Study design and ethical consideration
We conducted a cross-sectional study in Bujumbura, the largest city and economic capital of Burundi. We collected data from patients diagnosed with CLBP at a single point in time. The study protocol was approved by the National Ethics Committee (CNE/20/2019). Patients affirmed their agreement to participate by signing a consent form.
Setting
Recruitment started in September of 2019. The enrollment and assessment procedures took place at the Centre National de Référence en Kinésithérapie et Réadaptation médicale (CNRKR), Bujumbura, in Burundi. Data collection started in November 2019 and was completed in February 2020.
Participants
Volunteer participants were recruited through advertisements about the study and by consulting admission records of hospitals and rehabilitation centers in Bujumbura. The principal investigator screened potential participants by phone. Those who were eligible and interested made appointments to come to the CNRKR, where they signed a written consent form before undertaking the study assessments. The inclusion criteria were: having a diagnosis of non-specific CLBP; being 18–65 years old; Burundi residence; and mobility sufficient to enable walking and sit-to-stand transition without assistance. LBP was defined as chronic when the pain had been persistent for at least 12 weeks19 and nonspecific when the pain was not attributable to a recognizable pathology (e.g., infection, tumor, osteoporosis, rheumatoid arthritis, fracture, inflammation).20 The exclusion criteria were: pregnancy; any sign of serious spinal pathology (e.g., cancer, cauda equina lesion); radicular pain indicative of nerve root compression; severe spinal stenosis; spondylolisthesis; and fibromyalgia. The final study cohort included 58 adult patients with CLBP.
Data collection and variables descriptions
The principal investigator (I.N.) and two clinician co-authors conducted the evaluations. Before data collection, the evaluators were trained to standardize instrument administration. Because some participants lacked reading fluency, the assessments were interviewer-administered and the measures were adapted to Kirundi via evidence-based guidelines.21 Individual and psychosocial outcome data were collected. CLBP related data were collected according to the International Classification of Functioning, Disability, and Health.
Biopsychosocial factors
Individual characteristics
The sociodemographic variables analyzed were age, gender, weight, height, BMI, marital status, profession, education level, healthcare coverage, and previous treatments (e.g., medications, physical therapy).
Depression
CLBP-associated depression was measured with Beck Depression Inventory (BDI)-II, a 21-item questionnaire designed to measure severity of depressiveness. Each item references a symptom in four statements worth 0, 1, 2, and 3 points, respectively; the respondent chooses the statement that best describes the severity of his/her symptoms over the past 2 weeks.22, 23 BDI-II scores (range, 0–63) were obtained by summing the number of each marked statement and interpreted as follows: <10, no/minimal depression; 10–18, mild to moderate depression; 19–29, moderate to severe depression; and 30–63, severe depression.24
Fear avoidance beliefs
The Fear-Avoidance Beliefs Questionnaire (FABQ)25 was used to measure how participants’ fear avoidance beliefs about physical activity and work may affect their LBP. The FABQ consists of 16 items in which agreement with the statement in each item is rated on a 7-point Likert scale (0 = completely disagree, 6 = completely agree). The FABQ consists of a four-item physical activity subscale (FABQ-PA; maximum score 24), a seven-item work subscale (FABQ-Work; maximum score 42), and five additional informational/categorical items.
Physical fitness
- Muscle endurance
The Shirado test26 of static endurance of the abdominal muscles was applied. The participants lay in a supine position with their hips and knees bent at 90°, calves resting on a stool or chair, and arms crossed over the chest with their hands resting on their shoulders. They were asked to lift their scapulas off the ground and maintain this crunch position as long as possible. We noted the held time in seconds without encouraging the subject or specifying the time during the test. The test ended for each participant when his or her scapulas went down due to fatigue or discomfort, or after a maximum duration of 240 s.
The Sorensen test was applied to assess endurance of the trunk extensor muscles. The participants lay on the examining table in the prone position with the upper edge of the iliac crests aligned with the edge of the table. Their lower bodies were fixed to the table with their arms folded across their chest, and they were asked to maintain their upper bodies in a horizontal position isometrically.27, 28 The time during which each participant held his/her upper body straight and horizontal was recorded. The test was stopped if the trunk went down due to fatigue or discomfort, or after a maximum duration of 240 s.
- Perceived exertion
To assess perceived exertion, we applied Borg’s category ratio-scale (Borg CR10)29, a common scale used to assess sensory perceptions, subjective symptoms, and feelings. The Borg CR10 was completed at the end of each stage of a step test by asking the participants to rate their perception of physical effort or exertion after 2 min of stepping up and down. The step test30 was organized according to submaximal, gradational, and discontinuous principles. We used four wooden platforms of different heights (0.07, 0.12, 0.19, and 0.24 m). Patients were instructed to step up and down for 2 min at a frequency of 84 steps/min (given by a metronome). Patients were allowed to rest seated on a chair for 2 min after each stage. They were encouraged to perform as many stages as they could.
CLBP related outcomes
Pain
Participants were asked to report the intensity of their pain on an 11-point numerical rating scale (NRS) ranging from 0 to 10, wherein 0 represented the absence of pain and 10 represented the worst pain imaginable.31, 32 In accordance with Jansen et al.’s recommendations, we adopted the following NRS interpretation rubric: 1–4, mild pain; 5–6, moderate pain; and 7–10, severe pain.33
Activity limitations
ADL limitations were measured with the Roland Morris Disability Questionnaire (RMDQ) and the Canadian Occupational Performance Measure (COPM). The RMDQ34 consists of 24 items that refer to different ways that LBP may affect activities. Participants ticked the limitation items that applied to themselves. The RMDQ scores were the number of ticked items, such that higher RMDQ scores indicate greater ADL limitations, and thus greater disability. The COPM35 is a patient-specific measure intended to determine what problems are having the greatest impact on occupational performance in the areas of self-care, productivity, and leisure. During a semi-structured interview, the patient identified important activities that are difficult to perform, and then rated the importance of each activity on a 1–10-point scale. Next, they rated their performance in the five activities rated as most important on a 1–10-point scale, with higher scores reflecting better performance in ADLs (i.e., less limitations).
Restrictions in participation
Restrictions in SP were assessed with a 5-Item Pain Disability Index (5-IPDI),36 which consists of the first five items (family/home responsibilities, recreation, social activity, occupation, and sexual behavior) of the 7-Item Pain Disability Index37. The index items were rated on a 0–10 numeric scale from 0 (no participation) to 10 (maximum participation), with possible total scores ranging from 0 to 50 such that higher scores reflect greater restrictions in SP participation, and thus greater disability.
Data analysis
The data were analyzed in SPSS, version 27 software. For each study variable, the normality of data was verified by means of histograms and Q-Q plots. Descriptive statistics were used to present the study sample’s biopsychosocial and CLBP outcomes. Outcomes are reported as means with standard deviations for continuous and normally distributed variables, medians with interquartile ranges for ordinal and non-normally distributed variables, and numbers of cases with percentages for nominal variables. We used Mann-Whitney and Kruskall-Wallis tests to investigate the impact of nominal biopsychosocial factors on CLBP outcomes, and used Spearman correlation test to explore associations of quantitative biopsychosocial factors with CLBP outcomes. Correlation coefficient values were reported with p-values and interpreted as follows38: 0.0–0.10, negligible; 0.10–0.39, weak; 0.40–0.69, moderate; 0.70–0.89, strong; and 0.90–1.0, very strong.