RESNA 26th International Annual Confence
THE ABILITY OF PHYSICAL AND OCCUPATIONAL THERAPISTS TO RECOGNIZE ELECTRIC POWERED WHEELCHAIR DRIVNG ACCIDENTS
Each year over 36,000 wheelchair-related accidents cause injury to wheelchair users. Most of these accidents can be attributed to tips and falls. The purpose of this investigation was to determine if physical and occupational therapists view and categorize electric powered wheelchair (EPW) driving accidents and severity differently. Thirteen certified physical and occupational therapists independently reviewed a videotape containing EPW driving scenarios and rated EPW accident severity when an adverse event occurred. No significant differences were found between the ratings of physical and occupational therapists. In addition, no significant differences were found between the ratings of ATP certified and non-ATP certified therapists. Although not significant, occupational therapists and non-ATP certified therapists judge EPW accidents more conservatively.
In the United States, an average of 36,559 wheelchair-related accidents each year are serious enough to require the user to seek attention in an emergency room (1). In addition, an average of 51 deaths are caused by wheelchair-related accidents each year (2). Between 1973 and 1987, there were 770 wheelchair-related deaths reported to the United States Consumer Product Safety Commission (USCPSC), 68.5% of which were attributed to falls and tips (2). Of the 2,066 non-fatal accidents reported between 1986 and 1990 to the USCPSC, falls and tips were the cause 73.2% of the time (1). An estimated 24.6% of wheelchair-related accidents involve electric powered wheelchairs (EPW) (3).
Users of EPWs often have difficulty maintaining a supported seated posture when subjected to external forces (4). These external forces can be induced by ordinary obstacles which an EPW user encounters everyday thus exposing them to the risk of falling from the EPW or completely tipping the EPW. Further increasing the risk to EPW users is the lack of seatbelt use and/or the use of improperly adjusted legrests.
With the incidence of tips and falls in the EPW population, there is a need to characterize the cause of these adverse events and for therapists to reliably recognize accident risk during EPW driving. In order to decrease the severity and frequency of EPW accidents those involved in EPW prescription and driver training need adequate information and training on dangerous EPW driving conditions (4). This study will help to elucidate the adequacy of therapist training in matters of EPW accident etiology.
The specific aim of this study was to discern differences between physical therapist's and occupational therapist's ability to recognize safe versus unsafe EPW driving conditions, their ability to judge speed of the EPW and loss of control of the EPW driver, and their opinion as to whether or not an injury would occur during certain EPW driving conditions.
Thirteen certified physical and occupational therapists were asked to view a videotape. The videotape contained 75 scenes of EPW driving, using a 50th percentile anthropometric Hybrid II test dummy (HTD) to simulate a person driving an EPW, over four obstacles in four different EPWs. The 75 EPW driving scenarios occurred at either 1m/s or 2m/s. The HTD used in this study has previously been used in studies of wheelchair stability and is operated via a radio control model airplane controller (4).
Each therapist reviewed the videotape independently. Each trial was scored on an ordinal/nominal scale using the following notation: "N" for no fall; "L" for loss of control (e.g., the HTD falls forward or sideways but remains in chair); "F" when the HTD falls completely out of the chair; and "T" for a complete tip of the EPW. In the case of an adverse event occurrence, such as the F, L, or T condition, the therapists were asked to rate the conditions (safe or unsafe) under which the adverse event occurred and whether or not injury might occur. If an "unsafe" score was given to a trial the therapists were asked to state why the conditions were unsafe (high speed, no legrests on EPW, poor approach to the obstacle, etc.). Years as a therapist, and in what capacity, were also noted to discern differences between therapist types.
Statistical Analysis. Descriptive statistics of the characteristics of the therapists were analyzed. The Mann-Whitney U test was performed to detect differences between the scores given by physical therapists and occupational therapists as well as between the scores given by ATP certified therapists and non-ATP certified therapists.
Descriptive statistics of the 13 therapists involved in this investigation can be found in Table 1.
Comparison of the scores given by physical therapists and occupational therapists yielded no significant differences (p>0.05) between scores of N, L, F, and T. In addition, no significant differences (p>0.05) were found between the ratings of unsafe driving conditions, injury to the EPW driver, and driving speed between physical therapists and occupational therapists. Comparison of the scores given by ATP certified therapists and non-ATP certified therapists also yielded no significant differences (p>0.05) between scores of N, L, F, and T and the ratings of unsafe driving conditions, injury to the EPW driver, and driving speed. Tables 2 and 3 show the mean number of scores given for HTD loss of control, HTD fall, unsafe driving condition, driver injury occurrence, and EPW fast speed given by physical and occupational therapists and ATP and non-ATP certified therapists, respectively.
The results of this study demonstrate that both physical and occupational therapists recognize and categorize EPW driving accidents in the same manner. This is also true of ATP certified and non-ATP certified therapists. However, these results were found in a convenience sample of therapists and may change when a more diverse subject population is studied. Although not significant, the slight differences between physical therapists and occupational therapists and the ATP certified therapists and the non-ATP certified therapists reveal that occupational therapists and non-ATP certified therapists judge EPW accidents more conservatively. These two groups were noted to give more HTD loss of control, HTD fall, unsafe, and injury scores (Tables 2 and 3).
The agreement between therapists in EPW accident severity bodes well for the scoring tool used in this investigation. However, more therapists, rehabilitation engineers, and those working in the field of EPW service delivery should be tested on their ability to judge EPW accident severity. This may help to further validate the scoring tool and decrease the frequency and severity of EPW accidents.
This investigation supports the results of previous research in this area (5). In the present study thirteen therapists were able to independently recognize adverse EPW driving events, the majority of which occur while descending a ramp, ascending a curb-cut, and ascending a 50mm curb.
At this time there is no evidence to support that physical and occupational therapists view EPW accidents and severity differently. The same is also true of ATP certified and non-ATP certified therapists. The addition of specialized training in dynamic EPW situations in the course of therapist certification and wheelchair prescription may alter the findings of this study.
This work was partially supported by the Centers for Disease Control, Center for Injury Research and Control (R49/CCR310285-04), and the US Dept of Veterans Affairs, RR&D Service (F2181C).
T.A. Corfman (tacst49@pitt.edu)
Human Engineering Research Laboratories,
VAMC, 7180 Highland Dr, Pittsburgh, PA. 15206.