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Conteúdo (article):

Prevalence and factors associated with chronic back problem in women of childbearing age

Abstract
Chronic Back Problem (CBP) is a public health concern. In Brazil, data from the National Health Survey (PNS) estimated 27.0 million people (18.5%) who reported CBP, affecting more women than men. This study aims to identify the factors associated with CBP among women of childbearing age. It is a cross-sectional study carried out with data from the PNS, where the dependent variable was the prevalence of CBP, and associated factors included socio-demographic items, life habits, reproductive history, nutritional status, diagnosis of depression and health perception. A total of 22,621 women aged 18 to 49 years were interviewed. Of these, 14.8% reported having CBP. The risk factors studied were: increased age; living with spouse; multiparity; smoking; overweight or obese, having Waist Circumference (WC) above 80cm and Circumference/Height (C/E) index above 0.5; negative self-perception of health; and depression. The only protective factor associated with CBP risk reduction was education level. We conclude that age, living with a spouse/partner, smoking, multiparity, being overweight or obese, increased risk for cardiovascular diseases, depression and negative self-perceived health are associated with the development of CBP in women of childbearing age.
Keywords: Chronic Back Pain; Spine; Women.

INTRODUCTION
Although not fatal, Chronic Back Problem (CBP) constitutes an important public health1,2,3, economic and social problem4,5. Also known as chronic back pain, chronic back problems encompass neck pain, thoracic pain, sciatica, intervertebral disc disorders, spondylosis, radiculopathy, and general back pain6.
According to data from the National Health Survey (PNS, 2013) in Brazil,7 approximately 27.0 million people aged 18 years or older (18.5%) were estimated to have reported CBP, similar to that observed in other countries8, being more prevalent among women and among individuals over 60 years of age. According to Romero et al.9, the mean age of onset of CBP complaints in Brazil is at 35 years of age and reaches up to 28.1% of the population aged 60 years9.
Considered as one of the commonly reported complaints by the adult population, CBP can lead to disability, reduced functionality, and absenteeism from work10. Therefore, it compromises quality of life, entails a greater search for medical attention11,12, and has been one of the main causes of disability retirement13.
The literature indicates a set of factors associated with CBP such as sociodemographic factors including age, gender, income and education level; behavioral factors referring to smoking, sedentary lifestyle, exposures occurring in daily activities such as strenuous physical work, vibration, awkward position, repetitive movements; in addition to other factors such as obesity14.
According to the PNS data, several international studies15,16,17,18 point to gender inequality in CBP, with a higher prevalence among women due to the musculoskeletal constitution and the daily activities performed by them19. Osteoporosis, menstruation, pregnancy and cultural aspects are also factors that may be related to the higher prevalence of CBP among women20.
It is important to note that a woman’s life is marked by specific anatomical-physiological changes in puberty, gestation and climacteric21 periods that may favor the onset of CBP. In addition, women of childbearing age usually have a double working day, having to simultaneously respond to the demands of paid and domestic-family work22, which generates health effects23 such as a higher prevalence of Chronic Non-Communicable Diseases (CNCD), with hypertension, CBP, depression, arthritis or rheumatism and diabetes among them7.
Although the topic of CBP is relevant, there are still no representative studies for the Brazilian population regarding the use of treatments for this morbidity9. According to Frasson24, conservative treatment of low back pain should preferably address drug treatment, exercise, manual therapy, education, a biopsychosocial approach, and cognitive-behavioral therapy.
Treatments for CBP generate a burden on the public health system, since there is a need for exams, medications, physiotherapy, hospitalizations and surgeries25,26, and on the economy, specifically related to Social Security, since there are high insurance fees for health due to work remission27 and disability pension related to back pain in Brazil13.
Thus, CBP represents a public health problem1,2,3 that has an impact on the professional lives of people with this diagnosis13, and especially in women due to the genetic, physical and cultural factors20 that predispose them to morbidity. Thus, considering the relevance of this topic and a lack of studies in Brazil on the subject, this work aims to identify the factors associated with CBP among women of childbearing age.

METHODS
This is a cross-sectional study carried out with data from the National Health Survey (PNS) of the Lifestyles module of PNS (2013)7. The PNS was developed by the Brazilian Institute of Geography and Statistics (IBGE) in partnership with the Ministry of Health. The study population was composed of residents of private households in Brazil, except those located in the special census tracts (barracks, military bases, camps, boats, penitentiaries, penal colonies, prisons, jails, asylums, orphanages, convents and hospitals).
The sampling of the PNS is characterized by a sub-sample of the master sample of the IBGE Integrated System of Household Surveys (IBGE), whose geographic coverage is made up of the census tracts of the Geographical Operational Base of the 2010 Demographic Census, except for those with very small numbers of households and special sectors.
The PNS had a total sample of 60,202 people over 18 years of age, and the employed sampling plan was that of sampling by conglomerate in three selection stages (sectors, families and individuals)28.
In the first stage, selection of the primary analysis units was obtained by simple random sampling previously selected in the master sample. In the second, a fixed number of permanent households was selected by simple random sampling in each of the primary analysis units selected in the first stage. In the third stage, within each domicile of the sample, a resident aged 18 years or more was selected - also by simple random sampling - to respond to the 3rd (individual) part of the questionnaire. This selection was made based on a list of eligible residents, conducted at the time of the interview28.
The applied questionnaire was divided into three parts; the first two for questions on household characteristics, socioeconomic and health status of the residents, while the third was individual and directed to the previously selected resident of 18 years or more, in which questions about morbidity and lifestyle were answered29.
Women aged 18 to 101 years were evaluated in the PNS. In the present study, women of childbearing age in the age group of 18 to 49 years were considered, since the PNS did not evaluate women under 18 years old, being a higher limit than the classification of women of childbearing age in Brazil, which is 10 to 49 years old30. Thus a total of 22,621 women of childbearing age were evaluated in Brazil.
The analyzed dependent variable was the prevalence of CBP, investigated through the question: "Do you (a) have a chronic back problem, such as chronic back or neck pain, low back pain, sciatic, vertebral or disk pain?", which had two options: yes or no.
The independent variables included socio-demographic items, life habits, reproductive history, nutritional status and diagnosis of diseases, being categorized as follows: a) Age, in years, 18-26, 27-32, 33-39, 40-49; b) Education level: without education, up to complete elementary school, incomplete high school, incomplete higher education or more; c) Race or color of skin: white for women who self-declared white, and black, yellow, brown or other indigenous for women who self-declared black, yellow, brown or indigenous; d) Marital status: living or not with spouse/partner; e) Occupation: to be employed or not.
Regarding life habits as risk and protection factors: a) Physical activity: to have practiced or not physical activity in the last three months, and in addition a weekly physical activity practice score was constructed, in which the time spent in the activities was multiplied by the number of days and the cut-off point was practice or not of 150 minutes or more per week31; b) Treatment for CBP: whether or not they have had physiotherapy because of CBP and whether or not they have taken CBP injection/medication; c) Smoking: smoking or not; d) Watching television: less than 2 hours and equal to or more than 2 hours.
Regarding reproductive history, the number of births was considered: none, up to two, and three or more.
Regarding metabolic risk factors: a) classifying body mass via the Body Mass Index (BMI): leanness and eutrophy (≤ 24.9 kg/m²), overweight (> 24.99 and ≤ 29.99 kg/m²), obesity grade I (> 29.99 and ≤ 34.99 kg/m²), obesity grade II and III (> 34.99 kg/m²); b) waist circumference (WC)32; c) Waist-to-height ratio (WC/H)33: <0.5 reduced risk for cardiovascular disease and >0.5 increasead risk for cardiovascular disease.
Depression was used as a parameter for the diagnosis of diseases: a) diagnosis or not of depression performed by the physician.
For the self-perceived state of health, a stratified health self-assessment was used as follows: very good and good for women who self-rated their health as very good and good, and regular, bad and very bad for women who self-rated their health as regular, bad and very bad.
The PNS was approved by the National Commission of Ethics in Research (CONEP) of the National Health Council (CNS) under the number 328,159 on June 26, 2013. All interviewed individuals were consulted, clarified and accepted to participate in the study by signing a clear and Informed Consent Form.
A descriptive analysis was performed in which simple and relative frequencies of the independent variables were estimated and dependent according to the covariates of the study. The variables were described by proportions. The prevalence and prevalence ratios of presenting chronic back problem according to the covariables were estimated through logistic regression.
The analysis was performed in the survey module for complex samples of the Stata version 9.0 program (StataCorp., College Station, USA).

RESULTS

A total of 22,621 women aged 18-49 years were evaluated, of which 3,355 (14.8%) reported having CBP. Most of the women declared themselves as black, yellow, brown or indigenous and 62.7%, lived with their spouse or partner (61%), studied until high school (40.5%) and worked (59.9%) (Table 1).
In terms of life habits, the majority were non-smokers (90.2%) and 80.6% were sedentary because they practiced less than 150 minutes of physical activity per week (Table 1). Regarding nutritional status, it was verified that 44.7% were eutrophic and 31.3% were overweight. Most women (69.2%) had a high risk for cardiovascular disease according to the waist-to-height ratio33 (Table 1).
Regarding health conditions such as reproductive history, it was verified that the majority of the women were multiparous (50.3%); for the question of health perception, it was observed that most of the interviewees reported having very good or good health (95.7%); and 91.7% of the interviewees reported not having a medical diagnosis of depression (Table 1).
Among the studied variables, it was verified that age group (all age groups above 27 years, being highest in the range of 40 to 49 years); living with spouse/partner (OR = 1.13; 95% CI = 1.04-1.22); being a smoker (OR = 1.63, 95% CI = 1.46-1.81); multiparous, especially more than three births (OR = 1.37, 95% CI = 1.07–1.75); being overweight (OR = 1.33, 95% CI = 1.22–1.45) or obese, mainly obesite grade I (OR = 1.53, 95% CI = 1.37 - 1.70), having WC above 80cm and Waist-to-height ratio above 0.5 (OR = 1.51, 95% CI = 1.39-1.65); bad perception of health (OR = 3.58, 95% CI = 3.13-4.11); or diagnosis of depression (OR = 95% CI = ) are risk factors for CBP in women of childbearing age. The only protection factor for CBP was schooling (OR = 0.69, 95% CI = 0.60-0.80) (Table 2).
The variables race/color, employment, practice of physical activity in the last 3 months, practice of weekly physical activity equal to or greater than 150 minutes, or watching TV for more than two hours were not associated with the outcome (Table 2).
DISCUSSION
From the PNS data it was verified that of the 22,621 evaluated women of childbearing age, 3,355 (14.8%) reported having CBP. The characteristics associated to the higher prevalence of CBP with logistic regression were: increased age; living with a spouse or partner; being a smoker; multiparity; being overweight or obese; have WC above 80cm and waist-to-height ratio above 0.5, both indicating an increased risk of cardiovascular disease; self-referred health as bad, very bad or regular when compared to very good and good evaluation; and diagnosis of depression.
In the present study, the increase in the age group, especially in the 40-49 age group (OR = 2.70, 95% CI = 2.42-3.03), indicated a greater chance of developing CBP, which was also observed in studies with data from the National Household Sample Survey (PNAD) in 2003 and 200834,35. This fact may be due to changes in the body due to the aging process, such as reduced flexibility, postural problems, increased musculoskeletal degeneration, and consequently an aggravation of pain36.
Another risk factor for developing CBP was the relationship with spouse or partner (OR = 1.13, 95% CI = 1.04-1.22). No studies were found that directly address the relationship between CBP and relationship with spouse or partner. In a study by Dutra et al.37, it is suggested that this relationship may be due to the double burden of professional work and care with the family and household chores that women are often submitted to, especially when they have a stable relationship.
Regarding smoking, it was found that women who smoke are more likely to develop CBP than those who do not smoke; a result similar to that found by Malta et al. (2017) (OR = 1.59, 95% CI = 1.38-1.84). Smoking is currently recognized as a risk factor for cardiovascular diseases38 and has also been identified as a factor associated with negative health perception38. In addition, there is evidence that smokers and ex-smokers have a greater predisposition to develop chronic pain, since nicotine would activate the immune system, predisposing them to low back pain and rheumatic diseases, among other conditions39,40,41.
Concerning reproductive history, it was observed that the higher the number of births, the chance of presenting CBP increases by 37%. This association has also been found in other studies that consider pregnancy and postpartum as explanatory factors for higher prevalence of back pain among women26,42,43. This can be explained by pregnancy hormones such as relaxin, estrogen, and progesterone, which are responsible for increasing flexibility of the spinal and hip ligaments and lumbar lordosis increase, increased muscle contractions due to increased weight and posture caused by fetal growth. In the puerperium, CBP can be attributed to inadequacies in breastfeeding, the child’s weight and other factors26,42.
Regarding BMI, WC and waist-to-height ratio, it was observed that the higher the body mass and central adiposity, the greater the chance of developing CBP; a result similar to that found in other studies, since women of reproductive age and with obesity presented more complaints of low back pain when compared to eutrophic women44. According to Malta et al.36, the increase in body mass causes muscle overload, inflammatory processes in the bones and wear in the vertebral disc, favoring the onset of low back pain and herniated disc, among other diseases in the spine that are associated with CBP36.
Regarding self-perception of health, it was observed that women who reported bad, very bad or regular self-perception of health were 3 times more likely (OR = 3.58, 95% CI = 3.13-4.11) to develop CBP when compared to women who referred to their health as good and very good. It is worth noting that there is a shortage of studies on the subject with women of childbearing age, but a similar result to that found in this study was pointed out in the literature45 with women in the climacteric phase, where it was verified that 54% of climacteric women evaluated in the study who had CBP referred to negative self-perceived health when compared to those who indicated having a positive self-perception of health45.
The diagnosis of depression was associated with 3 times more chances of having CBP, which can be explained by the limitations that this dysfunction can cause. A study of patients suffering from a spinal disorder revealed that 12% had depression due to morbidity, and that most of them expected to improve with treatment (Pacola, 2014).
Education was associated as a protective factor, in which the women who studied until completing elementary school had an 84% protection factor for CBP, followed by those who completed high school (65%) and completed higher education or higher (69%). Data from the National Household Sample Survey35 and in a study conducted in Southern Brazil47 found that less educated individuals had more chronic pain. According to Plouvier et al.48, one explanation for this is that people with low education are more exposed to poor working conditions and therefore have more CBP complaints when compared to those with higher education. According to data from the Surveillance System for Chronic Diseases by Telephone Inquiry (Vigitel)49 in a national survey conducted in all Brazilian capitals and in the Federal District, there was a significant reduction in the frequency of negative self-assessment of health with increased education49.
The present study presents some limitations because it is a cross-sectional study, since it does not allow cause-effect inferences to be made regarding CBP and the studied variables. In addition, there is still a relative scarcity of studies on this subject in women, both in the childbearing age and in the climacteric period.
It is worth mentioning that the generic term of Chronic Back Problems used in the PNS made it difficult to discuss the results found in this study, since most of the studies in foreign literature refer to chronic low back pain. A similar perception was observed in Romero et al20.
Through the study, it can be concluded that CBP affects 14.8% of women of childbearing age and is associated with negative self-perception of health, as well as the advancement of age, relationship with spouse/partner, smoking, multiparity, overweight and obesity and diagnosis of depression. Education was the only protective factor for CBP in women of childbearing age.
Therefore, since the factors associated with CBP can be controlled, the results presented in this study can contribute to preventing the development of CBP, thus reducing costs for the treatment of patients under the unified public health system, as well as for social security by reducing the incidence of work absenteeism and disability retirement.

Funding: This study was financed in part by Graduate School from Universidade Federal do Rio Grande do Norte.

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