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Abstract

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

Aim  Our aims were to (1) describe the conceptual basis of popular generic instruments according to World Health Organization (WHO) definitions of functioning, disability, and health (FDH), and quality of life (QOL) with health-related quality of life (HRQOL) as a subcomponent of QOL; (2) map the instruments to the International Classification of Functioning, Disability and Health (ICF); and (3) provide information on how the analyzed instruments were used in the literature. This should enable users to make valid choices about which instruments have the desired content for a specific context or purpose.

Method  Child health-based literature over a 5-year period was reviewed to find research employing health status and QOL/HRQOL instruments. WHO definitions of FDH and QOL were applied to each item of the 15 most used instruments to differentiate measures of FDH and QOL/HRQOL. The ICF was used to describe the health and health-related content (if any) in those instruments. Additional aspects of instrument use were extracted from these articles.

Results  Many instruments that were used to measure QOL/HRQOL did not reflect WHO definitions of QOL. The ICF domains within instruments were highly variable with respect to whether body functions, activities and participation, or environment were emphasized.

Interpretation  There is inconsistency among researchers about how to measure HRQOL and QOL. Moreover, when an ICF content analysis is applied, there is variability among instruments in the health components included and emphasized. Reviewing content is important for matching instruments to their intended purpose.


Abbreviations
FDH

Functioning, disability, and health

HRQOL

Health-related quality of life

ICF

International Classification of Functioning, Disability and Health

ICF-CY

International Classification of Functioning, Disability and Health for Children and Youth

PedsQL

Pediatric Quality of Life Inventory

PRO

Patient-reported outcome

QOL

Quality of life

What this paper adds

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information
  •  This paper makes explicit the content of health, HRQOL, and QOL patient-reported outcomes (PROs) according to WHO definitions of functioning, disability, and health and QOL.
  •  It contrasts the use of popular PROs with their actual content.
  •  The paper provides a discussion about the implications of mismatch between PRO content and their use.

The effectiveness of health programmes and interventions has traditionally been decided by clinicians, administrators, researchers, and policy makers with little input from patients.1–4 With more children living with chronic, episodic, or progressive health conditions,5,6 health professionals need to assess the impact of care on day-to-day life, rather than restrict measurement to biomedical issues, such as morbidities, that might not resolve.7 In parallel, health care resources are becoming an increasingly precious commodity around the world and difficult decisions need to be made about the focus and allocation of health services.8 The impact of these services as reported by children and their families can provide insight that can help with these difficult decisions.

Scaled questionnaires that assess health, health-related quality of life (HRQOL), and quality of life (QOL) are valuable tools for capturing child and parent experiences. When these validated questionnaires are administered directly to children or their families without clinicians, they are called patient-reported outcomes (PROs).9 Patient-reported outcome instruments are essential patient appraisal tools, but they are often developed and implemented without a firm conceptual basis or a clear definition of what they are intended to measure. Many PROs were developed before there was clarity in the literature on what constituted functioning, disability, and health (FDH) rather than HRQOL or QOL.

This lack of agreement about definitions affects the ability to interpret the results collected from different instruments.7,10,11 The results obtained from one HRQOL instrument applied in particular context cannot easily be compared with results obtained with another HRQOL instrument if they are composed of different content. Envision the example of anti-spasticity therapy being provided to similar groups of children but measured with different instruments; one showing change following intervention, the other showing no change. Without detailed knowledge of the conceptual basis and content of both PROs, it is difficult to interpret whether the observed change or lack of change is due to the intervention or to the instrument (or possibly both).

Many clinicians and researchers choose to adopt the most popular instruments for their studies in the belief that use of a generic PRO will overcome measurement discontinuity between clinical situations. The reasoning behind this is that the results of one study will be comparable to another so long as the same generic instrument is employed. This approach may resolve the comparability problem between studies but what was being measured from the first place remains unclear (e.g. functioning, HRQOL, or QOL). The items, components, and domains found in the PRO, therefore, need to be assessed with a conceptual definition that clarifies the domain being measured.

In order to address this challenge, our group synthesized World Health Organization (WHO) definitions found in the International Classification of Functioning, Disability and Health (ICF) and the WHO-Quality of Life Instrument (WHOQOL) manual.12 We interpreted the definitions relative to the concepts of FDH, HRQOL, and QOL in order to delineate the constructs used within existing instruments (Fig. 1). According to this interpretation, FDH comprises the biopsychosocial components and interactions among body structures and function, and activities and participation in the context of the environment and personal factors.13,14 Quality of life is a person’s perception of their position in life… in relation to their goals, expectations, standards and concerns;12 therefore mention of perceptual or subjective elements of life must be explicit in order to measure a child’s QOL.11 Although some researchers and clinicians choose to define HRQOL as that portion of life affected by a health condition,15 this definition was not distinguishable from FDH as found in the ICF. Instead, HRQOL was interpreted to be subsumed under QOL such that it was defined by a child’s perception of his or her health and health-related states.

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Figure 1.  Organization of concepts based on World Health Organization definitions. aHealth-related quality of life is not a WHO definition but was subsumed as a component of WHO-defined quality of life in this analysis

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These definitions form one part of a content analysis that has been validated specifically for child health PROs16 and applied in whole or in part in numerous studies of child health instruments, including, but not limited to, the areas of cancer, epilepsy, and cerebral palsy.11,17,18 The content analyses used in this study are based upon a method initially developed in 2002 by Cieza et al.19 followed by multiple iterations of validation in the subsequent revisions.16,20 Applying this analysis can help to decipher and code the differences between instruments that use an FDH approach to assessment according to the ICF or a QOL approach using the definition set forth by the WHOQOL group, with HRQOL subsumed as a branch of QOL focused on health (as interpreted by our group).

This method can also provide detailed information about the health and health-related content (if any) contained in FDH, HRQOL, and QOL instruments by mapping the content to the ICF. Functioning, disability, and health, as defined in the ICF, are conceptualizations of health that can be defined and measured; therefore, the classification provides an excellent base for the description of any FDH or HRQOL PROs.

Although there is general acceptance in the literature of the ICF emphasis on functioning as the basis for conceptualizing health,7,13,14,21 and of the WHOQOL definition as the basis for defining QOL,12,22 operationalization of these concepts into instruments measuring FDH, HRQOL, and QOL for children has been less readily observed. For example, many authors argue that HRQOL/QOL concepts require a child’s subjective evaluation of his or her life or health in order to be authentic.22–24 Yet assessments of health and life satisfaction or priorities are often omitted from so-called HRQOL or QOL instruments.

Previous reviews of PROs have discussed the conceptual inconsistencies of the measures, but few have offered a systematic approach to dealing with the problem.10,25 The challenges of measuring FDH and QOL/HRQOL with existing instruments have become increasingly evident, because of the inconsistencies between them; however, discarding existing PROs because they are ambiguously defined by today’s standards could be equally detrimental to understanding FDH and HRQOL/QOL outcomes in children. Therefore, this study seeks to make explicit the perspectives of FDH, HRQOL/QOL and the ICF-based health content of commonly used PROs so that the instruments currently in use can be more easily interpreted relative to each other, and so that they can be applied more consistently relative to WHO definitions.

Overall purpose

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

The purpose of this study is to present content information for commonly used generic PROs so that clinicians and researchers can match the content of the instrument to their intended purpose. In part I, PROs are analysed to determine whether their content reflects an FDH or HRQOL/QOL perspective. In part II, the health and health-related domains found in these instruments are categorized according to the ICF for Children and Youth (ICF-CY) using a content analysis method created specifically for this purpose (if any were found). Finally, the results from the part I ‘perspective’ analysis are contrasted with how the instruments have actually been used in the peer-reviewed literature over a 5-year period.

Method

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

Literature search and patient-reported outcome inclusion strategy

A literature search was conducted on MEDLINE, PsycINFO, and CINAHL for articles published between January 2004 and December 2008. The search was limited to three databases, which were chosen for their uniqueness of content relative to each other. The search terms ‘health’, ‘quality of life’, ‘disability’, etc. were cross-referenced with search terms relating to questionnaires and instruments, which were also cross-referenced relative to the child and youth population. The final syntax for the search was checked by a medical librarian specializing in systematic review and is available in Appendix S1 (supporting information).

An overview of the search procedure and results is presented in Figure 2. Once the results of the search were obtained and duplicates deleted, 22 001 abstracts were screened by one reviewer and a 60% random selection was screened by a second reviewer. Next, 2145 full-text articles were assessed by one of four trained reviewers and their data extracted according to the criteria described in the following section. Any peer-reviewed study using a named and validated PRO on children to measure FDH or QOL (and related concepts such as well-being or HRQOL) was eligible for inclusion. We excluded articles that used only clinical assessments or instruments meant to be administered or rated by a third party (e.g. WeeFIM or PEDI) because they were not considered PROs. We excluded studies with fewer than 10 participants; those that did not focus on children or young adults (e.g. a clinical trial involving people 16–80y of age with no child-specific focus); studies using only population surveys; studies reporting ad hoc or unnamed instruments created for the study without prior validation; non-peer-reviewed studies; and reviews or editorials.

image

Figure 2.  Overview of the literature search.

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Data extraction

Data from each article were extracted by one of four reviewers, each of whom was ‘calibrated’ to the first author based on a sample of 10 articles at a time. A reviewer and the first author included or excluded groups of 10 articles independently until their agreement reached 90%. In addition, all reviewers met regularly with the lead author to review difficult cases, a record of which was kept and reviewed periodically with all data extractors. Any PRO that appeared in 1% or greater of the included articles was obtained for this analysis. The titles of excluded questionnaires are available upon request.

Article characteristics

Study characteristics were extracted in a systematic manner. Study types were grouped according to a modified approach to classifying studies.26 Ages were grouped as follows: 0 to 12 months, infants; 13 to 36 months, toddlers; from 3 to 5 years, pre-school; from 5 to 12 years, school age; 13 to 19 years, adolescents; 20 to 25 years, young adults. Language of data collection was recorded for each article. If data collection occurred in more than one country or in a country with more than one language, all countries and languages where PROs were extracted from children or their families were recorded.

Characteristics pertaining to PRO instruments and their use were extracted, including the name of the instrument (and the version if reported), the language in which the data collection occurred, whether the child only, proxy only, or both child and proxy completed the questionnaire, and the author’s stated purpose in using the instrument (e.g. to measure FDH, HRQOL, QOL, well-being, physical, or mental health, etc.).

Part I: Functioning, disability, and health versus HRQOL/QOL perspectives

Ia: coding the researcher’s intention for instrument application in the peer-reviewed literature

All coding was performed by applying the definitions of FDH and QOL/HRQOL provided in Figure 1 and through applying published methods of content analysis.16,19,20 Before coding, the exact quotation from the text regarding the intent of questionnaire use was added to the database and the content analysis method was applied to code the outcome that the instrument was used to measure. Statements about functioning, disability or health, HRQOL or QOL, and general mental or physical health were mapped directly onto the terms FDH, HRQOL, or QOL. Examples of less straightforward statements were coded as follows: adaptive behaviour and development were coded as ‘functioning’; burden of [health condition] on daily life was coded as ‘disability’; health satisfaction was coded as ‘HRQOL’; and subjective well-being was coded as ‘QOL’.

Ib: determining perspectives (functioning vs HRQOL/QOL) using WHO definitions

The 15 included instruments were reviewed using the ICF-CY by three content assessors trained in the coding of PROs. These included three clinician-scientists (an occupational therapist [NF], a paediatrician [OKDC] and a neuropsychologist [EK]). The assessors reviewed the WHO definitions of FDH (from the ICF-CY) and QOL (from WHOQOL task force) as presented in Figure 1, as well as the previous application of this method published in the peer-reviewed literature. Items that asked about the presence or absence, capacity, performance, severity, frequency, or length of a functioning or disability domain or about barriers or facilitators of environmental domains were coded as ‘FDH’. Items that questioned a child’s enjoyment, satisfaction, expectations, standards, or concerns about a health or health-related domain or about life in general were coded as ‘HRQOL’ or ‘QOL’ respectively. For example, a question about walking difficulty would align with the FDH perspective but a question about walking satisfaction would align with the HRQOL perspective.

Each assessor individually coded the perspectives found in the instruments on an item-by-item basis and these results were set aside for a reliability analysis. The assessors then met to combine the results and come to a consensus regarding the items on which there was disagreement or lack of clarity. What is reported here is the final consensus list of perspectives for each item within each PRO.

Ic: initial reliability of the coding method

Agreement for the first round of independent coding of the PRO perspectives was analysed on an item-by-item basis for each instrument using percentage agreement.

Part II: Describing health and health-related content according to the ICF

IIa: mapping content to ICF-CY categories

First, assessors NF, AD, and OKDC met to review the purpose, background, and typical applications of the 15 instruments so that the context in which instruments were developed was understood. Second, the health or health-related domain expressed in each item from each questionnaire was extracted.

The content of the items was linked to the ICF-CY according to the components of the classification system using standardized linking rules developed and tested explicitly for analysing the content of health instruments.19,20 The ICF-CY classification scheme represents a variety of health and health-related domains that can be accessed online at http://apps.who.int/classifications/icfbrowser/. Assessors completed the item-by-item content analysis by first deciding what each item was about. As with most PROs, the item could often be taken quite literally, but occasionally interpretation of the item was required in order to answer the question: ‘What is it about?’ For example, the question ‘[h]ave you been afraid of other girls and boys?’ from KIDSCREEN asks about the child’s fears but is more about the social environment, bullying, or other children.

Once the concepts within the items were decided, the assessors then assigned the specific alphanumeric ICF-CY code to the concept. The first letter of the code represents the ICF-CY component of body functions (b), or structures (s), activities and participation (d), or environment (e). The digits of the code that follow are numeric. A health or related domain that was linked to the ICF-CY by an individual assessor (NF, AD, or OKDC), was deemed ready for the reliability analysis.

Concepts that were too general to be assigned to a code but still suited the concepts contained in the classification were assigned the code nd (not defined). For example, the concept ‘general mental health’ is part of the conceptual underpinning of the classification but does not have a specific ICF code. General mental health was thus assigned the code nd-gmh. Concepts that were not covered by codes in the classification or included as part of the conceptualization of the ICF-CY were assigned the code nc (not covered). The code pf was used to denote personal factors. All concepts that were labelled with ICF categories were grouped into the ICF and nd or nc components described above.

IIb: reliability analysis

Agreement between the content assessors (NF, AD or OKDC) was determined with agreement statistics for categorical data using kappa statistics (SAS version 9.1 statistical software; SAS Inc. San Antonio TX, USA) and percentage agreement. Two out of three identical ICF categories was considered agreement for an item.

The data extraction form for assessing the perspectives and the health content of the instruments with sample items entered can be found in Appendix I.

Results

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

A total of 709 studies yielded 1151 occasions of generic PRO instrument use applied to children. The characteristics associated with generic PROs are presented in Tables SI–SIII (supporting information online), which show that the PRO use is used in cross-sectional studies, with school-aged children using child respondents. Languages of PRO use, in order of descending frequency, were English, Dutch, German, Spanish, French, Swedish, Italian, Chinese, Norwegian, and Portuguese.

Part I: Functioning, disability, and health versus HRQOL/QOL perspectives

The perspectives found in the generic instruments, presented in Table I, indicate that the FDH perspective is the predominant approach in 9 out of 15 instruments. On the other hand, application of the same instruments in the literature showed researchers intended to measure an HRQOL/QOL approach for 12 out of 15 instruments (Table II).

Table I. Perspectives (%) found in generic instruments according to part Ib content analysis
 QOL/HRQOL FDHOther or unknown
  1. QOL, quality of life; HRQOL, health-related quality of life; FDH, functioning, disability, and health; PedsQL, Pediatric Quality of Life Inventory; SSWLS, Student Satisfaction with Life Scale; MSSWLS, Multidimensional Student Satisfaction with Life Scale.

Child Health and Illness Profile4.6893.81.56
Child Health Questionnaire33.359.96.8
DISABKIDs76.923.10.0
Functional Disability Inventory0.00100.000.00
Functional Status Questionnaire0.0100.00.0
General Health Questionnaire42.957.10.00
Health Utilities Index12.587.50.0
KIDSCREEN69.228.81.9
KINDL36.653.310.0
PedsQL 4.04.096.00.0
Satisfaction with Life Scale (Diener’s)100.00.00.0
SSWLS/MSSWLS (Huebner’s)100 (65.0)0.0 (30.0)0.0 (5.0)
SF-3622.277.80.0
TAPQOL36.663.40.0
Youth Quality of Life Instrument76.617.17.3
Table II. Reported use of generic patient-reported outcomes (PROs) from included studies according to Part Ia content analysis
  Researcher reported aim of generic PRO use (%)
NoneQOLHRQOLFunctioningDisabilityGeneral healthMental healthPhysical health
  1. PRO, patient-reported outcome; QOL, quality of life; HRQOL, health-related quality of life; PedsQL, Pediatric Quality of Life Inventory; SSWLS, Student Satisfaction with Life Scale; MSSWLS, Multidimensional Student Satisfaction with Life Scale.

Child Health and Illness Profile5.920.626.50.00.047.10.00.0
Child Health Questionnaire4.829.838.97.13.613.12.00.8
DISABKIDs33.346.720.00.00.00.00.00.0
Functional Disability Inventory0.00.00.027.369.73.10.00.00
Functional Status Questionnaire10.00.05.020.030.035.00.00.0
General Health Questionnaire0.08.38.316.70.00.066.70.0
Health Utilities Index2.08.259.22.00.028.60.00.0
KIDSCREEN0.034.264.50.00.01.30.00.0
KINDL0.052.345.50.00.02.30.00.0
PedsQL 4.05.027.960.71.90.82.70.70.4
Satisfaction with Life Scale (Diener’s)0.083.38.30.00.08.30.00.0
SSWLS/MSSWLS (Huebner’s)0.0100.00.00.00.00.00.00.0
SF_8_12_360.033.330.87.70.028.20.00.00
TNO-AZL Series1.625.059.412.51.60.00.00.0
Youth Quality of Life Instrument0.0100.00.00.00.00.00.00.0

The agreement for the coding perspectives for each instrument is listed in Table SIV (supporting information online) and was the lowest (46.5%) for the KINDL27 and the highest (100%) for the Diener’s Satisfaction with Life Scale,23 the Functional Disability Inventory,28 the Functional Status II Revised,29 and the Huebner’s Student Satisfaction with Life Scale.30 Agreement on the perspective for each item was above 75% in 14 out of 15 of the instruments. Overall, percentage agreement for all items combined was 81.1%.

Part II: describing the health and health-related content according to the ICF

An overview of the distribution of item representation according to ICF components is found in Table III. Tables with more detailed information for the ICF content found in each instrument are available as supporting information published online (Tables SV–SXX), which show the specific ICF codes found in each instrument. Table SV is shown as a sample summary table in Appendix II. These supplementary tables can be consulted when in-depth consideration of an instrument’s content is needed relative to a particular assessment purpose.

Table III. Composition of ICF components found in each instrument according to part II content analysis
 Body functionActivities and participationEnvironmentPersonal factorsNot defined (but part of the ICF)Not covered by the ICF (health condition)Not covered by the ICF (QOL)Not covered by the ICF (other)Total items coded
  1. aMore than one ICF category was assigned to some items. ICF, International Classification of Functioning, Disability and Health; QOL, quality of life; CHQ, Child Health Questionnaire; PedsQL, Pediatric Quality of Life Inventory; HUI, Health Utilities Index; CHIP, Child Health and Illness Profile; FSIIR, Functional Status; GHQ-28, General Health Questionnaire-28; SWLS, Satisfaction With Life Scale; FDI, Functional Disability Inventory; SSWLS, Student Satisfaction with Life Scale; MSSWLS, Multidimensional Student Satisfaction with Life Scale; YQOL, Youth Quality of Life Instrument.

CHIP2021901120164
CHIP (optional section)121622390062
CHQ2554133021087a
DISABKIDS3340064013a
FDI21300000015
FSIIR9500000014
GHQ-2813900301228
HUI64000000 8a
KIDSCREEN1121120204252
KINDL121130262232a
PedsQL71340100023a
SWLS00000050 5
SSWLS00000070 7
MSSWLS617170000040
SF-361624001000036a
TAPQOL261410020043
YQOL814101008041

Table SXXI (supporting information online) shows the agreement with bootstrapped confidence intervals between assessors for each instrument using kappa and bootstrapped confidence intervals. Agreement was the lowest for the KIDSCREEN (0.73)31 and highest (1.00) for Diener’s Satisfaction with Life Scale,23 the Health Utilities Index32 and Huebner’s Student Satisfaction with Life Scale.30 Overall kappa for all items combined was 0.86.

Summary of parts I and II

Summaries of the dominant perspectives and health domains, as well as brief summaries of each instrument, are included in Table IV.

Table IV. Summary of instrument use and content
Instrument nameOverall PRO use in included articles (%)Dominant outcome targeted by PRO use in the literature (Ia)Dominant perspective found in the PRO from content analysis (Ib)Dominant ICF Component (II)Instrument summary
  1. PRO, patient-reported outcome; ICF, International Classification of Functioning, Disability and Health; PedsQL, Pediatric Quality of Life; HRQOL, health-related quality of life; QOL, quality of life; FDH, functioning, disability, and health; SSWLS, Student Satisfaction with Life Scale; MSSWLS, Multidimensional Student Satisfaction with Life Scale.

Child Health and Illness Profile3FunctioningFDH (with an unknown subcomponent)Body functions and activity and participationFDH instrument
Child Health Questionnaire22.1HRQOL/QOLFDH (with QOL/HRQOL and some unknown features)Activities and participationFDH with some QOL features
DISABKIDs1.3HRQOL/QOLHRQOL/QOL (with some functioning features)Body functions, activities and participation, and environmentHRQOL instrument with biopsychosocial components
Functional Disability Inventory2.9FunctioningFDHActivities and participationFDH instrument focused on functioning and disability
Functional Status Questionnaire II1.7FunctioningFDHBody functionsFDH instrument with emphasis on body functions
General Health Questionnaire1HRQOL/QOLFDH and QOL/HRQOLBody functionsFDH instrument focused on body functions (emotions) with QOL features
Health Utilities Index4.3HRQOL/QOLFDH (with one HRQOL/QOL attribute)Body functionsFDH instrument with emphasis on body functions
KIDSCREEN6.6HRQOL/QOLHRQOL/QOL (with some functioning features)Activities and participationHRQOL instrument with biopsychosocial components
KINDL3.8HRQOL/QOLFDH (HRQOL/QOL subcomponent)Body functions, activity, and participationFDH instrument with some QOL features
PedsQL 4.022.8HRQOL/QOLFDHActivities and participationFDH instrument
SF_8_12_363.4HRQOL/QOLFunctioning (with HRQOL/QOL subcomponent)Activities and participationFDH with minor QOL features
Satisfaction with Life Scale (Diener’s)1HRQOL/QOLHRQOL/QOLNoneQOL instrument
SSWLS/MSSWLS (Huebner’s)0.8HRQOL/QOLSLSS: HRQOL/QOLNonePure QOL instrument
0.5MSLSS: HRQOL/QOL (health subcomponent)Activities and participation and environmentHRQOL instrument with biopsychosocial functioning components
TNO-AZL Series5.6HRQOL/QOLFDH (HRQOL/QOL subcomponent)Body functions and activity and participationFDH instrument with some HRQOL features
Youth Quality of Life Instrument1.4HRQOL/QOLHRQOL/QOL (health facilitators/barriers subcomponent)Activities and participation and environmentHRQOL instrument with biopsychosocial health components

Discussion

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

When WHO definitions of biopsychosocial health (FDH) and QOL health are applied to PRO instruments, inconsistency is revealed between the measurement perspective of the PRO and the purposes to which that instrument is being applied. Of the 15 instruments analyzed, 12 were (most frequently) applied to measure HRQOL or QOL but only four were coded as having mainly an HRQOL/QOL perspective using WHO definitions.

The largest discrepancy between an instrument’s content and its application was found for the Pediatric Quality of Life Inventory (PedsQL).33,34 Using WHO definitions, this measure was found to represent FDH, not HRQOL or QOL perspective for all of its items. It should be noted that analysis of the PedsQL showed that the items represented a broad biopsychosocial definition of health and health-related domains.11 Thus, conceptually, the PedsQL spans a wide definition of functioning, disability, and health (FDH) that includes some contextual factors, but the breadth of its health content should not be confused with WHO definitions of QOL.

The assumption of this analysis is that the difference between an FDH and QOL/HRQOL instrument is not so evident in what is measured, because both functioning and HRQOL instruments can measure the same (biopsychosocial) health and health-related domains. Both functioning and HRQOL instruments should address biological, psychological, and social components. What distinguishes the functioning approach from that of HRQOL/QOL is how the domains of life and health are measured. For example, a parent could be asked: ‘How difficult is it for your child to walk short distances?’ or ‘How satisfied do you feel with your child’s ability to walk short distances?’ These items both refer to the same domain (walking); however, where the first question targets functioning from a performance point of view the second targets satisfaction with a domain of functioning, which is a dimension of HRQOL.

In our sample of articles, researchers demonstrated greater consistency between instrument application and content when seeking to measure FDH than when seeking to measure QOL/HRQOL. Instruments that were named by developers as FDH measures (e.g. Functional Disability Inventory,28 Child Health Illness Profile,35 Functional Status29) were applied consistently in the literature relative to the ICF terms of functioning, disability, and health.

Although it is unclear why this mismatch between content and application occurred for QOL/HRQOL, we suspect that the time and context in which these instruments were developed played a role in the discrepancy. Instruments such as the Child Health Questionnaire and PedsQL were developed before conceptual differences between a biopsychosocial approach to FDH (as in the ICF/ICF-CY) and of QOL (according to the WHOQOL task-force) were made clear in the health literature. Our results do not indicate that these instruments should cease to be used; rather we argue that it is important to be aware of their perspectives relative to current standard definitions, as well as of the ICF domains in each instrument relative to the intended purpose.

In addition to this review, guidelines about health status measurement selection expressed in checklists such as COSMIN36–38 can be helpful because they focus on psychometric properties and instrument use. A conceptual understanding of FDH and QOL/HRQOL is still vital to the PRO selection process because it is crucial to have a firm understanding of the concept to be measured before selecting an instrument to measure it,38 irrespective of previously reported psychometric performance. These results are not intended to suggest that the importance of psychometrics be overlooked; rather we suggest that a good understanding of FDH and QOL concepts is a crucial to measurement validation and good psychometric performance.

The good news about the FDH and QOL instruments reported in this study is that the items can often be taken at face value, that is, the content of an item and what it is designed to measure are usually much more straightforward than when using a diagnostic assessment (e.g. depression questionnaires).39 If users possess a firm conceptual understanding of the difference between FDH, HRQOL, and QOL, then they will have the critical skills necessary to understand the face validity of these instruments. Thus, if an instrument user can properly identify (1) which approach/perspective they seek to measure (FDH vs QOL/HRQOL), and (2) the health or health-related domain (e.g. relative to the ICF) that describes or evaluates changes in a group of children, then the user has grounds for (3) assessing whether the content of an instrument overlaps with their intended purpose.

Another finding of this literature review was that the majority of the studies using PRO instruments for children did so in the context of cross-sectional research. We question whether instruments that have been useful to describe, distinguish, or differentiate populations of children will perform comparably well as the objective of child health research shifts towards more evaluative purposes. When evaluating interventions, the responsiveness of a PRO depends on its ability to detect change.40 As a first, step to selecting an instrument it is necessary to determine if a PRO includes domains that describe a population of interest or has domains that are expected to change following intervention. This information can be found in the supplementary Tables SI–SXXI linked to this article.

Finally, researchers should be clear about whether they are seeking to measure FDH (which includes the capacity, performance, presence/absence, frequency, severity, etc. of biopsychosocial domains), HRQOL (the expectations, standards, or concerns about those health domains), or QOL (the child’s personal assessment of their position in life). Such efforts will help determine whether interventions are being accepted or rejected based on whether the correct instruments were chosen, with appropriate content for what is being measured.

Conclusion

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

We applied a systematic method for assessing the perspectives of FDH and QOL/HRQOL instruments based on their content using WHO definitions of the ICF/ICF-CY and QOL. Analysis showed that there is little agreement in the literature about what the generic instruments are intended to measure or how to make conceptual distinctions between FDH and HRQOL/QOL. Overlooking such issues will result in the dissemination of study results that are incompatible and difficult to interpret. The results of this review can facilitate instrument selection for content validation purposes.

Acknowledgements

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

The first author acknowledges support of a Marie-Curie Fellowship and the MURINET group as well as the Ontario Graduate Scholarships during the completion of this work. Additionally, the abstract screening support provided by Alicia Garza and Christine Leon, as well as the database management support from Heinrich Gall were important to the completion of this project.

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  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information
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Appendices

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information

Appendix I: Data extraction table for sample items from the Child Health Questionnaire, PedsQL, and DISABKIDS

Items with instructionsResponse optionsPerspective (FDH, HRQOL/QOL)What is it about?ICF code and categoryConnectorsAnnotation
  1. FDH, functioning, disability, and health; HRQOL, health-related quality of life; QOL, quality of life; ICF, International Classification of Functioning, Disability and Health; CHQ, Child Health Questionnaire.

CHQ section #1: your global health
 1.1. In general, would you say your health is:Severity/extent (five levels)Functioning (FDH)General healthNot defined/general health (nd-gh) Past 4wks
CHQ section #3: your everyday activities
 3.1. During the past 4wks, has it been difficult to do your school work or usual activities with friends because of problems like feeling sad or worried?Difficulty (five levels)Disability (FDH)School work, usual activities with friends, feeling sad, feeling worriedSchool education d820, informal relationships with friends d7500, emotional functions b152and/because ofPast 4wks
 3.2. During the past 4wks, has it been difficult to do your school work or usual activities with friends because of problems with your behaviour?Difficulty (five levels)Disability (FDH)Complete/finish schoolwork, accomplish  activities with  friends, behaviourSchool education d820, informal relationships with  friends d7500, managing one’s own behaviour d250and/because ofPast 4wks
PedsQL health and activities (problems with …)
 Please tell us how much of a problem each one has been for you during the past 1mo
  2. It is hard for me to walk more  than one blockFrequency (five levels)Disability (FDH)RunningRunning d4552 1mo
  5. It is hard for me to take a bath  or shower by myselfFrequency (five levels)Disability (FDH)Independent bathing and/or showeringWashing whole body d5101 1mo, independence
DISABKIDS (short version) sections: about your life/about your medical treatment
  9. Do you think that you can do   most things as well as other   children/adolescents?Frequency (five levels)QOLDoing things kids doActivities and participation d Past 4wks
  11. Do you take any medicine   for your condition? (by medicine   we mean tablets, cream, spray,   insulin, or any other medicine)Frequency (5 levels)Functioning (FDH)DrugsDrugs e1101 Past 4wks

Appendix II: Sample instrument summary table for the PedsQL

Perspectives of items coded according to WHO definitions (Ib)Health-related (ICF-based) content coded according to linking rules for children (II)Non-ICF-based content coded according to linking rules for children (II)
QOL/HRQOLFunctioning/disabilityUnknown/otherBody functionActivities and participationEnvironmentPersonal factorsNot defined (but part of the ICF)Not covered by the ICF (health condition)Not covered by the ICF (QOL)Not covered by the ICF (other)
  1. Instrument summary: this instrument uses a functioning, disability, and health perspective (100%) to assess activity and participation in 59% of items and some body function (32%) and environment content (18%). aThe health or health-related domain is connected to another domain within an item, hence there are more ICF categories than questionnaire items. WHO, World Health Organization; ICF, International Classification of Functioning, Disability and Health; QOL, quality of life; HQOL, health-related quality of life.

1/23 items22/23 items0/23 itemsb1300da d640e325None nd-gha NoneNoneNone
b134d d750e425
b144d160 d820e425
b152d430 d820ae580a
b152d4500 d820a 
b152d4552 d9201 
b280d5101 
 d640 

Supporting Information

  1. Top of page
  2. Abstract
  3. What this paper adds
  4. Overall purpose
  5. Method
  6. Results
  7. Discussion
  8. Conclusion
  9. Acknowledgements
  10. References
  11. Appendices
  12. Supporting Information
FilenameFormatSizeDescription
dmcn4393_sm_AppendixS1-TableS1-S21.docx172KSupporting info item

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