Low back pain and associated risk factors among medical students in Bangladesh: a cross-sectional study

Study settings and population

This cross-sectional study was conducted on MBBS students (first year to final year) and medical interns in Faridpur Medical College from October to December 2020. Every year, around 120 students are admitted to this medical college; hence typically, there are about 600 students and 120 medical interns in the medical college at any given time.

The study’s sample size was calculated as 251 using OpenEpi version 3.1, assuming 47.5% as the estimated prevalence rate¹⁰ at a 95% confidence level with 5% precision. The sample size was calculated based on an Indian study¹⁰ as the Bangladeshi medical students have relatively similar curriculum, clinical class exposure, study load, and social and cultural demographics as Indian medical students. Because of the possibility of sample loss, the final sample size was determined as 270. Forty-five students from each batch (1^st year to 5^th year) and 45 medical interns were selected randomly by lottery method using their roll number. The study was reported following the STROBE guidelines for reporting observational studies.²⁶

Inclusion and exclusion criteria

Full-time medical students studying 1^st year to 5^th year at Faridpur Medical College and medical interns were included in that study. Students who refused to give full consent to participate in the study were excluded.

Instruments

An online, standardized, self-administrated questionnaire²⁷ was used for data collection. The questionnaire was in English language and had three sections. Different sections of the questionnaire were adapted from the minimal dataset reported by Deyo et al.,²⁸ and the questionnaires that were validated and used in previous studies.^29,30

Section 1 contained five questions related to socio-demographic data, including gender, age, height, weight, and educational level. Body mass index (BMI) was calculated as weight (in kg) divided by height squared (in meters). In Section 2, lifestyle-related questions, such as exercise frequency, smoking habits, total sitting time in a day (in hours), type of activity mostly done in a day, and availability of enough rest time, were inquired. In addition, the ergonomic characteristics (availability of back support, adjustable back support, adjustable sitting surface) of participants’ chairs were also assessed in that section. To determine the prevalence of LBP at different time points, participants were asked whether they suffered from LBP during the survey, the last 6 months, and the last 12 months (dichotomous scale, Yes/No) in Section 3. This section also included data regarding the first appearance, causes, and aggravating factors of LBP; duration and episode of LBP in the last 12 months; the presence of associated leg pain; and type of received treatment.

The questionnaire was piloted on 15 students before administration in the study to confirm the appropriateness and understandability of questions. The questionnaire was modified according to the feedback, and the responses from the pilot study were not included in the main study.

Operational definitions and study variables

Dependent variable:

Independent variables:

Data collection

We used the online survey software from Google Drive to conduct the survey and record the responses. The weblink of the questionnaire was sent to selected participants via email with a cover letter that informed the objective of the study and assurance confidentiality of the responses. Participants’ full consent was taken before collecting the data, and they had the right to withdraw anytime without completing the questionnaire. We did not offer any incentives or rewards for participation.

Data analysis

After receiving responses from the participants, the accuracy and completeness were checked manually, and data were cleaned when required. All statistical analyses were performed using IBM Statistical Package for Social Sciences (SPSS) Version 26. Descriptive statistics were calculated, and the continuous variables were summarized as mean and standard deviation, whereas the categorical variables were summarized as frequency and percentage. Bivariate analysis using the chi-square test was performed to evaluate the variables associated with LBP at different time points. In addition, binary logistic regression was applied to determine the relative odds of occurrence of LBP in the last 12 months due to the presence of a particular factor. The results were presented with an adjusted odds ratio (OR) and confidence intervals for 95% (95% CI). All statistical analysis was set at a 5% level of significance (p < 0.05).

Ethics

Permission was taken from the Ethical Review Committee (ERC) of Faridpur Medical College.

Characteristics of participants

A total of 223 subjects responded to the survey, with a response of 82.6%. However, 16 participants did not complete the survey fully; hence they were excluded. Eventually, 167 medical students and 40 medical interns participated entirely in the study and were included in the analysis. Breakdown of the students was: 31 (15%) in the first, 31 (15%) in the second, 30 (14.5%) in the third, 35 (16.9%) in the fourth, and 40 (19.3%) in the final year of MBBS course (Figure 1).

Figure 1. Flow chart of the participants’ inclusion for analysis.

Among all participants, 44.4% were males, and 55.6% were females. The mean age of the participants was 22.4 ± 1.9 years, ranging between 19 and 27 years. Based on the mean age, participants were divided into ≤ 21, 22 – 24, and ≥ 25 age groups. Regarding weight, participants were divided into two groups, namely, below normal to normal weight (BMI ≤ 25 kg/m²) and above normal weight (BMI > 25 kg/m²). Three out of five participants (61.4%) had BMI ≤ 25 kg/m².

The frequency of physical activity was categorized into three groups: Low level (< 4 times/month), moderate level (1-4 times/week), and high level (≥ 5 times/week). Among all participants, almost half (45.4%) performed a low level of physical activity, the majority (83.1%) were non-smokers, nearly half (48.3%) reported that they performed most of their daily activities by sitting, more than two-thirds (69.1%) of participants spent ≥ 6 hours/day in sitting, and four out of five participants (80.2%) had enough rest time. Moreover, the majority (76.3%) used chairs with back support, almost two-thirds (65.2%) used chairs with nonadjustable back support, and more than half (55.6%) used chairs without an adjustable sitting surface (Table 1).

LBP prevalence and LBP characteristics

The point, 6-month, and 12-month prevalence of LBP was 25.6%, 46.9%, and 63.3%, respectively. Nearly two-thirds (65.9%) of participants with LBP informed that they suffered the first episode of LBP after being admitted in medical, while only 5.5% experienced it during the internship. 35.1% of participants reported that they experienced only one episode of LBP, whereas 35.1% experienced 2–3 episodes, and 29.8% experienced more than three episodes in the previous 12 months. More than half of the respondents (55%) had a short duration (1 – 7 days) of LBP, while 8.4% reported they had LBP every day in the past year.²⁷

As for causes or diagnosis of LBP, the majority (70.8%) reported no diagnosis, therefore had non-specific LBP. More than half of the participants (53.2%) reported no associated leg pain, while 31.2% reported radiated leg pain. Regarding aggravating factors, more than half of the participants (55.2%) reported that LBP worsened when they maintained a static position for a long time followed by bending or twisting (18.8%), lifting any object (8.4%), sudden movement (5.2%), performing repetitive tasks (3.2%) and non-specific (9.1%). Three-fifths of the participants (60.4%) reported their pain relieved without taking any specific treatment while the remaining received different medications in the form of opioid analgesics (22.1%), exercise therapy (9.1%), steroid injection (1.3%), both opioid and exercise therapy (5.2%), and opioid with steroid injection (1.9%) (Table 2).

Relationship between socio-demographic factors and LBP prevalence

Bivariate analysis showed no significant association between LBP and age groups (p > 0.160) or the education level of participants (p > 0.161) regardless of the time of occurrence (Table 1).

In contrast, the 6-month and 12-month prevalence of LBP was significantly correlated with gender or being overweight. The number of females with LBP was more than the number of males with LBP during the survey (20.7% vs 29.6%, p = 0.144), in the last 6 months (38% vs 53.9%; p = 0.023) and in the last 12 months (52.2% vs 72.2%; p = 0.003). In addition, participants with BMI > 25 kg/m² reported the presence of LBP more frequently than the participants with BMI ≤ 25 kg/m² during the survey (22.8% vs 30%), in the past 6 months (39.4% vs 58.8%) and in the last 12 months (56.7% vs 73.8%) (Table 1).

In the logistic regression analysis, females were 2.3 times more likely to have LBP compared to males (OR: 2.4, 95% CI: 1.3 – 4.2; p = 0.003), and the participants with BMI > 25 kg/m² were around two times at higher risk of developing LBP than the participants with BMI ≤ 25 kg/m² (OR: 2.1, 95% CI: 1.2 – 3.9; p = 0.014) in the last 12 months (Table 3).

Relationship between lifestyle factors and LBP prevalence

According to the bivariate analysis, the factors that significantly contributed to LBP occurrence in the last 6 months and 12 months were frequency of physical activity, total sitting time per day, availability of rest time, and type of activity mostly done in a day. However, the point prevalence of LBP was significantly correlated with only physical activity and the type of activity mostly done in a day. Results demonstrated that the respondents who performed a high frequency of physical activity, those who spent < 6 hours per day by sitting, those who had enough rest time, and those who did not perform any specific task for a long time had the least prevalence of LBP in all time points compared to their counterparts (Table 1).

Results of logistic regression analysis showed that the participants who performed moderate and low frequency of physical activity were 6.3 times (OR: 6.3, 95% CI: 2.7 – 14.5; p < 0.005), and 6.2 times (OR: 6.2, 95% CI: 2.8 – 13.7, p < 0.005) more likely to develop LBP in last 12 months than the participants who performed a high frequency of physical activity, respectively. Moreover, the odds of LBP were 1.7 times higher among smokers than non-smokers (OR: 1.7, 95% CI: 0.7 – 4.2; p = 0.259), more than three times higher among participants who spent ≥ 6 hours in sitting than those spent < 6 hours (OR: 3.0, 95% CI: 1.6 – 5.5; p < 0.005), and almost 10 times higher among the subjects who had insufficient rest time than those who had enough rest time (OR: 9.9, 95% CI: 2.9 – 33.5; p < 0.005). In addition, the participants who did most of the activity in a day by sitting, standing, or walking, and bending were about 7.3 times (OR: 7.3, 95% CI: 3.7 – 14.4; p < 0.005), 1.7 times (OR: 1.7, 95% CI: 0.6 – 4.8; p = 0.338) and 4.5 times (OR: 4.5, 95% CI: 0.8 – 23.4; p = 0.078) more likely to suffer from LBP in last year compared to the participants who did not perform any activity in a specific position for a long time, respectively (Table 3).

Relationship between participants’ chair type and LBP prevalence

Bivariate analysis revealed that the prevalence of LBP, regardless of the time of occurrence, was significantly correlated with the presence of back support, adjustable back support, and adjustable sitting surface of participants’ chairs. Results showed that the participants who had chairs with back support, adjustable back support, and adjustable sitting surface had a lower LBP prevalence than their counterparts (Table 1).

Further analysis showed that the 12-month prevalence of LBP was about 2.5 times higher among participants who used chairs without back support (OR: 2.4, 95% CI: 1.2 – 5.1; p = 0.020), nearly 5.6 times higher among participants who used chairs without adjustable back support (OR: 5.6, 95% CI: 2.9 – 10.4; p < 0.005), and almost 3.7 times higher among participants who used chairs without adjustable sitting surface (OR: 3.7, 95% CI: 2.0 – 6.7; p < 0.005) compared to their respective reference group (Table 3).

LBP prevalence

The results of our study indicated that almost half (46.9%) and two-thirds (63.3%) of the participants experienced LBP in the past 6 months and 12 months, respectively, while 25.6% reported LBP at the time of the survey. Compared to this study, 12-month prevalence of LBP was lower among the medical students in Pakistan (38.6%),¹⁹ China (40.1%),²⁰ the US (42.8%),²¹ Malaysia (46.1%),²² India (47.5%),¹⁰ Austria (53.4%),¹⁴ Serbia (59.5%),⁵ Brazil (59.9%),²³ Saudi Arabia (61.4%),²⁰ and was higher among the medical students in Turkey (96.4%).³⁴ The discrepancy in the LBP prevalence could be from some factors, including the variation of faculty year of study, academic curriculum, methodological heterogenicity, mode of data collection, cross-cultural factors, and subjective perception of pain.^35,36

Socio-demographic factors and LBP prevalence

The findings of the study showed that sex and weight are two socio-demographic factors that were associated with 12-month prevalence of LBP among Bangladeshi medical students. Results showed that females had a significantly higher prevalence of LBP than males, which was consistent with several studies.^{5,12,30,37,38} Males are structurally, anatomically, and physiologically different from females, and researchers asserted that females have lower pain thresholds and higher sensitivity to pain than males.^39,40 For these reasons, females are more likely to report LBP than males. Although, some studies did not reveal any significant association between LBP prevalence and gender.^{10,20,22,38,41} In addition, participants with BMI > 25 kg/m² had a higher prevalence of LBP than the participants with BMI ≤ 25 kg/m², which is comparable with the findings of a meta-analysis by Shiri et al.⁴² and a study by Webb et al.⁴³ Researchers showed that as weight increases, it creates higher pressure on the intervertebral disc and other spine structures, consequently triggers pain.⁴⁴ However, few studies did not find any association between weight and LBP prevalence.^11,34,38,41

In contrast, several studies have stated that the prevalence of LBP increases with age,^11,45 although some studies revealed that the prevalence of LBP was higher among younger nurses than older nurses.^46–48 Contrary to these findings, our study demonstrated no significant relationship between age and prevalence of LBP, which is comparable with several studies.^41,49 Moreover, several studies demonstrated a significant correlation between the year of study with MSP, including LBP among medical students.^13,22,23,38 However, the results of our study indicated no association between the year of the study and LBP prevalence, although the second-year students had a higher prevalence of LBP than others. The reason could be that the second-year students need to appear for their first professional exam, and at that time, different factors, including more study hours, stress, and psychological imbalance, could evoke LBP. In contrast, few studies did not find any association between MSP prevalence, including LBP, and study year among medical students.^19,24,41,49

Lifestyle factors and LBP prevalence

The results of our study revealed that physical activity patterns and total sitting hours were significantly associated with the 12-month prevalence of LBP among the participants. Prolonged sitting is a risk factor of LBP^50,51 as it increases spinal compression load and dysfunction of paraspinal muscles.^52,53 Nyland and Grimmer⁵¹ affirmed that ‘a sitting and looking down position’ was a potential risk factor of LBP, and studies demonstrated a positive correlation between staying in a sitting position for a long time and LBP.^34,41,54 Our study revealed that participants who spent ≥ 6 hours sitting had a significantly higher prevalence of LBP than participants who spent < 6 hours sitting. Conversely, Hartvigsen et al.,⁵⁵ Spyropoulos et al.,³⁰ and Tavares et al.,⁴⁹ reported no association between sitting time and LBP prevalence. Moreover, medical students generally remain busy with their classes and hospital visits, making their life sedentary. A study on medical students of Delhi showed that only one-third of the medical students performed the recommended amount of physical activity.⁵⁶ Physical exercise or regular sports practice are encouraged in different studies as it helps to minimize the rate of LBP prevalence and is effective for primary and secondary prevention of LBP.⁵⁷ The findings of our study demonstrated a significant relationship between the prevalence of LBP and frequency of physical activity, which was supported by previous studies.^5,38 Moreover, The American College of Sports Medicine recommended that to promote and maintain health, physical activity should be performed for at least 30 minutes at moderate intensity with a minimum frequency of 5 days/week.^58,59 The findings of our study were in line with this recommendation as the participants who performed high frequency (≥ five days/week) of physical activity had a significantly lower prevalence of LBP than those who performed low or moderate frequency (< five days/week) of physical activity. However, several studies did not reveal any significant association between physical activity and LBP prevalence among medical students.^{10,23,30,34,60}

Conversely, our study revealed no association between smoking habit and LBP prevalence at any time point, in accordance with other studies.^{13,19,20,24,61} While Shiri et al.⁶² found the correlation between smoking habits and LBP prevalence in their meta-analysis, and they reported that smokers and ex-smokers had a higher prevalence of LBP than non-smokers. Other studies also revealed that medical students who smoked were more likely to suffer LBP.^41,60 This discrepancy could be for the low number of smokers as it can be inferred that studies with less than 10% prevalence of smoking did not find any association between smoking habits and LBP prevalence. Moreover, research showed a positive relationship between the risk of LBP and smoking dose.⁶³ Our study did not assess the intensity of smoking and the duration of exposure to the habit.

LBP characteristics

We found that in the majority of cases (64.9%), LBP was recurrent, and more than half (55%) of the participants had a short annual duration (1–7 days) of LBP which was consistent with previous studies on Greek public office workers,³⁰ and nursing students and graduate nurses.²⁹ That indicated the high chance of LBP recurrence and chronicity in the future. In addition, most of the participants (53.2%) had localized LBP, and 31.2% reported radiated leg pain, which was consistent with several studies.^64,65

El-soud et al.⁶⁵ found that LBP was non-specific in most cases. In agreement with that result, our study also revealed that 70.8% of the subjects had non-specific LBP. Regarding treatment, the majority (60.4%) of participants reported they did not seek any medication for their symptoms, which is comparable with the findings of studies from Wong et al. (65.9%),⁶⁴ Hafeez et al. (64.5%)⁶⁰ and Falavigna et al. (67.3%).²³ Moreover, maintaining a specific posture, including standing and sitting, for a long time was the most cited (55.2%) aggravating factor for LBP in our study. In agreement with our finding, previous studies⁶⁶ also reported LBP mostly worsened after prolonged standing/sitting.

Hestbaek et al.⁶⁷ claimed that the lifetime prevalence of LBP increases markedly between 12 and 22 years of age. Our study came to the same conclusion as we found that 28.7% and 65.7% of participants had LBP before commencing their medical studies and during medical studies, respectively; and more than half (50.4%) of the participants who had LBP in the last 12 months aged ≤ 22 years. That indicated the importance of implementing the LBP prevention strategies before or at the beginning of the medical course.

Type of chair and LBP prevalence

Individuals suffering from different musculoskeletal pains due to prolonged sitting are recommended to use ergonomically sound chairs as the chair directly influences body alignment or posture.^68,69 Researchers concluded that scarcity of knowledge, understanding, or application of ergonomics’ basic principles and rules could lead to LBP.⁷⁰ Moreover, it is vital to adjust the height of the sitting surface of the chair to meet individual biomechanical requirements so that they can use the desk with ease without aggravating the spine.^71,72 Our results showed that the participants who used chairs with back support, adjustable back support, and the adjustable sitting surface had a significantly lower prevalence of LBP compared to their counterparts at all time points. However, previous studies did not show any significant association between LBP prevalence and using a chair with back support^30,60 or using a chair with an adjustable sitting surface.³⁰ Whereas Makhsous et al.⁷³ and Spyropoulos et al.³⁰ demonstrated that LBP prevalence could be lowered using chairs with back support.

Strengths and limitations

This study was the first study that estimated the prevalence of LBP among Bangladeshi medical students, and the response rate of the study was satisfactory. However, our study has some limitations that should be acknowledged. First, as we included students from only one medical college, the outcomes may not fully represent the situation for all medical students in Bangladesh. Second, the study outcomes relied solely on the self-administrated questionnaire, and we did not perform any medical tests to confirm the presence of LBP. Therefore, information bias and subject bias cannot be ruled out. Moreover, the difficulty in recalling arises the possibility of over-or underreporting of LBP as participants reported the presence of LBP in the last one year, which entirely depended on the participants’ memory. Finally, as it was a cross-sectional study, the exposure to risk factors and outcomes were evaluated concurrently. Hence, we showed only the relationship but could not establish any evidence of the causal association between exposure and LBP occurrence.

Underlying data

Mendeley Data: Low back pain and associated risk factors among medical students in Bangladesh: A cross-sectional study. https://doi.org/10.17632/mfky2jttwp.3.²⁷

The project contains the following underlying data:

Extended data

Mendeley Data: Low back pain and associated risk factors among medical students in Bangladesh: A cross-sectional study. https://doi.org/10.17632/mfky2jttwp.3.²⁷

The project contains the following extended data:

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).