This was a descriptive cross-sectional survey with a nested case-control component involving students at the University of Dschang. The descriptive component aimed to determine the prevalence of CLBP, which is typically defined as pain in the posterior aspect of the body from the lower margin of the 12th ribs to the lower gluteal folds, with or without pain referred into one or both lower limbs, and lasting more than 12 weeks (1). The case-control component was designed to investigate the determinants of chronic LBP in students at the University of Dschang.

The study took place on the main campus of the University of Dschang, in the West Region of Cameroon, which has six faculties and two institutes. These are the Faculty of Letters and Social Sciences (FLSS), Faculty of Economics and Management Sciences (FEMS), Faculty of Law and Political Sciences (FLPS), Faculty of Sciences (FS), Faculty of Agronomy and Agricultural Sciences (FAAS), Faculty of Medicine and Pharmaceutical Science (FMPS), and the Fotso Victor's University Institute of Technology (FV-UIT) in Bandjoun and the Institute of Fine Arts in Foumban (IFAF). In 2023, the institution had 19,971 students supervised by several research, teaching, and non-teaching staff.

The study took place from October 2023 to May 2024, i.e., over a period of 1 year and 7 months. Data collection took place between the 1st November 2023 and the 28th February 2024.

The source population was any student regularly enrolled at the University of Dschang, whose faculty is based on the main campus in Dschang, for the 2023–2024 academic year, in the bachelor's or master's cycle.

For the descriptive component, all students who consented to participate in the study were included, and all students who withdrew their consent during the study were excluded.

For the analytical part, the cases were students with CLBP. Students without LBP were also included as controls. Any student who participated in the study and had chronic LBP was included as a case, and any student who participated in the study but did not have LBP was included as a control. Matching was done by age and sex.

The initial sample size for the descriptive component was 184 participants, calculated using a prevalence of 12.0% among secondary schoolchildren and adolescents, a 95% confidence interval (CI) with a precision of 5%, and a non-respondent rate of 10%. Given that the prevalence of CLBP in our study population is very low, at 12.4% (7, 36). We chose to increase the size of our initial sample. This meant that in order to have 70 cases of chronic LBP for the analytical component calculated using the Schlesselman formula (with Zα/2: 95%; α: 0.05; Zβ of 0.84 for a power of 80% and the ratio = 2:1), we needed a minimum of 688 participants for the descriptive component.

After obtaining approval from the Vice-Chancellor of the University of Dschang and the Regional Human Health Ethics Committee, we conducted a random cluster sampling of our participants. First, in all the faculties on the main campus (FLSS, FLPS, FS, FAAS and FMPS), we randomly selected five departments within each of these faculties. The initial contact was made via a telephone call to the department representatives to explain the study and request their assistance with the field visits. We then consecutively visited the rooms (clusters), each representing a single level of study within a specific program in each department, based on their indicated availability. Visits, generally, took place during students' free time or breaks. Within each room, we surveyed as many students as were willing to participate, within the limits of the allocated period. We repeated this process in each faculty until the desired number of students was reached. Participants were asked to complete the questionnaire truthfully and honestly to minimise information bias. Priority was given to the health of the participants.

An online, well-structured self-report questionnaire was developed based on the results of various pilot articles aligned with our research topic and was validated by medical researchers’ expertise to specifically meet the research objectives. It was also pre-tested. Data was collected through face-to-face interviews, each lasting 15 min. During these interviews, weight and height were measured using the same ultra-slim electronic scale and measuring rod.

The dependent variable was chronic LBP (pain located between the lower margins of the 12th rib and the gluteal folds, persisting for more than 12 weeks) and the independent variables were: -

overweight/obese (BMI greater than 25 kg/m² of body surface),

Data were analyzed using IBM Statistical Package for the Social Sciences®, v.20.0. Categorical variables were presented in terms of numbers and frequencies, while quantitative variables were presented in terms of mean ± standard deviation or median [interquartile range] and extremes. The Chi-square test was used to determine the association between the qualitative variables. Associations between low back pain and relevant categorical variables were assessed using the Pearson chi-square test for independence of observations, the Fisher exact test and the Fisher-Freeman-Halton exact test. Associations between low back pain and ordinal variables were performed using the Cochran-Armitage test for trend. Binomial logistic regression and linear regression analyses were employed to assess the independent factors affecting low back pain. Variables at p ≤ 0.25 in univariate analysis were entered into multiple logistic regression. The threshold for significance was p < 0.05 in multiple logistic analysis.

A total of 1,780 students were approached, of whom 1,645 agreed to take part in the study, representing a response rate of 92.4%. However, 106 were excluded for incomplete responses. Finally, 1,539 (93.5%) fully participated in the study and were included in the analysis.

Of the 1,539 students included in the study, 857 (55.7%) were female. The median age was 20 years [9–22], with the extremes of 16–34 years. The 20–24 age group was the most represented, at 58.5%. In terms of faculties and levels, our study population consisted mainly of students from the Faculty of Science, 470 (30.5%), followed by the Faculty of Economics and Management, 298 (19.4%). The Faculty of Medicine and Pharmaceutical Sciences was the least represented, with 123 (8%). The L2 level was the most represented, with 512 (33.3%). The M2 level was in the minority: 119 (7.7%). Almost all the students in our study were of Cameroonian nationality: 1,388 (90.2%). Chad was the most represented foreign nationality, with 142 (9.2%). Almost all of our students were single, 1,511 (98.1%), and only 26 (1.7%) were married. The majority, 821 (53.3%) of our participants, lived in studios (Table 1).

At the end of our study, 726 of the 1,539 students included, i.e., 47.2% [95% CI: 44.7–49.6], had had at least one episode of LBP in their lifetime. Of the 1,539 students included, 95 [6.2% (95% CI: 5.0–7.3)] had CLBP. Five hundred and eighty-five students [38% (95% CI: 35.3–40.5)] had acute LBP, and 46 [3% (95% CI: 2.1–3.9)] had subacute LBP (Figure 1).

Table 2 shows the distribution of students with CLBP by socio-demographic characteristics. The majority of students with CLBP were male (6.3%). Their median age was 21 [19–23] years, with extremes of 17 and 30. According to the faculties, 16 (13%) of the students suffered from LBP in the Faculty of Medicine and Pharmaceutical Sciences.

Table 3 shows the distribution of students with chronic LBP according to clinical characteristics and lifestyle. Over 6.4% of the students with poor posture in class had chronic LBP. Thirty-nine (7.5%) of the students taking classes for more than 6 h a day had chronic LBP.

Clinically, weight ranged from 50 to 104 Kg, with a median of 68.1 Kg [60–75]. Of the students with a high BMI, 31 (15.9%) had chronic LBP. And among those with a parental history of LBP, 60 (8.5%) also had chronic LBP.

Chronic LBP was expressed in 45.3% of cases as mechanical LBP. It radiated to the buttocks and lower limbs in 20% of cases. The pain was intermittent in 64.2% of cases, permanent in 22.1% and a single episode in 13.7% of cases. Pain was described as burning in 38.9% (n = 37) and numbness in 37.9% (n = 36) (Figure 2).

The effort of lifting a load was the triggering factor for LBP in 39.5% of cases (n = 34). Lying down relieved the pain in 76.7% of cases (n = 66). Pain intensity was classified as mild, according to the numerical pain scale (NPS), in 46.2% of cases (Table 4).

The student was forced to interrupt academic activities in 57.9% of cases. The number of days of interruption of academic activities ranged from 1 day to 38 days, with a median of 3 days [1–4]. Of the 95 students suffering from chronic LBP, 30 (31.6%) had sought medical advice. Of these, 60% had consulted a general practitioner and 36% a rheumatologist (Figure 3).

Ninety-five students with chronic LBP completed the Roland-Morris questionnaire on quality of life with chronic LBP. The score ranged from 0 to 12, with a median of 4 and an interquartile range of 1–6. Most students with chronic LBP obtained a score of 1–6 (64.2%), followed by 7–14 (20%), then 0 (15.8%). No student obtained a score higher than 14 (Table 5).

Bivariate analysis showed that being overweight/obese (p = 0.026) and having a parental history of LBP (p < 0.001) were significantly associated with chronic LBP. Overweight or obese students were 1.87 times more likely to have chronic LBP than those with a normal BMI. Students with a family history of LBP were 2.46 times more likely to have chronic LBP.

After adjustment for confounding factors (type of course, parental history of LBP for the overweight/obesity factor; type of course and overweight/obesity for the parental history of LBP factor), being overweight/obese [ORa = 1.82 (95% CI: 1.02–3.24); p = 0.041], as well as having a parental history of LBP [ORa = 2.6 (95% CI: 1.53–4.43); p < 0.001] remain significantly associated with chronic LBP. Unexpectedly, the following factors were not associated with the development of chronic LBP in our study population: physical inactivity; poor posture in the classroom; and poor ergonomics of bench tables (Table 6).