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

Background: Low back pain (LBP) is one of the leading causes of disability worldwide. Different studies showed the high prevalence of LBP among medical students. However, no study has been conducted on Bangladeshi medical students to estimate the prevalence of LBP. This study determined the prevalence, characteristics, and associated risk factors of LBP among medical students in Bangladesh. Methods: A cross-sectional study was conducted from October to December 2020 among randomly selected 270 medical students and medical interns in Faridpur Medical College, Bangladesh, using an online questionnaire. In data analysis, chi-square test and binary logistic regression were performed, and a p-value of < 0.05 was regarded as statistically significant. Results: A total of 207 participants responded fully to the survey, and were included in the analysis. The mean age of the participants was 22.4 ± 1.9 years. The point, 6-month, and 12-month prevalence of LBP was 25.6%, 46.9%, and 63.3%, respectively. In most participants, LBP was localized (53.2%), recurrent (64.9%), non-specific (70.8%), affected for a short period (55%), and relieved without receiving any treatment (60.4%). Participants who had a significantly higher 12-month prevalence of LBP included females (72.2% vs 52.2%), with BMI >25 kg/m 2 (73.2% vs 56.7%), those who performed physical activity at low to moderate frequency (72.4% vs 29.5%), those who spent > 6 hours/day by sitting (71.3% vs 45.3%), and those who did not have enough rest time (92.7% vs 56%). Ergonomic features of chairs, such as having back support, adjustable back support, and adjustable sitting surface, significantly (p < 0.05) influenced the outcomes. Conclusion: The prevalence of LBP among medical students in Bangladesh was high, and most of the risk factors associated with the high prevalence of LBP were modifiable. Hence, LBP can be prevented by implementing preventive strategies and providing ergonomic training and physical activity facilities.


Introduction
Low back pain (LBP) is considered the single leading cause of disability-related musculoskeletal conditions globally. [1][2][3] Researchers showed that 70-80% of people suffer from LBP at least once in their lifetime, 2,4 and 18% of the people suffer from LBP at any given time. 5 The healthcare-related costs due to LBP are increasing; hence it is becoming a burden in developed countries, as well as in low-income and middle-income countries. 3 In Bangladesh, the prevalence of LBP ranges between 18.6-60.8%. [6][7][8][9] Individuals of all ages, including young people and students, can be affected by LBP. [10][11][12][13] Medical students are at high risk of developing LBP as they have highly demanding curricula that facilitate a sedentary lifestyle, stressful routines, fewer sleeping hours, long hours of study, hospital training, and classes. 5,13,14 It is therefore essential to identify the potential risk factors that lead to LBP at an early phase of their career. Prolonged exposure to these risk factors increases wear and tear of the back and consequently raises the injury rate in older age that leads to recurrent and chronic LBP. [15][16][17] Moreover, Burton et al. 18 addressed the modification of risk factors as the most crucial prevention strategy of LBP.
However, very few studies 5,10,14,[19][20][21][22][23][24] have been conducted that evaluated the prevalence and potential risk factors associated with LBP among medical students. These studies showed a high prevalence of LBP. However, regarding the associated risk factors, the findings were inconsistent.
In Bangladesh, every year, approximately 10,500 students are admitted to 37 public, 70 private, and six armed forces medical colleges. 25 To achieve an MBBS (Bachelor of Medicine and Surgery) degree in Bangladesh, students must study for at least five years, and after graduation, they have to complete a compulsory one-year training at the medical college hospital as medical interns. Hence, more than 50,000 students are studying MBBS courses in Bangladesh at any given time. Despite the high number of this specific vulnerable population, no study has been conducted to evaluate LBP prevalence among Bangladeshi medical students. Mondal et al. reported that three in every five physiotherapists in Bangladesh suffer from LBP. 7 That showed that the people involved in the health sector are at higher risk of developing LBP. Hence, it is essential to conduct more studies to determine the prevalence and risk factors of LBP among health science students and health professionals in Bangladesh so that the results can be compared to know the exposure better, which will help to take necessary initiatives to lessen its impact. Therefore, we aimed to conduct this study to determine the prevalence of LBP and its characteristics and identify the risk factors associated with LBP among medical students of a typical public medical college in Bangladesh.

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 rate 10 at a 95% confidence level with 5% precision. The sample size was calculated based on an Indian study 10 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.

REVISED Amendments from Version 1
We clarified the ethical issue raised by one of the reviewers. We described it under the heading "Ethics". Except that we did not make any other changes in the manuscript. Some minor comments from the reviewers were addressed and responded to fully.
Any further responses from the reviewers can be found at the end of the article Instruments An online, standardized, self-administrated questionnaire 27 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 • Point prevalence: Presence of LBP at the time of the survey. 5 • 6-month prevalence: Had at least one episode of LBP in the last 6 months. 5 • 12-month prevalence: Had at least one episode of LBP in the last 12 months. 5 Dependent variable: • Low back pain (LBP): LBP is the pain, muscle tension, or stiffness localized below the costal margin and above the inferior gluteal folds with or without leg pain. 31 Independent variables: • Body mass index (BMI): the weight in kilograms, divided by height in meters squared. 32 • Aggravating factors of LBP: The activities that cause the low back symptoms to recur.
• Exercise: A controlled, structured, and repetitive subset of physical activity with an ultimate or intermediate objective to improve or maintain physical fitness. 33

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. No formal approval was required as this institution's ERC usually does not assign any approval number unless the study is a clinical trial. Since this study was questionnaire-based, and there was no human participation in the lab, permission from ERC sufficed the ethical requirement.

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).   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 twothirds (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, 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.  (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).

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  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/m 2 had a higher prevalence of LBP than the participants with BMI ≤ 25 kg/m 2 , 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][47][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 Grimmer 51 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 studies 66 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.

Conclusion
The overall results of our study demonstrated the high prevalence of LBP among Bangladeshi medical students and indicated the necessity of formulating and implementing comprehensive preventive strategies. The majority of the risk factors are modifiable. Hence, initiatives can be taken to inspire them to avoid those risk factors, which could improve medical students' and future doctors' overall health and quality of life. Students should be encouraged to perform the recommended amount of physical activity by providing education and facilities and reserving a couple of hours exclusively for exercise and sports activities. Moreover, education on ergonomics and providing sound ergonomic chairs to the students could help minimize LBP prevalence.
Future studies should be undertaken with a larger sample size by including students from more than one medical college. Epidemiological longitudinal studies should be conducted to confirm the association of risk factors with LBP.

Data availability
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: • Raw dataset.xlsx

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: • Course Evaluation -Google Forms.pdf

Open Peer Review
Let me commend the authors for an interesting paper addressing a significantly important health issue in Bangladesh about the prevalence of low back pain and associated risk factors among medical students.
I have minor comments only.

General comment:
"These studies showed a high prevalence of LBP. However, regarding the associated risk factors, the findings were inconsistent" Kindly expand by adding a statement or two, providing the evidence on the inconsistencies, referencing current studies validating your point above. 1.
"No formal ethical approval was required from the institution; hence, no approval number was provided. The institution requires formal ethical approval for clinical trials involving human participants." Check with the journal requirements or the handling editor for this part. My understanding is that primary research with human participants requires ethical approval prior to conduction. 2.
"Because of the possibility of sample loss, the final sample size was determined as 270": Provide the minimum sample calculated first from estimated prevalence figures, precision effect, and confidence interval parameters and how the maximum sample of 270 was arrived at. This helps with the reproduction of the study in other settings.

3.
No further comments. Thank you for your valuable time to review this manuscript again. Also, we are grateful to you for your comments which will increase the quality of the manuscript. We want to respond to your comments first before submitting the revised version of the manuscript. We will be happy to submit the revised manuscript (if required) if our responses do not suffice to get approval.

Kindly expand by adding a statement or two, providing the evidence on the inconsistencies,
referencing current studies validating your point above.
Response: Thank you for your comment. However, inconsistencies in findings were described in detail in the 'Discussion' section. As the inconsistencies were observed in the case of different risk factors, it will be difficult to refer to every study. Therefore, we did not include any statement regarding this in the introduction section.
2. Check with the journal requirements or the handling editor for this part. My understanding is that primary research with human participants requires ethical approval prior to conduction.
will have a high potential for citation because future studies may use different recall periods.
Provide a hint on the significance of this study in your context.

Methods
Clearly provide details of the psychometric properties of the LBP questionnaire used in the study. How was the questionnaire tested for reliability and logical validity against the set objectives?
○ Kindly reference your operational variables such as point prevalence.  The Ethical approval number from the "institute" should be provided.

Results
Your final sample size was less than the calculated minimum sample size? ○ The use of a flow chart is commendable. ○ Statistical analysis is appropriate and well explained.

Discussion and conclusion
May I suggest removing sub-headings in the discussion section for clarity.

○
The first paragraph of the discussion should summarise the main findings from the study addressing the main research question.
○ Discuss briefly your findings on the association between age and LBP as they contrasted many findings from the literature. The overall results of our study demonstrated the high prevalence of LBP among Bangladeshi medical students and indicated the necessity of formulating and implementing ○ comprehensive preventive strategies": May I suggest you expand briefly on the possible preventative strategies based on your study findings. This is the most important part of this study. What can be done to curtail the problem of LBP among medical students given contextual information and study results?

References
Lack of consistency in referencing style in the reference list.

References 6 and 22 duplicated.
○ us to improve the quality of the manuscript. We took into consideration all comments and concerns in the paper. Detailed responses are given below:

Introduction:
Thank you for your valuable suggestion. We have made some changes as you suggested, especially we described the necessity of conducting the current study.
Although several studies have been conducted globally to determine the prevalence of LBP, the results were inconsistent. Particularly regarding the risk factors, the results were contradictory as the socio-demographic factors of participants, study design, and exposure to risk factors were not the same. Therefore, this study was conducted to estimate the prevalence of LBP among medical students of Bangladesh.
The results of this study will help to better know about the risk factors and their impact. We can also compare the results with other studies which will help to examine the validity of evidence and take initiatives to prevent LBP.

○
We have also included the studies that determined LBP prevalence among medical students of different countries.
clarity. The association between age and prevalence of LBP was discussed under the subheading titled 'Socio-demographic factors and LBP prevalence.' The preventive measure was discussed briefly. It would have been better to expand it. However, in the case of our study, it seems slightly out of scope. Future studies involving medical students with more than one medical college are warranted for better evidence and giving the appropriate recommendation for implementing preventive measures.

References:
The correction was done as you suggested. The reference style was autogenerated by using Mendeley software. Later it was published following the journal's formatting style.
in the general population, and the introduction could build on this and the discussion could also benefit from adding this.
Bangladesh is much lower. There was another COPCORD study that reported LBP among other rheumatic disorders. Response: Thank you for pointing this out. However, the prevalence of LBP is relatively higher among the people involved with health professions. Physiotherapists in Bangladesh, for instance, had a 60.8% prevalence of LBP, which is higher than other professions [1]. Moreover, our study was the first study that determined LBP prevalence among Bangladeshi medical students. Therefore, we calculated the sample size based on an Indian study as the Bangladeshi medical students have relatively similar curriculum, clinical class exposure, study load, and social and cultural demographics as Indian medical students.
Logistic regression analysis was done for a 12-month recall period, which has a potential of recall bias; this could be done for point prevalence.
○ Response: You have raised an important point here. However, determining risk factors was one of the study's primary objectives; we opted to do logistic regression analysis for 1-year prevalence instead of point prevalence despite the potential of recall bias. Point prevalence could be too short a period to conclude the effect of exposure of any particular risk factor. Ethical clearance has been obtained from the institute. Which institute? ○ Response: Thank you for pointing this out. We have corrected it. The ethical Permission was taken from the Ethical Review Committee (ERC) of Faridpur Medical College.

Results:
The results described have many digits after the decimal point; these could be up to one decimal point. No message will be lost by removing extra decimal points.
○ Response: Agree. We have incorporated your suggestion throughout the manuscript. Dividing a small number of students (207) into so many age and educational groups is meaningless. There are hardly any points of implications by age and educational years, the differences in education and age are obviously very narrow. The message of the study could be generated for one group only. At best, the results could be presented for male and female, and students and interns. ○ Response: Thank you for your comment. However, previous studies showed a significant association between medical students' age and education years and LBP prevalence. For this reason, we wanted to observe it among Bangladeshi medical students, and we divided the students into three age groups and academic years. We found that the 2 nd year medical students had a higher prevalence of LBP, although the difference was not significant. (Table 3). ○ Response: Thank you for pointing this out. We have modified Table 3 as you suggested.

Discussion:
The discussion is quite long. There are so many subheadings used because authors have discussed all variables under study. They could highlight the main points of the message that the study transmits to the readers. For example, years cannot be changed or intervened separately but it has a lengthy description.