Evaluation of the internal construct validity of the Personal Care Participation Assessment and Resource Tool (PC-PART) using Rasch analysis

Abstract

BackgroundThe Personal Care Participation Assessment and Resource Tool (PC-PART) is a 43-item, clinician-administered assessment, designed to identify patients’ unmet needs (participation restrictions) in activities of daily living (ADL) required for community life. This information is important for identifying problems that need addressing to enable, for example, discharge from inpatient settings to community living. The objective of this study was to evaluate internal construct validity of the PC-PART using Rasch methods.MethodsFit to the Rasch model was evaluated for 41 PC-PART items, assessing threshold ordering, overall model fit, individual item fit, person fit, internal consistency, Differential Item Functioning (DIF), targeting of items and dimensionality. Data used in this research were taken from admission data from a randomised controlled trial conducted at two publically funded inpatient rehabilitation units in Melbourne, Australia, with 996 participants (63% women; mean age 74 years) and with various impairment types.ResultsPC-PART items assessed as one scale, and original PC-PART domains evaluated as separate scales, demonstrated poor fit to the Rasch model. Adequate fit to the Rasch model was achieved in two newly formed PC-PART scales: Self-Care (16 items) and Domestic Life (14 items). Both scales were unidimensional, had acceptable internal consistency (PSI =0.85, 0.76, respectively) and well-targeted items.ConclusionsRasch analysis did not support conventional summation of all PC-PART item scores to create a total score. However, internal construct validity of the newly formed PC-PART scales, Self-Care and Domestic Life, was supported. Their Rasch-derived scores provided interval-level measurement enabling summation of scores to form a total score on each scale. These scales may assist clinicians, managers and researchers in rehabilitation settings to assess and measure changes in ADL participation restrictions relevant to community living.Trial registrationData used in this research were gathered during a registered randomised controlled trial: Australian and New Zealand Clinical Trials Registry ACTRN12609000973213. Ethics committee approval was gained for secondary analysis of data for this study.

Measurement properties of the Health Literacy Questionnaire (HLQ) among older adults who present to the emergency department after a fall: a Rasch analysis

“…This occurs where the response to one item is not dependent on the response to another item [ 18 , 26 ]. Person-item residual correlation value <0.2 indicates local independence [ 34 ]. Internal consistency reliability The degree to which items in each scale measure the same construct [ 16 ].…”

“… Internal consistency reliability The degree to which items in each scale measure the same construct [ 16 ]. Person Separation Index (PSI) > 0.7 indicates good internal consistency reliability [ 15 , 28 , 34 ]. Response format Whether or not participants are able to consistently choose a response category appropriate for their level of health literacy.…”

“…The point between two response categories (such as strongly agree and agree) where either response is equally probable is known as a ‘threshold’ [ 28 ]. The absence of disordered thresholds on the category probability curve graphs indicates appropriate response format [ 34 ]. Item bias Whether or not different subgroups within the sample respond differently to an item, despite having equal levels of health literacy [ 16 , 18 ].…”

Responsiveness, construct and criterion validity of the Personal Care-Participation Assessment and Resource Tool (PC-PART)

“…Each Not OK represented an ADL participation restriction. These item response categories were shown to be valid using Rasch analysis [ 32 ]. When used clinically, the raw score for each scale is the total number of Not OK scores observed for an individual patient, with a range of possible scores of 0–16 ( Self Care ) and 0–14 ( Domestic Life ).…”

“…Subsequent research has demonstrated that the PC-PART has good inter-rater reliability for group applications but not for individual applications, such as in the clinical setting [ 31 ]. Using Rasch methods, a further study generated evidence supporting internal validity of 30 of the original 43 items, when grouped into separate Self Care (16 items) and Domestic Life (14 items) scales [ 32 ]. The objective of this present study was to evaluate the construct validity, criterion validity and responsiveness of the Rasch-derived Self Care and Domestic Life scales in an adult inpatient rehabilitation setting.…”