The Prediction of Chronicity in Patients With Acute and Subacute Nonspeciﬁc Low Back Pain and Associated Risk Factors: A Case-Control Study

Background: Chronic low back pain is one of the most common musculoskeletal disorders in different countries. Aims: This study aimed to predict the chronicity of nonspeciﬁc acute and nonspeciﬁc low back pain (LBP) and related risk factors among cases referred to physiotherapy clinics. Design: A case-control and cross-sectional study. Settings: Two physiotherapy centers in Tehran, Iran. Participants: This study included 502 patients with acute, subacute and chronic LBP. Method: This study included 502 patients with acute, subacute and chronic LBP. Data were obtained using the Fear-Avoidance Beliefs Questionnaire, Patient Health Questionnaire, Pain Catastrophic Scale, Tampa Scale for Kinesiophobia, Pittsburgh Sleep Quality Index, Walker’s Health-Promoting Lifestyle Questionnaire, Roland Morris Disability Questionnaire, and Numerical Pain Rating Scale. Data analysis was performed by applying independent sample t test, χ 2 , and multiple logistic regression in SPSS software version 25. IBM Amos version 22 was used for path analysis. Results: It was found that some demographic parameters (i.e., weight, BMI, job, type of occupational task performance, history of low back pain, work shift, underlying diseases and income), some cognitive parameters (i.e., fear-avoidance beliefs, kinesiophobia, catastrophic pain, and depression), some lifestyle parameters (i.e., health responsibility, physical activity, and interpersonal relationships), sleep quality and pain related disability were among the most critical risk factors in the chronicity of acute and subacute LBP ( p < .05). Conclusions: Personal, psychological, and psychosocial parameters can be among the most critical predictors in the chronicity of acute and subacute nonspeciﬁc LBP. Hence, paying attention to all the mentioned factors at the beginning of patients’ treatment to create a targeted treatment algorithm and prevent the conversion of acute and subacute into chronic LBP has particular importance.

into chronic pain ( Manchikanti et al., 2009 ). In Iran, LBP is one of the most prevalent issues, so that its prevalence among high school students, nurses, and pregnant women has been reported to be 17%, 62%, and 84%, respectively ( Ramezani et al., 2015 ). The overall prevalence of LBP in Iranian society has been reported between 14.4%-84.1%. LBP is also known as the third cause of the discomfort conditions in population age range of 15-69 years old in Iran ( Mousavi et al., 2011 ).
Numerous studies have introduced different variables as risk factors affecting the prevalence of nonspecific CLBP, which may vary depending on the study's objectives. These include demographic parameters, lifestyle, general health components, smoking, physical activity, medical facilities, occupational factors, psychological factors like fear-avoidance belief, fear of movement, stress, anxiety, and depression ( Boissoneault et al., 2017 ;Pinheiro et al., 2016 ). Also, risk factors like sleep disorders, resilience variables like optimism, lack of social support, and biophysical risk factors like body composition have rarely been studied in related research ( Gheldof et al., 2007 ).
Psychological processes have a unique role in pain experience; however, psychological factors are not fully understood. The use of psychological knowledge in the treatment stages of patients is subject to challenge ( Yadollahpour et al., 2019 ). For example, parameters like fear of movement, catastrophic pain, and the establishment of extreme beliefs about fear and avoidance of activity are among risk factors that can lead to limitation of activities, sedentary life, depression, and stress and eventually lead to CLBP ( Alhowimel et al., 2018 ;Wertli et al., 2014 ); therefore, proper and timely understanding of the exact role of each of these risk factors in the chronicity of LBP through predictive models in different communities can be a practical step in the implementation of proper planning for physical and psychological therapy of patients with acute and subacute nonspecific LBP ( Mehling et al., 2015 ).
Cohort studies have shown that cognitive factors exert a greater effect on nonspecific LBP chronicity in some cases compared with biophysical factors ( Bogduk, 2006 ). It should be noted that predicting the results of LBP is not a simple process. It is common to utilize the information obtained from the initial evaluation to predict future clinical outcomes. Therefore, establishment of predictive models provides beneficial information for health professionals specially in occupational health settings. Hence, according to mentioned points, the importance of understanding actual risk factors affecting the chronicity of nonspecific LBP, preventing the conversion of acute and subacute LBP into chronic state, and also due to the lack of similar studies that consider the role of mentioned parameters as the underlying factors of CLBP to create practical predictive patterns, according to the different social, economic, medical and health conditions of developing countries compared to developed countries, the present study aimed to predict the chronicity of acute and subacute LBP and related risk factors among patients referred to physiotherapy clinics in Iran.

Study Design
This case-control study was conducted from August to December 2020. The statistical population includes all patients referred to two physiotherapy centers (including two groups of patients with acute or subacute nonspecific LBP as "control group" and chronic nonspecific LBP as "case group") in Tehran, Iran. The optimal sample size was determined at α level of 0.05, and the desired power analysis of 80% with a β level of 20% (according to previous studies and the mean of main variables). Accordingly, it was calculated to be at least 240 participants per group. Assuming a sample drop rate of 10%, the final sample size was estimated as 528 individuals who were selected by convenience sampling method using inclusion criteria. Finally, according to the participants' response rate, 502 patients were studied (response rate: 95%). A physiotherapist first examined patients for inclusion in the study.
Four criteria were considered as inclusion criteria: • Adults between 30 and 60 years with acute and subacute nonspecific LBP, because of the similarities between the LBP patterns (including the presence of pain less < 7 days in the lumbar vertebral column, buttocks, and lower limbs for acute patients and pain between 8 and 12 weeks for subacute patients). • Adults between 30 and 60 years with chronic nonspecific LBP (including pain between 3 to 6 months in the lumbar vertebrae, buttocks, and lower limbs). • Ability to reading and writing Persian language.
Exclusion criteria also included: • The presence of systemic complications like orthopedic, rheumatologic, and inflammatory diseases. • History of cancer.
• The presence of focal point tenderness on the spine.
• History of structural spine problems.
• History of the prolonged systemic use of corticosteroids.
• History of spinal surgery.
• History of major trauma to the spine (fall from a height, accident, and sports incidents). • History of mental illness.
• Lack of sufficient satisfaction to participate in the study.
All the required information about the study's purpose was presented to the individuals, and informed consent form was signed by the participants. Patients were able to leave the study at any stage of the research. Patients completed the questionnaire package within 90 minutes, which was completed in 30 minute sessions, considering the rest periods. The ethics committee of the University of Medical Sciences approved the study's methodology, and the study was conducted following the Helsinki Declaration ( Goodyear et al., 2007 ).

Data Collection
All the studied parameters have been determined based on the review of valid scientific texts and experts' opinions. Demographic data were extracted using a self-administrated questionnaire, and to obtain the main variables, the following questionnaires were applied.

Fear-Avoidance Beliefs Questionnaire (FABQ)
The Fear-Avoidance Beliefs Questionnaire (FABQ) was used to assess the extent of fear-avoidance beliefs ( Waddell et al., 1993 ). This scale shows how much fear-avoidance beliefs affect patients' LBP. In this questionnaire, four items are related to physical activity (score range 0 to 24), and seven items are related to working activity (score range 0-42). Each item was scored using the Likert scale, from a score of zero "strongly disagree" to a score of six "strongly agree." High scores on both subscales indicate higher levels of fearavoidance beliefs. This tool's validity and reliability have been confirmed in previous studies (Cronbach's alpha: 0.88) ( Rostami et al., 2014 ).

Pain Catastrophizing Scale
Catastrophic pain is reflected to be a cognitive element of the pain fear process associated with pain-related disability in patients. This scale evaluates the range of patients' catastrophic thoughts and behaviors when faced with pain and consists of three subscales of mental rumination, exaggeration, and despair. Patients are asked to indicate how often they used each of the 13 phrases in this questionnaire when faced with pain based on their pain experience. The questionnaire is scored on a Likert scale with five options from zero "not at all" to four "all the time" range from 0-52 as total score. Higher scores indicate more catastrophic pain ( Sullivan et al., 1995 ). This tool's validity and reliability have been confirmed in an Iranian research (Cronbach's alpha: 0.93) ( Mohamadi et al., 2013 ).

Tampa Scale of Kinesiophobia (TSK-11)
The 11-item version of the Tampa Scale of Kinesiophobia (TSK-11) questionnaire was used to assess participants' fear of movement or reinjury. Kinesiophobia, or fear of movement, refers to an excessive, irrational, and debilitating fear of physical movement described as a result of a person's sense of vulnerability to reinjury ( Silver et al., 2002 ). The TSK-11 is an 11-item questionnaire with scores ranging from 11-44, that higher scores indicating greater fear of movement. Each item was scored using a Likert scale with four options, from a score of zero "strongly disagree" to three "strongly agree." This questionnaire's appropriate validity and reliability have been reported in an Iranian research (Cronbach's alpha: 0.80) ( Jafari et al., 2010 ).

Pittsburgh Sleep Quality Index
The Pittsburgh Sleep Quality Index (PSQI) is a self-rated questionnaire that assesses sleep quality and disturbances over a 1month time interval. This questionnaire has seven scales that include subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency (ratio of sleep duration to elapsed time in bed), sleep disturbances (waking up at night), use of sleeping medication, and daytime dysfunction (problems caused by insomnia during the day). The calculation of scores for these seven components yields one final score. Each scale's score is between 0-3, and the score of three on each scale indicates the maximum negative value. This questionnaire's overall score is between 0-21, and the overall score of 6 and above indicates the inadequate quality of sleep. This questionnaire's validity and reliability have been confirmed in several studies (Cronbach's alpha: 0.83) ( Mansouri et al., 2012 ;Moghaddam et al., 2012 ).

Walker's health-promoting lifestyle questionnaire
This questionnaire was first designed by Walker et al. and consists of 52 questions that measures six dimensions of spiritual growth, health responsibility, interpersonal relationships, stress management, physical activity, and nutrition with 8 or 9 questions. Each question has 4 Likert-scale answer options, including never, sometimes, most of the time, and always. The minimum score on this questionnaire is 52, and the maximum is 208. High scores are indicating a better health-promoting lifestyle. A score of 52-104 is classified as a "poor lifestyle," a score of 105 to 156 is classified as an "average lifestyle," and a score of 157-208 is classified as a "good lifestyle" ( Sadeghi Yarandi et al., 2020 ). This tool's validity and reliability have been confirmed by Mohammadi Zeidi et al. (2012) in Iran (Cronbach's alpha 0.82).

Roland-Morris Disability Questionnaire
In this questionnaire, the patient reads a series of phrases, and if the terms indicate the patient's current condition, he or she selects the desired phrase. These expressions represent a wide range of daily activities that are disrupted by LBP. This questionnaire's total score is obtained by the sum of the number of marks that the patient has placed in front of each phrase (0-24). A higher score on this scale indicates greater physical disability ( Roland & Fairbank,20 0 0 ). This tool's validity and reliability have been confirmed in an Iranian research (Cronbach's alpha: 0.92) ( Asghari & Golak, 2005 ).

Numeric Pain Rating Scale
Participants' pain intensity was assessed using a numerical pain scale from zero (no pain) to 10 (maximum pain intensity). This scale consists of a calibrated line in which expressions are used to describe each number. The patient marked the current, lowest and highest pain intensity experienced during the last 24 hours. The average of the three pain intensities was considered the individual's pain level ( Childs et al., 2005 ). The validity and reliability of this tool have been confirmed in Iran ( Nakhostin Ansari et al., 2018 ).

Data Analysis
Data analysis was performed in SPSS software version 25.0 (SPSS Inc Chicago, Illinois). Kolmogorov-Smirnov test was used to check the normality of the data distribution. The normality test results revealed that the data distribution was normal in all cases ( p > .05). Accordingly, to investigate the relationship between quantitative data and type of LBP, two-independent sample t test and to investigate the relationship between qualitative data and type of LBP, χ 2 was also used at a significance level of 0.05. Equality of variances was also assessed using Levene's Test.
In the first step, the multiple logistic regression model was used to predicting the chronicity of acute and subacute LBP. In this model, by eliminating the effect of confounding variables, the most significant risk factors in the chronicity of LBP are identified.
For this purpose, based on the independent sample t test and χ 2 test results, variables significantly associated with the type of LBP were entered into the regression model. Then, to obtain the final regression model, the backward elimination method was used. In this method, all the independent parameters that effective in the chronicity of LBP were entered into the model. The less-effective variables were removed step by step. The Nagelkerke and Cox & Snell R-square were regarded as a measure for overall predictive performance. Calibration (i.e., the agreement between predicted and observed CLBP risks) was assessed by the Hosmer-Lemeshow goodness-of-fit test; p ≥ .05 indicates that predicted risks do not deviate significantly from observed risks, meaning that calibration is acceptable.

Path Analysis
In second step, path analysis was performed to predict the chronic LBP. In the present study, IBM SPSS Amos version 22.0 was used for path analysis. Path analysis is a useful tool for assessing some direct and indirect effects of variables on a specific target variable, which was the chronicity of LBP in the present study. The strength of a path is described by a coefficient conceptually equal to standardized partial regression coefficients. A coefficient has a range from −1 to + 1. the effect one variable has on another. In addition to each path, the goodness of fit of a path analysis model can also be defined using indices available for such evaluations. These indices can be classified into two main groups: absolute fit indices and comparative fit indices. Absolute fit indices describe how well the hypothesized model fits the data. The model χ 2 value, root mean square error of approximation (RMSEA), goodness-of-fit index, and root mean square residual are some indices classified in this group. RMSEA is another absolute fit index recommended because of its sensitivity and informative and easy-to-interpret nature. This index is computed using the model χ 2 value, df, and sample size (N).
An RMSEA value < 0.07 indicates a good fit, values < 0.1 indicate mediocre fit, and values > 0.1 describe the unacceptable model fit ( Hooper et al., 2008 ).

Demographic Parameters
The mean age and BMI in all patients were 43.94 ± 6 .72 years and 25.69 ± 3.54 kg.m −2 , respectively. It was found that 49.7% (250 patients) had chronic LBP, and 50.3% (252 patients) had acute and subacute LBP. The study of the occupational task during working times showed that 30% of the participants have a sitting task, 31.9% have a standing task, 15.2% have manual material handling, 4.1% have exposure to whole-body vibration, and hand-arm vibration, 6.1% have repetitive movements, and 12.7% have twisting and bending movements in the lumbar region. Other demographic characteristics are presented in Table 1 . Examination of patients' demographic parameters according to type of LBP revealed that there was a significant difference between age, weight, BMI, job, work experience, working hours per day, type of work shift, education level, monthly income level, type of occupational task, history of previous LBP, history of underlying diseases, and the type of LBP in the subjects ( p < .05; Table 1 ).
Examination of depression levels among participants showed that 41.1%, 10.6%, 9.3%, 23.8%, and 15.2% of patients were at minimal, mild, moderate, moderately severe, and severe levels of depression, respectively. Analysis of depression levels showed that all patients with acute or subacute LBP (100%) were at low levels of depression, and 89.4% of patients with CLBP were at moderately severe and severe levels of depression.
The mean values of the pain catastrophizing scale among patients with acute or subacute and chronic LBP were 9.53 ± 1.06 and 32.46 ± 4.15, respectively. It was also found that the mean values of kinesiophobia among patients with acute/subacute and    chronic LBP were 19.13 ± 1.26 and 34.72 ± 3.49, respectively. Ultimately, the present study's obtained findings demonstrated that the mean values of all cognitive parameters, including fearavoidance beliefs, depression, pain catastrophizing, and kinesiophobia were at much higher levels in patients with CLBP compared to other patients. Also, statistical analysis showed that there was a significant relationship between the values of all cognitive parameters and the type of LBP ( p < .05; Table 2 ).

Sleep Quality Components
The average score of PSQI among all patients was 13.68 ± 3.79. The average sleeping hours per day among all subjects was 5.81 ± 1.32 hours. The results showed that the average score of all sleep quality components except subjective sleep quality was at higher levels among patients with CLBP (compared to acute/subacute LBP). The average score of PSQI among patients with acute or subacute and chronic LBP were 10.25 ± 0.16 and 16.78 ± 0.33, respectively. Other values of sleep quality components according to the type of LBP are presented in Table 3 . Considering the cut point of six for the border of low sleep quality, it was found that 95% of participants have undesirable sleep quality ( Table 3 ).

Lifestyle Components
The mean lifestyle score among all the participants was 123.58 ± 28.68. It was indicated that 40.4% of the participant had a poor lifestyle, 49.7% had moderate, and 9.9% had a good and favorable lifestyle. The average score of lifestyle among patients with acute or subacute and chronic LBP were 140.67 ± 1.01 and 104.12 ± 3.04, respectively. It was also observed that the dimensions of spiritual growth, interpersonal relationships, physical activity, and nutrition were lower in patients with CLBP. Among patients with acute or subacute LBP, 80% had a poor lifestyle, and 20% had a favorable lifestyle level. Among patients with chronic LBP, 72.7% had a poor lifestyle, 16.7% had a moderate lifestyle, and 10.6% had a favorable lifestyle level. There was also a significant relationship between the dimensions of spiritual growth, health responsibility, interpersonal relationships, stress management, physical activity, nutrition and overall lifestyle score and type of LBP ( p < .05; Table 4 ).

Disability and Pain Intensity
The evaluation of disability and pain intensity indices showed that the mean value of the two mentioned indices among all participants was 13.70 ± 7.39 and 5.98 ± 1.74, respectively. The mean disability index among patients with acute/subacute and chronic LBP was 7.46 ± 0.57 and 20.48 ± 0.56, respectively. The mean numerical pain intensity index among the mentioned patients was 5.44 ± 0.14 and 7.46 ± 0.18, respectively. There was a significant correlation between the type of LBP and the mean score of two indicators of disability and pain intensity ( p < .05). The mean values of disability and pain intensity were much higher among patients with CLBP. The majority of patients with acute or subacute LBP (53.4%) reported mean numerical pain intensity of "five," and the majority of patients with CLBP (37.9%) reported mean numerical pain intensity of "eight." Please cite this article as: M. Sadeghi-Yarandi, M. Ghasemi Table 5 shows the most important risk factors for chronicity of acute and subacute nonspecific LBP based on a modified multiple logistic regression model. The values of Negelkerke and Cox & Snell R 2 of the model were 0.957 and 0.846, respectively.

Path Analysis Model
The path analysis model revealed that lifestyle, disability, pain intensity, sleep quality, depression, and fear-avoidance beliefs are among the most important predictors of chronic LBP. Lifestyle indirectly predicts CLBP and apply large effects on the parameters of disability, pain intensity, sleep quality, depression, and fearavoidance beliefs. Other parameters can directly affect and predict the chronicity of LBP. The model fit indices and standardized path coefficients, and significant level are presented in Tables 6 and 7 . The final obtained path analysis model is presented in Figure 1 .

Discussion
CLBP was responsible for the creation of 60.1 million disabilityadjusted life-years in 2015. Since 1990, with a 54% increase, it has the highest prevalence in low-and middle-income countries ( Nakhostin Ansari et al., 2018 ). Examination of patients' demographic parameters demonstrated that there was a significant relationship between age, BMI, job, work experience, working hours per day, type of work shift, education level, monthly income, type of occupational task, previous LBP, history of underlying diseases and type of LBP in the subjects ( Table 1 ). Previous studies have shown that these parameters are among the influencing factors in the chronicity of LBP ( Boissoneault et al., 2017 ;Shmagel et al., 2016 ). It has been found that patients with older ages, higher BMI, higher working hours, and jobs with higher workload are at   higher risk of CLBP ( Ahmadi et al., 2014 ;Akbari et al., 2017 ). Previous studies have shown that income levels are also an important factor in preventing CLBP, and people with higher incomes are likely to be in better lifestyle status and have a lower risk of CLBP ( Shmagel et al., 2016 ), which is consistent with the findings of the present study. A history of previous LBP is also a crucial factor in the chronicity of LBP. So that if the patient has not been appropriately treated in the past, the pain has entered into the chronic phase, and in the case of recurrence of LBP, the person is entirely prone to CLBP. It was also found that a history of underlying diseases can affect the patient psychologically and physiologically dimensions and facilitate the chronicity of LBP ( Shmagel et al., 2016 ). Shift work schedule was also an important factor in the LBP chronicity. Perhaps the reason can be found in the decrease in sleep quality. A higher percentage of patients with CLBP were working nights and alternate shifts, compared with patients with acute and subacute LBP. Among patients with CLBP the mean score of fear-avoidance beliefs about work activities (FABQ-W) and fear-avoidance beliefs about physical activity (FABQ-PA) was significantly higher than patients with acute/subacute LBP ( Table 2 ). The study by Woby et al. showed that as people's self-efficacy decreases due to LBP, fear of movement and avoidant behaviors increase, which can lead to CLBP. Also, reducing fear-avoidance beliefs concerning work activities and physical activity leads to increased self-control against pain and disability. It can be a useful step in preventing the CLBP ( Woby et al., 2007 ). Chung et al. (2013) also showed that fearavoidance beliefs are an important factor in the chronicity of LBP and related disability that is in line with the findings of the present study.  JID: YJPMN [mNS;February 14, 2022;15:26 ] The rate of depression among patients with CLBP was significantly higher than patients with acute and subacute LBP ( Table 2 ). The study conducted by Cougot et al. (2015) revealed that depression is an important factor in CLBP and long absences from work. The study by Shmagel et al. also demonstrated that a high percentage of patients with CLBP were in severe and very severe depression levels, which is consistent with the findings of the present study ( Shmagel et al., 2016 ). Depression, stress, and anxiety are risk factors and a consequence for the chronicity of LBP and lead to a decrease in the treatment process's efficiency ( Boissoneault et al., 2017 ). Depression severely affects a patient's life quality, reduces physical activity, increases the risk of a variety of mental illnesses, and in some patients can lead to refusal to continue treatment ( Boissoneault et al., 2017 ;Pinheiro et al., 2016 ).

ARTICLE IN PRESS
The catastrophic rate of pain in patients with CLBP was significantly higher compared with the control group. Individuals with acute and subacute LBP, due to their pain's destructive nature, imagine it more intensely, exert more physical and psychological pressure on themselves, and thus pave the way for chronicity of LBP. It is quite probable that patients engage in pain avoidance behaviors and are always waiting for the occurrence of pain in response to the fear of catastrophic pain and in an attempt to control the painful event that may occur in the future. Many empirical studies have shown that catastrophic pain is directly associated with CLBP, which is consistent with the present study ( Boissoneault et al., 2017 ;Woby et al., 2004 ). The mean value of kinesiophobia among patients with CLBP is much higher than other patients. Previous studies have shown a direct and significant relationship between psychological factors like kinesiophobia and catastrophic pain, and chronicity of acute and subacute LBP, which is in line with the present study findings ( Alhowimel et al., 2018 ;Boissoneault et al., 2017 ). Some studies have explicated that in many cases, fear of movement and pain can be more debilitating than pain and accelerates LBP chronicity ( Woby et al., 2004 ). In general, it can be claimed that all three parameters of kinesiophobia, catastrophic pain, and fear-avoidance beliefs are closely related to each other, and each parameter can accelerate the process of LBP chronicity.
The sleeping hours of patients with CLBP were shorter than control group, which was rooted in their pain. The results explained that the mean score of all sleep quality components except subjective sleep quality among patients with CLBP was higher ( Table 3 ). The mean total score of sleep quality among patients with CLBP was higher than control group, which indicates poor sleep quality among them and can lead to more psychological and physical stress and as a result, the chronicity process of LBP can be facilitated ( Shmagel et al., 2016 ). It can be explained that patients with CLBP have more delayed sleep, shorter sleep duration, more sleep disturbances, and higher use of sedative medication compared with other patients. Previous studies have shown that the quality of sleep among patients with CLBP was significantly lower than patients with acute LBP, and sleep is one of the effective parameters in the chronicity of LBP, which was compatible with the present research ( Boissoneault et al., 2017 ).
The score of some lifestyle components like spiritual growth, interpersonal relationships, physical activity, and nutrition in patients with CLBP was lower than other patients ( Table 4 ). The obtained results indicate that patients with acute and subacute LBP are more sensitive to their health status due to the shorter LBP duration ( < 3 months) and have more social interactions and interpersonal relationships. Despite the presence of pain, they had more physical activity and better nutritional status than patients with CLBP. Furthermore, patients with CLBP have experienced more pain tolerance because they have struggled with pain for a more extended time and have generally been more successful in man-aging the stress caused by their pain. Finally, it was noticed that patients with acute and subacute LBP had a better lifestyle, which is consistent with previous studies' results ( Hartvigsen et al., 2018 ;Sadeghi Yarandi et al., 2020 ). Previous studies have revealed that increasing muscle strength through light exercise can help support the spine. Improving the flexibility of the muscles, tendons, and ligaments of the back increases the range of motion and help improve patient function. Aerobic exercise also increases blood flow and nutrients to the back's soft tissues and accelerates the healing process ( Gordon & Bloxham, 2016 ). There is a significant relationship between the degree of disability, depression, anxiety, and lifestyle levels of patients, and lifestyle is a strong predictor for LBP chronicity ( Alhowimel et al., 2018 ). Brox et al. (2005) also revealed that the rate of disability in patients with CLBP was significantly higher than acute and subacute cases. The degree of disability is an important predictor for LBP chronicity, which is consistent with the present study results ( Brox et al., 2005 ). The disability and severity of pain are both a risk factor and a consequence of LBP, which can be subjective or objective. In both cases, it can lead to a variety of physical and psychosocial problems and eventually CLBP.
The regression model explicated that weight, BMI, job, type of occupational task, previous LBP, work shifts, underlying diseases, income, fear-avoidance beliefs, kinesiophobia, pain catastrophizing, depression, health responsibility, physical activity, interpersonal relationships, sleep duration, sleep disturbances, sleep quality, and patients' disability are among the most important risk factors in the chronicity of LBP. These findings indicate that LBP is a complex and multifactorial phenomenon that different pathologic, anatomic, neurophysiologic, physical, and psychologic factors are influential in its development and chronicity.
The path analysis model revealed that lifestyle indirectly predicts CLBP and avoids large effects on the parameters of disability, pain intensity, sleep quality, depression, and fear-avoidance beliefs, and other parameters can directly affect and predict the chronicity of LBP. Depression was the most important predictor of CLBP with a standardized path coefficient of 0.68 ( Figure 1 ).
Longer work hours, high-stress levels, high cognitive workload, and high interaction with people per day at work can be significantly correlated with the high prevalence of LBP in nurses. To enhance the prevention of this disorder and efficiently decrease the turnover rate due to this situation, the practice of individual nurses caring for substantial numbers of patients per shift should be controlled. Occupational safety and educational programs are also suggested at workplaces to educate the nursing staff on adjusting to proper cognitive situations, particularly for those with mental disorders. Because nurses are one of the most critical personnel in medical settings, using the present study results can lead to a more understanding of nurses about the impact of psychological parameters on the chronicity process of LBP.
Among the strengths of the present study, we can point out the evaluation and modeling the wide range of individual, psychological, psychosocial, and physical parameters in the development of CLBP for the first time in Iran. Our findings can create a novel insight into various risk factors affecting the chronicity of acute and subacute LBP. The present study can be a practical step toward establishing a targeted treatment plan and also preventing the chronicity of LBP. The cost of treatment and health care systems differ considerably from country to country and are influenced by local health, treatment, and social systems. CLBP and its associated costs are projected to increase in the coming decades, especially in low-and middle-income countries, such as Iran, where health care systems are often somewhat hard to access in case of critical situations (like coronavirus pandemic) and have fewer financial resources. Therefore, global research efforts and initiatives are  JID: YJPMN [mNS;February 14, 2022;15:26 ] needed to reduce LBP and prevent the chronicity of LBP as an important and crucial public health problem.

Limitations
Among the limitations of the present study, it can be noted as the impossibility of conducting a prospective cohort study and examining the trend of changes in various physical, psychological, and psychosocial parameters during the therapeutic interventions, and evaluating the effectiveness of intervention measures. Also, during the present study, temporal relationships or causal inferences between different risk factors were not investigated. Therefore, it is suggested that in the future, researchers will conduct prospective studies with appropriate physical and psychological clinical interventions and also report the effectiveness of each intervention.

Conclusions
The results of the present study revealed that demographic and individual risk factors as well as parameters like the level of fearavoidance beliefs, fear of movement (kinesophobia), catastrophic pain, depression, lifestyle, sleep quality, disability, and pain intensity are among important parameters and risk factors in the chronicity of acute and subacute LBP. Therefore, paying attention to all the mentioned aspects at the beginning of treatment of patients with acute and subacute nonspecific LBP to improve the treatment process, generate a meaningful treatment algorithm in order to prevent the typical clinical scenario of a conversion of acute and sub-acute into chronic low back pain.

Implication for Nurses
Nurses' proper understanding of the most critical cognitive parameters affecting the chronicity of acute and subacute nonspecific LBP can lead to more precise guidance to patients in implementing an appropriate treatment plan. Also, due to the physical nature of their occupational tasks, nurses can be more successful in preventing the chronicity of nurses' work-related musculoskeletal disorders like LBP by understanding and controlling some of the most critical cognitive risk factors.