This is the first known study that reports on LBP prevalence and associated exposures in undergraduate physiotherapy students in one Australian tertiary institution. The findings of this study suggest LBP is a reality for many physiotherapy students, and it could be proposed that new graduates from this sample may now be entering the workplace with existing LBP.
The response to this survey was reasonable, with the third year student response being attenuated by poor attendance at the data-collection lecture (although over 90% of the third year students who attended the lecture completed the questionnaire). The non-responding students were unable to attend the data collection class because of delays in earlier classes. There was no reason to suspect that the non-responders in any year level would have completed the survey differently than the responders. There is high academic criteria for entering this program, and the highly competitive nature of assessment suggests that all students are similarly committed to the study requirements of their program year. Moreover, the response rate gender-proportions were no different from the gender-proportions of enrolled students in each year level, suggesting no systematic bias in respondents.
Although there were differences in data collection methodology, we do not believe that this influenced the results, as the study instrument, instructions and time frame were the same for all students. The response rates by the fourth year students to the mailed survey did not differ from the response rates of the other students who completed the questionnaire at the end of a lecture. Sensitivity analysis [32, 33] indicated that the sample was sufficiently powered to provide robust estimates of difference in lifetime prevalence across the year levels, although it was less well powered to detect differences in more recent estimates of LBP prevalence.
The lifetime prevalence of LBP for student physiotherapists in this study is generally higher than that reported in studies on graduate physiotherapists in Australia or internationally (see Table 6). These differences may well relate to the focus of comparison studies on work-related LBP only (using different descriptions of LBP), and collecting LBP experiences from older physiotherapists, which may attenuate the high prevalence of LBP reported by students or young graduates. However, the reported 12-month prevalence in our study is similar to that reported by Cromie et al , an Australian study using a similar definition of LBP, and measuring 12 month prevalence of LBP in binary terms. This suggests that once LBP is first experienced, it is a common feature of life for many physiotherapy students and graduates.
In our sample, being aged 20 or 21 years was a significant contributor to LBP prevalence. Considering those students who progressed through the physiotherapy program immediately after leaving high school (aged 17–23 years), the relationship between age and length of study was linear (r2 = 0.21). Thus, the 20–21 year old students would generally be in the final year of the physiotherapy program, and these findings concur with the elevated risk of LBP for the fourth year students compared with the first year students. However, the association with length of study for all subjects in the sample (from 17 to 35 years) is less convincing (r2 = 0.09), as eight percent of students aged 22 and over years commenced study after a number of years in the workforce (on average 6.7 working years (SD 2.4)). The average length of tertiary study for these mature aged students was 1.8 years (SD 1.6). Thus, we contend that while the older students may have been exposed to greater occupational and sport lifetime hazards than their younger counterparts, they may consequently have developed an enhanced ability to withstand workplace injury risk [21–24].
Occupational, sports and educational exposures
Our study found no association with any prevalence of LBP of lifetime recalled cumulative sporting and occupational exposures. Although these exposures were significantly and positively associated with age (r2 values of 0.56 and 0.61 respectively), the method of capturing and calculating exposure may well have attenuated potential associations. Physiotherapy students are believed to be involved in a variety of employment whilst studying, and many of the mature aged students worked at a range of occupations prior to entering the physiotherapy program.
The significance of the association of the educational exposure 'treating patients' at one-month and one-week LBP prevalence is related to increasing years of study only in the sense that none of the first or second year students reported this exposure. This concurs with the structure of the undergraduate physiotherapy program in the participating institution. There was also no increase in risk related to 'sitting looking down' across the years of study, as the students' year of exposure to the physiotherapy program was not significantly related to the association between this educational exposure and LBP in the previous month. Despite being reported to be an important element in undergraduate physiotherapy education , manual handling was not specifically measured in this study as an educational exposure. The survey questions related to educational exposures were generated by the students themselves (during the focus groups that developed and validated the questionnaire). The educational questions were based on student perceptions of their common educational activities. Only one educational category, 'treating patients', potentially contained elements of the variable working postures and manual handling activities that are associated with patient care [23, 24]. Question construction in this survey potentially highlights students' limited knowledge of workplace exposures.
The strong association between educational posture of 'sitting looking down' and one-month prevalence of LBP suggests that exposure to general undergraduate university student experiences could contribute to student physiotherapist LBP. Thus, further studies are required to test the prevalence of LBP in other undergraduate student groups. Important educational exposures could well incorporate aspects of university life that were not measured in this study, such as repeated exposure to (for instance) poor sitting and standing postures, stress, frequency and severity of injury, eating and recreational habits. It seems important therefore to further test in controlled comparison studies, whether physiotherapy students are more at risk of LBP than any other group of university students when undertaking educational activities.
Potential measurement error
Quantification of exposure, and measurement error in estimating exposures to educational activities, occupation and sport and fitness levels needs to be considered, as the associations with LBP may have occurred by chance, and may reflect artefacts in our estimation of risk. Further research is required to develop better measures of undergraduate physiotherapy training exposures, lifetime occupational and sports exposures, and a better understanding of the forces on the spine resulting from these exposures related to LBP. This study may also have been improved had we been able to quantify exposure to recognised physical risk factors for adult LBP in the undergraduate educational setting (such as twisting, lifting, manual handling etc), and to determine intra- and inter-individual variability in these activities [22, 24, 41]. The characterisation of exposure to workplace factors is however, frequently constrained by the multiple physical demands of many workplace tasks, whose inter-relationships are not well understood [26, 35, 36]. Moreover, comparisons of self-reported questionnaire assessments with observational data have shown poor agreement for factors such as the average duration of time spent standing, sitting, lifting and bending and/or rotating the trunk [35–37, 42]. Thus it appears that questions on duration of time spent in particular occupational positions may be difficult to answer accurately using any current data collection approach.
Commencement of LBP
It is of note that most LBP in our sample was reported as commencing in mid-teens, with the most common onset related to sport. As the teenage years are often a time of intense physical growth [39, 40], the potential for lifetime experiences of LBP to commence at this time needs to be carefully considered with a view to reducing adulthood LBP incidence. Thus, a better understanding is required of how age-related experiences, environmental factors, physical activity and individual physical growth relate to LBP, before the effect of 'age' alone can be understood. In retrospect, we should have asked for more recent information about sport and occupational exposures that could have allowed us to calculate not only lifetime exposure for both measures (for association with the lifetime LBP measure), but more recent exposures to correlate with the relevant LBP prevalence measures. In this way we may have gained a more robust understanding of LBP related to sport and occupation.
Time frame of data collection
Ideally in studies such as this, data should be collected at the one point in time, and in the same manner, to ensure the same length of exposure to the demands of each physiotherapy student year, and the same potential for error (or bias) in response. This was not possible for this study due to timetable constraints. We recommend that future surveys of this nature should be conducted at the end of the student year, possibly in examination week. This would ensure a full year of educational exposures for each year level and recognition by students of all likely workplace occupational exposures, thus enabling all students to have the opportunity to participate in data collection in the same manner at the same time.