Low back pain (LBP) is defined as pain located below the costal margin and above the inferior gluteal folds, with or without radiating down to the lower limb [1]. LBP is one of the most common reasons for consulting a primary health care physician. In 2020, LBP affected 619 million people globally, and it is estimated that this number will increase to 843 million cases by 2050, driven largely by population expansion and aging [2]. LBP is increasingly becoming a major public health concern, with an estimated global lifetime prevalence of 85% [3]. In Africa, LBP is increasingly recognized as a major health problem. A systematic review of epidemiological studies across Africa reported a pooled adult prevalence of 32%, with an average lifetime prevalence of 62% [4]. In Cameroon, a study done at the Rheumatology Service of the Douala General Hospital reported a prevalence of chronic low back pain (CLBP) of 19.1% [5]. Age, gender, body mass index (BMI), lifting heavy objects, and lifestyle have been identified as factors associated with LBP [6]. Management of LBP is multidisciplinary [7], in which treatment plans aiming to achieve pain relief, functional improvement, and minimization of absence from work can be formulated with the patient [8].

Unfortunately, published data on LBP in Cameroon are limited. Therefore, in this study, we aimed to describe the epidemiology, clinical patterns, and treatment modalities in patients presenting with LBP at the Kumba Regional Hospital Annex (KRHA). This study was carried out at the KRHA because it is a recently upgraded regional hospital located in the Meme Division of the Southwest Region of Cameroon, which serves as a referral center to three other divisions. In addition, Kumba has a population of over 400,000 inhabitants, representing the largest in the Southwest Region, with inhabitants consisting mostly of farmers, petit traders, and laborers. Hence, this study helps to improve the management of these patients and provide information that adds to existing knowledge about LBP in our context.

We carried out a hospital-based cross-sectional descriptive study over four months, from December 1, 2023, to April 1, 2024. The study was carried out at the outpatient consultation department of KRHA. We targeted all adult patients presenting at the outpatient department using a consecutive, non-exhaustive sampling method. Patients were included if they were ≥18 years of age, presented with LBP at outpatient consultations during the study period, and provided consent to participate in the study. All pregnant women and patients with previous spine surgery were excluded from our analysis. Data were collected using a data entry form. The main variables included socio-demographic data (age, gender, marital status, occupation, address, level of education, religion, height, weight); relevant past history (history of neoplasm, systemic corticosteroid use, intravenous drug use, smoking, tuberculosis, post-menopausal, human immunodeficiency virus, prior lumbar surgery); clinical features of LBP (onset, duration, character, aggravating factors, relieving factors, intensity rated from 0 to 10 based on the Verbal Numeric Scale of Pain, level of activity compromise, neurologic symptoms); physical examination findings (deformity of the spine, tenderness in the lumbar area, other neurological findings), investigations requested (imaging: X-ray, computed tomography scan, magnetic resonance imaging of the lumbar spine; biological: Full Blood Count, Erythrocyte Sedimentation Rate, C-Reactive Protein, others), and details regarding the various treatment modalities.

Data collection and analysis: After drafting a concise research protocol, ethical clearance was requested from the institutional review board of the Faculty of Health Sciences, University of Buea. Administrative authorizations were obtained from the Regional Delegate for Health, Southwest Region, and the Director of the KRHA. Patients were received by the nurses at the outpatient department, their vital parameters taken, and major complaints requested. Those who presented with LBP as their chief complaint were then given an explanation of the aim and procedure of the study in English or pidgin English. Consent was requested and obtained from all participants. We then proceeded with the consultation and examination of the patients, during which a one-on-one interview was conducted with the help of a structured, pretested questionnaire. Based on the clinical symptoms presented by the patients and the physical examination, LBP was grouped into three different clinical patterns: Mechanical, Systemic, and Referred LBP, according to the criteria described in Table 1.

Table 1. Classification of clinical patterns of LBP based on symptoms and signs, as used for this study.

LBP: low back pain, Tb: tuberculosis.

The treatment modalities for the patients were divided into three groups: pharmacological methods such as nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, and muscle relaxants; non-pharmacological methods such as lifestyle modification and physical therapy/rehabilitation; and surgical methods. Data were collected daily, and then coded and entered into Microsoft Excel spreadsheets to ensure data completeness. The entered data were always cross-checked to minimize errors. The data were analyzed using Statistical Package for Social Sciences version 26.0. Prevalence was calculated as the proportion of the number of adult outpatients presenting with LBP to the total number of outpatient consultations during the study period multiplied by 100. The various clinical patterns were grouped into mechanical, systemic, and referred LBP. These variables are presented as frequencies and percentages. The factors associated with LBP were analyzed using a bivariate logistic regression model by comparing gender, age, occupation, and BMI between patients with LBP and those who consulted at the same period without LBP (obtained from consultation records/registers), and factors with a p-value of <0.05 at a 95% confidence interval were considered statistically significant.

This study aimed to determine the prevalence of low back pain (LBP), describe its most common clinical patterns, identify the factors associated with the development of LBP, and describe the treatment modalities of LBP in adult non-pregnant outpatients consulting at the Outpatient Department of the Kumba Regional Hospital Annex, a resource-limited setting in the South-west Region of Cameroon.

In this study, the prevalence of LBP was found to be 15.1% in non-pregnant out patients, similar to that reported by Doualla and collaborators in Douala, Cameroon [5] and that reported in Ghana (15.7%) [9]. However, our reported prevalence was lower than those reported in Nigeria, Rwanda, Ethiopia and Bamenda (46.8%, 55.4%, 66.1%, and 36.1%, respectively) [10]-[13]. These discrepancies are most likely due to differences in study designs, target population included, and differences in study settings.

The most common clinical pattern observed was mechanical LBP (94.9%), similar to what was described in studies from the Netherlands (90.0%) and India (95.0%) [14][15]. In this study, 91.6% of patients presented with LBP with a duration of >12 weeks (chronic), which was similar to results from a study in Nigeria [16]. Radicular neuropathic pain to the lower limbs was found in 76.7% of the participants, which was lower than that found in Tanzania (84.2%) but higher than that found in Nigeria (32.5%) [16]. The neuropathic component of chronic LBP can be caused by a nociceptive stimulus related to nerve sprouting inside degenerated vertebral discs, mechanical compression of the nerve root, and release of inflammatory mediators by injured discs but with no mechanical involvement [17].

On bivariate analysis, the female gender, age > 50 years, and BMI > 25 kg/m² were unadjustably significantly associated with LBP. These findings were similar to those of studies done in Douala, Cameroon, India, Ethiopia, and Kuwait [5][13][18] and [19]. In this study, female gender was associated with developing LBP (OR 1.48, 95% CI 1.24 - 1.77), similar to findings from Southwest Nigeria, China, Ethiopia, and Iran [20]-[23]. This gender-based difference can be explained by the fact that related conditions specific to women, such as premenstrual syndrome, premenstrual dysmorphic disorder, and dysmenorrhea, could mimic certain clinical presentations of LBP [24]. Furthermore, heightened pain sensitivity among women, menstrual cycle fluctuations, biological response to pregnancy and childbearing, and the physical stress of child-raising may make women more prone to LBP compared to men [25]. However, our findings were in sharp contrast with those of other studies in which the male gender was found to be associated with LBP [17][26] and [27].

Furthermore, in our study, a BMI of >25 kg/m² was also found to be unadjustably significantly associated with LBP (OR: 3, 95%CI: 2.5 - 3.7), the same as seen in a study carried out in Southern Nigeria [9]. One explanation for this association is that a gain in mass in the upper body area due to overweight could increase the load on the vertebral discs, leading to LBP development. In contrast, one study conducted in Malaysia revealed that BMI had no significant association with LBP [6].

Moreover, we found that patients aged >50 years were at greater unadjusted odds (OR: 3.8, 95% CI: 3.3 - 4.6) for developing LBP than younger patients, similar to findings in studies conducted in Brazil and China [26][28]. An observation noted in a study carried out in Nigeria found that aging increases the risk of LBP due to senile spinal degeneration processes that accompany increased age [9]. In contrast, some studies conducted in Ethiopia and Nigeria found no association between age and the development of LBP [18][20].

Finally, our results showed that professions requiring manual labor such as farming were not associated with developing LBP (p = 0.07), contrary to findings obtained in studies done in Southwest Nigeria and Brazil [15][29]. These authors explained that, due to the working postures and movements of the lower back during the work process, load is generated on the lumbar region, which can overload tissues and exceed their thresholds of tolerable stress, causing injury due to overexertion or imbalance. These conflicting results are mainly attributed to our relatively smaller sample size and to the differences in the various study designs, which were either prospective cohort designs or case-control studies, compared to our cross-sectional design.

Treatment modalities of low back pain: Over 90% of patients with low back pain were managed in the limited resource setting of the Kumba Regional Hospital Annex, without needing any further, more specialized procedures or referrals to higher level health facilities. The most common treatment modalities employed were pharmacological (NSAIDs, weak opioids, myorelaxants) and non-pharmacological (modification of activities of daily living and physical therapy). Similar results have been reported in Rwanda and the United Kingdom [10][17].

Less than 10% of the patients with low back pain needed more specialized medical management and care at higher healthcare facilities in other towns.

The prevalence of LBP is high (15.1%) in outpatient consultations, with the most common clinical pattern being chronic mechanical LBP associated with bilateral sciatica and paresthesia. The main factors unadjustably associated with the development of LBP were female gender, age of >50 years, and a BMI of ≥25 kg/m². The most common treatment modalities were lifestyle modification and prescription of NSAIDs in combination with weak opioids and myorelaxants. Therefore, proper understanding of factors associated with low back pain and an appropriate management approach will better curb this very frequent health challenge in local resource-limited areas.

Our study was a single-centered, cross-sectional study, using a proposed clinical description of low back pain based on symptoms/signs without any radiologic confirmation. Also, the non-exhaustive sampling method constitutes a limitation in our study. The factors unadjustably associated with LBP were evaluated only using the bivariate regression model; multivariate analysis was not done to rule out confounders.

The authors would like to thank all the patients who agreed to participate in the study, as well as the entire staff of the Outpatient Department of the Kumba Regional Hospital Annex.

All authors have reviewed the final version to be published and agree to be accountable for all aspects of the work.

Concept and design:Ernest K. Ndifor, Ashley Vera, Bokwe Melissa.

Acquisition, analysis, or interpretation of data: Ernest K. Ndifor, Ashley Vera

Drafting of the manuscript: Ernest K. Ndifor, Nana Theophile, Ashley Vera, Bokwe Melissa, Fokam Pius.

Critical review of the manuscript for important intellectual content: Ernest K. Ndifor, Nana Theophile, Itambi Maxwell, Dora Makia, Marc L. Guifo, Fokam Pius.

Supervision:Marc L. Guifo, Fokam Pius.

Informed consent for treatment and open access publication was obtained or waived by all participants in this study. The Faculty of Health Sciences Institutional Review Board issued approval 2023/21811/UB/SG/IRB/FHS. After drafting a concise research protocol, ethical clearance and administrative authorizations from the Regional Delegate for Health Southwest Region, the Dean of the Faculty of Health Sciences, University of Buea, and the Director of the Kumba Regional Hospital Annex were obtained.