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Rasch Analysis of the Community Integration Measure in Persons With Traumatic Brain Injury

Published:December 20, 2013DOI:https://doi.org/10.1016/j.apmr.2013.11.020

      Abstract

      Objective

      To examine the measurement properties of the Community Integration Measure (CIM) in persons with traumatic brain injury (TBI).

      Design

      Rasch analysis was used to retrospectively evaluate the CIM.

      Setting

      Rehabilitation hospital.

      Participants

      Persons (N=279) 1 to 15 years after a TBI.

      Interventions

      None.

      Main Outcome Measure

      CIM.

      Results

      The CIM met Rasch expectations of unidimensionality and reliability (person separation ratio=2.01, item separation ratio=4.52). However, item endorsibility was poorly targeted to the participants' level of community integration. A ceiling effect was found with this sample.

      Conclusions

      The CIM is a relatively reliable and unidimensional scale. Future iterations might benefit from the addition of items that are more difficult to endorse (ie, improved targeting).

      Keywords

      List of abbreviations:

      CIM (Community Integration Measure), RSM (rating scale model), TBI (traumatic brain injury), TBIMS (Traumatic Brain Injury Model Systems)
      Many individuals with traumatic brain injury (TBI) encounter lasting impediments to satisfactory reintegration into their communities in terms of return to work,
      • Kreutzer J.S.
      • Marwitz J.H.
      • Walker W.
      • et al.
      Moderating factors in return to work and job stability after traumatic brain injury.
      recreation,
      • Wise E.K.
      • Mathews-Dalton C.
      • Dikmen S.
      • et al.
      Impact of traumatic brain injury on participation in leisure activities.
      mobility,
      • Rapport L.
      • Hanks R.A.
      • Bryer R.C.
      Barriers to driving and community integration after traumatic brain injury.
      and engaging in social relations.
      • Prigatano G.P.
      Work, love, and play after traumatic brain injury.
      Community integration is an important facet of recovery to consider because it is intimately connected with autonomy, productivity, and quality of life after injury. Moreover, enhanced community integration is associated with improved physical, cognitive, and psychosocial outcomes.
      • Bodenheimer C.F.
      • Roig R.L.
      • Worsowicz G.M.
      • Cifu D.X.
      Geriatric rehabilitation. 5. The societal aspects of disability in the older adult.
      As such, reliable and valid tools to measure community integration are valuable for clinicians and researchers interested in assessing outcomes in TBI. Rasch analysis
      • Rasch G.
      Probabilistic models for some intelligence and attainment tests.
      is a family of statistical models used to construct and evaluate measures of latent constructs (eg, questionnaires). A number of instruments assessing rehabilitation outcomes have been subject to Rasch analysis, including the FIM instrument,
      • Hamilton B.B.
      • Granger C.V.
      • Sherwin F.S.
      • Zielezny M.
      • Tashman J.S.
      A uniform national data system for medical rehabilitation.
      the National Institutes of Health Stroke Scale,
      • Millis S.R.
      • Straube D.
      • Iramaneerat C.
      • Smith E.V.
      • Lyden P.
      Measurement properties of the National Institutes of Health Stroke Scale for people with right- and left-hemisphere lesions: further analysis of the clomethiazole for Acute Stroke Study-Ischemic (class-I) trial.
      and the Beck Depression Inventory II.
      • Siegert R.J.
      • Tennant A.
      • Turner-Stokes L.
      Rasch analysis of the Beck Depression Inventory-II in a neurological rehabilitation sample.
      The central aim of the current study was to evaluate the measurement properties of the Community Integration Measure (CIM) using Rasch analysis.
      A comprehensive assessment of community integration may require >1 approach.
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      Many commonly used community integration assessment tools focus on measuring observable, objective aspects of community integration, such as the number of hours spent in recreational activities. Although those tools provide important information, they do not capture a person's subjective sense of integration within their community. Researchers have emphasized that not only should objective indicators of community integration be measured, but also “the satisfaction of persons with their participation levels.”
      • Sander A.M.
      • Clark A.
      • Pappadis M.R.
      What is community integration anyway?: defining meaning following traumatic brain injury.
      (p125) There are a growing number of instruments designed to assess perceived community integration. Of these, one of the most common and well-researched instruments is the CIM.
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      The CIM was designed to quickly assess an individual's subjective sense of integration into his or her community. It is thought to capture one's sense of participating and belonging.
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      Interestingly, although the authors of the CIM adopted a 4-factor theoretical model of community integration (assimilation, social support, occupation, independent living),
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      their preliminary validation study
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      was more supportive of a 1-factor solution. Psychometric properties of the CIM have since been explored using traditional psychometric methods in a variety of health populations, including oncology,
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      spinal cord injury,
      • De Wolf A.
      • Lane-Brown A.
      • Tate R.L.
      • Middleton J.
      • Cameron I.D.
      Measuring community integration after spinal cord injury: validation of the Sydney psychosocial reintegration scale and community integration measure.
      and TBI.
      • Willer B.
      • Rosenthal M.
      • Kreutzer J.S.
      • Gordon W.A.
      • Rempel R.
      Assessment of community integration following rehabilitation for traumatic brain injury.
      • Reistetter T.A.
      • Spencer J.C.
      • Trujilo K.
      • Abreu B.C.
      Examining the Community Integration measure (CIM): a replications study with life satisfaction.
      A previously published analysis of the CIM in the current sample
      • Griffen J.A.
      • Hanks R.A.
      • Meachen S.J.
      The reliability and validity of the community integration measure in persons with traumatic brain injury.
      showed that the CIM had adequate reliability, criterion validity, and utility when examined using a traditional psychometric approach. To date and to our knowledge, the psychometric properties of the CIM have not been examined via Rasch analysis.
      A Rasch model
      • Rasch G.
      Probabilistic models for some intelligence and attainment tests.
      is a criterion (or set of criteria), against which data can be evaluated for conformity or fit. Rasch analysis is particularly well suited to examine whether the CIM is unidimensional in nature, as suggested in the preliminary validation study of McColl et al
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      (as opposed to the 4-dimensional theoretical model that originally guided its development).

      Methods

       Participants

      Data for this study were deidentified archival data derived from a larger database. The study protocol was approved by the Wayne State University investigational review board. The sample included 279 individuals from the Southeastern Michigan TBI System research project, which is part of the nationwide TBI Model Systems (TBIMS) research study funded by the National Institute of Disability and Rehabilitation research. TBI is defined by the TBIMS as an injury to brain tissue caused by an external mechanical force. Any of the following indicators were taken as evidence of TBI: loss of consciousness from brain trauma, posttraumatic amnesia, skull fracture, or objective neurologic findings that could reasonably be attributed to TBI by physical or mental status examination. All participants were at least 16 years old at the time of injury, they received acute care at a designated TBIMS site within 72 hours of injury, and they received inpatient rehabilitation at the Rehabilitation Institute of Michigan. Individuals were considered for inclusion if their Glasgow Coma Scale score at admission to the emergency department was between 3 and 12 or if their Glasgow Coma Scale score was higher (13–15) but there was evidence of intracranial pathology such as hemorrhage. TBI severity was defined as days to obtain a motor score of 6 on the motor subscale of the Glasgow Coma Scale twice consecutively within a 24-hour period. The sample excluded individuals with mild or very severe injuries because these individuals either did not require inpatient rehabilitation (mild injuries) or were deemed unlikely to benefit from it (very severe injuries).

       Outcome measures

       Community integration measure
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.

      The 10-item CIM requires participants to appraise the quality of their integration into their community using a 5-point scale: 5 (always agree), 4 (sometimes agree), 3 (neutral), 2 (sometimes disagree), and 1 (always disagree). Item content is provided in full in table 1. The CIM has a Flesch Reading Ease Score
      • Flesch R.F.
      A new readability yardstick.
      of 76.2, which corresponds to a Flesch-Kincaid Grade Level
      • Kincaid J.P.
      • Fishburne R.P.
      • Rogers R.L.
      • Chissom B.S.
      Derivation of new readability formulas (automated readability index, fog count, and flesch reading ease formula) for Navy enlisted personnel.
      of 5.6.
      Table 1Demographic characteristics of the sample (N=279)
      Characteristicn%
      Sex
       Male22580.6
       Female5419.4
      Ethnicity
       Black20774.2
       White6422.9
       Latin American41.4
       Asian20.7
       Native American20.7
      Years of education
       <12y12444.5
       High school diploma13749.0
       Bachelor's degree113.9
       Postgraduate degree72.6

       Procedures

      The Southeastern Michigan TBI System assesses a variety of outcomes at routine follow-up points: 1, 2, and 5 years postinjury and every 5 years thereafter. The CIM, along with other outcome measures, was administered at those follow-up points. Hence, some participants completed the CIM on multiple occasions. However, each participant contributed only 1 CIM administration to the dataset: the earliest administration of the CIM was analyzed.

       Data analysis

      The Rasch rating scale model (RSM)
      • Andrich D.
      A rating formulation for ordered response categories.
      was used to evaluate the CIM. The RSM rather than the partial credit model was used because the CIM items all share the same rating scale structure. The partial credit model is used when each item has a unique rating scale structure. Rasch analysis was implemented using Winsteps 3.80.1 software.a In evaluating the CIM, we examined the unidimensionality, reliability, targeting, and response categories. To assess unidimensionality, we examined infit and outfit mean squares.
      • Gustafson J.E.
      Testing and obtaining fit of data to the Rasch model.
      • Wright B.D.
      • Linacre J.M.
      Reasonable mean-square fit values.
      These fit statistics have a theoretical range of 0 to infinity. Under good fit conditions of the data to the expectation of unidimensionality, the expected value of these fit statistics is 1. Infit and outfit mean-square ranges of 0.6 to 1.4 are reasonable for rating scales/surveys.
      • Wright B.D.
      • Linacre J.M.
      Reasonable mean-square fit values.
      We also assessed unidimensionality of the CIM using a principal component analysis of Rasch residuals where residuals can be understood as the difference between observed and expected data values. We evaluated the internal consistency of person and item performance on the CIM by examining separation reliability estimates and separation ratios.
      • Wright B.D.
      Reliability and separation.
      Separation reliability for persons refers to the consistency of person responses across items, whereas the separation reliability for items refers to the consistency of item performances across persons. Much like the Cronbach alpha, separation reliability estimates the ratio of the true score variance to the observed score variance, and its value ranges from 0 to 1. To overcome the potential for a ceiling effect in separation reliability, each separation reliability estimate has a corresponding separation ratio (theoretical value ranging from 0 to infinity), which is the ratio of the true (adjusted) SD of measures to the average SE of measures. Separation ratios >2 provide evidence of internal consistency.
      • Linacre J.M.
      What do infit and outfit, mean-square and standardized mean?.
      Targeting of item endorsibility to a person's level of community integration was assessed by comparison of the distribution and spread of items and persons along a common logit scale of the latent construct (eg, examination of the item-person map).
      • Bond T.G.
      • Fox C.M.
      Applying the Rasch model: fundamental measurement in the human sciences.
      Similar to the Rasch model for dichotomous items, the RSM reports both the item difficulties and person abilities, and it also provides a single set of thresholds for the rating scale that is common to all the items. These Rasch-Andrich thresholds represent the point or boundary at which the likelihood of being observed in a given response category is exceeded by the likelihood of being observed in the next higher category.
      • Bond T.G.
      • Fox C.M.
      Applying the Rasch model: fundamental measurement in the human sciences.
      The number of Rasch-Andrich thresholds is equal to the number of response categories minus 1; in the case of the CIM, there are 4 thresholds (5 response categories).

      Results

       Participant characteristics

      Demographic characteristics of the sample are shown in table 1. The average age of the participants was 44.9±13.6 years (range, 18–90y). Nearly three quarters of the sample (74.2%) identified as black. The ratio of men to women was approximately 4:1. Almost half of the sample reported <12 years of high school education. Participants took an average of 7.9 hours to obtain a motor score of 6±12.8 on the Glasgow Coma Scale (range, 1–99). The average Glasgow Coma Scale score on admission to the emergency department was 9±4 (range, 3–15). Blunt assaults comprised almost a third of the cases in the sample, and motor vehicle collisions comprised an additional third. Gunshot wounds, falls, and pedestrian versus motor vehicle collisions were each responsible for close to 10% of the sample. Injury characteristics of the sample are shown in table 2. The mean raw score on the CIM for this sample was 39.3±8.1 (range, 14–50).
      Table 2Injury characteristics (N=279)
      Characteristicn%
      Cause of injury
       Vehicles8932.0
       Gunshot3111.1
       Blunt assaults9132.6
       Other violence51.8
       Sports20.8
       Fall269.3
       Struck by object10.4
       Pedestrian3412.2
      Time since injury (y)
       17727.6
       24114.7
       54516.1
       106422.9
       155218.6

       Rasch analysis of the CIM

      Infit and outfit mean squares for each item are shown in table 3. Fit values were generally acceptable (range, .70–1.45), suggesting that items fit the RSM expectation of unidimensionality. However, initial examination of the Rasch–residual-based principal component analysis did not provide additional evidence of the unidimensionality of the CIM. Variance explained by the measures was only 44.4%. However, modeled variance was 45.2%, that is, the variance that would be explained if the data exactly fit the Rasch model. What might account for this apparent discrepancy? Some possible explanations are sample ability variance was narrow (person separation=2.01), the CIM is a short instrument (only 10 items), sample-item targeting was poor, and there was a ceiling effect in this sample with 9% of the participants obtaining the maximum score.
      Table 3CIM items: item level statistics
      No.ItemItem Difficulty (logits)Item Fit (mean squares)Response Categories Endorsed
      InfitOutfit1 (%)2 (%)3 (%)4 (%)5 (%)
      8I know a number of people in this community well enough to say hello and have them say hello back.−.540.940.9924112856
      3I know the rules in my community and I can fit in with them.−.321.100.9945112752
      2I know my way around this community.−.251.451.407692454
      5I can be independent in this community.−.231.041.0545162749
      4I feel that I am accepted in this community.−.070.710.7047192545
      7There are people I feel close to in this community..090.910.8976163039
      9There are things that I can do in this community for fun in my free time..180.830.8488162938
      6I like where I'm living now..191.281.251010142045
      10I have something to do in this community during that main part of my day that is useful and productive..451.071.09118203030
      1I feel like part of this community, like I belong here..500.881.04109262629
      NOTE. Items are shown in order of ascending difficulty.
      As noted, the person separation ratio was 2.01 with a corresponding person reliability of .80. The item separation ratio was 4.52 with a corresponding item reliability of .95. These values reflect relatively good reliability for this instrument within this sample; although, a higher person separation would be desirable.
      The Winsteps item-person map is shown in figure 1. An item-person map with good targeting would be symmetric along the vertical axis with items and persons clustered in a similar fashion with a similar range. This was not the case for the CIM in this sample where item measures ranged from −.54 to .50 logits, whereas person measures ranged from −1.66 to 4.47 logits. Inspection of the item-person map illustrates this poor targeting of items. It is easily visually appreciated that the items (shown on the right side of the map) measure a much narrower range of the construct of community integration than would be necessary to adequately characterize the participants (represented by x on the left side of the map). The polytomous distribution map (fig 2) provides additional information. In the middle column, each item is placed at its mean calibration. In the left column, the item is shown at the measure level corresponding to a probability of 0.5 of exceeding the bottom rating scale category. In the right column, the item is shown at the level corresponding to the probability of 0.5 of being endorsed in the top rating scale category.
      Figure thumbnail gr1
      Fig 1Item-person map. Abbreviations: frequ, frequent; M, mean; S, 1 standard deviation; T, 2 standard deviations.
      The Rasch expectation is that individuals with higher ability, in this case a higher level of community integraton, will have a higher likelihood of endorsing higher response categories on the CIM. Examination of the average abilities of persons endorsing a given response category in the current study showed this expected monotonicity, that is, persons with greater community integration were more likely to endorse the higher response categories. However, examination of the step calibration estimates for the CIM revealed disordered Rasch-Andrich thresholds. This occurred between the neutral and somewhat disagree rating categories. However, further examination revealed that CIM item categories were not substantively disordered. The category mean-square fit statistics did not markedly exceed 1, and the average measured increased monotonically. In this case, the disordering of the step calibrations reflected the relative infrequency of category 2 (sometimes disagree) (see table 3). Therefore, collapsing categories was ruled out.

      Discussion

      Rasch analysis provided additional evidence that the CIM is reliable and unidimensional. Although the test authors used a 4-factor theoretical model of community integration in developing the CIM, the current finding of unidimensionality is not surprising. A similar 1-factor solution was supported by principal components factor analysis in the test authors' preliminary validation study.
      • McColl M.A.
      • Davies D.
      • Carlson P.
      • Johnston J.
      • Minnes P.
      The community integration measure: development and preliminary validation.
      Unfortunately, in the current sample, there was evidence of poor targeting of items to persons (ie, items were too easily or frequently endorsed). There was a ceiling effect. The CIM needs additional items reflecting high levels of community integration.
      The selection of items with a difficulty level that is appropriately targeted at the ability level of the persons on whom the test is intended to be used is a key consideration in developing a test or questionnaire. In the case of attitudinal questionnaires, the term difficulty can be understood in terms of the endorsibility of an item, whereas ability can be understood in terms of the level or degree of community integration and depression. On a depression instrument, for example, some items have content that clearly assesses more severe symptoms (eg, suicidal ideation) than others (eg, disturbed sleep). In Rasch terms, the former items would be said to have a higher difficulty level, and highly depressed individuals would be said to have higher ability than less depressed individuals.

       Study limitations

      It is possible that the CIM would be well targeted to populations in which individuals have a much lower subjective sense of community integration than was the case in the current sample. For instance, the present sample was composed primarily of urban and suburban-dwelling individuals. Persons in remote rural areas might respond quite differently to CIM items. Similarly, participants in the current sample were all at least 1 year postinjury; in many cases they were considerably further. Individuals who are earlier postinjury might have greater barriers to community integration such that current CIM items could be better targeted to such persons.
      If the CIM is to be used with populations similar to the population in the current sample, future versions could include a wider range of items, particularly more difficult items (ie, items that require much higher levels of subjective community integration in order to endorse them). For example, mobility and/or transportation within the community are frequently reduced after TBI, often permanently.
      • Rapport L.
      • Hanks R.A.
      • Bryer R.C.
      Barriers to driving and community integration after traumatic brain injury.
      The CIM could include items addressing this barrier to community integration, such as “it is easy for me to travel from place to place within my community.” Resumption of leisure activities is often reported to be incomplete after TBI as well.
      • Bier N.
      • Dutil E.
      • Couture M.
      Factors affecting leisure participation after a traumatic brain injury: an exploratory study.
      Items focused on participation in leisure activities might improve the targeting of the CIM for use in TBI samples. For instance, “I am able to take full advantage of recreational or leisure activities in my community.”

      Conclusions

      The current study sought to examine the measurement properties of the CIM for use in measuring subjective community integration in persons recovering from TBI. Findings from this study provide support for the CIM to assess community integration after TBI, particularly when the clinician or investigator seeks a brief instrument. Users of the CIM need to be aware that the scale is most useful in assessing lower levels of community integration. Alternative measures should be considering when needing to assess high levels of community integration.

      Supplier

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