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Differences Between Manufacturers in Reported Power Wheelchair Repairs and Adverse Consequences Among People With Spinal Cord Injury

  • Lynn Worobey
    Affiliations
    Human Engineering Research Laboratories, Rehabilitation Research and Development Service, Department of Veterans Affairs, Pittsburgh, PA

    Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA

    Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA
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  • Michelle Oyster
    Affiliations
    Human Engineering Research Laboratories, Rehabilitation Research and Development Service, Department of Veterans Affairs, Pittsburgh, PA

    Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA
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  • Jonathan Pearlman
    Affiliations
    Human Engineering Research Laboratories, Rehabilitation Research and Development Service, Department of Veterans Affairs, Pittsburgh, PA

    Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA
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  • Benjamin Gebrosky
    Affiliations
    Human Engineering Research Laboratories, Rehabilitation Research and Development Service, Department of Veterans Affairs, Pittsburgh, PA
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  • Michael L. Boninger
    Correspondence
    Corresponding author Michael L. Boninger, MD, Human Engineering Research Laboratories, Department of Veterans Affairs, VA Pittsburgh Healthcare System, 6425 Penn Ave, Ste 400, Pittsburgh, PA 15206.
    Affiliations
    Human Engineering Research Laboratories, Rehabilitation Research and Development Service, Department of Veterans Affairs, Pittsburgh, PA

    Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA

    Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA

    Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA
    Search for articles by this author
Published:December 23, 2013DOI:https://doi.org/10.1016/j.apmr.2013.11.022

      Abstract

      Objective

      To compare the frequency of power wheelchair (PWC) repairs and consequences experienced over a 6-month period by individuals with spinal cord injury (SCI) who use a PWC ≥40h/wk, based on manufacturer, seating functions, Healthcare Common Procedure Coding System (HCPCS) group, and model, and over time.

      Design

      Convenience observational sample survey.

      Setting

      Spinal Cord Injury Model System centers.

      Participants

      Individuals with SCI (N=945) who use a PWC ≥40h/wk.

      Interventions

      Not applicable.

      Main Outcome Measures

      Number of required wheelchair repairs and resulting consequences (ie, being stranded, missing work/school, or missing a medical appointment).

      Results

      Rates of required repairs (47.6%–63.3%) and consequences (26.7%–40.7%) were high across manufacturers. Differences between manufacturers were found among PWCs without seating functions (P<.001–.008) and among group 2 wheelchairs (P=.007). Across the 10 most prescribed wheelchairs in this study, 54.5% to 73.9% of users required 1 or more repairs over a 6-month period. Increases in the number of repairs were also found for several PWC manufacturers with time. Differences were found in participant age, working status, years since injury, and presence of seating functions between manufacturers.

      Conclusions

      The differences found in the number of repairs reported by survey respondents based on PWC manufacturer and the increases in repairs over time require further evaluation.

      Keywords

      List of abbreviations:

      ANSI (American National Standards Institute), CMS (Centers for Medicare and Medicaid Services), E&J (Everest & Jennings), HCPCS (Healthcare Common Procedure Coding System), NSCID (National Spinal Cord Injury Database), PWC (power wheelchair), RESNA (Rehabilitation Engineering and Assistive Technology Society of North America), SCI (spinal cord injury), SCIMS (Spinal Cord Injury Model Systems)
      In 2009, the Centers for Medicare and Medicaid Services (CMS) reported providing power wheelchairs (PWCs) to 46,134 wheelchair users.
      U.S. Department of Health & Human Services
      Office of Inspector General. Power wheelchairs in the Medicare program: supplier acquisition costs and services.
      Wheelchairs allow individuals to overcome physical limitations and increase independence.
      • LaPlante M.P.
      • Kaye H.S.
      Demographics and trends in wheeled mobility equipment use and accessibility in the community.
      • Fitzgerald S.G.
      • Kelleher A.
      • Teodorski E.
      • Collins D.M.
      • Boninger M.
      • Cooper R.A.
      The development of a nationwide registry of wheelchair users.
      Further, PWCs offer seating functions that are essential to pressure relief, functional support, and postural support.

      Trefler E, Schmeler M. Seating for postural control. In: Brubaker CE, Brienza DE, editors. Wheelchair Seating. Rehabilitation Engineering Center on Wheeled Mobility: Proceedings of State of the Science Conference of Seating Issues for Persons with Disabilities; 2001 Feb 19-20; Orlando FL. Pittsburgh: 2001. p 19-25.

      Unfortunately, studies
      • Rentschler A.J.
      • Cooper R.A.
      • Fitzgerald S.G.
      • et al.
      Evaluation of selected electric-powered wheelchairs using the ANSI/RESNA standards.
      • Fass M.V.
      • Cooper R.A.
      • Fitzgerald S.G.
      • et al.
      Durability, value, and reliability of selected electric powered wheelchairs.
      • Pearlman J.L.
      • Cooper R.A.
      • Karnawat J.
      • Cooper R.
      • Boninger M.L.
      Evaluation of the safety and durability of low-cost nonprogrammable electric powered wheelchairs.
      have shown that wheelchairs often fail to meet their expectations for durability and reliability as set by the American National Standards Institute (ANSI) and Rehabilitation Engineering and Assistive Technology Society of North America (RESNA), who create and oversee the wheelchair standards in the United States. ANSI/RESNA standards allow for objective wheelchair comparison and include standardized testing for durability and safety by simulating 3 to 5 years of typical use.
      • Fass M.V.
      • Cooper R.A.
      • Fitzgerald S.G.
      • et al.
      Durability, value, and reliability of selected electric powered wheelchairs.
      The aforementioned studies demonstrate that subpar durability in wheelchairs is spread across various manufacturers and wheelchair types. However, these tests only mimic wheelchair use and are not actual reports of failures related to use.
      Worobey et al
      • Worobey L.
      • Oyster M.
      • Nemunaitis G.
      • Cooper R.
      • Boninger M.L.
      Increases in wheelchair breakdowns, repairs, and adverse consequences for people with traumatic spinal cord injury.
      reported that wheelchair breakdowns and consequences have increased in recent years. As a follow-up to that study, the goal of this study was to identify differences between PWC manufacturers in terms of the amount of reported repairs and adverse consequences. Wheelchairs were compared overall and also based on PWC Healthcare Common Procedure Coding System (HCPCS) groups. We also examined the rates of required repairs and adverse consequences based on the presence of seating functions and among the 10 most frequently prescribed PWC models. Additionally, this study sought to determine whether there were any differences over time within each manufacturer by comparing the frequency of reported repairs and the consequences between a current and historical data set. Outcomes of this study may inform clinicians about rates of required repairs and consequences as well as draw attention to high repair rates across manufacturers.

      Methods

       Participants

      Participants were enrolled if they were older than 16 years, had neurologic impairment resulting from a spinal cord injury (SCI) that occurred at least 1 year before the study, were treated at a national Spinal Cord Injury Model System (SCIMS) site, and used a wheelchair ≥40h/wk.

       Data collection

      Participants completed a questionnaire over the phone or in person regarding the number of repairs required in the 6 months before the study. The 6-month period was selected to maximize the likelihood of accurate recall of the number of required repairs.
      • Cummings S.R.
      • Nevitt M.C.
      • Kidd S.
      Forgetting falls: the limited accuracy of recall of falls in the elderly.
      If repairs were required, participants were asked to indicate whether the following consequences occurred: no consequence, been stranded, been injured, missed work or school, and/or missed a medical appointment. Participants reported sex, race, age, years since injury, occupation, and characteristics of the wheelchair they used most often including type and seating functions (tilt-in-space, recline, elevating leg rests, seat elevator, standing).
      Data were collected from participants at SCIMS facilities. The SCIMS program maintains the National Spinal Cord Injury Database (NSCID), which is the world's largest SCI research database. Participants of the NSCID are contacted 1 year after injury and every 5 years thereafter. NSCID participants in our study completed the survey as part of their follow-up. The NSCID has been found to be a reliable source regarding persons with SCI and captures approximately 13% of new injuries.
      • Lammertse D.P.
      • Jackson A.B.
      • Sipski M.L.
      Research from the Model Spinal Cord Injury Systems: findings from the current 5-year grant cycle.
      • Devivo M.J.
      • Go B.K.
      • Jackson A.B.
      Overview of the National Spinal Cord Injury Statistical Center database.
      All SCIMS centers obtained approval from their local institutional review boards before the implementation of study procedures.
      For the historical data set, participants were recruited from 16 SCIMS facilities from April 2004 through March 2006 in the following cities: Atlanta, GA; Ann Arbor, MI; Birmingham, AL; Boston, MA; Columbia, MO; Englewood, CO; Downey, CA; Houston, TX; Miami, FL; New York, NY; West Orange, NJ; Philadelphia, PA; Pittsburgh, PA; Richmond, VA; Seattle, WA; and San Jose, CA. Participants in the current data set were recruited from 6 SCIMS facilities from June 2006 through February 2011 from the following cities: Chicago, IL; Cleveland, OH; Washington, DC; West Orange, NJ; Philadelphia, PA; and Pittsburgh, PA. In addition to NSCID participants (n=116), the current data set also drew from local research registries that allowed sites to have people complete the survey who were receiving care at an SCIMS facility but were not currently enrolled in the NSCID (n=141).
      To be included in the analysis, participants had to report the manufacturer of their wheelchair and the number of repairs experienced. In order to be inclusive and have a large enough sample to draw conclusions, we only included PWCs by manufacturers that had at least 20 users; thus, Frank Mobility was excluded. Not all of the wheelchairs used by participants in this study are still on the market. However, because models are constantly changing and because performance of previous models could be indicative of performance of later models by the same manufacturer, we elected to keep them in the study.

       Data reduction and statistical analysis

      The number of repairs reported was dichotomized into 2 groups: repairs and no repairs. Consequences experienced were analyzed individually and also dichotomized as consequences and no consequences. The number of seating functions was dichotomized as present or absent. Occupation was dichotomized to working/student (working, on-the-job training, sheltered workshop, student) or unemployed/at home (homemaker, retired, unemployed).
      For the participants who reported the manufacturer's name and model of their PWC, we determined the appropriate HCPCS groups, and comparisons were made across HCPCS groups.

      Application and checklist for PDAC HCPCS coding verification request: manual wheelchairs [page on the Internet]. Fargo ND: Noridian Healthcare Solutions, LLC; c2013 [updated 2012 May]. Available from: https://www.dmepdac.com/docs/review/manual_wheelchairs.pdf. Accessed January 9, 2014.

      CMS classifies PWCs into 4 HCPCS groups: 1, 2, 3, and 4. These groups classify wheelchairs based on the size of the wheelchair base, user weight that can be accommodated, range the wheelchair can travel, top speed, type of seating, and number of seating functions that can be accommodated. HCPCS groups were used rather than K-codes, since these data span a change in coding for K-codes and information such as type of seat and weight capacity that cannot always be determined from the make and model.
      Variables were not normally distributed, so comparisons were made using the Kruskal-Wallis and Mann-Whitney U tests. SPSS version 19a was used to perform all statistical analyses. The significance level was set a priori to alpha=.05. Addressing the primary hypothesis, comparisons were made between manufacturers. For our secondary hypotheses, comparisons were also made based on HCPCS groups, wheelchair model, and seating functions, and between data sets, to look for changes over time.

      Results

      A total of 1114 full time PWC users met inclusion criteria for this study. Data from 146 of the 1114 participants were excluded from the analysis because information on the wheelchair manufacturer was not provided; data from 7 participants were excluded because they did not use a chair with at least 20 users (Frank Mobility); and data from 16 participants were excluded because they did not report the number of repairs. Of the 945 participants whose data were included, 688 wheelchair users were from the historical data set and 257 wheelchair users were from the current data set. Participants were on average 44.2±13.3 years of age and 12.5±10.3 years since injury. All subjects who completed the NSCID follow-up completed our questionnaire; therefore, the best way to estimate subject recruitment is from the NSCID annual lost to follow-up ratio at 15 years postinjury, which is 3.5 to 1, with “unable to contact” being the most common (31.1%) reason for being lost.
      National Spinal Cord Injury Statistical Center
      2012 annual statistical report.
      The following manufacturers provided PWCs to the participants in this study: Everest & Jennings (E&J), Invacare, Permobil, Pride Health Care (Pride), and Sunrise Mobility (Sunrise). A summary of participant and wheelchair demographics by manufacturer can be found in table 1, with missing data indicated in parentheses. There were no differences in sex or race across manufacturers; however, differences were found in years since injury, age, the number of participants who were working or were students, and wheelchair seating functions. Those with E&J PWCs had the greatest years since injury, while Pride and Permobil had the least. Survey respondents using Pride PWCs were significantly older than those with Sunrise or Invacare PWCs. Participants with Invacare, Sunrise, and Permobil PWCs were more likely to be working or students than those with Pride PWCs. Participants with Permobil PWCs were significantly more likely to be equipped with (1) tilt-in-space as compared with Invacare, Pride and E&J PWCs users (P<.001–.003); (2) recline as compared with Invacare, Sunrise, and Pride PWC users (P<.001); (3) seat elevation as compared with all other PWC users (P<.001–.002); and (4) elevating leg rests as compared with Invacare, Sunrise, and Pride PWC users (P<.001).
      Table 1Demographics across manufacturers
      CharacteristicsE&J (n=21)Invacare (n=535)Permobil (n=98)Pride (n=116)Sunrise (n=175)
      Years since injury23.0±6.912.7±10.310.6±10.49.1±9.613.7±10.0
      Age (y)45.9±6.343.5±12.645.7±14.048.6±48.644.3±13.4
      Sex (men)76.279.1 (n=2)16.376.779.4
      Working/student38.9 (Missing: n=3)30.3 (Missing: n=63)34.9 (Missing: n=15)16.5 (Missing: n=31)31.3 (Missing: n=12)
      Funding sourcePrivate/prepaid: 50.0

      Medicare: 16.7

      Medicaid: 5.6

      Other: 27.8

      (Missing: n=3)
      Private/prepaid: 32.0

      Medicare: 22.2

      Medicaid: 23.6

      Other: 19.1

      (Missing: n=17)
      Private/prepaid: 54.7

      Medicare: 9.5

      Medicaid: 11.6

      Other: 24.2

      (Missing: n=3)
      Private/prepaid: 25.4

      Medicare: 36.0

      Medicaid: 18.4

      Other: 20.2

      (Missing: n=2)
      Private/prepaid: 40.7

      Medicare: 18.0 Medicaid: 19.8

      Other: 20.6

      (Missing: n=8)
      HCPCS groupGroup 2: 100 (Missing: n=14)Group 2: 4.5

      Group 3: 58.8

      Group 4: 36.7

      (Missing: n=132)
      Group 3: 48.4

      Group 4: 51.6

      (Missing: n=34)
      Group 2: 37.9

      Group 3: 58.6

      Group 4: 3.4

      (Missing: n=29)
      Group 2: 16.9

      Group 3: 24.6

      Group 4: 58.5

      (Missing: n=110)
      Tilt-in-space40.0 (Missing: n=11)75.1 (Missing: n=125)88.8 (Missing: n=0)68.5 (Missing: n=24)76.2 (Missing: n=70)
      Recline80.0 (Missing: n=11)57.1 (Missing: n=125)79.6 (Missing: n=0)54.3 (Missing: n=24)54.3 (Missing: n=70)
      Elevating leg rests60.0 (Missing: n=11)24.1 (Missing: n=125)71.4 (Missing: n=0)27.2 (Missing: n=24)21.0 (Missing: n=70)
      Seat elevator20.0 (Missing: n=11)11.0 (Missing: n=125)69.4 (Missing: n=0)18.5 (Missing: n=24)10.5 (Missing: n=70)
      Standing0.0 (Missing: n=11)1.7 (Missing: n=125)6.1 (Missing: n=0)1.1 (Missing: n=24)1.0 (Missing: n=70)
      NOTE. Values are mean ± SD, percentages, or as otherwise indicated.
      Abbreviations: Pride, Pride Health Care; Sunrise, Sunrise Mobility.
      Across survey respondents, 60.4% required 1 or more repairs, and 30.8% experienced 1 or more adverse consequences. The percentages of participants requiring repairs based on manufacturer were as follows: E&J, 47.6%; Invacare, 63.0%; Permobil, 63.3%; Pride, 50.9%; and Sunrise, 58.9%. No significant differences in repairs based on manufacturer were found overall or among participants with wheelchairs equipped with seating functions. An exploratory analysis of PWCs without seating functions revealed that significantly more participants using Invacare (P<.001), Sunrise (P=.001), and E&J (P=.008) wheelchairs reported at least 1 repair than those using Pride (fig 1). In particular, the much larger size of the Invacare study sample may underlie why the differences reached statistical significance for that manufacturer, and the trends for the other manufacturers should not be overlooked. Of note, all Permobil wheelchairs used by participants were equipped with seating functions, which is why they were not included in this comparison. No significant differences were found between manufacturers in this sample for wheelchairs based on type or total number of seating functions.
      Figure thumbnail gr1
      Fig 1Reported repairs across manufacturers for PWCs without seating functions (asterisks and arrows indicate significant difference). Abbreviations: Pride, Pride Health Care; Sunrise, Sunrise Mobility.
      Consequences reported by participants in this study are summarized in table 2. No significant differences were found between manufacturers of PWCs used by participants and the number of consequences experienced. However, greater than 25% of participants from each manufacturer reported experiencing 1 or more consequences. Being stranded was the most frequently experienced consequence across manufacturers. Pride had the highest number of participants who reported experiencing a consequence.
      Table 2Consequences experienced based on manufacturer among those reporting repairs
      ManufacturerExperienced 1+ ConsequencesStrandedInjuredMissed Work or SchoolMissed Medical Appointment
      Invacare (n=330)30.924.24.55.57.6
      Sunrise (n=101)26.715.85.95.99.9
      Pride (n=59)40.732.20.06.818.6
      Permobil (n=62)29.021.06.511.39.7
      NOTE. Values are percentages.
      Abbreviations: Pride, Pride Health Care; Sunrise, Sunrise Mobility.

       HCPCS groupings

      PWCs were compared by manufacturer within HCPCS group. No participants reported using a group 1 wheelchair. Invacare users reported experiencing ≥1 repair significantly more often than Pride users in the current data set for group 2 wheelchairs (P=.007). No other significant differences were found across manufacturers when analyzed by HCPCS group.

       Model

      Model information was provided by 671 participants. We have presented repair and consequence information for the 10 most frequently prescribed wheelchair models among those who participated in this study (fig 2). Of these most prescribed models, 7 were made by Invacare, 1 was made by Permobil, and 2 were made by Sunrise. Among these frequently prescribed wheelchairs there was an uneven spread of consequences, with the most associated with the Invacare Storm Series TDX5 and the Invacare TDX SP. The most commonly experienced consequence for each of these most frequently prescribed models was being stranded.
      Figure thumbnail gr2
      Fig 2Repairs required among participants with most frequently prescribed wheelchair models and percentage experiencing consequences.

       Historical and current data sets

      No significant differences existed in subject demographics between data sets. Repairs and consequences were not analyzed for E&J because the cell size was too small for the current data set. When comparing across data sets, reported repairs were higher in the current data set for all manufacturers and significantly greater for Invacare (P=.019). These increases in repairs can be seen in figure 3.
      Figure thumbnail gr3
      Fig 3Increases in percentage of participants reporting ≥1 repair in current data set (asterisk and arrow indicate significant increase).
      A significant increase in the number of study participants experiencing ≥1 consequence as a result of breakdown (P=.002), as well as a significant increase in the number stranded (P=.004), missing work or school (P<.001), and missing medical appointments (P=.011), was found between data sets for Invacare. As seen in figure 4, a trend for an increase in the proportion of persons reporting >1 consequence as a result of breakdown was seen for all manufacturers, and that reached statistical significance for Invacare (P=.002).
      Figure thumbnail gr4
      Fig 4Increases in reported number of consequences between data sets (asterisk and arrow indicate significant increase).

      Discussion

      The goal of this study was to determine whether differences existed between manufacturers in the incidence of repairs and consequences experienced by study participants. Secondary goals of this study included investigating differences in these rates based on wheelchair HCPCS groups, seating functions, and model, as well as over time, by comparing 2 data sets. This study found significant differences across manufacturers as well as over time in the number of participants reporting repairs and consequences. An optimal wheelchair maximizes user performance and mobility, both of which can be diminished by breakdowns and repairs. Of note, the definition of “required repairs” over the 6-month period was open to interpretation by the study participants and could have ranged from replacing a battery to replacing a broken axle or fixing a power seating function failure. Further work needs to be completed to determine the type of repair. This could lead to recommendations related to routine maintenance.
      While significant differences were found when examining wheelchairs not equipped with seating functions and group 2 PWCs, interpretation is limited by the small sample size. Pride users reported fewer repairs in both cases, which could be explained by a number of factors. Participants with Pride PWCs were significantly older and more likely to be unemployed or at home than those with Invacare, Sunrise, or Permobil PWCs. Along the same lines, the higher number of repairs reported by participants with Sunrise and Invacare PWCs is possibly related to higher activity levels. Another possible explanation is that Pride PWCs have greater durability, which has been found in laboratory-based tests.
      • Rentschler A.J.
      • Cooper R.A.
      • Fitzgerald S.G.
      • et al.
      Evaluation of selected electric-powered wheelchairs using the ANSI/RESNA standards.
      However, further study is warranted.
      When looking at the consequences of reported repairs, the percentage of participants reporting missing work or school does not take into account, for each manufacturer, the percentage of PWC users who were working or were students. It is possible that the higher incidence of missing work/school, such as was found for participants using Permobil PWCs, is associated with a greater percentage of these users who are working or are students. Further, the type of consequences experienced may also reflect the differences in demographics between groups, such as the older population of Pride PWC users sampled missing more medical appointments. Interestingly, while Pride PWCs had the fewest participants report requiring repairs among wheelchairs without seating functions, they had the highest overall percentage of participants who experienced adverse consequences as the result of a breakdown. It is possible that the low number of repairs and the high number of consequences reported by Pride wheelchair users are related to the required repairs' being more serious.
      The percentage of participants who reported requiring repairs over the 6-month period was high for all manufacturers, with almost two thirds of participants with wheelchairs from some manufacturers we sampled requiring repairs (47.6%–63.3%). A comparison between our current and historical data revealed that the prevalence of repairs for Invacare PWCs increased significantly over time. Although not statistically significant, required repairs also increased for the Sunrise and Pride PWCs sampled. The percent change is actually higher for these manufacturers—21.6% and 33.0%, respectively—compared with 18.3% for Invacare. It is possible that the larger sample size of Invacare PWC users made it possible to detect a difference over time as compared with smaller samples of Sunrise and Pride PWC users. Regardless of statistical significance, this increase in rates is concerning. While there were no demographic differences between the historical and current data sets, caution should be applied when interpreting these increases, as the study population was not consistent between the 2 collection periods.
      In response to a CMS initiative on public reporting of quality comparisons across hospitals, the Agency for Healthcare Research and Quality assembled a list of quality indicators used to measure and compare hospital performance.
      Department of Health and Human Services Agency for Healthcare Research and Quality
      AHRQ quality indicators—guide to inpatient quality indicators: quality of care in hospitals—volume, mortality, and utilization.
      With repairs rates increasing for 3 of 4 manufacturers sampled in this study, we suggest that a similar evaluation of wheelchair quality could be beneficial. Competitive bidding for durable medical equipment, such as wheelchairs, has been introduced in some regions, and the coverage area is increasing. While competitive bidding may cut Medicare program costs by limiting participation to suppliers awarded a contract by CMS, it also forces suppliers to reduce payment levels. As such, with no change in acquisition costs, it is possible that without simultaneous quality evaluation and control, as has been implemented in hospital settings, the quality of wheelchairs and services provided (such as repairs and maintenance) may be sacrificed.

       Study limitations

      While our data set was large (N=945), it was limited with regard to individual manufacturers and models, and further significant differences would likely have been uncovered with a larger sample. Further, there was an uneven distribution of wheelchairs across manufacturers, which may have affected the power to detect differences due to cell size restrictions. While it is unlikely that the percentage of failures seen would change significantly with a larger sample size, a larger sample may have helped to elucidate additional statistical differences when making comparisons.
      A second important limitation to this study is that we did not measure the amount of use or the age of the wheelchair. It is possible that certain makes and models were used more or were older, thus leading to use-related failures. Importantly, we do not know the nature of the repairs completed, and repairs were self-reported. As such, we are unable to conclude whether repairs were related to routine maintenance (replacement of batteries, arm pads, casters) or more serious mechanical failures (brakes, rotors, bearings). Further, study participants were only asked about types of consequences experienced and not the total number of consequences. It is possible that we are underrepresenting the amount of adverse consequences experienced.
      There was also a change in the number of SCIMS centers between the historical and current data sets. Consistent survey questions, inclusion criteria, and user identification were used to attempt to minimize the effect of change in population over time. SCIMS centers are designated centers of excellence, so we may be underestimating the number of repairs and consequences as compared with those for all individuals in the United States with SCI. Finally, caution is required for interpreting the differences in repair rates and consequences between the 2 study cohorts. In particular, we do not know to what extent these differences may be related to unmeasured differences in the study samples that might influence the need for repairs, the reporting of repairs, the consequences related to their wheelchair breakdown, or a combination of these.

      Conclusions

      This study found significant differences in repairs between manufacturers, and significant increases in repairs and consequences within manufacturers over time. Across all manufacturers, repair rates were approximately 50% or greater, while consequences were experienced by 27% to 41% of participants reporting repairs. Given the limitations of the study, it is difficult to recommend one manufacturer over another based solely on these data. Future studies need to investigate the details of the type and extent of required repairs to better understand the nature of the failures and how they can be avoided. One possible way to improve wheelchair quality would be to require external standards testing and uniform reporting of failures.

      Supplier

      • a.
        SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.

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        • National Spinal Cord Injury Statistical Center
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