Studies have shown that musculoskeletal problems are particularly common in health care workers who are in direct contact with patients [7
]. Reports from other populations have shown that nurses, nursing aides, and orderlies have the highest rates of WMSDS in the medical industry [28
]. The high prevalence of musculoskeletal disorders among nurses is thought to be due to physical work demands, as well as to work organizational factors, of which scheduling is an important component [28
]. However, there is a dearth of studies on WMSDs among nurses in Nigeria.
The results of this study indicated a lifetime prevalence of 84.4% among the nurses. The 12-months and point prevalence of WMSDs at any body region were 78% and 66.1% respectively. The prevalence rates of WMSDs in nurses have varied according to studies but have been generally high. In a previous study from Nigeria, Fabunmi et al [32
] reported the 12 months period prevalence of self reported musculoskeletal disorders at any body site to be 90.7%. Smith et al [33
] in a study from rural Japan reported a 12-month prevalence of 91.9%. In a study conducted in the US, Josephson [34
] reported a prevalence of 72.5% while Harber et al [24
] reported that 52% of nurses reported experiencing work-related back pain within a 6-month period. Prevalence of musculoskeletal disorders has been noted to vary across occupational groups and over national boundaries [33
]. Subjectivity of terms, variations in instrument, organizational differences in work settings, and cultural differences in the perception and reporting of pain and disorders are adduced for the variation in rates of WMSDs in the different studies.
The highest prevalence of 12 months period WMSDs in nurses according to body sites in this study was the low back (44.1%), followed by the neck (28.0%) and then knees (22.4%). This distribution pattern is consistent with literature. LBP is the most common musculoskeletal disorder in adult and about 60-80% of all individuals will experience the condition at some stage in their lifetime [35
]. LBP is one of the most important WMSDs among nursing professionals, accounting for a point prevalence of approximately 17%, an annual prevalence of 40-50% and a lifetime prevalence of 35-80% [36
]. Some researchers reported that more than half (56%) of their nurses have ongoing back troubles [37
]. However, previous studies have documented various rates of work-related low back pain (LBP) in nurses from various populations for a 12-month time period: Smith et al [38
] Korea 19.8%, Yip [17
] Hong Kong 40.6%, Limpscomb et al [23
] USA 29.0%, Niedhammer et al [39
] France 41.1%, Smedley et al [15
] England 45.0%, Smith and Leggat [29
] Australia 59.0%, Josephson et al [34
] Sweden 64.0%, and Fabunmi et al [32
] Nigeria 79.4%.
Lifting patients in bed, transferring patients out of bed, and lifting patients from the floor were the job activities most commonly reported as sources of back pain among nurses [15
]. Studies in biomechanics have also implicated factors such as physical loading, body flexion, rotation and weight loading in the aetiology of prevalent occupational LBP. Our finding on the high prevalence of work-related neck and knee pain among nurses is consistent with the pattern reported in literature. The neck and the knees have been recognized as common body sites of WMSDs among health care practitioners [29
A high percentage of the nurses in this study experienced their first episode of WMSDs in the first five year of clinical practice. Our results suggest that WMSDs increase with age and duration of employment respectively. It was observed that after age 50 years and at greater than 20 years of clinical practice, the prevalence of WMSDs declined. The lower rate of WMSDs among the very senior nurses in terms of age and years of clinical practice may be attributed to less patient handling but more administrative duties that often come with rise in job cadre. Another explanation might be that experienced and older nurses have increased level of knowledge about injury prevention, avoid harmful physical load, and have developed better coping strategies for musculoskeletal problems than the less experienced and younger nurses. Survivor effect was also implicated for the inverse trend observed between lower prevalence of WMSDs and each of older age and higher clinical experience. From occupational studies, healthy survivor effect describes a continuing selection process such that those who remain in an employment tend to be healthier over time. The healthy worker survivor effect generally attenuates an adverse effect of exposure [42
]. It is believed in cross-sectional studies, that survivor effects will typically decrease the observed associations between symptomatic disorders and physically demanding jobs [43
]. However, the mechanism of the survivor effect is still poorly understood.
From this study, the OR and 95%CI results indicate that the relative risk of WMSDs is about 4 times more among nurses with greater than 20 years of clinical experience than those with 11-20 years and are about 2 times more in those with 1-10 years of clinical years of experience respectively. However, this result may be due to chance rather than true effect as Chi square test of association result did not reveal significant association between rates of WMSDs and each of age and number of years of clinical practice. From the study population, 30.3% of the nurses in this study have sought treatment for their musculoskeletal disorders. Nurses with upper and lower back WMSDs sought treatment more than those with WMSDs in other body sites.
Working in the same positions for long periods, lifting or transferring dependent patients and treating an excessive number of patients in one day were the most perceived job risk factors precipitating WMSDs among the nurses in this study. These findings are consistent with previous reports indicating manual patient handling, transferring or moving as important predictors of musculoskeletal disorders and low back pain among nurses [14
]. Wilkinson et al [6
] and Harber et al [24
] implicated lifting patients as the most common mechanism for musculoskeletal disorders among nurses. Alexopoulos et al [18
] reported that handling of physical loads among nurses seems to put them at risk for the occurrence of musculoskeletal disorders. Ando et al [44
] also suggested that musculoskeletal pain among hospital nurses may have associations with some actual tasks and items related to work postures, work control, and work organization.
From this study, getting assistance or support staff in handling heavy patients, modification of nursing procedures in order to avoid re-injury or stressing an injury, and modification of patient's/nurse position were the top three coping strategies in ameliorating the risk of WMSDs. These coping strategies among Nigerian nurses seem similar to previous findings. Workers performing strenuous work are often advised to prevent problems and to cope with musculoskeletal symptoms by changing their working technique, using lifting equipment, taking breaks, and avoiding strenuous work tasks [45
]. This is also similar to the submission of Lambert and Lambert [48
] on methods for fostering effective coping strategies. Less than half of those with WMSDs visited other health practitioners for treatment or engaged in self-treatment. It can be adduced that those who sought medical care represent the more severe cases and the more serious pathology. However, this study did not assess the severity of pain or discomfort from WMSDs of the respondents.
Limitations of the study
This study is limited in its generalizability because of the non-probability sample employed. However, we tried to minimize this effect, by systematically selecting three of the Nigeria's leading and biggest hospitals in Ibadan, Nigeria each one representing the different tiers of health care providers. The variability of the workload and ergonomics knowledge of the study respondents in these different hospitals may influence homogeneity. This study investigated the lifetime and 12 months period experience of WMSDs which could also lead to some degree of misclassification due to recall bias. Like all other cross-sectional or self-report studies, it is possible that our respondents might have given vague answers or exaggerated their WMSDs. It is also possible that some of the respondents in our study perceived their musculoskeletal disorders as WMSDs regardless of whether they were caused by work or not. Adegoke et al [27
] posited that work may only be a contributory factor in the aetiology of musculoskeletal disorders among workers and that it may be difficult to distinguish between WMSDs and musculoskeletal disorders since their consequences in response to work demands may be similar. This study was delimited to nurses in active service only, those who left the workforce due to retirement or WMSDs or any other reason were not included in the current analysis. A prospective cohort study design with larger sample size is warranted in the future to provide more sound research evidence on WMSDs and healthy survivor effects among nurses in Nigeria.