Characteristics of the included studies
| Study | Design | Source and age group | Sample size | Prevalence of back pain | Weight of schoolbag (% BW) | Load carried (kg) | Method of carrying bag | Perceived weight | Main findings |
| Negrini et al 22 | RCT | Middle school in Italy (Mantua) Mean age: 11.2 years (range 10–12) | 108 | LBP: Lifetime 58.4% 3 month 41.9% | Mean: 19.9% of BW (SD 5.3) | Mean: 8.75 kg (SD 1.26) | – | – | LBP was not associated with load carried or weight of schoolbag (% BW) |
| Jones and Watson23 | Longitudinal cohort | 39 Secondary schools (Northwest of England) Age between 11 and 14 years | 933 | LBP: Point 168 (18.6%) | Median 9.9% of BW (IQR 7.4–12.9%) | Median 4.7 kg (IQR 3.7–6.0) | – | – | Incidence of LBP was not associated with load carried, bag design or method of carrying |
| Jones and Macfarlane21 | Longitudinal cohort | 39 Secondary schools (Northwest England) Age between 11 and 14 years | 1376 (330 followed) | LBP: Point 330 (24%) | – | – | On their back: n=248 (65.09%); on their shoulder: n=98 (25.72%); did not use bags at all: n=35 (9.2%) | Children who reported difficulty carrying their schoolbag experienced an approximately twofold to threefold increase in risk of persistent back pain | |
| Sjolie24 | Longitudinal cohort | All schoolchildren (and their parents) in Eastern Norway Mean age: 14.7 years (SD 0.7) | 88 | LBP: Point 58% 3 years (follow-up) 39% | – | – | – | – | No schoolbag variables reported—for the question on ‘pain-provoking situations’ none of them mentioned carrying the schoolbag |
| Szpalski et al 25 | Longitudinal cohort | School children in Antwerp, Belgium Age: 9 years | 392 | LBP: lifetime at baseline: 104 (36%); lifetime at follow-up: 101 (35%). Recent onset at baseline: 13 (4.5%); recent onset at follow-up: 16 (5.6%) | – | – | – | No quantitative data reported | Perceived weight of schoolbag was associated with LBP |
BW, body weight; LBP, low back pain; RCT, randomised controlled trial.