ABSTRACT

BACKGROUND AND OBJECTIVES:

Low back pain (LBP) is one of the leading causes of disability worldwide. Its etiology is multifactorial and results in losses for individuals and society. The biopsychosocial model of LBP offers a comprehensive approach to assessment and interventions. Researchers investigate the relationship between LBP and Common Mental Disorders (CMD) within this concept. This systematic review aimed to identify and analyze recent studies on the topic.

CONTENTS:

The study was submitted to the International Prospective Register of Systematic Reviews (registration number CRD 42020210375). The 27 articles in the corpus were selected from the Medlin/PubMed and BVS (Biblioteca Virtual em Saúde) databases from 2015 to 2022. Only those that investigated a possible relationship between CMD (anxiety or depression) and LBP in adult populations were included. Most articles in the corpus confirmed the relationship between LBP and CMD, however, gaps were identified regarding the direction of causality between the two outcomes and why this relationship was established. Methodological limitations in relation to sample selection and LBP assessment instruments used were also identified.

CONCLUSION:

This review highlights the need for studies on the topic with greater methodological criteria and with a design that allows causality to be assessed. Thus, it will be possible to guide clinical practice based on scientific evidence. Longitudinal studies with an emphasis on the biopsychosocial model can contribute to support specific therapeutic approaches.

Keywords:
Anxiety; Common mental disorders; Depression; Low back pain

RESUMO

JUSTIFICATIVA E OBJETIVOS:

A dor lombar (DL) é uma das principais causas mundiais de incapacidade. Trata-se de um desfecho cuja etiologia é reconhecidamente multifatorial, com prejuízos para os indivíduos e a sociedade. O modelo biopsicos-social da DL apresenta uma abordagem ampla, tanto na avaliação quanto nas intervenções. A relação entre DL e Transtorno Mental Comum (TMC) é objeto de estudo dentro da concepção desse modelo. O presente estudo teve como objetivo identificar e analisar os estudos recentes sobre esse tema.

CONTEÚDO:

O estudo foi submetido ao International Prospective Register of Systematic Reviews (número de registro CRD 42020210375). Os 27 artigos do corpus foram selecionados das bases de dados Medline/Pubmed e BVS (Biblioteca Virtual em Saúde) no período de 2015 a 2022. Foram incluídos apenas aqueles que investigaram possíveis relações entre TMC (ansiedade ou depressão) e DL em populações adultas. A maioria dos artigos do corpus confirmou a relação entre DL e TMC, no entanto foram identificadas lacunas sobre a direção de causalidade entre os dois desfechos e sobre os motivos pelos quais essa relação se estabeleceu. Também foram identificadas limitações metodológicas em relação à seleção da amostra e aos instrumentos de avaliação da dor lombar utilizados.

CONCLUSÃO:

Esta revisão destacou a necessidade de estudos sobre o tópico com maiores critérios metodológicos e com um desenho que permita avaliar a causalidade. Assim, será possível orientar a prática clínica baseando-se em evidências científicas. Estudos longitudinais com ênfase no modelo biopsicossocial podem contribuir para embasar abordagens terapêuticas específicas.

Descritores:
Ansiedade; Depressão; Dor lombar; Transtorno mental comum

HIGHLIGHTS

The association between low back pain, depression and anxiety is a relevant issue for clinical practice.

Longitudinal studies are necessary to research the causality between low back pain and common mental disorders.

Studies with greater methodological criteria about the association of common mental disorders and low back pain allow for more directed clinical interventions.

INTRODUCTION

Low back pain (LBP) is a phenomenon characterized by discomfort in the posterior part of the back that extends to the hips¹1 Almeida DC, Kraychete DC. Low back pain - a diagnostic approach. Rev Dor, 2017;18(2):173-7. Its intensity and duration may vary and eventually lead to chronic and disabling conditions²2 Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, Baker P, Smith E, Buchbinder R. Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol. 2012;65(9):934-9.. Due to its high prevalence, LBP is known as one of the major global causes of disability³3 Hartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, Hoy D, Karppinen J, Pransky G, Sieper J, Smeets RJ, Underwood M; Lancet Low Back Pain Series Working Group. What low back pain is and why we need to pay attention. Lancet. 2018;391(10137):2356-2367.,⁴4 Global Burden of Disease Study Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2015;386(9995):743-800., posing a public health problem which impairs the quality of life of populations and requires collective and individual coping measures⁵5 Lopez-Lopez D, Vilar-Fernandez JM, Calvo-Lobo C, Losa-Iglesias ME, Rodriguez-Sanz D, Becerro-de-Bengoa-Vallejo R. Evaluation of depression in subacute low back pain: a case control study. Pain Physician. 2017;20(4):E499-E505.,⁶6 Nascimento PRC, Costa LO. Prevalência de dor lombar no Brasil: uma revisão sistemática. Cad Saúde Pública, 2015;31(6):1141-55.. In 2020, LBP affected an estimated 619 million people worldwide, with a projection of 843 million prevalent cases by 2050. A total of 38.8% of cases were attributed to occupational factors, smoking and high body mass index (BMI)⁷7 GBD 2021 Low Back Pain Collaborators. Global, regional, and national burden of low back pain, 1990–2020, its attributable risk factors, and projections to 2050: a systematic analysis of the Global Burden of Disease Study 2021. Lancet Rheumatol 2023;5:e316-29.

LBP is multidimensional, with neurobiological alterations, lifestyle, general physical and mental health conditions, and exposure to physical and psychosocial stressors³3 Hartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, Hoy D, Karppinen J, Pransky G, Sieper J, Smeets RJ, Underwood M; Lancet Low Back Pain Series Working Group. What low back pain is and why we need to pay attention. Lancet. 2018;391(10137):2356-2367.,⁶6 Nascimento PRC, Costa LO. Prevalência de dor lombar no Brasil: uma revisão sistemática. Cad Saúde Pública, 2015;31(6):1141-55.,⁸8 Yang H, Hurwitz EL, Li J, de Luca K, Tavares P, Green B, Haldeman S. Bidirectional comorbid associations between back pain and major depression in US adults. Int J Environ Res Public Health. 2023;20(5):4217.,⁹9 Foster NE, Anema JR, Cherkin D, Chou R, Cohen SP, Gross DP, Ferreira PH, Fritz JM, Koes BW, Peul W, Turner JA, Maher CG; Lancet Low Back Pain Series Working Group. Prevention and treatment of low back pain: evidence, challenges, and promising directions. Lancet. 2018;391(10137):2368-83.,¹⁰10 Araujo JA, Campos MR, Santos MVF, Gonçalves DA, Mari JJ, Tófoli LF, et al. Dor lombar e transtornos mentais comuns na Estratégia Saúde da Família: uma associação pouco reconhecida. Rev Bras Med Fam Comunidade. 2018;13(40):1-14.. Acknowledging this etiologic multiplicity has led to the development of biopsychosocial explanatory models of LBP. These models have contributed to a better understanding of causal factors as well as the diversity of pain expression, including severity, chronicity, and impairment³3 Hartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, Hoy D, Karppinen J, Pransky G, Sieper J, Smeets RJ, Underwood M; Lancet Low Back Pain Series Working Group. What low back pain is and why we need to pay attention. Lancet. 2018;391(10137):2356-2367.. Due to the association between psychological symptoms and outcomes of spinal disorders, currently, the biopsychosocial model approach should be the basis for initial assessment, decision-making and final evaluation of these conditions¹¹11 Miki T, Kondo Y, Kurakata H, Takebayashi T, Samukawa M. Effects of a physiotherapist-led approach based on a biopsychosocial model for spinal disorders: protocol for a systematic review. BMJ Open. 2021;11(9):e055144..

In the study of LBP, it is important to highlight some features such as: the lack of longitudinal and experimental studies; understudied population groups; and limited standardization regarding research methods and terminology for describing the phenomenon¹²12 Marquez JO. A dor e os seus aspectos multidimensionais. Ciência e Cultura. 2011;63(2):28-32.. More specifically, it is worth noting that investigations into such associations are predominantly designed to investigate the presence of LBP as an exposure variable and CMD as an outcome variable. However, as suggested in biopsychosocial models⁷7 GBD 2021 Low Back Pain Collaborators. Global, regional, and national burden of low back pain, 1990–2020, its attributable risk factors, and projections to 2050: a systematic analysis of the Global Burden of Disease Study 2021. Lancet Rheumatol 2023;5:e316-29,¹³13 Castaneda L. Healthcare and the Biopsychosocial Model: understand to act. Codas. 2019;31(5):e20180312., it is legitimate to consider whether mental disorders are also a potential predictor of LBP.

Depressive and anxious disorders, defined by the World Health Organization as Common Mental Disorders (CMD), are increasingly prevalent worldwide¹⁴14 World Health Organization (WHO) (2017) World Health Statistics 2017: Monitoring Health for the SDGs, Sustainable Development Goals. WHO, Geneva.,¹⁵15 Oreskovic S. Breaking down the silo mentality in global mental health: the new role for the schools of public health. Psychiatr Danub. 2016;28(4):318-20.. The high prevalence of CMD in the population and its recognized relationship with the perception of painful manifestations highlights its relevance as an associated outcome of LBP¹⁶16 Bener A, Verjee M, Dafeeah EE, Falah O, Al-Juhaishi T, Schlogl J, Sedeeq A, Khan S. Psychological factors: anxiety, depression, and somatization symptoms in low back pain patients. J Pain Res. 2013;6:95-101.. However, it is not clear how this relationship is established¹⁰10 Araujo JA, Campos MR, Santos MVF, Gonçalves DA, Mari JJ, Tófoli LF, et al. Dor lombar e transtornos mentais comuns na Estratégia Saúde da Família: uma associação pouco reconhecida. Rev Bras Med Fam Comunidade. 2018;13(40):1-14.,¹⁶16 Bener A, Verjee M, Dafeeah EE, Falah O, Al-Juhaishi T, Schlogl J, Sedeeq A, Khan S. Psychological factors: anxiety, depression, and somatization symptoms in low back pain patients. J Pain Res. 2013;6:95-101.. Moreover, it is not clear if there is also a reverse relationship, that is, if LBP is a good predictor of CMD. Studies emphasize the need for global recognition of dysfunctions caused by the association between LBP and CMD¹⁷17 Ranger TA, Cicuttini FM, Jensen TS, Manniche C, Heritier S, Urquhart DM. Catastrophization, fear of movement, anxiety, and depression are associated with persistent, severe low back pain and disability. Spine J. 2020;20(6):857-65.,¹⁸18 Park SM, Kim HJ, Jang S, Kim H, Chang BS, Lee CK, Yeom JS. Depression is closely associated with chronic low back pain in patients over 50 years of age: a cross-sectional study using the sixth korea national health and nutrition examination survey (KNHANES VI-2). Spine (Phila Pa 1976). 2018;43(18):1281.. Symptoms of anxiety and depression are associated with chronic pain and are known to negatively impact the treatment of LBP, reduce the quality of life, and increase social costs¹⁹19 Fernandez M, Colodro-Conde L, Hartvigsen J, Ferreira ML, Refshauge KM, Pinheiro MB, Ordoñana JR, Ferreira PH. Chronic low back pain and the risk of depression or anxiety symptoms: insights from a longitudinal twin study. Spine J. 2017;17(7):905-12.. A review on the topic showed that about 85% of patients diagnosed with depressive episodes also reported LBP²⁰20 Bair MJ, Wu J, Damush TM, Sutherland JM, Kroenke K. Association of depression and anxiety alone and in combination with chronic musculoeskeletal pain in primary care patients. Psychosom Med. 2008,70(8):890-7.. The authors²¹21 Rocha JR, Karloh M, Santos AR, Sousa TR. Caracterização de fatores biopsicossociais de pacientes com dor lombar crônica inespecífica. BrJP. São Paulo, 2021;4(4):332-8. indicate that mental-health related factors can be important prognostic elements, which should reflect in therapeutic changes. Ignoring this relationship can lead to unnecessary suffering, restriction of daily activities, loss of productivity, and the waste of healthcare resources²¹21 Rocha JR, Karloh M, Santos AR, Sousa TR. Caracterização de fatores biopsicossociais de pacientes com dor lombar crônica inespecífica. BrJP. São Paulo, 2021;4(4):332-8.. The influence of exposure to occupational risks in triggering LBP and CMD must also be considered. Inadequate work environment and conditions, in addition to high demands, are associated with the physical and mental illness of workers²²22 Shiga K, Izumi K, Minato K, Yoshimura M, Kitazawa M, Hanashiro S, Cortright K, Kurokawa S, Momota Y, Sado M, Maeno T, Takebayashi T, Mimura M, Kishimoto T. Association of work environment with stress and depression among Japanese workers. Work. 2022;72(4):1321-35.,²³23 Campanini MZ, González AD, Andrade SM, Girotto E, Cabrera MAS, Guidoni CM, Araujo PCA, Mesas AE. Bidirectional associations between chronic low back pain and sleep quality: A cohort study with schoolteachers. Physiol Behav. 2022;254:113880.,²⁴24 Serranheira F, Sousa-Uva M, Heranz F, Kovacs F, Sousa-Uva A. Low Back Pain (LBP), work and absenteeism. Work. 2020;65(2):463-9.. In research and intervention models for LBP, the biomedical model still predominates over the biopsychosocial model. Exploring LBP through the biopsychosocial model involves considering more comprehensively some variables that can cause, influence, or exacerbate the intensity of pain¹¹11 Miki T, Kondo Y, Kurakata H, Takebayashi T, Samukawa M. Effects of a physiotherapist-led approach based on a biopsychosocial model for spinal disorders: protocol for a systematic review. BMJ Open. 2021;11(9):e055144.,²¹21 Rocha JR, Karloh M, Santos AR, Sousa TR. Caracterização de fatores biopsicossociais de pacientes com dor lombar crônica inespecífica. BrJP. São Paulo, 2021;4(4):332-8.. In this regard, the study of the relationship between CMD and LBP is the focus of some research aiming to understand the direct or indirect associations between these variables and their influences²³23 Campanini MZ, González AD, Andrade SM, Girotto E, Cabrera MAS, Guidoni CM, Araujo PCA, Mesas AE. Bidirectional associations between chronic low back pain and sleep quality: A cohort study with schoolteachers. Physiol Behav. 2022;254:113880.,²⁵25 Azfar SM, Murad MA, Azim SR, Baig M. Frequency of and various factors associated with stress, anxiety, and depression among low back pain patients. Cureus. 2019;11(9):e5701.,²⁶26 Hübscher M, Hartvigsen J, Fernandez M, Christensen K, Ferreira P. Does physical activity moderate the relationship between depression symptomatology and low back pain? Cohort and co-twin control analyses nested in the longitudinal study of aging Danish twins (LSADT). Eur Spine J. 2016;25(4):1226-33..

Some studies address the possibility of this relationship being bidirectional when considering the direction of causality¹⁹19 Fernandez M, Colodro-Conde L, Hartvigsen J, Ferreira ML, Refshauge KM, Pinheiro MB, Ordoñana JR, Ferreira PH. Chronic low back pain and the risk of depression or anxiety symptoms: insights from a longitudinal twin study. Spine J. 2017;17(7):905-12.,²³23 Campanini MZ, González AD, Andrade SM, Girotto E, Cabrera MAS, Guidoni CM, Araujo PCA, Mesas AE. Bidirectional associations between chronic low back pain and sleep quality: A cohort study with schoolteachers. Physiol Behav. 2022;254:113880.,²⁷27 Pinheiro MB, Ferreira ML, Refshauge K, Colodro-Conde L, González-Javier F, Hopper JL, Ordoñana JR, Ferreira PH. Symptoms of depression and risk of low back pain: a prospective co-twin study. Clin J Pain. 2017;33(9):777-85.. Knowledge of this relationship, the external influences it undergoes, and the direction of causality can provide a fresh perspective on the diagnosis and intervention in these variables. Considering this, the present study’s objective was to conduct a systematic literature review on the relationship between LBP and symptoms of CMD. Given this, it is necessary to understand how research on the relationship between LBP and CMD and its main results are conducted. This knowledge can contribute to guiding behaviors that reduce the prevalence of LBP and CMD with their respective individual and collective impacts. Therefore, the present study sought to carry out a systematic review of the literature on this relationship.

CONTENTS

For this review, articles published in English, Portuguese, and Spanish between 2015 and 2022 were included, provided that an abstract was available. Quantitative observational studies, including cross-sectional, longitudinal, case-control, and prospective or retrospective cohort designs, were selected. Only studies that investigated possible relationships between CMD (anxiety or depression) and LBP in adult populations were included. Studies that solely investigated mental disorders not classified as anxiety or depression (cognitive deficits, personality disorders, among others) were excluded.

Search strategy

The present review was conducted from November 22, 2020, to January 22, 2023. The PRISMA method²⁸28 Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, Shamseer L, Tetzlaff JM, Akl EA, Brennan SE, Chou R, Glanville J, Grimshaw JM, Hróbjartsson A, Lalu MM, Li T, Loder EW, Mayo-Wilson E, McDonald S, McGuinness LA, Stewart LA, Thomas J, Tricco AC, Welch VA, Whiting P, Moher D. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021;372:n71 was used to guide the entire review strategy. The study was submitted to the International Prospective Register of Systematic Reviews (registration number CRD 42020210375). The registration includes information about the review objectives, material search strategy, population of interest, outcomes, explanatory variables, and actions to analyze and avoid biases. The search was conducted in the Medline (via PubMed), LILACS, and Scielo (via BVS) databases. The descriptors used to investigate LBP and CMD were chosen according to each database, as well as the combination strategy between them, and are described in table 1.

The articles were selected by two independent examiners based on reading the title and abstract. Potentially eligible articles were read in full. The reference lists of eligible articles were checked to find other potential studies to include in this review.

Data extraction

For data extraction, a pre-established form was developed and reviewed by the other authors. This form collected the following data: country where the study was conducted, year of data collection, year of study publication, type of data collection instrument for LBP and CMD variables, information about the population and study sample, study objectives, inclusion and exclusion criteria for participants, descriptive results of the studied variables, and results related to the association between variables.

Assessment of selected articles quality

To assess the quality and risk of bias in the studies, methodological criteria from the instrument developed by the authos²2 Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, Baker P, Smith E, Buchbinder R. Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol. 2012;65(9):934-9. and recommendations from the study²⁹29 Sanderson S, Tatt ID, Higgins PT. Tools for assessing quality and susceptibility to bias in observational studies in epidemiology: a systematic review and annotated bibliography. Int J Epidemiol. 2007;36(3):666-76. for observational studies were used. The instrument²2 Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, Baker P, Smith E, Buchbinder R. Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement. J Clin Epidemiol. 2012;65(9):934-9. was designed to analyze studies of prevalence of LBP but can be adapted to other study designs. Thus, 11 criteria were analyzed: 1) Were the study objectives clearly stated? 2) Were the inclusion and exclusion criteria for participants presented? 3) Were the study population characteristics clearly presented? 4) Was the sampling method a true or close representation of the target population? 5) Was random selection or a census conducted to select the sample? 6) Was the non-response bias probability minimal? 7) Were the data collected directly from individuals (rather than from a representative)? 8) Did the study instrument measuring the parameter of interest demonstrate reliability and validity (if necessary)? 9) Was the same type of data collection used for all subjects? 10) Were the outcome assessment measures clearly presented? 11) Were the data analysis procedures clearly presented?

RESULTS

The flowchart constructed based on the PRISMA recommendation²⁸28 Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, Shamseer L, Tetzlaff JM, Akl EA, Brennan SE, Chou R, Glanville J, Grimshaw JM, Hróbjartsson A, Lalu MM, Li T, Loder EW, Mayo-Wilson E, McDonald S, McGuinness LA, Stewart LA, Thomas J, Tricco AC, Welch VA, Whiting P, Moher D. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021;372:n71 (Figure 1) shows that the initial search in the databases resulted in 2648 articles. After removing duplicates (n=3), 2645 articles were evaluated according to the previously established inclusion and exclusion criteria, resulting in the exclusion of 1485 studies. Another 1071 articles were excluded based on the abstract reading, resulting in 89 eligible articles for full-text reading. After the full-text reading, 62 articles were excluded because their main focus was not studying the relationship between LBP and CMD. In the end, the selection and analysis strategy resulted in 27 articles for the study corpus.

Figure 1
Flowchart of the systematic review stages on the relationship between common mental disorders and low back pain.

Table 2 presents the characteristics of the articles in the corpus. The distribution of articles according to the year of publication showed a greater number of publications (n=5) in the years 2016, 2017 and 2022, and a smaller number for the year 2015, when one publication on the subject was identified. Regarding the study locations, the theme was addressed in different countries and continents, with Spain having 4 studies. In terms of study design, most of the articles (n=16) were cross-sectional studies. Longitudinal, case-control, and prospective cohort study designs were also part of the corpus. Cross-sectional studies are more common in epidemiological studies; they aim to estimate prevalence, describe risk factors, and investigate possible associations between outcomes and exposures. The costs for developing cross-sectional studies are lower, and the results they provide are more immediate.

However, the possible inferences are limited by the design itself, characterized by the measurement of exposures and outcomes at a single moment³⁰30 Bastos JLD, Duquia RP. Um dos delineamentos mais empregados em epidemiologia: estudo transversal. Notas de Epidemiologia e Estatística. Scientia Medica, Porto Alegre. 2007;17(4):229-32.. Longitudinal studies, on the other hand, require more resources and time to develop. As an advantage, they allow for dynamic investigation of the relationships between exposure and outcome, enabling broader inferences about causality, especially when performing analyzes based on incidence values³¹31 Athias L. Reflexões sobre pesquisas longitudinais: uma contribuição à implementação do Sistema de Pesquisas Domiciliares. Rio de Janeiro: IBGE, Coordenação de População e Indicadores Sociais, 2011.. In this regard, of the few longitudinal studies in the present review, only one carried out analyzes based on incidence values. The others worked with time cuts in the study itself (cross-sectional or nested case-control). It is necessary to advance a research agenda that allows for investigating the central hypotheses outlined by biopsychosocial models¹¹11 Miki T, Kondo Y, Kurakata H, Takebayashi T, Samukawa M. Effects of a physiotherapist-led approach based on a biopsychosocial model for spinal disorders: protocol for a systematic review. BMJ Open. 2021;11(9):e055144.,²¹21 Rocha JR, Karloh M, Santos AR, Sousa TR. Caracterização de fatores biopsicossociais de pacientes com dor lombar crônica inespecífica. BrJP. São Paulo, 2021;4(4):332-8..

The largest identified sample (n=83748) was obtained from a national survey conducted in Taiwan, whose reference population covered a cohort of 1000000 individuals³²32 Kao YC, Chen JY, Chen HH, Liao KW, Huang SS. The association between depression and chronic lower back pain from disc degeneration and herniation of the lumbar spine. Int J Psychiatry Med. 2022;57(2):165-77.. The smallest sample refers to a clinical study with 42 patients treated at a US hospital³³33 Salt E, Wiggins AT, Hooker Q, Rayens MK. Clinical and psychosocial factors over time following an acute low back pain episode. Orthop Nurs. 2020;39(4):248-54.. Furthermore, the characteristics of the samples described in the articles indicate methodological limitations. Only 13 out of 27 articles provided adequate information about the reference population and 10 out of 27 about sampling procedures. In general, the samples were not representative of the reference populations, or the information described in the articles did not allow for any conclusion on the matter. The absence of characterization of the reference population, description of the sampling process, and information on response rates are limitations for a proper evaluation of sample representativeness in epidemiological studies³⁴34 Rouquayrol MZ. Epidemiologia & Saúde / Maria Zélia Rouquayrol, Marcelo Gurgel Carlos da Silva. 8ª ed. Cap. 7- Rio de Janeiro: Medbook, 2018.. The articles analyzed in the corpus indicate a risk of participant selection bias and, consequently, threats the internal and external validity of the studies. Positive examples were presented by the studies¹⁷17 Ranger TA, Cicuttini FM, Jensen TS, Manniche C, Heritier S, Urquhart DM. Catastrophization, fear of movement, anxiety, and depression are associated with persistent, severe low back pain and disability. Spine J. 2020;20(6):857-65.,³⁵35 Trocoli TO, Botelho RV. Prevalence of anxiety, depression and kinesiophobia in patients with low back pain and their association with the symptoms of low back spinal pain. Rev Bras Reumatol Engl. 2016;56(4):330-6.,³⁶36 Kim MG, Seo JI, Kim K, Ahn YS. Nationwide firefighter survey: the prevalence of lower back pain and its related psychological factors among Korean firefighters. Int J Occup Saf Ergon. 2017;23(4):447-56..

Regarding the sample type, it was identified that about two-thirds of the articles (18/27) analyzed studied clinical samples, i.e., patients from ambulatory care or hospitals who were admitted due to complaints of LBP. Clinical samples consist of individuals with chronic conditions and functional limitations resulting from pain perception. In this sense, the predominance of clinical studies on the relationship between CMD and LBP limits inferences to the general population.

There are restrictions on causal inferences, as participants enter the studies after the onset of LBP. It is notable that samples of workers were studied in only three articles³⁶36 Kim MG, Seo JI, Kim K, Ahn YS. Nationwide firefighter survey: the prevalence of lower back pain and its related psychological factors among Korean firefighters. Int J Occup Saf Ergon. 2017;23(4):447-56.,³⁷37 Watrous JR, McCabe CT, Jones G, Farrokhi S, Mazzone B, Clouser MC, Galarneau MR. Low back pain, mental health symptoms, and quality of life among injured service members. Health Psychol. 2020;39(7):549-57.,³⁸38 Santiago-Barzan C, Espinoza-Ventura AY. Lumbar pain related to anxiety and depression in police officers of a police station in Lima. Rev Fac Med Hum. 2021;21(1):75-81.; occupational risk factors were not explored in neither of them as possible determinants of CMD or LBP. This omission is noteworthy, especially considering that they are epidemiological surveys. It is an important limitation since exposure to physical and psychosocial risks at work are risk factors for both outcomes³⁹39 Castro TGM, Lima EP, Assunção AA. Panorama dos inquéritos ocupacionais no Brasil (2005- 2015): uma revisão sistemática da literatura. Ciênc Saúde Coletiva. 2019;24(8):2923-32.,⁴⁰40 Freitas PN, Barros SS, Ângelo RC, Uchôa E P. Occupational low back pain and the sitting position. Rev Dor. 2011;12(4):308-13.,⁴¹41 Sigurd M, Coggon D, Andresen JH, Casey P, Flachs EM, Kolstad HA, Mors O, Bond JP. Are depressive disorders caused by psychosocial stressors at work? A sistematic review with metaaanalysis. Eur J Epidemiol; 2021;36(5):479-96..

All articles in the corpus used questionnaires and scales as data collection instruments. Different instruments were determined for identifying LBP and CMD. Regarding data collection for LBP, it should be noted that some studies did not use instruments and relied only on non-standardized items constructed for the respective surveys or on hospital records for LBP complaints. On the other hand, the instruments used to identify CMD were more specific, with significant variation in the type of instrument.

The use of non-validated instruments negatively influences the quality, comparison, and continuity of the obtained results³⁹39 Castro TGM, Lima EP, Assunção AA. Panorama dos inquéritos ocupacionais no Brasil (2005- 2015): uma revisão sistemática da literatura. Ciênc Saúde Coletiva. 2019;24(8):2923-32.. There is a variety of instruments for LBP assessment and there is no consensus among researchers regarding their use. Despite the recognition of the biopsychosocial model for LBP and the studies addressing its relationship with CMD, the articles in the corpus did not use an assessment instrument with that specific approach, as presented in table 2. Such a model requires psychometric evaluation instruments that determine the psychological state of the assessed individual, such as the Distress Risk Assessment Method (DRAM), an instrument originally developed to measure psychological states in individuals with LBP⁴²42 Tucci Neto C, Jacob A, Amorim TB, Araújo AO, Cristante AF. Tradução, adaptação cultural e confiabilidade da versão em português do questionário DRAM (Distress Risk Assessment Method) para avaliação psicométrica em dor lombar. Rev Bras Ortop. 2020;55(1):54-61..

The standardization and validation of instruments are important criteria for analyzing the methodological quality of studies, but there are others that were considered in the present review (Table 3). In this regard, it is worth noting that only one article met all the quality criteria¹⁷17 Ranger TA, Cicuttini FM, Jensen TS, Manniche C, Heritier S, Urquhart DM. Catastrophization, fear of movement, anxiety, and depression are associated with persistent, severe low back pain and disability. Spine J. 2020;20(6):857-65.. The criteria that were least frequently met were those related to the sample (criteria 3, 4 and 5) and those that dealt with the sample selection and description (Table 3). Criterion 6, regarding the response rate, was also poorly met, either due to low response rates or not being mentioned in the study. Among those which reported response rates, one study³⁵35 Trocoli TO, Botelho RV. Prevalence of anxiety, depression and kinesiophobia in patients with low back pain and their association with the symptoms of low back spinal pain. Rev Bras Reumatol Engl. 2016;56(4):330-6. presented 81.2%, another study¹⁷17 Ranger TA, Cicuttini FM, Jensen TS, Manniche C, Heritier S, Urquhart DM. Catastrophization, fear of movement, anxiety, and depression are associated with persistent, severe low back pain and disability. Spine J. 2020;20(6):857-65. presented 66.4%, and another³⁶36 Kim MG, Seo JI, Kim K, Ahn YS. Nationwide firefighter survey: the prevalence of lower back pain and its related psychological factors among Korean firefighters. Int J Occup Saf Ergon. 2017;23(4):447-56. presented 81.0%. Regarding the instruments used (criterion 8), it is worth noting the contrast between instruments frequently validated for CMD and rarely standardized or validated for LBP. In some studies, the assessment of LBP did not even involve or mention the use of instruments (studies with clinical samples, where the criterion for identifying LBP was ambulatory care or hospitalization without specification).

DISCUSSION

Significant associations between CMD and LBP were found in 25 out of 27 articles and non-significant in 5 out of 27 articles (Table 1). These data are justified by the fact that 3 articles present more than one analysis strategy in the same publication. The authors used twins as a sample and carried out a cross-sectional analysis of the total sample, and another research with a case-control design with co-twins. Results from some studies¹⁹19 Fernandez M, Colodro-Conde L, Hartvigsen J, Ferreira ML, Refshauge KM, Pinheiro MB, Ordoñana JR, Ferreira PH. Chronic low back pain and the risk of depression or anxiety symptoms: insights from a longitudinal twin study. Spine J. 2017;17(7):905-12.,²⁷27 Pinheiro MB, Ferreira ML, Refshauge K, Colodro-Conde L, González-Javier F, Hopper JL, Ordoñana JR, Ferreira PH. Symptoms of depression and risk of low back pain: a prospective co-twin study. Clin J Pain. 2017;33(9):777-85. show a significant association in the cross-sectional design and not significant in the case-control design.

One study²⁶26 Hübscher M, Hartvigsen J, Fernandez M, Christensen K, Ferreira P. Does physical activity moderate the relationship between depression symptomatology and low back pain? Cohort and co-twin control analyses nested in the longitudinal study of aging Danish twins (LSADT). Eur Spine J. 2016;25(4):1226-33., however, presents a significant association both in the general analysis (cross-sectional) and in the co-twins’ case-control model. The first authors attribute the negative association results to family or genetic environmental influences, but consider limitations related to the sample.

The corpus analyzed in the present review presents, for the most part, the hypothesis of a positive association between CMD and LBP. This aspect should be emphasized as it has practical implications for healthcare services and the development of public health strategies. In clinical settings, extra attention should be given to the broader repercussions in health and well-being for patients with LBP, including the possibility of triggering or worsening mental disorders ¹⁰10 Araujo JA, Campos MR, Santos MVF, Gonçalves DA, Mari JJ, Tófoli LF, et al. Dor lombar e transtornos mentais comuns na Estratégia Saúde da Família: uma associação pouco reconhecida. Rev Bras Med Fam Comunidade. 2018;13(40):1-14.,⁴³43 Donatti A, Alves ES, Terassi M, Luchesi BM, Pavarini SCI, Inouye K. Relationship between the intensity of chronic low back pain and the generated limitations with depressive symptoms. BrJP. 2019;2(3):247-54.. In non-clinical contexts, including those where active workers are involved, it is necessary to adopt disease prevention and health promotion strategies that equally address the management of physical and psychosocial risks³⁶36 Kim MG, Seo JI, Kim K, Ahn YS. Nationwide firefighter survey: the prevalence of lower back pain and its related psychological factors among Korean firefighters. Int J Occup Saf Ergon. 2017;23(4):447-56.,³⁷37 Watrous JR, McCabe CT, Jones G, Farrokhi S, Mazzone B, Clouser MC, Galarneau MR. Low back pain, mental health symptoms, and quality of life among injured service members. Health Psychol. 2020;39(7):549-57.. Different statistical analysis strategies (regression analysis, bivariate corrections, comparison of means, among others) were used to study the relationship between LBP and CMD. In general, among the articles that found a significant association, one can consider the strength of association between these variables from low to medium. A more precise statement in this sense must be made with caution, as each study model chosen and the limitation of clinical samples present in most studies must be considered.

A second aspect that deserves attention based on the findings is the scarcity of studies which focus on LBP as a possible consequence of CMD (n=3). If there is an effort to develop theoretical biopsychosocial models, there should be an empirical research agenda that considers one of the basic premises of such models: health is multidimensional and, therefore, bidirectional relationships are an important part of explaining outcomes. Why is there little interest in investigating hypothesis of bidirectional associations between CMD and LBP?

One possible answer to this question includes the theoretical and practical challenges that educational institutions face in incorporating the broader concept of health into the training of healthcare professionals. Furthermore, truly multidisciplinary healthcare services are rare, contributing to the theme being minimized or overlooked in clinical practice²¹21 Rocha JR, Karloh M, Santos AR, Sousa TR. Caracterização de fatores biopsicossociais de pacientes com dor lombar crônica inespecífica. BrJP. São Paulo, 2021;4(4):332-8.,⁴²42 Tucci Neto C, Jacob A, Amorim TB, Araújo AO, Cristante AF. Tradução, adaptação cultural e confiabilidade da versão em português do questionário DRAM (Distress Risk Assessment Method) para avaliação psicométrica em dor lombar. Rev Bras Ortop. 2020;55(1):54-61.. It is also necessary to understand why research interests are currently limited to the hypothesis of CMD as a consequence of LBP, that is, studies that analyze LBP as a dependent variable.

The literature on mental disorders reinforces the importance of bidirectional investigations, which analyze the LBP and CMD variables either as a cause or as an outcome. Depression (depressive episodes, major depression, among others) and anxiety disorders (generalized anxiety, phobia, obsessive-compulsive disorder, among others) are psychiatric disorders with complex etiology and are associated with limitations in the individual’s daily life⁴⁴44 American Psychiatric Association - APA. Manual diagnóstico e estatístico de transtornos mentais: DSM-5. Porto Alegre: Artmed, 2014.. Individual factors (biological and psychological) and macro-environmental factors (socioeconomic and cultural) should be considered to identify the etiology and development of these conditions¹⁶16 Bener A, Verjee M, Dafeeah EE, Falah O, Al-Juhaishi T, Schlogl J, Sedeeq A, Khan S. Psychological factors: anxiety, depression, and somatization symptoms in low back pain patients. J Pain Res. 2013;6:95-101.,⁴⁵45 Costa CO, Branco JC, Vieira IS, Souza LDM, Silva RA. Prevalência de ansiedade e fatores associados em adultos. J Bras Psiquiatr. 2019;68(2):92-100.. On one hand, the presence of non-communicable chronic diseases (NCDs) and the imminent risk of complications can generate psychological distress⁴⁵45 Costa CO, Branco JC, Vieira IS, Souza LDM, Silva RA. Prevalência de ansiedade e fatores associados em adultos. J Bras Psiquiatr. 2019;68(2):92-100.. On the other hand, anxiety and depression can act as risk factors for NCD, leading to the onset of physical illnesses⁴⁶46 Furnaletto LM, Brasil MA. Diagnosticando e tratando depressão no paciente com doença clínica. J Bras Psiquiatr. 2006;55(1).

A limit of this review was not having the objective to evaluate the association strength between the variables, which could have brought more robust results. In summary, the current review suggests that it is necessary to advance the agenda of research on the theme. Longitudinal designs, attention to the listed methodological aspects, and biopsychosocial models approached with causality analysis are needed. More attention to the exposure to risk factors to CMD and LBP is also recommended, especially those present in the work environment.

CONCLUSION

The current review presents many studies with significant association between CMD and LBP and the prevalent analysis of LBP as an independent variable. Longitudinal studies were scarce and did not aim to evaluate causality. From the methodological point of view, investigations presented insufficient information about the reference population and, consequently, the sample representativeness. Most studies focused on patients with LBP clinical condition and highlighted the lack of standardization regarding the LBP assessment instruments.

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