Development of a new health-related quality of life measure for people with diabetes who experience hypoglycaemia: the Hypo-RESOLVE QoL.

AIMS/HYPOTHESIS: Valid and reliable patient-reported outcome measures are vital for assessing disease impact, responsiveness to healthcare and the cost-effectiveness of interventions. A recent review has questioned the ability of existing measures to assess hypoglycaemia-related impacts on health-related quality of life for people with diabetes. This mixed-methods project was designed to produce a novel health-related quality of life patient-reported outcome measure in hypoglycaemia: the Hypo-RESOLVE QoL. METHODS: Three studies were conducted with people with diabetes who experience hypoglycaemia. In Stage 1, a comprehensive health-related quality of life framework for hypoglycaemia was elicited from semi-structured interviews (N=31). In Stage 2, the content validity and acceptability of draft measure content were tested via three waves of cognitive debriefing interviews (N=70 people with diabetes; N=14 clinicians). In Stage 3, revised measure content was administered alongside existing generic and diabetes-related measures in a large cross-sectional observational survey to assess psychometric performance (N=1246). The final measure was developed using multiple evidence sources, incorporating stakeholder engagement. RESULTS: A novel conceptual model of hypoglycaemia-related health-related quality of life was generated, featuring 19 themes, organised by physical, social and psychological aspects. From a draft version of 76 items, a final 14-item measure was produced with satisfactory structural (χ2=472.27, df=74, p<0.001; comparative fit index =0.943; root mean square error of approximation =0.069) and convergent validity with related constructs (r=0.46-0.59), internal consistency (α=0.91) and test-retest reliability (intraclass correlation coefficient =0.87). CONCLUSIONS/INTERPRETATION: The Hypo-RESOLVE QoL is a rigorously developed patient-reported outcome measure assessing the health-related quality of life impacts of hypoglycaemia. The Hypo-RESOLVE QoL has demonstrable validity and reliability and has value for use in clinical decision-making and as a clinical trial endpoint. DATA AVAILABILITY: All data generated or analysed during this study are included in the published article and its online supplementary files ( https://doi.org/10.15131/shef. DATA: 23295284.v2 ).

Producing a preference-based quality of LIFE measure to quantify the impact of HYPOGLYCAEMIA on people living with diabetes: A mixed-methods research protocol.

BACKGROUND: Assessment of patient-reported outcome measures (PROMs), including quality of life (QoL), is essential in diabetes research and care. However, a recent review concluded that current hypoglycaemia-specific PROMs have limited evidence of validity, reliability and responsiveness for assessing the impact of hypoglycaemia on QoL in people living with diabetes. None of the PROMs identified could be used directly to inform the cost-effectiveness of treatments and interventions. There is a need for a new hypoglycaemia-specific QoL PROM, which can be used directly to inform economic evaluations. AIMS: This project has three aims: (a) To develop draft PROM content for measuring the impact of hypoglycaemia on QoL in adults with diabetes. (b) To refine the draft content using cognitive debriefing interviews and psychometrics. This will result in a condition-specific PROM that can be used to quantify the impact of hypoglycaemia upon QoL. (c) To generate a preference-based measure (PBM) that will enable utility values to be calculated for economic evaluation. METHODS: A mixed-methods, three-stage design is used: (a) Qualitative interviews will inform the draft PROM content. (b) Cognitive debriefing interview data will be used to refine the draft PROM content. The PROM will be administered in a large-scale survey to enable psychometric validation. Final item selection for the PROM will be informed by psychometric performance, translatability assessment and input from stakeholder groups. (c) A classification system will be generated, comprising a reduced number of items from the PROM. A valuation survey will be conducted to derive a value set for the PBM.

Four of five frequently used orthopedic PROMs possess inadequate content validity: a COSMIN evaluation of the mHHS, HAGOS, IKDC-SKF, KOOS and KNEES-ACL.

PURPOSE: Content validity is the most important property of PROMs. The COSMIN initiative has published guidelines for evaluating the content validity of PROMs, but they have only sparsely been applied to relevant PROMs for musculoskeletal conditions. The aim of this study was to use the COSMIN Risk of Bias checklist to evaluate the content validity of five PROMs, that are highly relevant in musculoskeletal research and used by the arthroscopic surgery community: the modified Harris' Hip Score (mHHS), the Copenhagen Hip and Groin Outcome Score (HAGOS), the International Knee Documentation Committee Subjective Knee evaluation Form (IKDC-SKF), the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Knee Numeric-Entity Evaluation Score ACL (KNEES-ACL). METHODS: The development articles for the five PROMs were identified through searches in PubMed and SCOPUS. A literature search was performed to identify additional studies assessing content validity of the PROMs. Additional information, necessary for the assessments, was obtained from the PROM developers after direct request. To evaluate the quality of the development studies and rate the content validity, the COSMIN Risk of Bias checklist was applied to all studies. RESULTS: All five development studies were identified. Three subsequent content validity studies were identified, all evaluating KOOS and one also IKDC. One content validity study was of inadequate quality and excluded from further analysis. The development of mHHS, IKDC-SKF, and KOOS was rated inadequate and possess insufficient content validity for their target populations. Due to the irrelevance of multiple items, KOOS was in particular inappropriate to evaluate patients with an ACL injury. The development of HAGOS was also rated inadequate, although the insufficiency aspects can be regarded as minor. KNEES-ACL possessed sufficient content validity. CONCLUSION: Out of five PROMs, only KNEES-ACL possessed sufficient content validity. Particularly, KOOS should not be used as an outcome for patients with an ACL injury. There is an urgent need for condition-specific PROMs for musculoskeletal conditions, developed with adequate methods. LEVEL OF EVIDENCE: III.

Patient reported outcome measures for ankle instability. An analysis of 17 existing questionnaires.

BACKGROUND: Patient reported outcome measures (PROMs) are essential for evaluating treatment of ankle instability (AI). The aim was to assess the content validity and the measurement properties of all relevant PROMs for AI. METHODS: Relevant PROMs were identified from PubMed and SCOPUS. The development and validation quality of the PROMs was assessed according to established scientific standards. RESULTS: Seventeen PROMs and 56 validation studies were analyzed. Content validity, which ensures the PROM measures what is relevant, is obtained by involving target patients in the development process. Only three PROMs identified had some degree of patient involvement (Cumberland Ankle Instability Tool (CAIT), Lower Extremity Function Scale (LEFS), and the Foot and Ankle Ability Measure (FAAM)). Of these, only FAAM was somewhat rigorously validated using modern psychometric validation methods, and exhibited superior measurement properties (construct validity). CONCLUSION: No existing PROM is completely adequate to evaluate AI. However, FAAM is the best choice.

Dual-panel translation to Danish and Rasch validation of the Foot and Ankle Ability Measure (FAAM-DK).

BACKGROUND: The Foot and Ankle Ability Measure (FAAM) was developed by involvement of patients with chronic ankle instability (CAI) and has acceptable measurement properties, but is not available in Danish. METHODS: FAAM was translated and culturally adapted into Danish, and its measurement properties were assessed using Rasch analyses. RESULTS: A Danish version was produced with small adaptations, and content relevance was confirmed by Danish patients. The 21-item ADL domain showed misfit to the Rasch model, but after removing six items, the resulting 15-item scale displayed adequate fit. The Sports domain also exhibited misfit, but after removing one item and adjusting due to differential item functioning related to age for another item, a 7-item scale showed good fit. This resulted in a 22-item 2-dimensional Danish version of FAAM. CONCLUSION: The 22-item Danish FAAM exhibits robust measurement properties for patients with various conditions of the lower leg, ankle, and foot, including CAI.

A catalogue of PROMs in sports science: Quality assessment of PROM development and validation.

Choosing the most adequate PROM for a study is a non-trivial process. The aim of this study was to provide a catalogue with analyses of content and construct validity of PROMs relevant to research in sports science, including all published local translations. The most commonly used PROMs in sports research were selected from a PubMed search "patient reported outcome measures sports", identifying 439 articles and 194 different PROMs. Articles describing development of the 61 selected PROMs were assessed for content validity, and all articles regarding construct validity of each PROM and all published translations (in total 622 articles) were analyzed. A catalogue with assessments of the 61 PROMs was produced. The majority were of inferior validity, with few exceptions. The most common reason for this was that the PROM had not been developed by methods that ensure high content validity. Another major reason for inferior validity was that construct validity had not been secured by adequate statistical methods. In conclusion, this catalogue provides a tool for researchers to facilitate choosing the most valid PROM for studies in sports research. Furthermore, it shows for popular PROMs where further validation is needed, and for fields in musculoskeletal medicine where valid PROMs are lacking. It is suggested that a targeted effort is made to develop valid PROMs for major conditions in musculoskeletal research. The current method is easier to practice compared with assessment after COSMIN guidelines.

Responsiveness, minimal important difference, minimal relevant difference, and optimal number of patients for a study.

Several terms are used to describe changes in PROM scores in relation to treatments. Whether the change is small, large, or relevant is defined in different ways, yet these change scores are used to recommend or oppose treatments. They are also used to calculate the necessary number of patients for a study. This article offers a theoretical explanation behind the terms responsiveness, minimal important difference (MID), minimal important change (MIC), minimal relevant difference (MIREDIF), and threshold of clinical importance. It also gives instructions on how these and the optimal number of patients for a study are calculated. Responses to two domains of the Knee Injury and Osteoarthritis Outcome Score (KOOS), before and 1 year after reconstruction of the anterior cruciate ligament of 164 patients, are used to illustrate the calculations. This paper presents the most common methods used to calculate and interpret MID. Results vary substantially across domains, patient location on the scale, and health conditions. The optimal number of patients depends on the minimal relevant difference (MIREDIF), the standard error of the measure (SEM), the desired statistical power for the measurement, and the responsiveness of the measurement instrument (the PROM). There is often uncertainty surrounding the calculation and interpretation of responsiveness, MID, and MIREDIF, as these concepts are complex. When MID is used to evaluate research results, authors should specify how the MID was calculated, and its relevance for the study population. These measures should only be used after thorough consideration to justify healthcare decisions.

Are PROMs used adequately in sports research? An analysis of 54 randomized controlled trials with PROMs as endpoint.

Deviations from adequate use and reporting of PROMs may be problematic and misleading. The aim of this study was to investigate the extent of such problems in randomized clinical trials (RCTs). RCTs involving sports medicine research that used PROMs as primary outcomes were identified in 13 preselected journals. The articles were reviewed for nine potential problems related to how the PROM was used and how the data had been reported. The potential problems were as follows: aggregating subscale scores; combining patient-reported scores with physical, clinical, or para-clinical measures; using a PROM to diagnose or evaluate the individual patient; using a PROM for one leg or arm; selectively excluding domains or items; constructing a PROM for the specific occasion; mixing PROM formats (ie, digital, paper, telephone, e-mail, in person); ambiguous instructions for how the PROM should be completed; and recall bias. As covariates, we registered journal impact factor, year of publication, and existence of a registered protocol. In 29 (53.7%) of 54 identified RCTs, at least one potential problem was identified, the most common being aggregation of domain scores. This was not different with a published protocol or dependent on journal rankings, except for exclusion of domains, which was most common in high-ranking journals. Aggregation of domain scores was significantly less common in recently published articles compared with older articles (P = .03). Potential problematic use of PROMs and reporting of PROM data are common in RCTs, also in high-ranking journals, but less so in more recent articles.

How to develop a condition-specific PROM.

Developing new patient-reported outcome measures (PROMs) for application in clinical studies can be necessary if an adequate PROM does not exist. For adequate measurement, it is essential that the PROM has face validity (ie, is perceived to be relevant by clinicians and researchers) and has high content validity (ie, content relevance and content coverage for the targeted patient group). The steps needed to create PROMs that possess face and content validity for a specific condition are described in this paper. Face validity is achieved by item identification and generation through literature review. Content validity is confirmed through repetitive cognitive interviews of patients from the targeted patient group in order to generate a consensus-based pilot-version of the new PROM. This qualitative process ensures that items are appropriately worded, understandable, and minimizes doubts about how items should be answered. A practical example of this process is presented, which shows the development of the Knee Numeric-Entity Evaluation Score (KNEES-ACL), a condition-specific PROM for patients with deficiency of the anterior cruciate ligament (ACL).

Choosing the most appropriate PROM for clinical studies in sports medicine.

Choosing the most appropriate patient-reported outcome measure (PROM) for a clinical study is essential in order to achieve trustworthy results. This choice will depend on (a) the objective of the study and hence the research question; (b) the choice of a theoretical framework, such as the World Health Organization's International Classification of Functioning, Disability, and Health (ICF); (c) whether there currently is a PROM that possesses high content validity and high construct validity for the specific patient group and objective, and if not; (d) the decision on whether to use a suboptimal PROM or develop and validate a new PROM. This paper presents the steps that should be followed in order to assess the relevance of PROMs and suggests ways to enhance the choice depending on the goal of the study.

Potential problems in the use of patient reported outcome measures (PROMs) and reporting of PROM data in sports science.

To use an inadequate patient reported outcome measure (PROM) or use a PROM in an inappropriate way potentially influences the quality of measurement. The objectives of this study were to define potential inadequate uses of PROMs in sports research studies and estimate how often they occur. A consensus group consisting of medical researchers, statisticians, and psychometricians identified and defined potentially irregular applications of PROMs. Occurrence of these in 349 consecutive articles in sports medicine in which PROMs were used as primary outcomes was reviewed. In all, 14 different potential problems were defined, and one or several occurred in 172 of the articles (49%). These were as follows: using a PROM that was developed for a different patient group (100 cases), using two or more PROMs with identical questions (94), aggregation of domain sum scores (82), combinations of subjective and objective measures (27), using a PROM to diagnose or evaluate the individual patient (7), using a PROM for a single limb (3), recall bias (3), exclusion of domains or items (3), construction of a PROM for a specific occasion (2), categorization of the scale (2), and mixing different versions of a PROM (1). Adaption of scale scores (e. g., to percentage) when results are reported (144) carries a risk of miscalculation and distorted impression of results. Data related to uncertainty about completing the PROM and the handling of missing data were not provided in the manuscripts. In conclusion, potential problems in the use and reporting of PROMs are common in sports research, and this can influence the validity of reported results.

Are adequate PROMs used as outcomes in randomized controlled trials? an analysis of 54 trials.

Results by patient-reported outcome measures (PROMs) from randomized controlled trials (RCTs) in musculoskeletal research often influence healthcare strategies. We aimed to evaluate to which extent these RCTs use adequate PROMs, and how this influences the results and conclusions. We identified RCTs of sports research relevance with PROMs as primary outcomes published in 13 preselected journals between January 1, 2008, and November 1, 2019; all journals regularly publish results from musculoskeletal research. Five journals have a high impact factor (>15), and eight with lower impact factors are widely read journals. It was assessed whether the RCTs had used PROMs with high content validity and whether the most adequate PROMs were used (ie, the most well developed and well validated for the patients enrolled in the study). We registered journal impact factor, year of publication, existence of a registered protocol, and whether the study showed significant difference between interventions. A total of 54 RCTs with 56 primary outcomes comprising 26 different PROMs were identified. For 13 RCTs (24%), a protocol was not published. In only 24 of RCTs (44%), the most appropriate PROM had been used as primary outcome, independent of a registered protocol, ranking of the journal, and year of publication. In seven cases, PROMs were used to evaluate a condition that they had not been developed for. RCTs that used the most adequate PROM showed significantly more often (46%) difference in outcomes in contrast to RCTs that used inadequate PROMs (22%) (P = 0.0483). In conclusion, in the majority of RCTs, the most adequate PROM had not been used. Studies, in which the most adequate PROM had been used as outcome, were significantly more likely to show significant difference between interventions. The extent to which protocols were not available was surprisingly high. Journals should request that adequate PROMs are used in RCTs, and if this is not the case that it is discussed how it might influence the results and conclusions. Likewise, it should be requested that a protocol is published or registered.

What is a PROM and why do we need it?

The purpose of this article was to introduce the reader to the nature of patient-reported outcome measures (PROMs) and pitfalls in their use. PROMs collect subjective information directly from the patient regarding specific or general conditions and add to clinical and functional outcomes, and turn unmeasurable subjective qualities into quantitative measures. PROMs are questionnaires consisting of items: questions or statements with predefined response options. The items in an adequate PROM have been developed by involvement of patients with the condition in focus, and the PROM has been validated for these patients using suitable statistical methods. An adequate well-targeted PROM is more responsive than an inadequate PROM. Unfortunately, many studies use inadequate PROMs as outcomes. The methods used to generate PROMs should be described as thoroughly as those used to develop any other types of measurement instruments, and the choice of PROM should always be explained and thereby justified. If the PROM used is not adequate, the consequences for the interpretation of the results should be discussed. In many cases, an adequate PROM does not exist. If the best available PROM is chosen, there are methods to validate the adequacy of the chosen PROM, which make an interpretation of the study results possible.

Psychometric validation of PROM instruments.

The aim was to provide an overview of the different statistical methods for validation of patient-reported outcome measures, ranging from simple statistical methods available in all software packages to advanced statistical models that require specialized software. A non-technical summary of classical test theory (CTT) and modern test theory (MTT) is provided. Specifically, confirmatory factor analysis, item response theory, and Rasch analysis is outlined. One CTT and three MTT methods were used to validate the two subscales (Symptoms and Quality of Life) from the Knee Injury and Osteoarthritis Outcome Score (KOOS). For each methodology, two analyses were considered: (i) a unidimensional analysis ignoring the pre-specified dimensionality, and (ii) a two-dimensional analysis using the pre-specified dimensionality. While CTT did not adequately address central issues regarding the validity of the KOOS subscales, the three MTT methods yielded very similar results. In conclusion, MTT methods offer analysis of all relevant properties related to the validity of patient-reported outcome measures, while this is not the case for CTT. Claims about sufficient validity based on CTT methods are inadequate and should not be trusted.

How to translate and locally adapt a PROM. Assessment of cross-cultural differential item functioning.

Translating patient-reported outcome measures (PROMs) can alter the meaning of items and undermine the PROM's psychometric properties (quantified as cross-cultural differential item functioning [DIF]). The aim of this paper was to present the theoretical background for PROM translation, adaptation, and cross-cultural validation, and assess how PROMs used in sports medicine research have been translated and adapted. We also assessed DIF for the Knee Injury and Osteoarthritis Outcome Score (KOOS) across Danish, Norwegian, and Swedish versions. We conducted a search in PubMed and Scopus to identify the method of translation, adaptation, and validation of PROMs relevant to musculoskeletal research. Additionally, 150 preoperative KOOS questionnaires were obtained from the Scandinavian knee ligament reconstruction registries, and cross-cultural DIF was evaluated using confirmatory factor analysis and Rasch analysis. There were 392 studies identified, describing the translation of 61 PROMs. Ninety-four percent were performed with forward-backward technique. Forty-nine percent used cognitive interviews to ensure appropriate wording, understandability, and adaptation to the target culture. Only two percent were validated according to modern test theory. No study assessed cross-cultural DIF. One KOOS subscale showed no cross-cultural DIF, two had DIF with respect to some (but not all) items, and thus conversion tables could be constructed, and two KOOS subscales could not be pooled. Most PROM translations are of undocumented quality, despite the common conclusion that they are valid and reliable. Scores from three of five KOOS subscales can be pooled across the Danish, Norwegian, and Swedish versions, but two of these must be adjusted for DIF.

KNEES-ACL has superior responsiveness compared to the most commonly used patient-reported outcome measures for anterior cruciate ligament injury.

PURPOSE: For clinical trials, it is essential that measures are sensitive to change. The aim of this study was to conduct a head-to-head comparison of responsiveness of four PROMs used to measure outcome after anterior cruciate ligament (ACL) reconstruction. The PROMs compared were the knee injury osteoarthritis outcome score (KOOS), the international knee documentation committee subjective form (IKDC), the Lysholm score, and the knee numeric-entity evaluation score (KNEES-ACL). We hypothesized that KNEES-ACL would be more responsive than the other PROMs, as KNEES-ACL was created based on patient interviews and validated using Rasch analysis. METHODS: One-hundred and sixty-six consecutive adults completed the four PROMs before and 3, 6, and 12 months after ACL-reconstructive surgery. Responsiveness was calculated as Cohen's Effect Size and Standardized Response Means. Bootstrapping was used to generate 95% confidence intervals for comparisons of responsiveness across PROMs. Repeated-measures ANOVA was also computed for each PROM. RESULTS: The largest effect sizes at 12 months were seen for KNEES-ACLSports-Behaviour (1.35, p < 0.001) and KNEES-ACLSports-Physical (1.19, p < 0.001), the smallest for KOOSADL (0.35, p < 0.001) and KOOSSymptoms (0.39, p < 0.001). IKDC and Lysholm lay between these with IKDC slightly more responsive. Head-to-head comparisons of similar subscales of KOOS and KNEES-ACL showed substantial differences in effect size in the domains of symptoms (0.69, p < 0.001), daily activities (0.31, p = 0.005), and Sports activity (0.63, p = 0.013) all in favour of KNEES-ACL. CONCLUSION: These results demonstrate superior responsiveness for KNEES-ACL, which is the only PROM that has been constructed through exhaustive patient feedback and validated for patients with ACL deficiency using the most stringent psychometric methods (Rasch analysis). KNEES-ACL is the most precise and accurate PROM for patients with ACL injury and the most trustworthy instrument for clinicians and clinical researchers. LEVEL OF EVIDENCE: Prospective cohort study, Level II.

Assessment of the Psychometric Properties of the Danish VISA-P.

Purpose: The objective of the current study was to conduct a rigorous assessment of the psychometric properties of the Victorian Institute of Sports Assessment-patellar tendinopathy (VISA-P). Methods: Rasch analysis, confirmatory factor analysis (CFA), and multivariable linear regression were used to assess the psychometric properties of the VISA-P questionnaire in 184 Danish patients with patellar tendinopathy who had symptoms ranging from under 3 months to over 1 year. A group of 100 healthy Danish persons was included as a reference for known-group validation. Results: The analyses revealed that the 8-item VISA-P did not fit a unidimensional model, yielded at best a 3-factor model, and exhibited differential item functioning (DIF) across healthy subjects versus people with patellar tendinopathy. Conclusion: VISA-P in its present form does not satisfy a measurement model and is not a robust scale for measuring patellar tendinopathy. A new PROM for patellar tendinopathy should be developed and appropriately validated, and meanwhile, simple pain scoring (e.g., numeric rating scales) and functional tests are suggested as more appropriate outcome measures for studies of patellar tendinopathy.

Assessment of content validity and psychometric properties of VISA-A for Achilles tendinopathy.

A recent COSMIN review found that the Victorian Institute of Sports Assessment-Achilles tendinopathy questionnaire (VISA-A) has flawed construct validity. The objective of the current study was to assess specifically the process of how VISA-A was constructed and validated, and whether the Danish version of VISA-A is a valid patient-reported outcome measure (PROM) for measuring the perceived impact of Achilles tendinopathy. The original item generation strategy for content validity and the process for confirming the scaling properties (construct validity) were examined. In addition, construct validity was evaluated directly using several psychometric methods (Rasch analysis, confirmatory factor analysis (CFA), and multivariable linear regression) in a cohort of 318 persons with Achilles tendinopathy with symptom duration groups ranging from less than 3 months to more than 1 year of chronicity, and a group of 120 healthy persons. We found that the item generation and item reduction in the original construction of VISA-A was based on literature review and clinician consensus with little or no patient involvement. We determined that 1) VISA-A consists of ambiguous conceptual item themes and thus lacks content validity, 2) there was no thorough investigation of the psychometric properties of the original version of VISA-A, which thus lacks construct validity, and 3) rigorous direct assessment of the psychometric properties of the Danish VISA-A revealed inadequate psychometric properties. In agreement with the COSMIN study, we conclude that when used as a single score, VISA-A is not an adequate scale for measuring self-reported impact of Achilles tendinopathy.

Psychometric Validation of the Danish Version of the Oswestry Disability Index in Patients With Chronic Low Back Pain.

STUDY DESIGN: Registry-based repeated-measures psychometric validation of the Danish Oswestry Disability Index (ODI). OBJECTIVE: The goal was to use classical and modern psychometric validation methods to assess the measurement properties and the minimally clinical important difference (MCID) of the ODI in a Danish cohort of patients with chronic low back pain being treated with spinal surgery. SUMMARY OF BACKGROUND DATA: Scores for the ODI, EQ-5D, SF-36, leg pain, back pain, and a general rating of pain item from 800 patients with chronic low back pain were extracted from the National Danish Spine Registry (DaneSpine) at baseline and 1-year postspine surgery. METHODS: Confirmatory factor analysis and item response theory (IRT) models were used to assess the psychometric properties of the ODI. MCID was also calculated based on generic legacy PROMs (EQ-5D and SF-36) and follow-up pain scores. RESULTS: While ODI did not fit a Rasch model, adequate fit to a confirmatory factor analysis and a two-parameter item response theory model was found when accounting for differential item functioning across diagnostic subgroups (degenerative spondylolisthesis, spondylosis, spinal stenosis, and herniated intervertebral disc). In addition, each group exhibited substantially different MCID values. CONCLUSION: The Danish version of the ODI is valid and responsive, but only within each of the four major diagnosis subgroups: degenerative spondylolisthesis, spondylosis, spinal stenosis, and herniated intervertebral disc. LEVEL OF EVIDENCE: 4.

Validation of a health screening questionnaire for primary care using Rasch models.

BACKGROUND: Health inequality is on the rise due to various social and individual factors. While preventive health checks (PHC) aim to counteract health inequality, there is robust evidence against the use of PHC in general practice. It is unknown which factors can identify persons who will benefit from preventive interventions that are more beneficial than harmful. Hence, valid screening instruments are needed. METHODS: The aim of this study was to assess the psychometric properties of a screening questionnaire (SQ-33), which targets vulnerable persons in primary care practice who can benefit from preventive consultations. Survey data were acquired from 20 primary care clinical practices in the Northern Region of Jutland, Denmark. Respondents were 2056 persons between 20 and 44 years old who, for any reason, consulted their family doctor. The psychometric properties of the SQ-33 were assessed using Rasch item response modelling. Follow-up analysis was performed on a subsample of 364 persons one year subsequent to initial inclusion, in order to assess responsiveness and predictive validity using a general health anchor item. RESULTS: Twenty-three of the SQ-33 items in four subscales fit a Graphical loglinear Rasch model (GLLRM) at baseline and follow-up, thus confirming the scaling properties. The modified 23-item version (HSQ-23) revealed superior responsiveness and predictive validity compared with the SQ-33. CONCLUSIONS: The Health Screening Questionnaire (HSQ-23) was shown to possess adequate psychometric properties and responsiveness and can thus be used as an outcome measure in preventive intervention studies. Future study should address whether the HSQ-23 successfully identifies patients who will benefit from PHC consultations.