Lower back pain has become one of the leading causes of absenteeism in industrialized countries, and Spain is no exception. However, the data points to a less intuitive reality than it might seem: having back pain does not guarantee that the worker will end up taking sick leave, and the type of employment contract has a greater impact than many realize.
Extensive research conducted in Spain over 17 years, with 18 months of follow-up per participant, has meticulously analyzed the factors that truly influence the frequency and duration of sick leave for lower back pain. The study, one of the most comprehensive carried out in Southern Europe, concludes that self-employment is the only factor consistently associated with a lower risk of taking sick leave and fewer days of absence from work when it does occur.
A large-scale study on work absenteeism due to lower back pain
The research, published in the specialized journal Occupational and Environmental Medicine of the British Medical Journal group, has been coordinated by the Spanish Network of Researchers in Back Pain (REIDE) and led by teams from the Institute of Biomedicine of the University of León (IBIOMED) , the Clinical Biostatistics Unit of the Puerta de Hierro-Segovia de Arana Health Research Institute , the University of Salamanca and the Kovacs Back Unit of the HLA University Moncloa Hospital in Madrid.
In total, 7.262 employed workers from 48 Spanish provinces were included , representing virtually all productive sectors, with the exception of the Water and Waste Management sector. The average age was around 42, and slightly more than half of the sample were women, providing a fairly representative snapshot of the country's working population.
For a period of 18 months, their sick leave and the reasons for it were tracked , using information recorded by the National Social Security Institute, collaborating mutual insurance companies, company medical services, and professionals from the National Health System. The authors highlight the enormous logistical effort involved in collecting, cross-referencing, and analyzing all this data over so many years.
The main objective was clear: to identify which worker profiles are more likely to request sick leave due to lower back pain and who tend to accumulate more days of incapacity, with the idea of ​​better guiding preventive strategies and health and labor resources.
To this end , 77 different variables were examined together that, according to previous work, could influence the intensity of pain, the degree of disability and the evolution of lower back pain: sociodemographic factors, clinical parameters, psychological aspects, working conditions and personal economic circumstances.
What has been analyzed: 77 factors under the microscope
The range of factors assessed was very broad. Sociodemographic variables included age, sex, and educational level . From a clinical perspective , the analysis focused on pain intensity, episode duration, triggers or aggravating factors, the presence of radiating pain, and a history of prolonged episodes of low back pain.
In the psychological realm, factors such as the use of anxiolytics and antidepressants , the tendency towards catastrophic thinking, the level of concern about the illness, and the fear of losing one's job were considered . Variables related to personal expectations were also taken into account , for example, whether the worker believed it was likely they would need to take sick leave for lower back pain within the next 12 months.
In the workplace, a distinction was made between self-employed and salaried workers , and the type and duration of contracts, the physical demands of the work, and job security were reviewed. From an economic perspective , income levels, the proportion of fixed and variable salary, and the impact of temporary leave on family finances were assessed.
With this level of detail, the researchers hoped to develop models that would predict with some accuracy the individual risk of a specific worker taking sick leave due to lower back pain and accumulating a certain number of days of incapacity.
However, when the statistical analyses were completed, the results were more modest in that sense: although many factors are statistically related to an increase or decrease in risk , none, except the type of employment relationship, made it possible to reliably calculate which specific person would end up on leave and for how long.
A key fact: the self-employed are less likely to deregister.
The most striking conclusion of the study is that being self-employed is the only factor associated with a lower risk of taking sick leave due to lower back pain and with fewer days lost if sick leave is taken. In fact, the probability of a self-employed person taking sick leave for this reason is approximately 33% lower than that of an employee.
Furthermore, among those who do end up taking sick leave, being self-employed also reduces the risk of accumulating 30 or more days of incapacity during the follow-up period. In other words, the data suggests that self-employed professionals not only take fewer absences, but when they do, they tend to return to work sooner.
The authors propose a primarily economic explanation: in the Spanish Social Security system, the self-employed typically have less favorable protection during periods of temporary incapacity , with greater uncertainty regarding their income and poorer coverage than salaried workers. This scenario would lead many to continue working despite the pain, while an employee, with a more stable financial cushion, would be in a better position to take sick leave.
Several co-authors highlight the striking fact that this work-related and economic component carries more weight than classic clinical parameters such as the intensity of lower back pain or the degree of disability. They point out that the data suggest that, "with equal pain levels," a self-employed person is more likely to continue working, while an employee is more likely to take sick leave.
This finding reinforces the idea that the decision to take time off work for health reasons does not depend solely on physical condition , but is greatly influenced by the social, economic, and work context of each individual.
Very common pain, few losses: what the numbers say
The study confirms that lower back pain is extremely common among the working population . Nearly 57% of the workers included reported discomfort or pain in the lower back at some point, and around 60% took medication to alleviate these symptoms.
Despite this high prevalence, only 7,4% of participants requested at least one sick leave for lower back pain during the 18-month follow-up period. Among them, approximately 30% accumulated 30 or more days of sick leave for this reason. In other words, many live with the pain, but only a minority end up temporarily leaving their jobs.
These data support the idea that lower back pain, although it is one of the main causes of disability and a frequent reason for visiting the doctor , only generates absenteeism from work when the pain is clearly disabling or when other factors are added that tip the scales towards the decision to stop working.
Researchers point out that back pain affects a large portion of the adult population at some point in their lives, impacting around eight out of ten people at some point. This makes it a major public health problem and an ongoing challenge for companies, healthcare systems, and workers' compensation insurers.
However, the fact that only a relatively small fraction ends up being sick leave suggests that prevention policies and health messages should focus not only on treating the acute crisis, but on maintaining activity as much as possible and better managing the factors that favor chronicity and disability.
The authors emphasize that requesting or maintaining sick leave is a complex behavior , in which the biological component is just one piece of the puzzle. Economic circumstances, fear of job loss, contract stability, perceived support at work, and even personal beliefs about the illness all play a significant role.
Factors that increase the risk of work absence due to lower back pain
In addition to the type of employment, the study identified several factors significantly associated with a higher risk of taking sick leave due to lower back pain . While none of these factors can predict an individual's behavior with 100% certainty, they do indicate clear trends:
First, age plays a significant role . For each additional year, the risk of taking time off work due to lower back pain increases by around 3% . This isn't a sudden spike, but rather a steady rise as one's working life progresses, which aligns with the gradual wear and tear on the spine and the accumulation of previous episodes.
Another significant factor is a history of prolonged lower back pain episodes . People who had experienced episodes lasting more than 14 days had a 43% higher probability of taking sick leave than those who had not experienced them or whose episodes had lasted for a shorter period. This finding reinforces the importance of properly treating initial episodes and preventing them from becoming chronic.
The worker's personal expectations are also a determining factor. Among those who believed it was likely they would need sick leave for lower back pain in the following year, the actual risk of actually requesting it was approximately 44% higher . This relationship between anticipation and subsequent behavior points to the weight of perception and prior experience in decisions about occupational health.
In economic terms, it was observed that the perception that taking sick leave would have a significant impact on income was associated with an increased risk of requesting it of around 48% . This may seem paradoxical, but it suggests that those who already consider their financial situation precarious may feel more vulnerable to pain and more inclined to stop working when lower back pain appears or intensifies.
Job insecurity and duration of sick leave
One of the most discussed findings by the authors is the relationship between perceived job insecurity and the likelihood of taking sick leave . According to the data, among workers who feel their job is at risk, the probability of requesting temporary disability leave due to lower back pain is 30% lower.
This result reflects the extent to which fear of losing one's job can lead many people to continue working despite pain , even in situations that, from a strictly clinical perspective, would justify rest or job adjustments. For researchers, it is an indication of the complexity of the psychosocial factors involved in absenteeism.
Regarding the duration of sick leave , the variables most associated with accumulating 30 or more days of incapacity during the follow-up period were being employed and experiencing lower back pain even while lying in bed . This latter clinical indicator is interpreted as a sign of greater functional severity, which is accompanied by a slower recovery.
Even so, statistical analyses reveal that, when it comes to explaining who ends up taking sick leave and for how long , work-related and economic factors carry far more weight than purely medical parameters. In other words, what happens in the workplace and in the household economy greatly influences the worker's behavior.
The authors insist that these findings should not be interpreted as an invitation to ignore pain, but as a wake-up call about the need to improve working conditions and social protection policies so that health decisions can be made with greater freedom and less external pressure.
Pain doesn't explain everything: the weight of psychosocial factors
One of the most frequently repeated conclusions by researchers is that pain intensity and the degree of disability have less influence than expected on the likelihood of taking sick leave , especially when compared to psychological and contextual factors. Although lower back pain is one of the most common reasons for visits to primary care physicians, it does not always result in work absences.
The data suggests that requesting or maintaining sick leave is a complex behavior , in which the biological component is just one piece of the puzzle. Economic circumstances, fear of job loss, contract stability, perceived support at work, and even personal beliefs about the illness all play a significant role.
In this regard, several experts involved in the study point out that, in practice, at the same level of pain, an employee is more likely to take sick leave , while a self-employed person tends to "tough it out" and remain active. It's not that some suffer less, but rather that they experience the impact of pain in a different work and economic context.
This explains why the research concludes that strategies for preventing lower back pain and its impact on work should not be directed solely at specific groups . Since it is not possible to accurately predict who will end up taking sick leave, the authors recommend addressing the problem across the entire working population, with measures that combine clinical care, ergonomics, and organizational changes.
Another consequence of these results is the need to integrate a psychosocial perspective into the management of low back pain , both in medical consultations and in workplace prevention programs. Aspects such as communication with the company, stress management, and perceived job security can make a difference in the progression of low back pain and in the decision to take time off work.
Prevention: physical activity, ergonomics and global policies
Given that lower back pain is almost inevitable at some point in one's working life, experts agree that the key lies in reducing its impact and preventing it from becoming a prolonged cause of disability . To this end, research emphasizes that preventive measures should be applied to all workers , without attempting to target only those considered "high risk."
Among the general recommendations, the importance of maintaining the highest possible level of physical activity stands out . Available evidence indicates that remaining active, within the limits imposed by pain, is usually more beneficial than prolonged rest, both for recovery from an acute episode and for preventing relapses.
The authors also emphasize the role of physical fitness and muscle strength . A trained body, with good supporting musculature, makes it easier to maintain a more balanced posture throughout the day and protects against strain in the lower back . Therefore, they recommend incorporating regular exercise, adapted to each age and situation, beyond simply correcting posture at specific times.
Regarding workplace ergonomics , the study's results indicate that these measures are especially useful in specific contexts, such as jobs involving the regular handling of heavy loads or repetitive movements. In these cases, using assistive devices, adjusting table heights, improving lifting techniques, or redesigning tasks can make a significant difference.
For the rest of the working population, experts believe that a combination of good physical fitness, active breaks, and some organizational flexibility can be more decisive than simply using special chairs, cushions, or ergonomic devices. Ultimately, it's about creating work environments that facilitate movement, changing posture, and balancing work with maintaining good back health.
Beyond the individual level, the study highlights the need to review temporary disability policies and social security coverage , so that workers can make informed decisions about their health without being forced to choose between pain and financial loss. Only in this way, the authors argue, will it be possible to reduce both unjustified absenteeism and working under conditions that are clearly detrimental to health.
Taken together, the findings of this extensive research highlight a key point: absenteeism due to lower back pain is not solely explained by what happens in the worker's spine , but rather by the interplay of their medical history, personal circumstances, fears, and work and economic realities. Understanding and addressing this complex web of factors will be crucial for designing more effective and, at the same time, fairer prevention policies for all involved.
