Calibration and Validation of the Dutch-Flemish PROMIS Pain Interference Item Bank in Patients with Chronic Pain

Psychometric properties and post-hoc CAT analysis of the pediatric PROMIS® item banks anxiety and depressive symptoms in a combined Swedish Child and Adolescent Psychiatry and School sample

PURPOSE

The objective of this study is to assess the psychometric properties and reliability of the Swedish Patient-Reported Outcomes Measurement Information System (PROMIS) item banks for anxiety and depressive symptoms with item response theory analysis and post-hoc computerized adaptive testing in a combined Swedish Child and Adolescent Psychiatry (CAP) and school sample.

METHODS

Participants (n = 928, age 12-20) were recruited from junior and high schools and Child and Adolescent Psychiatry Clinics in the region of Västerbotten. Unidimensionality, local independence, and monotonicity was tested. We fitted a graded response model to the data and tested differential item functioning (DIF) for sex, age group, sample type, and language (Swedish vs. U.S.). Moreover, a post-hoc computer adaptive testing (CAT) simulation was performed. All analysis were made in R.

RESULTS

Unidimensionality, local independence, and monotonicity were acceptable. The graded response model yielded acceptable item fit, discriminative, and threshold values for all items in both item banks. DIF for language (Swedish vs. U.S.) was found for two items from the anxiety and one item from the depressive symptoms item banks. A Stocking-lord transformation was used for the items displaying language DIF, and post-hoc CAT simulations were performed. The post-hoc CAT simulation showed reliability around 0.9 for both Swedish and official U.S. item parameters T-scores calibration from within normal limits to severe anxiety and depressive symptoms.

CONCLUSION

The Swedish pediatric PROMIS item banks of anxiety and depressive symptoms are appropriate to assess mild to severe symptoms of anxiety and depressive symptoms in Swedish school- and CAP samples.

The Reha-Toolbox Project: Linking Item Subsets of 3 Established Rehabilitation PROMs to 9 Domains of the Patient-Reported Outcomes Measurement Information System (PROMIS)

OBJECTIVE

The overarching goal of the patient-reported outcomes measurement information system (PROMIS) is to standardize patient-reported outcomes across settings and health conditions globally. Following this purpose, the Reha-Toolbox study aimed to link item subsets of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0), the Indicators of Rehabilitation Status (IRES-3), and the Hamburg Modules for the Assessment of Psychosocial Health (HEALTH-49) to the standardized metrics provided by PROMIS.

DESIGN

Cross-sectional, single-group linking study.

SETTING

Online survey.

PARTICIPANTS

Experts (N=5) mapped items from the 3 rehabilitation measures to PROMIS scales. Data were collected online from a general population sample (N=1000). Items from the rehabilitation measures and their corresponding PROMIS short forms were administered to facilitate item linkage.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

WHODAS 2.0, IRES-3, HEALTH-49, and PROMIS scales.

RESULTS

Overall, 96 of 171 outcome items (56%) from the legacy measures and 1 additional IRES-3 item were mapped to 9 PROMIS domains, including pain interference, physical function, dyspnea, fatigue, depression, anxiety, cognitive function, ability to participate in social roles and activities, and satisfaction with participation in social roles and activities. Ninety-five items fulfilled the linking assumptions of construct similarity, unidimensionality, and measurement invariance. The legacy items were successfully calibrated on the corresponding PROMIS metrics using graded-response models. The range and precision of the measures varied, depending on the number of items in each domain. Domains that were assessed with 4 or more items achieved sufficient reliability for group-based analyses. Crosswalk tables were created for each measure and domain. We discussed the reasons for and implications of the fact that the rehabilitation measures were only partially linked to the PROMIS metrics.

CONCLUSIONS

The study achieved robust linking between subsets of WHODAS 2.0, IRES-3, HEALTH-49 items, and 9 PROMIS scales.

Assessing the measurement properties of PROMIS Computer Adaptive Tests, short forms and legacy patient reported outcome measures in patients undergoing total hip arthroplasty

BACKGROUND

The commonly used ('legacy') PROMs evaluating outcomes of total hip arthroplasty (THA), have several limitations regarding their measurement properties and interpretation of scores. One innovation in PROMs is the use of Computerized Adaptive Testing (CAT). The Patient-Reported Outcomes Measurement Information System (PROMIS®) is a validated system of CATs. The aim of this study was to assess the measurement properties of PROMIS and legacy instruments in patients undergoing THA.

METHODOLOGY

Patients in this multicenter study filled out a questionnaire twice, including Dutch-Flemish PROMIS v1.2 Physical Function (PROMIS-PF) and v1.1 Pain Interference (PROMIS-PI) CATs and short forms, PROMIS v1.0 Pain Intensity, and legacy PROMs (Hip disability and Osteoarthritis Outcome Score (HOOS), HOOS-Physical function Shortform (HOOS-PS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Hip Score (OHS), and two numeric rating scales measuring pain). The reliability, measurement precision (Standard Error of Measurement (SEM)), smallest detectable change (SDC), and burden of PROMIS instruments were presented head-to-head to legacy PROMs. Furthermore, construct validity was assessed.

RESULTS

208 patients were included. All instruments had a sufficient test-retest reliability (range ICC: 0.83-0.96). The SEM of PROMIS CATs and short forms ranged from 1.8 to 2.2 T-score points, the SEM of legacy instruments 2.6-11.1. The SDC of PROMIS instruments ranged from 2.1 to 7.3 T-score points, the SDC of legacy instruments 7.2-30.9. The construct validity of PROMIS CAT and short forms were found sufficient, except for the PROMIS-PI short form. The burden of PROMIS CATs was smaller than PROMIS short forms (range 4.8-5.2 versus 8-20 items, respectively). The burden of legacy instruments measuring physical functioning ranged from 5 to 40 items.

CONCLUSIONS

The PROMIS-PF is less burdensome, with high measurement precision, and almost no minimal or maximal scores, and an equal reliability compared to legacy instruments measuring physical functioning in patients undergoing THA. The PROMIS Pain Intensity 1a is comparable to the legacy pain instruments in terms of burden, reliability and SDC. Measuring the construct Pain Interference may not have additional value in this population because of its high correlation with instruments measuring physical functioning. The SDC values presented in this study can be used for individual patient monitoring.

Enhancing the Evaluation of Physical Function Following Orthopaedic Trauma Care: Comparison of PROMIS Computerized Adaptive Testing and Short Musculoskeletal Function Assessment

OBJECTIVES

To compare measurement properties of Patient-Reported Outcomes Measurement Information System (PROMIS) (physical function [PF] and pain interference [PI]) computerized adaptive testing to traditional Short Musculoskeletal Function Assessment (SMFA) (dysfunction index [DI] and bother index [BI]). To explore factors associated with PROMIS scores.

METHODS

DESIGN

Cross-sectional study.

SETTING

Level I Trauma Center.

PATIENT SELECTION CRITERIA

Isolated upper/lower extremity fracture patients were recruited from the orthopaedic trauma outpatient clinic (October 1, 2021 to January 1, 2023).

OUTCOME MEASURES

Correlations (Pearson), reliability (standard error [SE] [T score]), efficiency (amount of information per item [1 - SE2/Nitems]), and floor/ceiling effects were assessed. An r > 0.7 represented high correlation, and SE ≤ 2.2 represented sufficient reliability. Factors associated with worse PROMIS scores were also identified.

RESULTS

In total, 202 patients completed PROMs at median 98 days follow-up. Correlations between PROMIS-PF and SMFA-DI, and PROMIS-PI and SMFA-BI were -0.84 and 0.65. Reliability was very high for both instruments (mean SE 2.0 [PROMIS-PF], SE 2.1 [PROMIS-PI], and SE 1.2 [SMFA-DI], SE 1.8 [SMFA-BI]). Relative efficiency for PROMIS-PF versus SMFA-DI, and PROMIS-PI versus SMFA-BI was 7.8 (SD 2.5) and 4.1 (SD 1.7), respectively. Neither PROMIS nor SMFA exhibited floor/ceiling effects. In the multivariable regression analyses, elevated levels of depression, among other factors, showed an (independent) association with worse PROMIS-PF and PROMIS-PI scores.

CONCLUSIONS

PROMIS-PF and PROMIS-PI CATs showed a (high and moderate) correlation with SMFA and hence measure a comparable construct of physical function and discomfort. As computerized adaptive tests are much more efficient to administer, they present a compelling alternative to SMFA for evaluating impact of fracture treatment. The relation between symptoms of depression and PROMIS scores emphasizes the importance of psychosocial aspects of health in orthopaedic trauma patients.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Country-specific reference values for PROMIS® pain, physical function and participation measures compared to US reference values

INTRODUCTION

Patient-Reported Outcomes Measurement Information System (PROMIS^®) is commonly used across medical conditions. To facilitate interpretation of scores across countries, we calculated Dutch reference values for PROMIS Physical Function (PROMIS-PF), Pain Interference (PROMIS-PI), Pain Behavior (PROMIS-PB), Ability to Participate in Social Roles and Activities (PROMIS-APSRA), and Satisfaction with Social Roles and Activities (PROMIS-SSRA), as compared to US reference values.

PATIENTS AND METHODS

A panel completed full PROMIS-PF (n=1310), PROMIS-PI and PROMIS-PB (n=1052), and PROMIS-APSRA and PROMIS-SSRA (n=1002) item banks and reported their level of health per domain (no, mild, moderate, severe limitations). T-scores were calculated by sample and subgroups (age, gender, self-reported level of domain). Distribution-based and anchor-based thresholds for mild, moderate, and severe scores were determined.

RESULTS

Mean T-scores were close to the US mean of 50 for PROMIS-PF (49.8) and PROMIS-APSRA (50.6), lower for PROMIS-SSRA (47.5) and higher for PROMIS-PI (54.9) and PROMIS-PB (52.0). Distribution-based thresholds for mild, moderate, and severe scores were comparable to US recommended cut-off values (except for PROMIS-PI) but participants reported limitations 'earlier' than suggested thresholds.

CONCLUSION

Dutch reference values were close to US reference values for some PROMIS domains but not all. We recommend country-specific reference values to facilitate worldwide PROMIS use.KEY MESSAGESPROMIS offers universally applicable IRT-based efficient and patient-friendly measures to assess commonly relevant patient-reported outcomes across medical conditions.To support the use of PROMIS in daily clinical practice and research across the world, country-specific general population reference values should be obtained.More research is necessary to obtain reliable and valid cut-off values for what constitutes mild, moderate and severe scores from the patients' perspective.

Measuring PROMIS pain interference in German patients with chronic conditions: calibration, validation, and cross-cultural use of item parameters

PURPOSE

To calibrate the item parameters of the German PROMIS® Pain interference (PROMIS PI) items using an item-response theory (IRT) model and investigate psychometric properties of the item bank.

METHODS

Forty items of the PROMIS PI item bank were collected in a convenience sample of 660 patients, which were recruited during inpatient rheumatological treatment or outpatient psychosomatic medicine visits in Germany. Unidimensionality, monotonicity, and local independence were tested as required for IRT analyses. Unidimensionality was examined using confirmatory factor analyses (CFA) and exploratory factor analysis (EFA). Unidimensional and bifactor graded-response IRT models were fitted to the data. Bifactor indices were used to investigate whether multidimensionality would lead to biased scores. To evaluate convergent and discriminant validity, the item bank was correlated with legacy pain instruments. Potential differential item functioning (DIF) was examined for gender, age, and subsample. To investigate whether U.S. item parameters may be used to derive T-scores in German patients, T-scores based on previously published U.S. and newly estimated German item parameters were compared with each other after adjusting for sample specific differences.

RESULTS

All items were sufficiently unidimensional, locally independent, and monotonic. Whereas the fit of the unidimensional IRT model was not acceptable, a bifactor IRT model demonstrated acceptable fit. Explained common variance and Omega hierarchical suggested that using the unidimensional model would not lead to biased scores. One item demonstrated DIF between subsamples. High correlations with legacy pain instruments supported construct validity of the item bank. T-scores based on U.S. and German item parameters were similar suggesting that U.S. parameters could be used in German samples.

CONCLUSION

The German PROMIS PI item bank proved to be a clinically valid and precise instrument for assessing pain interference in patients with chronic conditions.

Psychometric properties and reference values of the Patient-Reported Outcomes Measurement Information System (PROMIS) sleep item banks in the Dutch general population

Psychometric properties of the v1.0 Patient-Reported Outcomes Measurement Information System (PROMIS®) sleep disturbance (27 items) and sleep-related impairment (SRI; 16 items) item banks, short forms derived from the item bank, and simulated computerised adaptive test (CAT), were assessed in a representative sample of 1,006 adults from the Dutch general population. For sleep disturbance all items fitted the item response theory model. Four items showed differential item functioning (i.e., lack of measurement invariance) for age and two for language but the impact on scores (expressed as T-scores) was small. Reliable scores (r > 0.90) were found for 92.2%-96.3% of respondents with the full bank, short forms with six and eight items, and CAT, but for only 25.6% with the four-item short form. For SRI two items did not fit the item response theory model. Four items showed differential item functioning for language but the impact on T-scores was small. Reliable scores were found for 82.1% with the full bank, for 47.8%-69.5% with short forms and CAT. T-scores of 49.7 and 49.3 represent the average score of the Dutch general population for sleep disturbance and SRI, respectively. In conclusion, sufficient structural validity, reliability, and cross-cultural validity was found for the full banks but short forms of four items are not reliable enough for clinical practice. For SRI we recommend the full item bank if this is the primary outcome.

Responsiveness and Minimal Important Change of the PROMIS Pain Interference Item Bank in Patients Presented in Musculoskeletal Practice

We evaluated the responsiveness of the Patient Reported Outcome Information System Pain Interference item bank in patients with musculoskeletal pain by testing predefined hypotheses about the relationship between the change scores on the item bank, change scores on legacy instruments and Global Ratings of Change (GRoC), and we estimated Minimal Important Change (MIC). Patients answered the full Dutch-Flemish V1.1 item bank. From the responses we derived scores for the standard 8-item short form (SF8a) and a CAT-score was simulated. Correlations between the change scores on the item bank, GRoC and legacy instruments were calculated, together with Effect Sizes, Standardized Response Means, and Area Under the Curve. GRoC were used as an anchor for estimating the MIC with (adjusted) predictive modeling. Of 1,677 patients answering baseline questionnaires 960 completed follow-up questionnaires at 3 months. The item bank correlated moderately high with the GRoC (Spearman's rho 0.63) and with the legacy instruments (Pearson's R ranging from .45 to .68). It showed a high ES (.97) and Standardized Response Means (.71), and could distinguish well between improved and not improved patients based on the GRoC (Area Under the Curve .77). Comparable results were found for the derived SF8a and CAT-scores. The MIC was estimated to be 3.2 (CI 2.6-3.7) T-score points. PERSPECTIVE: Our study supports the responsiveness of the PROMIS-PI item bank in patients with musculoskeletal complaints. Almost all predefined hypotheses were met (94%). The PROMIS-PI item bank correlated well with several legacy instruments which supports generic use of the item bank. MIC for PROMIS-PI was estimated to be 3.2 T-score points.

Meaningful Improvement in General Health Outcomes with Guselkumab Treatment for Psoriatic Arthritis: Patient-Reported Outcomes Measurement Information System-29 Results from a Phase 3 Study

OBJECTIVE

The Phase 3 DISCOVER-1 study of guselkumab is the first randomized controlled trial to use Patient-Reported Outcomes Measurement Information System (PROMIS) measures to assess the effects of treatment on general health outcomes in patients with psoriatic arthritis (PsA).

METHODS

Patients (N = 381) with active PsA were randomized 1:1:1 to guselkumab 100 mg every 4 weeks (Q4W); guselkumab 100 mg at Week 0, Week 4, then every 8 weeks (Q8W); or placebo with Week 24 crossover to guselkumab Q4W. The PROMIS-29 Profile contains four items for each of seven domains (anxiety, depression, fatigue, pain interference, physical function, sleep disturbance, and social participation) and one pain-intensity item. Raw domain scores are converted to standardized T-scores, with norms based on a US general population mean of 50 (1 standard deviation (SD) = 10). T-score changes of ≥ 5 are considered clinically meaningful. Least-squares mean PROMIS-29 T-score changes from baseline to Week 24 and Week 52 were summarized for the guselkumab and placebo groups; nominal p-values comparing results between guselkumab and placebo were calculated at Week 24 using a mixed model for repeated measures. The proportions of patients who achieved clinically meaningful improvement in PROMIS-29 T-scores were also summarized at Week 24 and Week 52; nominal p-values comparing results between guselkumab and placebo were calculated at Week 24 using the Cochran-Mantel-Haenszel test.

RESULTS

In the DISCOVER-1 patient population, mean PROMIS-29 T-scores at baseline were ~ 1 SD worse for physical function and pain interference and were numerically worse for social participation, fatigue, and sleep disturbance compared with the US general population. At Week 24, mean PROMIS-29 T-scores improved in guselkumab-treated patients, approaching US population norms; T-scores continued to improve through Week 52. Significantly higher proportions of patients in both guselkumab treatment arms (31-52% across domains) had clinically meaningful improvements in pain interference, fatigue, physical function, sleep, and social participation at Week 24 versus placebo (all nominal p ≤ 0.05).

CONCLUSION

In patients with active PsA, guselkumab treatment provided clinically meaningful reductions in fatigue and pain and improvement in physical function and social participation, as measured by the PROMIS-29 Profile. These improvements were maintained through 1 year.

CLINICALTRIALS

GOV: Registration number, NCT03162796; Submission date 19 May 2017.

Measurement properties of the Dutch PROMIS-29 v2.1 profile in people with and without chronic conditions

PURPOSE

To investigate the structural validity, internal consistency, measurement invariance, and construct validity of the Dutch PROMIS-29 v2.1 profile, including seven physical (e.g., pain, physical function), mental (e.g., depression, anxiety), and social (e.g., role functioning) domains of health, in a Dutch general population sample including subsamples with and without chronic diseases.

METHODS

The PROMIS-29 was completed by 63,602 participants from the Lifelines cohort study. Structural validity of the PROMIS-29, including unidimensionality of each domain and the physical and mental health summary scores, was evaluated using factor analyses (criteria: CFI ≥ 0.95, TLI ≥ 0.95, RMSEA ≤ 0.06, SRMR ≤ 0.08). Internal consistency, measurement invariance (no differential item functioning (DIF) for age, gender, administration mode, educational level, ethnicity, chronic diseases), and construct validity (hypotheses on known-groups validity and correlations between domains) were assessed per domain.

RESULTS

The factor structure of the seven domains was supported (CFI = 0.994, TLI = 0.993, RMSEA = 0.046, SRMR = 0.031) as was unidimensionality of each domain, both in the entire sample and the subsamples. Model fit of the physical and mental health summary scores reached the criteria, and scoring coefficients were obtained. Cronbach's alpha for the seven PROMIS-29 domains ranged from 0.75 to 0.96 in the complete sample. No DIF was detected. Of the predefined hypotheses, 78% could be confirmed.

CONCLUSION

Sufficient structural validity, internal consistency and measurement invariance were found, both in the entire sample and in subsamples with and without chronic diseases. Requirements for sufficient evidence for construct validity were (almost) met for most subscales. Future studies should investigate test-retest reliability, measurement error, and responsiveness of the PROMIS-29.

Generic PROMIS item banks in adults with hemophilia for patient-reported outcome assessment: Feasibility, measurement properties, and relevance

BACKGROUND

Legacy hemophilia-specific questionnaires are considered too long, show floor-/ceiling effects, and/or include irrelevant questions. Patient Reported Outcomes Measurement Information System (PROMIS) item banks, including Computer Adaptive Tests (CATs) and short forms, were designed for more efficient outcome assessment.

OBJECTIVES

Evaluate the feasibility, measurement properties, and relevance of seven PROMIS CATs and two short forms in patients with hemophilia.

PATIENTS/METHODS

In this cross-sectional study, Dutch adults with hemophilia completed nine PROMIS item banks electronically. Feasibility was assessed by number of items and floor/ceiling effects. Reliability was determined as the proportion of reliable scores (standard error ≤3.2). Construct validity was assessed by comparison with legacy instruments and expected differences between subgroups. Relevance of item banks was determined by proportions of limited scores.

RESULTS

Overall, 142 of 373 invited patients (mean age, 47 [range, 18-79], 49% severe hemophilia, 46% receiving prophylaxis) responded. Per CAT item bank, mean number of items answered varied from 5 (range, 3-12) to 9 (range, 5-12), with floor effects in pain interference (26% lowest scores) and depression (18% lowest scores). Construct validity and reliability were good for physical function, pain interference, satisfaction with social roles and activities, and fatigue. The CAT physical function showed the most limited scores (38%). The self-efficacy short forms showed ceiling effects (22%-28%) and no relation with the legacy instruments.

CONCLUSIONS

The PROMIS CATs physical function, pain interference, satisfaction with social roles and activities, and fatigue are feasible, reliable, and valid alternatives to legacy instruments for patients with hemophilia, with few items and low floor-/ceiling effects.

A confirmatory factor analysis approach was found to accurately estimate the reliability of transition ratings

INTRODUCTION

Transition ratings (TRs) are single item measures which ask patients to report on their health change. They allow for a simple assessment of improvement or deterioration and are frequently used as an "anchor" to determine interpretation thresholds on a patient-reported outcome measure (PROM). Despite their widespread use, a routinely applicable method to assess their reliability is lacking. This paper introduces a method to estimate the reliability of TRs based on confirmatory factor analysis (CFA) for categorical data.

METHOD

We modelled longitudinal PROM data as independent factors representing Time 1 and Time 2 in a CFA model. PROM items taken at Time 1 (T1) loaded on the first factor, although the same items taken at Time 2 (T2) loaded on the second. The TR item loaded onto both T1 and T2 factors. Three models with various constraints on the loadings and thresholds were examined. The communality (R²) statistic was used as a measure of the TR reliability. The approach was evaluated using simulated data and exemplified in four empirical datasets.

RESULTS

The simplest CFA model without constraints on the item loadings and thresholds performed equivalently to models with constraints on loadings and thresholds over time. Further constraints on the TR item loadings to be equal and opposite over time caused biased TR reliability estimates if the T1 and T2 loadings differed in magnitude. In the four empirical datasets, reliability of TRs ranged from 0.27 to 0.48. In three examples the TR had numerically stronger loading on T2 than on T1.

DISCUSSION AND CONCLUSIONS

Results support the use of the proposed method in understanding the reliability of TRs. Empirical study results reflect the typical range of reliability that has previously been reported for single items. Methodological considerations to improve TR reliability are presented, and developments of this method, are posited.

Psychometric properties of the PROMIS-57 questionnaire, Norwegian version

Purpose

The aims of this cross-sectional study were to explore reliability and validity of the Norwegian version of the Patient-Reported Outcome Measurement System^®—Profile 57 (PROMIS-57) questionnaire in a general population sample, n = 408, and to examine Item Response properties and factor structure.

Methods

Reliability measures were obtained from factor analysis and item response theory (IRT) methods. Correlations between PROMIS-57 and RAND-36-item health survey (RAND36) were examined for concurrent and discriminant validity. Factor structure and IRT assumptions were examined with factor analysis methods. IRT Item and model fit and graphic plots were inspected, and differential item functioning (DIF) for language, age, gender, and education level were examined.

Results

PROMIS-57 demonstrated excellent reliability and satisfactory concurrent and discriminant validity. Factor structure of seven domains was supported. IRT assumptions were met for unidimensionality, local independence, monotonicity, and invariance with no DIF of consequence for language or age groups. Estimated common variance (ECV) per domain and confirmatory factor analysis (CFA) model fit supported unidimensionality for all seven domains. The GRM IRT Model demonstrates acceptable model fit.

Conclusions

The psychometric properties and factor structure of Norwegian PROMIS-57 were satisfactory. Hence, the 57-item questionnaire along with PROMIS-29, and the corresponding 8 and 4 item short forms for physical function, anxiety, depression, fatigue, sleep disturbance, social participation ability and pain interference, are considered suitable for use in research and clinical care in Norwegian populations. Further studies on longitudinal reliability and sensitivity in patient populations and for Norwegian item calibration and/or reference scores are needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11136-021-02906-1.

International application of PROMIS computerized adaptive tests: US versus country-specific item parameters can be consequential for individual patient scores

OBJECTIVE

PROMIS offers computerized adaptive tests (CAT) of patient-reported outcomes, using a single set of US-based IRT item parameters across populations and language-versions. The use of country-specific item parameters has local appeal, but also disadvantages. We illustrate the effects of choosing US or country-specific item parameters on PROMIS CAT T-scores.

STUDY DESIGN AND SETTING

Simulations were performed on response data from Dutch chronic pain patients (n = 1110) who completed the PROMIS Pain Behavior item bank. We compared CAT T-scores obtained with (1) US parameters; (2) Dutch item parameters; (3) US item parameters for DIF-free items and Dutch item parameters (rescaled to the US metric) for DIF items; (4) Dutch item parameters for all items (rescaled to the US metric).

RESULTS

Without anchoring to a common metric, CAT T-scores cannot be compared. When scores were rescaled to the US metric, mean differences in CAT T-scores based on US vs. Dutch item parameters were negligible. However, 0.9%-4.3% of the T-score differences were larger than 5 points (0.5 SD).

CONCLUSION

The choice of item parameters can be consequential for individual patient scores. We recommend more studies of translated CATs to examine if strategies that allow for country-specific item parameters should be further investigated.

First Validation of the Full PROMIS Pain Interference and Pain Behavior Item Banks in Patients With Rheumatoid Arthritis

OBJECTIVE

Pain interference and pain behavior are highly relevant outcomes in patients with rheumatoid arthritis (RA). The Patient-Reported Outcomes Measurement Information System (PROMIS) is a universally applicable set of item banks measuring patient-reported health, and if applied as computerized adaptive tests (CATs), more efficiently and precisely than current instruments. The objective was to study the psychometric properties of the Dutch-Flemish PROMIS pain interference (PROMIS-PI) and the PROMIS pain behavior (PROMIS-PB) item banks in patients with RA.

METHODS

A total of 2,029 patients with RA completed the full PROMIS-PI (version 1.1, 40 items), and 1,554 patients completed the full PROMIS-PB (version 1.1, 39 items). The following psychometric properties were studied: unidimensionality, local dependence, monotonicity and graded response model (GRM) fit, cross-cultural validity (differential item functioning [DIF] for language [Dutch versus Flemish]), other forms of measurement invariance, construct validity, reliability, and floor and ceiling effects.

RESULTS

The PROMIS-PI and PROMIS-PB banks were sufficiently unidimensional (Omega-hierarchical [Omega-H] 0.99, 0.95, and explained common variance 0.95, 0.78, respectively), had negligible local dependence (0.3-1.4% of item pairs), good monotonicity (H 0.75, 0.46), and a good GRM model fit (no misfitting items). Furthermore, both item banks showed good cross-cultural validity (no DIF for language), measurement invariance (no DIF for age, sex, administration mode, and disease activity), good construct validity (all hypotheses met), high reliability (>0.90 in the range of patients with RA), and an absence of floor and ceiling effects (0% minimum or maximum score, respectively).

CONCLUSION

Both PROMIS-PI and PROMIS-PB banks showed good psychometric properties in patients with RA and can be used as CATs in research and clinical practice.

Graded response model fit, measurement invariance and (comparative) precision of the Dutch-Flemish PROMIS® Upper Extremity V2.0 item bank in patients with upper extremity disorders

BACKGROUND

The Dutch-Flemish PROMIS® Upper Extremity (DF-PROMIS-UE) V2.0 item bank was recently developed using Item Response Theory (IRT). Unknown for this bank are: (1) if it is legitimate to calculate IRT-based scores for short forms and Computerized Adaptive Tests (CATs), which requires that the items meet the assumptions of and fit the IRT-model (Graded Response Model [GRM]);(2) if it is legitimate to compare (sub) groups of patients using this measure, which requires measurement invariance; and (3) the precision of the estimated patients' scores for patients with different levels of functioning and compared to legacy measures. Aims were to evaluate (1) the assumptions of and fit to the GRM, (2) measurement invariance and (3) (comparative) precision of the DF-PROMIS-UE v2.0.

METHODS

Cross-sectional data were collected in Dutch patients with upper extremity disorders. Assessed were IRT-assumptions (unidimensionality [bi-factor analysis], local independence [residual correlations], monotonicity [coefficient H]), GRM item fit, measurement invariance (absence of Differential Item Functioning [DIF] due to age, gender, center, duration, and location of complaints) and precision (standard error of IRT-based scores across levels of functioning). To study measurement invariance for language [Dutch vs. English], additional US data were used. Legacy instruments were the Disability of the Arm, Shoulder and Hand (DASH), the QuickDASH and the Michigan Hand Questionnaire (MHQ).

RESULTS

In total 521 Dutch (mean age ± SD = 51 ± 17 years, 49% female) and 246 US patients (mean age ± SD = 48 ± 14 years, 69% female) participated. The DF-PROMIS-UE v2.0 item bank was sufficiently unidimensional (Omega-H = 0.80, Explained Common Variance = 0.68), had negligible local dependence (four out of 1035 correlations > 0.20), good monotonicity (H = 0.63), good GRM fit (no misfitting items) and demonstrated sufficient measurement invariance. Precise estimates (Standard Error < 3.2) were obtained for most patients (7-item short form, 88.5%; standard CAT, 91.3%; and, fixed 7-item CAT, 87.6%). The DASH displayed better reliability than the DF-PROMIS-UE short form and standard CAT, the QuickDASH displayed comparable reliability. The MHQ-ADL displayed better reliability than the DF-PROMIS-UE short form and standard CAT for T-scores between 28 and 50. For patients with low function, the DF-PROMIS-UE measures performed better.

CONCLUSIONS

The DF-PROMIS-UE v2.0 item bank showed sufficient psychometric properties in Dutch patients with UE disorders.

A study of alternative approaches to non-normal latent trait distributions in item response theory models used for health outcome measurement

It is often unrealistic to assume normally distributed latent traits in the measurement of health outcomes. If normality is violated, the item response theory (IRT) models that are used to calibrate questionnaires may yield parameter estimates that are biased. Recently, IRT models were developed for dealing with specific deviations from normality, such as zero-inflation (“excess zeros”) and skewness. However, these models have not yet been evaluated under conditions representative of item bank development for health outcomes, characterized by a large number of polytomous items. A simulation study was performed to compare the bias in parameter estimates of the graded response model (GRM), polytomous extensions of the zero-inflated mixture IRT (ZIM-GRM), and Davidian Curve IRT (DC-GRM). In the case of zero-inflation, the GRM showed high bias overestimating discrimination parameters and yielding estimates of threshold parameters that were too high and too close to one another, while ZIM-GRM showed no bias. In the case of skewness, the GRM and DC-GRM showed little bias with the GRM showing slightly better results. Consequences for the development of health outcome measures are discussed.

Associations between the measures of physical function, risk of falls and the quality of life in haemodialysis patients: a cross-sectional study

BACKGROUND

Impaired physical function due to muscle weakness and exercise intolerance reduces the ability to perform activities of daily living in patients with end-stage kidney disease, and by consequence, Health-Related Quality of Life (HRQoL). Furthermore, the risk of falls is an aggregate of physical function and, therefore, could be associated with HRQoL as well. The present study examined the associations between objective and subjective measures of physical function, risk of falls and HRQoL in haemodialysis patients.

METHODS

This cross-sectional multicentre study included patients on maintenance haemodialysis. Physical function (quadriceps force, handgrip force, Sit-to-Stand, and six-minute walking test), the risk of falls (Tinetti, FICSIT-4, and dialysis fall index) and HRQoL (PROMIS-29 and EQ-5D-3 L) were measured and analysed descriptively, by general linear models and logistic regression.

RESULTS

Of the 113 haemodialysis patients (mean age 67.5 ± 16.1, 57.5% male) enrolled, a majority had impaired quadriceps force (86.7%) and six-minute walking test (92%), and an increased risk of falls (73.5%). Whereas muscle strength and exercise capacity were associated with global HRQoL (R² = 0.32) and the risk of falls, the risk of falls itself was related to psycho-social domains (R² = 0.11) such as depression and social participation, rather than to the physical domains of HRQoL. Objective measures of physical function were not associated with subjective fatigue, nor with subjective appreciation of health status.

CONCLUSIONS

More than muscle strength, lack of coordination and balance as witnessed by the risk of falls contribute to social isolation and HRQoL of haemodialysis patients. Mental fatigue was less common than expected, whereas, subjective and objective physical function were decreased.

Impact of Patient Demographic Factors on Preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function, Pain Interference, and Depression Computer Adaptive Testing Scores in Patients Undergoing Shoulder and Elbow Surgery

Background:

There has been a growing emphasis in orthopaedics on providing patient-centered care. The US National Institutes of Health launched the Patient-Reported Outcomes Measurement Information System (PROMIS) initiative that incorporates patient-reported outcome measures across a number of medical domains. The relationship between PROMIS domains and the impact of patient demographic factors in those undergoing upper extremity surgery remains unclear.

Purpose/Hypothesis:

The goal of this study was to investigate the correlation between physical function, pain interference, and depression in patients undergoing shoulder and elbow surgery as measured by PROMIS computer adaptive testing (CAT) forms and to determine the impact of patient demographic factors. We hypothesized that there would be a significant negative correlation between physical function and both pain interference and depression in this patient population.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

All patients who underwent elective shoulder or elbow surgery by 3 shoulder, elbow, and/or sports medicine fellowship–trained orthopaedic surgeons were included in the study. Preoperative PROMIS–Upper Extremity (PROMIS-UE), PROMIS–Pain Interference (PROMIS-PI), and PROMIS-Depression (PROMIS-D) CAT scores were analyzed. Pearson correlations were calculated between PROMIS domains as well as between PROMIS outcomes with patient demographic factors.

Results:

Preoperative PROMIS CAT scores for all 3 domains were collected and analyzed from 172 unique patients (516 individual CAT forms) with shoulder and elbow injuries. A negative correlation of moderate strength was found between the PROMIS-UE and PROMIS-PI (R = –0.61; P < .001), and a negligible correlation was found between the PROMIS-UE and PROMIS-D (R = –0.28; P < .001). When stratified by patient demographic factors, the correlation between the PROMIS-UE and PROMIS-PI was stronger in female patients compared with male patients (R = –0.77 vs –0.46, respectively; P < .001 for both), stronger in black patients compared with white patients (R = –0.72 vs –0.56, respectively; P < .001 for both), and highest in current tobacco users (R = –0.80; P < .001).

Conclusion:

Before shoulder and elbow surgery, patients demonstrated impairments in physical function and pain interference as measured by CAT forms, with a moderate negative correlation between baseline upper extremity physical function and pain interference scores. In certain subpopulations, such as female patients, black patients, and current tobacco users, the correlations between these tested domains were stronger than in other groups.

Measurement properties of PROMIS short forms for pain and function in orthopedic foot and ankle surgery patients

PURPOSE

To examine the measurement properties of the German PROMIS short forms for pain intensity (PAIN), pain interference (PI) and physical function (PF) in orthopedic foot and ankle surgery patients.

METHODS

Patient-rated outcomes were collected from consecutive patients of our foot and ankle registry before and 6 months after surgery. Measurement properties were tested according to the COnsensus-based Standards for the selection of health status Measurement Instruments (COSMIN). The German Foot Function Index (FFI-D) served as a legacy measure.

RESULTS

748 patients were included in our cross-sectional sample. Longitudinal and test-retest data were available for 202 and 65 patients, respectively. Construct validity of all short forms was good. All Cronbach's α and intraclass correlation coefficients were > 0.7. The smallest detectable change (SDC) was highest for PF (8.9) and lowest for PI (6.5). Minimal important change was 4 to 5 points and thus smaller than SDC for all instruments. We observed a baseline ceiling effect for PF. PI showed insufficiently correlated change scores with FFI-D disability change scores, and therefore failed the responsiveness testing.

CONCLUSION

Our study showed some adequate psychometric properties, but also certain aspects regarding interpretability and responsiveness that researchers must be aware of when using PROMIS short forms of pain and function in foot and ankle surgery patients.

Validation of the Dutch-Flemish PROMIS Pain Interference Item Bank in Patients With Musculoskeletal Complaints

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The aim of this study was to validate the Dutch-Flemish PROMIS Pain Interference item bank in patients with musculoskeletal complaints.

SUMMARY OF BACKGROUND DATA

PROMIS item banks have been developed and validated in the US. They need to be further validated in various patient populations and in different languages.

METHODS

One thousand six hundred seventy-seven patients answered the full item bank. A Graded Response Model (GRM) was used to study dimensionality with confirmatory factor analyses and by assessing local independency. Monotonicity was evaluated with Mokken scaling. An Item Response Theory (IRT) model was used to study item fit and to estimate slope and threshold parameters. Differential item functioning (DIF) for language, age, and gender was assessed using ordinal logistic regression analyses. DIF for language was evaluated by comparing our data with a similar US sample. Hypotheses concerning construct validity were tested by correlating item bank-scores with scores on several legacy instruments.

RESULTS

The GRM showed suboptimal evidence of unidimensionality in confirmatory factor analysis [Comparative Fit Index (CFI): 0.903, Tucker-Lewis Index (TLI): 0.897, Root Mean Square Error of Approximation (RMSEA): 0.144], and 99 item pairs with local dependence. A bifactor model showed good fit (CFI: 0.964, TLI: 0.961, RMSEA: 0.089), with a high Omega-H (0.97), a high explained common variance (ECV: 0.81), and no local dependence. Sufficient monotonicity was shown for all items (Mokken H(i): 0.367-0.686). The unidimensional IRT model showed good fit (only two items with S-X < 0.001), with slope parameters ranging from 1.00 to 4.27, and threshold parameters ranging from -1.77 to 3.66. None of the items showed DIF for age or gender. One item showed DIF for language. Correlations with legacy instruments were high (Pearson R: 0.53-0.75), supporting construct validity.

CONCLUSION

The high omega-H and the high ECV indicate that the item bank could be considered essentially unidimensional. The item bank showed good item fit, good coverage of the pain interference trait, and good construct validity.

LEVEL OF EVIDENCE

N/A.

Mindfulness is associated with psychological health and moderates the impact of fibromyalgia

OBJECTIVE

Previous studies suggest mindfulness is associated with pain and depression. However, its impact in individuals with fibromyalgia remains unclear. We examined associations between mindfulness and physical and psychological symptoms, pain interference, and quality of life in fibromyalgia patients.

METHODS

We performed a cross-sectional analysis on baseline data from a fibromyalgia clinical trial. Mindfulness was assessed using the Five Facet Mindfulness Questionnaire (FFMQ). Pearson's correlations and multivariable linear regression models were used to evaluate associations between mindfulness and fibromyalgia impact, pain interference, physical function, depression, anxiety, stress, self-efficacy, and health-related quality of life. We also examined whether mindfulness moderated associations between fibromyalgia impact and psychological outcomes.

RESULTS

A total of 177 participants (age 52.0 ± 12.2 (SD) years; 93.2% women; 58.8% white; body mass index 30.1 ± 6.7 kg/m²; FFMQ score 131.3 ± 20.7; Revised Fibromyalgia Impact Questionnaire score 57.0 ± 19.4) were included. Higher total mindfulness was significantly associated with lower fibromyalgia impact (r = - 0.25), pain interference (r = - 0.31), stress (r = - 0.56), anxiety (r = - 0.58), depression (r = - 0.54), and better mental health-related quality of life (r = 0.57). Describing, Acting-with-awareness, and Non-judging facets of mindfulness were also associated with these outcomes. Mindfulness moderated the effect of fibromyalgia impact on anxiety (interaction P = 0.01).

CONCLUSION

Higher mindfulness is associated with less pain interference, lower impact of fibromyalgia, and better psychological health and quality of life in people with fibromyalgia. Mindfulness moderates the influence of fibromyalgia impact on anxiety, suggesting mindfulness may alter how patients cope with fibromyalgia. Future studies should assess how mind-body therapies aiming to cultivate mindfulness may impact the well-being of patients with fibromyalgia.

KEY POINTS

• Higher mindfulness was associated with better psychological health and lower overall impact of fibromyalgia. • Mindfulness moderated the relationship between overall fibromyalgia impact and anxiety.

Differential item functioning of the PROMIS physical function, pain interference, and pain behavior item banks across patients with different musculoskeletal disorders and persons from the general population

PURPOSE

To investigate the validity of comparisons across patients with different musculoskeletal disorders and persons from the general population by evaluating differential item functioning (DIF) for the PROMIS physical function (PROMIS-PF), pain interference (PROMIS-PI), and pain behavior (PROMIS-PB) item banks.

METHODS

Patients with chronic pain, rheumatoid arthritis (RA), or osteoarthritis (OA); patients receiving physiotherapy (PT); and persons from the Dutch general population completed the full Dutch-Flemish PROMIS-PF (121-items), PROMIS-PI (40-items), or PROMIS-PB (39-items) banks. DIF was assessed with ordinal logistic regression models and McFadden's pseudo R²-change of ≥ 2% as critical value. The impact of DIF on item scores and the T-scores per bank was examined by inspecting item characteristic curves (ICCs) and test characteristic curves (TCCs).

RESULTS

2762 patients with chronic pain, 2029 with RA, 1247 with OA, 805 receiving PT, and 1310 healthy persons participated. For the PROMIS-PF, 25 out of 121 items were flagged for DIF, of which 10 items were flagged in multiple comparisons. For the PROMIS-PI, only 2 out of 40 items were flagged for DIF and for the PROMIS-PB, only 3 out of 39 items. Most DIF items had R² values just above the critical value of 2% and all showed uniform DIF. The ICCs and TCCs showed that the magnitude and impact of DIF on the item and T-scores were negligible.

CONCLUSIONS

This study supports the universal applicability of PROMIS across (patient) populations. Comparisons across patients with different musculoskeletal disorders and persons from the general population are valid, when applying the PROMIS-PF, PROMIS-PI, and PROMIS-PB banks.

Validation of two PROMIS item banks for measuring social participation in the Dutch general population

BACKGROUND

The Patient-Reported Outcomes Measurement Information System (PROMIS) item banks 'Ability to Participate in Social Roles and Activities' (35 items) and 'Satisfaction with Social Roles and Activities' (44 items) were developed to measure (satisfaction with) participation more efficiently and precisely than current instruments, by using Computerized Adaptive Testing (CAT). We validated these item banks in a Dutch general population.

METHODS

Participants in an internet panel completed both item banks. Unidimensionality, local dependence, monotonicity, Graded Response Model item fit, Differential Item Functioning (DIF) for age, gender, education, region, ethnicity, and language (Dutch compared to US Social Supplement), and reliability were assessed.

RESULTS

A representative Dutch sample of 1002 people participated. We found for the Ability to Participate and Satisfaction with Participation item banks, respectively, sufficient unidimensionality (CFI: 0.971, 0.960; TLI: 0.970, 0.958; RMSEA: 0.108, 0.108), no local dependence, sufficient monotonicity (H: 0.75, 0.73), good item fit (2 out of 35 items, 1 out of 44 items with S-X2p-value < 0.001). No DIF was found. We found a reliability of at least 0.90 with simulated CATs in 86% and 94% of the participants with on average 4.7 (range 2-12) and 4.3 (range 3-12) items, respectively.

DISCUSSION

The PROMIS participation item banks showed sufficient psychometric properties in a general Dutch population and can be used as CAT. PROMIS CATs allow reliable and valid measurement of participation in an efficient and user-friendly way with limited administration time.

Measurement invariance and general population reference values of the PROMIS Profile 29 in the UK, France, and Germany

PURPOSE

Comparability of patient-reported outcome measures over different languages is essential to allow cross-national research. We investigate the comparability of the PROMIS Profile 29, a generic health-related quality of life measure, in general population samples in the UK, France, and Germany and present general population reference values.

METHODS

A web-based survey was simultaneously conducted in the UK (n = 1509), France (1501), and Germany (1502). Along with the PROMIS Profile 29, we collected sociodemographic information as well as the EQ-5D. We tested measurement invariance by means of multigroup confirmatory factor analysis (CFA). Differences in the health-related quality of life between countries were modeled by linear regression analysis. We present general population reference data for the included PROMIS domains utilizing plausible value imputation and quantile regression.

RESULTS

Multigroup CFA of the PROMIS Profile 29 showed that factor means are insensitive to potential measurement bias except in one item. We observed significant differences in patient-reported health between countries, which could be partially explained by the differences in overall ratings of health. The physical function and pain interference scales showed considerable floor effects in the normal population in all countries.

CONCLUSIONS

Scores derived from the PROMIS Profile 29 are largely comparable across the UK, France, and Germany. Due to the use of plausible value imputation, the presented general population reference values can be compared to data collected with other PROMIS short forms or computer-adaptive tests.

Development of a Computerized Adaptive Test for Anxiety Based on the Dutch–Flemish Version of the PROMIS Item Bank

We used the Dutch–Flemish version of the USA PROMIS adult V1.0 item bank for Anxiety as input for developing a computerized adaptive test (CAT) to measure the entire latent anxiety continuum. First, psychometric analysis of a combined clinical and general population sample ( N = 2,010) showed that the 29-item bank has psychometric properties that are required for a CAT administration. Second, a post hoc CAT simulation showed efficient and highly precise measurement, with an average number of 8.64 items for the clinical sample, and 9.48 items for the general population sample. Furthermore, the accuracy of our CAT version was highly similar to that of the full item bank administration, both in final score estimates and in distinguishing clinical subjects from persons without a mental health disorder. We discuss the future directions and limitations of CAT development with the Dutch–Flemish version of the PROMIS Anxiety item bank.

Language-related differential item functioning between English and German PROMIS Depression items is negligible

To investigate differential item functioning (DIF) of PROMIS Depression items between US and German samples we compared data from the US PROMIS calibration sample (n = 780), a German general population survey (n = 2,500) and a German clinical sample (n = 621). DIF was assessed in an ordinal logistic regression framework, with 0.02 as criterion for R² -change and 0.096 for Raju's non-compensatory DIF. Item parameters were initially fixed to the PROMIS Depression metric; we used plausible values to account for uncertainty in depression estimates. Only four items showed DIF. Accounting for DIF led to negligible effects for the full item bank as well as a post hoc simulated computer-adaptive test (< 0.1 point on the PROMIS metric [mean = 50, standard deviation =10]), while the effect on the short forms was small (< 1 point). The mean depression severity (43.6) in the German general population sample was considerably lower compared to the US reference value of 50. Overall, we found little evidence for language DIF between US and German samples, which could be addressed by either replacing the DIF items by items not showing DIF or by scoring the short form in German samples with the corrected item parameters reported.

Choosing the right outcome measurement instruments for patients with low back pain

Choosing the most fit-for-purpose outcome measurement instruments is fundamental because using inappropriate instruments can lead to detection bias and measurement inconsistency. Recent recommendations, consensus procedures and systematic reviews on existing patient-reported outcome measures (PROMs) informed this manuscript, which provides suggestions on which outcome domains and measurement instruments to use in patients with low back pain (LBP). Six domains are identified as highly relevant: (1) physical functioning, (2) pain intensity, (3) health-related quality of life, (4) work, (5) psychological functioning and (6) pain interference. For each domain, one or more PROMs are suggested for clinical research and practice, selecting among those that are most frequently used and recommended, and that have satisfactory measurement properties in patients with LBP. Further research on the measurement properties of these suggested PROMs is needed while also considering other emerging instruments, such as the PROMIS computerised adaptive testing and short forms.

The Dutch-Flemish PROMIS Physical Function item bank exhibited strong psychometric properties in patients with chronic pain

OBJECTIVE

The objective of this study was to assess the psychometric properties of the Dutch-Flemish Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function item bank in Dutch patients with chronic pain.

STUDY DESIGN AND SETTING

A bank of 121 items was administered to 1,247 Dutch patients with chronic pain. Unidimensionality was assessed by fitting a one-factor confirmatory factor analysis and evaluating resulting fit statistics. Items were calibrated with the graded response model and its fit was evaluated. Cross-cultural validity was assessed by testing items for differential item functioning (DIF) based on language (Dutch vs. English). Construct validity was evaluated by calculation correlations between scores on the Dutch-Flemish PROMIS Physical Function measure and scores on generic and disease-specific measures.

RESULTS

Results supported the Dutch-Flemish PROMIS Physical Function item bank's unidimensionality (Comparative Fit Index = 0.976, Tucker Lewis Index = 0.976) and model fit. Item thresholds targeted a wide range of physical function construct (threshold-parameters range: -4.2 to 5.6). Cross-cultural validity was good as four items only showed DIF for language and their impact on item scores was minimal. Physical Function scores were strongly associated with scores on all other measures (all correlations ≤ -0.60 as expected).

CONCLUSION

The Dutch-Flemish PROMIS Physical Function item bank exhibited good psychometric properties. Development of a computer adaptive test based on the large bank is warranted.

Differential item functioning of the patient-reported outcomes information system (PROMIS®) pain interference item bank by language (Spanish versus English)

BACKGROUND

About 70% of Latinos, 5 years old or older, in the United States speak Spanish at home. Measurement equivalence of the PROMIS^® pain interference (PI) item bank by language of administration (English versus Spanish) has not been evaluated.

METHODS

A sample of 527 adult Spanish-speaking Latinos completed the Spanish version of the 41-item PROMIS^® pain interference item bank. We evaluate dimensionality, monotonicity and local independence of the Spanish-language items. Then we evaluate differential item functioning (DIF) using ordinal logistic regression with item response theory scores estimated from DIF-free "anchor" items.

RESULTS

One of the 41 items in the Spanish version of the PROMIS^® PI item bank was identified as having significant uniform DIF.

CONCLUSIONS

English- and Spanish-speaking subjects with the same level of pain interference responded differently to 1 of the 41 items in the PROMIS^® PI item bank. This item was not retained due to proprietary issues. The original English language item parameters can be used when estimating PROMIS^® PI scores.

On the effect of adding clinical samples to validation studies of patient-reported outcome item banks: a simulation study

PURPOSE

To increase the precision of estimated item parameters of item response theory models for patient-reported outcomes, general population samples are often enriched with samples of clinical respondents. Calibration studies provide little information on how this sampling scheme is incorporated into model estimation. In a small simulation study the impact of ignoring the oversampling of clinical respondents on item and person parameters is illustrated.

METHOD

Simulations were performed using two scenarios. Under the first it was assumed that regular and clinical respondents form two distinct distributions; under the second it was assumed that they form a single distribution. A synthetic item bank with quasi-trait characteristics was created, and item scores were generated from this bank for samples with varying percentages of clinical respondents. Proper (using a multi-group model, and sample weights, respectively, for Scenarios 1 and 2) and improper (ignoring oversampling) approaches for dealing with the clinical sample were contrasted using correlations and differences between true and estimated parameters.

RESULTS

Under the first scenario, ignoring the sampling scheme resulted in overestimation of both item and person parameters with bias decreasing with higher percentages of clinical respondents. Under the second, location and person parameters were underestimated with bias increasing in size with increasing percentage of clinical respondents. Under both scenarios, the standard error of the latent trait estimate was generally underestimated.

CONCLUSION

Ignoring the addition of extra clinical respondents leads to bias in item and person parameters, which may lead to biased norms and unreliable CAT scores. An appeal is made for researchers to provide more information on how clinical samples are incorporated in model estimation.

Differential Item Functioning in the SF-36 Physical Functioning and Mental Health Sub-Scales: A Population-Based Investigation in the Canadian Multicentre Osteoporosis Study

Background

Self-reported health status measures, like the Short Form 36-item Health Survey (SF-36), can provide rich information about the overall health of a population and its components, such as physical, mental, and social health. However, differential item functioning (DIF), which arises when population sub-groups with the same underlying (i.e., latent) level of health have different measured item response probabilities, may compromise the comparability of these measures. The purpose of this study was to test for DIF on the SF-36 physical functioning (PF) and mental health (MH) sub-scale items in a Canadian population-based sample.

Methods

Study data were from the prospective Canadian Multicentre Osteoporosis Study (CaMos), which collected baseline data in 1996–1997. DIF was tested using a multiple indicators multiple causes (MIMIC) method. Confirmatory factor analysis defined the latent variable measurement model for the item responses and latent variable regression with demographic and health status covariates (i.e., sex, age group, body weight, self-perceived general health) produced estimates of the magnitude of DIF effects.

Results

The CaMos cohort consisted of 9423 respondents; 69.4% were female and 51.7% were less than 65 years. Eight of 10 items on the PF sub-scale and four of five items on the MH sub-scale exhibited DIF. Large DIF effects were observed on PF sub-scale items about vigorous and moderate activities, lifting and carrying groceries, walking one block, and bathing or dressing. On the MH sub-scale items, all DIF effects were small or moderate in size.

Conclusions

SF-36 PF and MH sub-scale scores were not comparable across population sub-groups defined by demographic and health status variables due to the effects of DIF, although the magnitude of this bias was not large for most items. We recommend testing and adjusting for DIF to ensure comparability of the SF-36 in population-based investigations.