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In Switzerland, musculoskeletal disorders (MSD) are responsible for causing economic costs of 3.3 billion and 0.97 billion Swiss francs, due to loss of productivity and absence from work, respectively . Back pain alone, for example, entails costs of between 6 billion and 14 billion Swiss francs, which amounts to 1.3–3.2% of the gross domestic product in Switzerland (Schweizerischer Nationalfonds SNF 2009). More specifically, low back pain is responsible for about 3.2 billion Swiss francs in direct costs, and its direct medical costs make up 6.1% of the total healthcare expenditure in Switzerland . Intangible costs should not be underestimated either, even if they prostanoid receptors are extremely difficult to estimate. They include psychosocial burdens, such as job stress, suffering, family stress, and economic stress, which all result in a reduced quality of life . Taking a closer look at the general prevalence of MSD, Elfering and Mannion  estimated that the yearly prevalence of back pain ranges from 25% to 45% in Europe, and from 15% to 20% in the United States, whereas the prevalence of low back pain in Switzerland increased from 13% in 1984 to 21% in 1998 .
Not every profession seems to be equally affected by MSD. According to the Bureau of Labour Statistics, nurses are at an especially high risk of developing musculoskeletal problems . Overall, the annual occurrence of MSD for registered nurses ranged from 30% to 60%, depending on the specific body region involved . An even higher prevalence is found for operating room (OR) nurses. Studies dealing with the specific occupational group of OR nurses found that in different studies, the majority of the OR nurses reported shoulder and lower back pain in the last 12 months, with frequencies ranging from 58% to 90% [7–10]. In Choobineh et al , lower back symptoms were found to be the most prevalent musculoskeletal problem in OR nurses.
It is suggested that repetitive movements and remaining in a static position [11,12] for hours when holding and reaching the surgical instruments are reasons for this high occurrence. Indeed, research shows that the typical working life of nursing staff is characterized by unusual motions and postures [13,14], and that being exposed to physical risks like repetitive motions, excessive work load, bad posture, vibrations, motions, lifting and bearing heavy things increased the risk of developing musculoskeletal problems in general . The mentioned physical risks are also found to be associated with back pain in particular .
The psychosocial aspects of work that contribute to MSD in OR nurses have rarely been investigated so far. Such factors found in the literature include: shift work, conflicting demands, time pressure, and static stress [8,11,12]. This means that the more affected OR nurses were by these factors, the higher/more often their reported musculoskeletal complaints were.
To the knowledge of the authors, important and frequent work stressors, including work–family conflict and interruptions at work, have not been investigated yet in OR nurses, although a recent meta-analysis underlined the impact of the work–family conflict and privacy-work conflict on wellbeing and health . Grzywacz et al  found that work–family conflict was a previously neglected, but salient, problem among nurses, as 50% reported chronic work interference with family, meaning that conflicts occur at least once a week because of it. Even though the work–family conflict seems to affect one\’s health, short-day plants has rarely been studied in association with pain . According to the study by Hämmig et al , employees who were most frequently exposed to the work-to-life conflict were also most at risk for developing low back pain and neck/shoulder pain. Furthermore, having a variable work schedule was found to be an important predictor of work-to-life conflict . Variable work schedules are common factors in the typical work life of OR nurses [8,9]. Thus, the current study assumes that the work–family conflict might be an important work stressor for OR nurses and will therefore predict significantly and positively lumbar and cervical musculoskeletal pain (Hypothesis 1).
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