3.8.1 Measurement Instrument
Standard self-administered questionnaires were used. The instrument to determine the prevalence of low back pain and its associated risk factors is a questionnaire that had been used in a previous study investigating the risk factors associated with low back pain amongst therapists (the Perreira questionnaire) [48]. The Perreira questionnaire was adapted slightly for the current study amongst nurses. The Perreira questionnaire was adapted in Section 1 to determine the shift work details and employment history of the respondents. The Perreira questionnaire consisted of closed ended questions which included Likert scales, binary scales and multiple answer questions (See Appendix A).
Given the association of low back pain with psychosocial factors [36] a psychosocial questionnaire, the Depression, Anxiety and Stress Scale (DASS) [49] was used to measure the emotional states of depression, anxiety and stress (See Appendix A). The DASS was adopted unchanged for the current study.
DASS is a 42- item self report measure of depression, anxiety and stress that was developed by Lovibond and Lovibond. It has been previously used in other studies and has been found to be valid and reliable [49].
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3.8.2 Variables
The variables measured in the questionnaire (refer to Appendix A) included:
3.8.2.1 Personal Factors
The section on personal factors collected information on demographic variables such as nursing category, age, sex, height and weight, and substance use (alcohol consumption per week and smoking history).
3.8.2.2 Employment History
Employment details were also elicited: years since practising as a nurse, years at Edendale Hospital, period working in the current ward; and other wards worked in the last year.
3.8.2.3 Low Back Pain History
Information was gathered on the history of previous low back pain: in the past 3 months; past 12 months; any low back pain during their career as a nurse; and whether they suffered from low back pain before working as a nurse. The number of days that respondents were absent from work in the past year due to low back pain was established. The respondents were also asked about the activities that cause the low back pain to recur. Those respondents who reported that they are suffering from low back pain were also asked if they were aware of their diagnosis and to state at what stage in their career did they start experiencing a major episode of low back pain.
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3.8.2.4 Occupational Factors
Information was collected on: current work activities; work activity when first injured; work activities that cause low back pain to recur; length of time spent on each activity; and occupational risk factors
3.8.2.5 Environmental Factors
The respondents were asked about their manual handling activities, work surface height and chair height. Shift work details were also obtained, that is whether the respondents were currently working on day vs. night shift; whether permanently on night duty or permanently on day duty or whether they rotated between day shifts and night shifts.
3.8.2.6 Current Low Back Pain History
Information on the history of current low back pain included whether the respondents were currently suffering from low back pain and whether they believe that the low back pain is due to their occupation. They were asked about the type of ward they were working in when the current low back pain first occurred. They were further asked if the low back pain is exacerbated by nursing activities and the effect the pain has on activities of daily living. Intensity of pain and the frequency of pain were determined. Height and weight were measured and used to calculate respondents’ body mass index.
3.8.2.7 Psychosocial Factors
Psychological factors were obtained using the depression, anxiety and stress scale [49]. The depression scale included items that measure symptoms associated with dysphoric mood (e.g. sadness and worthlessness). The anxiety
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scale included items that are related to symptoms of physical arousal, panic attacks and fear. Finally the stress scale items measure symptoms such as tension, irritability, and tendency to overreact to stressful events [49].
3.8.3 Reliability and Validity of Instruments
Both questionnaires have been tested and validated in previous studies. The questionnaires were in English, which is the main language of communication in the hospital [48, 49]. Orthopaedic specialists and qualified physiotherapists that work in the spinal and back care field were consulted to establish the face and content validity of the Perreira questionnaire. The experts consulted gave input on the lay out of the questionnaire.
The Perreira questionnaire was pre-tested through a pilot study, to ensure that it was user friendly. The pilot study was conducted at Edendale Hospital, with a purposive sample of 20 nurses. Qualified physiotherapists were utilized as research assistants to assist with the distribution and completion of questionnaires and to ensure clarity of questions asked through the questionnaire. The research assistants were advised about the research by the researcher. One week prior to the pilot study, a meeting was held to explain the research process and to clarify the requirements. The pilot resulted in minor modification of the data collection process. It was decided that weight and height measurements should be taken in the beginning, to minimize incomplete data for these variables.
To ensure that the correct weight and height were recorded, a calibrated weighing scale and a tape measure were provided. The research assistants assisted the respondents to measure their weight and height.
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