems to be very common with a prevalence resembling that of high-income countries. Our data suggest that the perceived heaviness of school bag is far more important than the actual bag weight. Current recommendations about the weight of school bags, which are not supported by evidence, should be revised to take into account the students’ perceived heaviness of school bag.

BackgroundRefining and individualizing treatment of acute pain in the emergency department (ED) is a high priority, given that painful complaints are the most common reasons for ED visits. Few tools exist to objectively measure pain perception in the ED setting. We speculated that variation in perception of fixed painful stimuli would explain individual variation in reported pain and response to treatment among ED patients.Materials and methodsIn three studies, we 1) describe performance characteristics of brief quantitative sensory testing (QST) in 50 healthy volunteers, 2) test effects of 10 mg oxycodone versus placebo on QST measures in 18 healthy volunteers, and 3) measure interindividual differences in nociception and treatment responses in 198 ED patients with a painful complaint during ED treatment. QST measures adapted for use in the ED included pressure sensation threshold, pressure pain threshold (PPT), pressure pain response (PPR), and cold pain tolerance (CPT) tests.ResultsFirst, all QST measures had high inter-rater reliability and test–retest reproducibility. Second, 10 mg oxycodone reduced PPR, increased PPT, and prolonged CPT. Third, baseline PPT and PPR revealed hyperalgesia in 31 (16%) ED subjects relative to healthy volunteers. In 173 (88%) ED subjects who completed repeat testing 30 minutes after pain treatment, PPT increased and PPR decreased (Cohen’s dz 0.10–0.19). Verbal pain scores (0–10) for the ED complaint decreased by 2.2 (95% confidence intervals [CI]: 1.9, 2.6) (Cohen’s dz 0.97) but did not covary with the changes in PPT and PPR (r=0.05–0.13). Treatment effects were greatest in ED subjects with a history of treatment for anxiety or depression (Cohen’s dz 0.26–0.43) or with baseline hyperalgesia (Cohen’s dz 0.40–0.88).ConclusionQST reveals individual differences in perception of fixed painful stimuli in ED patients, including hyperalgesia. Subgroups of ED patients with hyperalgesia and psychiatric history report larger treatment effects on ED pain and QST measures.