WORK-RELATED MUSCULOSKELETAL

DISORDERS IN PHYSICAL THERAPISTS:

A PROSPECTIVE COHORT STUDY WITH 1-YEAR FOLLOW UP

PHYS THER. 2008; 88:608-619 Originally published online February 14, 2008

doi: 10.2522/ptj.20070127

Tuğçehan KARA 20131403056

Marc CAMPO Sherri WEISERKaren L KOENIGMargareta NORDIN

INTRODUCTION

Work-related musculoskeletal disorders (WMSDs) have a significant impact on physical therapists, but few studies have addressed the issue.

Research is needed to determine the scope of the problem and the effects of specific risk factors.

Cromie et al2 reported that 1 in 6 physical therapists changed settings or left the profession due to WMSDs.

Glover et al3 reported that 32% of physical therapists with WMSDs lost work time.

Molumphy et al6 reported that 18% of physical therapists with WMSDs of the low back changed their work setting and that 12% of the physical therapists reduced their patient care hours.

Exposure to risk factors for WMSDs is likely to result from patient care activities that include

lifting patients, transferring patients and the performance of manual therapy.

Each activity involves the application of relatively high levels of force, and each activity may have to be performed in hazardous postures.

Patient handling has been consistently associated with WMSDs in nurses,7–11 and biomechanical studies12,13 have demonstrated very high associated loads.

Nurses have one of the highest rates of nonfatal occupational musculoskeletal injuries.14,15

The objectives of this study were:

(1)to determine the 1-year incidence and prevalence rates of WMSDs in physical therapists and

(2) to determine the effects of specific risk factors.

Subjects

The study was a nonexperimental, prospective cohort study with a 1-year follow-up.

Data were gathered using 4-page, self-report, mailed questionnaires at baseline and at follow-up.

The questionnaires and protocols of this project were approved by the University Committee on Activities Involving Human Subjects at the Graduate School of Arts and Science, New York University.

MethodStudy Design

The American Physical Therapy Association (APTA) randomly selected 1,500 members using a Microsoft Access (version 2003)* query.

(n=9) Did not reside in the United States.(n=4) Had invalid adresses.(n=1) On the doctoral dissertation committee of the primary investigator (MC) was excluded.

Questionnaires were sent to the 1,486 members who were potentially eligible.

Inclusion and Exclusion CriteriaThe project included

• licensed physical therapists who were APTA members• involved in direct patient care at least 1 hour per week at their

primary position• therapists had to return both questionnaires, • they had to reside in the United States.

There were no exclusion criteria.Background/Demographics

A series of background and demographic items including age, sex, experience, hours worked per week, practice setting, hours of patient care per week, and holding a second job were included in the baseline questionnaire.

Exposure Assessment

Exposure was assessed at baseline.

Specific physical therapy tasks included patient transfers and patient repositioning (almost never or not at all, 1–5 times per day, 6–10 times per day, 11–15 times per day,or more than 15 times per day) and passive range of motion (PROM), joint mobilization, and soft tissue work (performed on 0 patients per day, 1–5 patients per day, 6–10 patients per day, 11–15 patients per day, or more than 15 patients per day).

General physical risk factors included kneeling or squatting, working with the trunk bent or twisted, awkward postures, static postures, and repetition (almost never or not at all, about 10% of the workday, about 25% of the workday, half of the workday or more).

Psychosocial risk factors were assessed with scales from the Job Content Questionnaire (JCQ).22 Used initially to study heart disease and cardiovascular outcomes, it also has been applied in studies with musculoskeletal outcomes.

Outcome Variables

Outcomes were assessed with a series of questions adapted from Hagberg et al29

and the Nordic Musculoskeletal Questionnaire (NMQ).30

The NMQ is a widely used, valid, and reliable musculoskeletal surveillance and exposure assessment tool.31–33

The primary outcome variable was the 1-year incidence of WMSDs.

A case was defined as a report of WMSD rated at least 4/10 on a visual analogpain scale from 0 to 10 and lasting more than 1 week or present at least once a month.

An incident case was considered to be when a subject met the case definition during the follow-up period but was free of the disorder for 8 weeks prior to baseline.

Secondary outcomes included visiting a physician, changing settings, andleaving the profession due to WMSDs.

A complaint of WMSD was established with the question “Have you had any musculoskeletal pain during the past 12 months that you believe to be related to your work?”

Duration of WMSD was assessed by the question “How long does the pain or discomfort usually last (24 hours or less, 24 hours to 1 week, 1 week to 1 month, 1 month to 6 months, or 6 months)?”

Frequency of WMSD was assessed by the question “How many times have you had the pain or discomfort (once every 6 months or less, once every 2–3 months, once a month, once a week, or more often than once a week)?”

Respondents were directed to answer each question separately for each body region.

Pilot Testing

The questionnaire was given to physical therapists and physical therapy educators for informal feedback. The questionnaire was formally pilot tested in 2 phases.

The first phase was a panel discussion with 8 physical therapists. Panel participants were selected by judgment sampling so that they included both expert and novice clinicians. The mean age of panel participants was 38.7 years, and the mean experience was 11.4 years. The panel included 3 boardcertified clinical specialists.

Both during the panel discussion and during informal feedback from physical therapists, a pain level of 4/10 was determined to be a reasonable level to differentiate minor complaints from more serious WMSDs.

The second phase was a test-retest reliability study with a 1-month follow-up period.Test-retest stability of the JCQ scales was good for decision authority (ICC=.71) andpsychological demands (ICC=.69) but fair for skill discretion (ICC=.35).

Data Analysis

The questionnaires were entered and coded using SPSS Data Entry Builder (version 4.0.1).†

Data Entry

Data were analyzed using SPSS for Windows (Graduate Pack, version 14.1)† and Intercooled Stata (version 9.2 for Windows)‡ computer programs.

Descriptive statistics were produced for all background factors, exposure factors, and outcomes.

The effect of background factors on WMSDs was analyzed using independent-sample t tests for continuous variables and the chi-square test of association for categorical variables.

Prevalence (for each body region) was calculated by taking the number of cases in that body region and dividing it by the total number of therapists who responded to the follow-up questionnaire.

Incidence (for each body region) was calculated by taking the number of cases in that body region and dividing it by the number of therapists who did not have a WMSD in the same body region for at least 8 weeks prior to baseline.

ResultsResponse

1029 physical therapists responded to the baseline questionnaire. 77 respondents were not included in the study.

(n=21) did not have any clinical hours,(n=18) were retired(n=35) did not have any patient care responsibilities(n=1) planned on retiring before follow-up(n=1) were students (n=1) declined to complete the questionnaire

The follow-up questionnaire was mailed to each of the remaining 952 subjects who responded to the baseline questionnaire. Responses to the follow-up questionnaire mailing were received from 882 physical therapists (93%) before the deadline. The mean time between responses was 369 days (SD=20).

Work-Related Musculoskeletal Disorders

In the follow-up year, 507 physical therapists (57.5%) reported a workrelated ache, pain, or discomfort in 678 body regions.

The 1-year prevalence rate for WMSDs in any body region was 28.0%.

The 1-year incidence rate was 20.7%.

In total, 183 physical therapists reported 243 incident cases.

Table 1 lists the proportions of incident cases for the follow-up year. The greatest proportion of incident cases was seen in the low back, followed by the wrist and hand, neck, and shoulder.

Impact of WMSDs

115 physical therapists (13%) reported visiting a physician due to WMSDs.

62 therapists (7%) lost work time due to WMSDs.

18 therapists (2.0%) reported changing settings due to WMSDs.

4 physical therapists (0.5%) reported leaving the profession due to WMSDs.

Associations Between Background Factors and WMSDs

The mean difference between therapists with and without WMSDs was marginally significant for age (mean difference=1.8 years, P=.05) but not for experience (mean difference=1.2 years, P=.18).

The difference in proportions of WMSDs among male and femalephysical therapists was not significant.

Risk Factors For WMSDs Of The Low Back

Patient transfers, patient repositioning, bent or twisted postures, and job strain increased the risk for low back WMSDs.

Therapists who transferred patients 6 to 10 times per day had odds of developing low back WMSDs that were 2.4 times higher than those of therapists who did not perform any transfers Therapists who repositioned patients more than 10 times per day had odds of developing low back WMSDs that were 2.61 times higher than those of therapists who did not reposition patients

Therapists who reported exposure to bent or twisted postures had 5.74 times higher odds of developing WMSDs than therapists who reported no exposure to bent postures

Therapists who reported job strain had 2.52 times higher odds of developing a low back WMSDs during the follow-up year.

Risk Factors For WMSDs of the Wrist and Hand

All 3 manual techniques increased the risk for WMSDs of the wrist and hand. Of the 3 techniques, the most substantial effect was seen with higher levels of soft tissue work.

Therapists who performed soft tissue work on more than 10 patients per day had odds of developing WMSDs that were 13.61 times higher than those therapists who performed no soft tissue work

Therapists who performed joint mobilization on more than 10 patients per day had odds of developing wrist WMSDs that were 7.95 times higher than those of therapists who did not perform joint mobilization.

Therapists who performed more than 5 transfers or who repositioned patients more than 5 times had lower odds of developing wrist and hand WMSDs.

Discussion

A substantial number of respondents reported WMSDs. The prevalence of work-related musculoskeletal complaints (57.5%) was similar to the rates found in prior studies. The 1-year incidence rate of 20.7% represented a substantial proportion of therapists who developed a new WMSD based on a fairly stringent case definition. Incidence for some therapists represented a completely new WMSD. For other therapists, it represented a transition from complaint to case status. Intervention strategies, therefore, should be focused on secondary prevention as well as primary prevention.The vast majority of studies do not evaluate every body region and among those that do, a standardized case definition is rarely used despite being recommended. The physical therapists did not appear to seek treatment, take time off from

work, or seek evaluation in response to WMSDs. Cultural factors may be responsible, in part, for this behavior.

Work-related musculoskeletal disorders were associated with increasing age.

Patient handling (transfers and repositioning) increased the risk forWMSDs of the low back

Protective measures should be considered for lifting and handling patients whenever possible. Use of equipment such as sliding boards, sit-to-stand devices, sliding sheets, lifting equipment (free-standing and ceiling mounted), and heightadjustable beds can reduce the risk of WMSDs.44 Soft tissue work emerged as the most substantial risk factor. A variety of protective measures for manual therapy such as thumb splints, mobilization wedges, and soft tissue devices are available. Job strain was associated with WMSDs of the low back in both the

baseline and longitudinal analyses.

Limitations The main limitation of this study was the instability of the exposure data from baseline. About 23% of the subjects had a significant change in their work status over the follow-up year. This study included APTA members only. The results, therefore, may be generalizable to the population of APTA members but not necessarily to physical therapists in general. Power for evaluating the specific effects of certain exposure levels was limited. There are no generally accepted guidelines for power in logistic regression Conclusion In conclusion, there were 2 major findings to consider from these data. The first major finding was that about 57% of the respondents reported a complaint of a work-related ache, pain, or discomfort. About 1 in 5 respondents (20.7%) reported a WMSD that met a stringent incident case definition. The second major finding was a clear association between physical therapy work and WMSDs. Patient transfers and repositioning were associated with WMSDs in the low back ,and soft tissue work and joint mobilization were associated with WMSDs in the wrist and hand.

Recommendation

To reduce the rate of WMSDs in physical therapists, 2 recommendations are proposed. The first recommendation is wider consideration of safe patient-handling and movement policies within the professionThe second recommendation is an expansion of the research agenda related to WMSDs in physical therapists and other health care workers. Studies with large sample sizes and multivariate models are needed to further examine the link between physical therapy exposures and WMSDs.

THANK YOU…

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