The feasibility of applying item response theory to measures of migraine impact: A re-analysis of three clinical studies

Background: Item response theory (IRT) is a powerful framework for analyzing multiitem scales and is central to the implementation of computerized adaptive testing. Objectives: To explain the use of IRT to examine measurement properties and to apply IRT to a questionnaire for measuring migraine impact – the Migraine Specific Questionnaire (MSQ). Methods: Data from three clinical studies that employed the MSQ-version 1 were analyzed by confirmatory factor analysis for categorical data and by IRT modeling. Results: Confirmatory factor analyses showed very high correlations between the factors hypothesized by the original test constructions. Further, high item loadings on one common factor suggest that migraine impact may be adequately assessed by only one score. IRT analyses of the MSQ were feasible and provided several suggestions as to how to improve the items and in particular the response choices. Out of 15 items, 13 showed adequate fit to the IRT model. In general, IRT scores were strongly associated with the scores proposed by the original test developers and with the total item sum score. Analysis of response consistency showed that more than 90% of the patients answered consistently according to a unidimensional IRT model. For the remaining patients, scores on the dimension of emotional function were less strongly related to the overall IRT scores that mainly reflected role limitations. Such response patterns can be detected easily using response consistency indices. Analysis of test precision across score levels revealed that the MSQ was most precise at one standard deviation worse than the mean impact level for migraine patients that are not in treatment. Thus, gains in test precision can be achieved by developing items aimed at less severe levels of migraine impact. Conclusions: IRT proved useful for analyzing the MSQ. The approach warrants further testing in a more comprehensive item pool for headache impact that would enable computerized adaptive testing.     

The psychometric properties of the Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ) in chronic migraine patients

Objective

The Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ) has been shown to have good psychometric performance in measuring headache impact in migraine patients, but its properties specifically in chronic migraine (CM) patients are unknown. The objective of this study was to evaluate the psychometric properties of the MSQ in a group of CM patients undergoing prophylactic treatment.

Methods

Measurement properties of the MSQ were examined using two international, multicenter, randomized clinical trials evaluating onabotulinumtoxinA as headache prophylaxis in CM patients (N = 1,376). Confirmatory factor analysis (CFA) was used to test the latent structure of the MSQ in CM patients. The reliability, convergent and discriminant validity, and responsiveness of the MSQ were assessed.

Results

CFA confirmed the currently proposed three-factor MSQ latent structure across the two studies. Good reliability was observed for all three MSQ scales, across studies and time points. MSQ scale scores strongly correlated with the scores of the Headache Impact Test-6 (HIT-6). Analysis of known-groups validity indicated that MSQ scale scores discriminated between groups of patients differing in their 28-day headache frequency were as follows <10, 10–14, and ≥15 days, and the sample-derived quartiles of the total cumulative hours of headache were as follows <140, 140 to <280, 280 to <420, and ≥420 h (p < 0.0001), across both studies and time points. MSQ change scores were higher in magnitude in groups experiencing greater decline in headache frequency (p < 0.001).

Conclusion

The MSQ is a psychometrically valid tool that can be used to reliably measure the impact of migraine among CM patients.     

Item Response Theory Methods can Improve the Measurement of Physical Function by Combining the Modified Health Assessment Questionnaire and the SF-36 Physical Function Scale

Objective:

To compare the measurement properties of the Modified Health Assessment Questionnaire [MHAQ], the SF-36^® Health Survey 10 item Physical Functioning scale [PF10], and scores from an item response theory (IRT) based scale combining the two measures.

Study Design:

Rheumatoid arthritis (RA) patients (n = 339) enrolled in a multi-center, randomized, double-blind, placebo-controlled trial completed the MHAQ and the SF-36 pre- and post-treatment. Psychometric analyses used confirmatory factor analysis and IRT models. Analyses of variance were used to assess sensitivity to changes in disease severity (defined by the American College of Rheumatism (ACR)) using change scores in MHAQ, PF10, and IRT scales. Analyses of covariance were used to assess treatment responsiveness.

Results:

For the entire score range, the 95% confidence interval around individual patient scores was smaller for the combined (total) IRT based scale than for other measures. The MHAQ and PF10 were about 70% and 50% as efficient as the total IRT score of physical functioning in discriminating among ACR groups, respectively. The MHAQ and PF10 were also less efficient than the total IRT score in discriminating among treatment groups.

Conclusions:

Combining scales from the two short forms yields a more powerful tool with greater sensitivity to treatment response.     

Using item response theory to calibrate the Headache Impact Test (HIT™) to the metric of traditional headache scales

Background: Item response theory (IRT) scoring of health status questionnaires offers many advantages. However, to ensure backwards comparability and to facilitate interpretations of results, we need the ability to express the IRT score in the metrics of the traditional scales. Objectives: To develop procedures to calibrate IRT-based scores on the Headache Impact Test (HIT) into the metrics of the traditional headache scales. To assess the degree to which the calibrated HIT scores agree with the observed traditional scores and lead to the same conclusions in group comparisons. Methods: We used telephone interview data (n = 1016) and Internet data (n = 1103) from general population surveys of recent headache sufferers. Analyses were conducted in four steps: (1) develop IRT models for all items, (2) for each IRT score level, calculate the expected score on each of the traditional scales (calibration), (3) adjust this calibrated score for measurement error in the IRT score, (4) for each of the traditional scales, assess agreement between calibrated HIT scores and observed scores using intraclass correlation (ICC) and evaluate the agreement of mean scores and the relative validity (RV) in discriminating among groups differing in migraine diagnosis, headache severity, and change in impact over time. Results: For the traditional categorical questionnaire items (the Migraine Specific Questionnaire (MSQ) and the Headache Disability Inventory (HDI)) the calibrated HIT agreed with the observed traditional scores: ICC's were between 0.80 and 0.94. In RV analyses the maximum mean difference between the observed and expected scores was 1.7 points on a 0–100 scale for comparisons at one point in time. Analyses of change over time and analyses calibrating scores from the fixed-form HIT-6 to the metric of other questionnaires were also satisfactory although less precise. Analysis of non-standard questionnaire items (e.g. On how many days in the past 3 months did you have a headache, from the HIMQ and the MIDAS) required special IRT models. Agreement was less good: ICC's were between 0.56 and 0.61 and the maximum mean differences were 2.9 (on a 0–270 scale) and 3.8 (on a 0–450 scale) in RV analyses at one point in time. The ability of the calibrated scale scores to discriminate between groups was at least as good as the ability of the observed sum scales and often remarkably better. Conclusion: The theoretical advantage of IRT models in scale calibration is supported by our results. This approach to achieving comparability of new and widely-used scales and accelerating the accumulation of interpretation guidelines based on previous work warrant testing for measures of other generic and disease-specific concepts.     

Responsiveness of disease-specific and generic utility instruments in prostate cancer patients

Background Preferences (utilities) for health outcomes have an important role in decisions about prostate cancer screening and treatment. The responsiveness of utility instruments has not been evaluated. Subjects Prostate cancer outpatients from the Princess Margaret Hospital, Toronto (n = 248) were allocated into three cohorts: N – newly diagnosed and treated; M – metastatic disease; O – all others. Measures We measured quality of life at 3 points within 12 months using 3 disease-specific utility instruments (Patient Oriented Prostate Utility Scales), 3 generic utility instruments (Health Utilities Index, EQ-5D, Quality of Well-Being Scale), and 3 profile scales (PORPUS-P profile, Prostate Cancer Index, QLQ-C-30). Responsiveness was assessed using measures of internal responsiveness (standardized effect size, standardized response mean) and external responsiveness (receiver operator curve analysis, mixed model regression). Results Cohort N patients showed post-treatment declines followed by improvement in global health and functional status. Disease specific instruments detected moderate (0.4–1.3) decrements followed by small increments (0.1–0.4) in standardized effect size and standardized response mean. Most instruments detected change using external responsiveness measures (all cohorts). Conclusions Disease-specific utility instruments appeared to be more responsive than generic instruments. Use of generic instruments should be supplemented with a responsive disease-specific instrument, particularly for applications in early prostate cancer.     

Responsiveness of the generic EQ-5D summary measure compared to the disease-specific EORTC QLQ C-30

Introduction: We investigated whether the sensitivity of the generic health-related quality of life (HRQoL) EQ-5D summary measure (or index) to detect changes over time in a clinical setting is comparable with that of a disease-specific HRQoL questionnaire. Methods: Patients with liver metastases (n = 75) filled out the five domains of the EQ-5D self-classifier, the EQ VAS, and the EORTC QLQ C-30 (a disease-specific (cancer) HRQoL questionnaire). The HRQoL instruments were completed before intervention, and 1/2 month and 3 and 6 months after intervention. Three analyses were performed. First, the EQ-5D index (based on self-classification) was compared to the EQ VAS. Second, the EQ-5D domains were compared to corresponding EORTC QLQ C-30 scales. Third, EQ-5D index and EQ VAS were compared with the EORTC QLQ C-30 global health-status scale. Effect size was chosen as the metric of responsiveness. Results: The EQ-5D index was slightly less responsive than the EQ VAS. Overall, the responsiveness of the EQ-5D index and EQ VAS was equal to the EORTC QLQ C-30 global health-status scale. Conclusion: Despite its generic principle and the apparent crudeness of its framework, the responsiveness of the EQ-5D proved to be comparable to that of a disease-specific HRQoL questionnaire in this specific clinical setting.     

Limitations of the statistics used to measure responsiveness in two longitudinal cohort studies of cognitive function and the utility of approaches derived from item response theory

Purpose: We are interested in measuring changes in cognitive function in longitudinal cohort studies. Specifically, we were interested in the responsiveness of the Mini-Mental Status Exam (MMSE), or its ability to detect changes over time. We were unable to find any previous published reports on the responsiveness of the MMSE. Responsiveness has been hailed as the principal criterion for determining the utility of an instrument for assessing change in the context of evaluative studies such as clinical trials or longitudinal cohort studies. Previous statistics that have been advocated to measure responsiveness have implicitly assumed a constant variance. The variance structure can be empirically determined and the assumption of constant variance can be tested. However, such determinations can only be carried out after the fact, after the choice of scale has already been made and the data are available to analyze.Methods: Item response theory (IRT) provided tools that proved useful in analyzing these data with respect to responsiveness. Specifically, IRT enabled the direct visualization of the variance structure across the entire spectrum of cognitive function as measured by the MMSE.Results: In our studies, we found that the assumption of constant variance did not hold for the MMSE, precluding our use of currently available responsiveness statistics.Conclusions: Currently available statistics for assessing responsiveness have significant limitations due to their assumption of constant variance. IRT allows the direct visualization of the expected variance structure across the entire spectrum of the trait measured by the instrument. In our case, this visualization led us to discard existing techniques to measure the responsiveness of the MMSE. IRT should be used as a first step in assessing the responsiveness of instruments in order to determine whether the assumption of constant variance is appropriate.     

A health related quality of life measure for use in patients with urge urinary incontinence: A validation study

Objective: Urge incontinence has substantial impact on health related quality of life (HRQOL). The purpose of this research was to test the psychometric properties of the Urge-Incontinence Impact Questionnaire (U-IIQ) and Urge-Urinary Distress Inventory (U-UDI). Methods: The U-IIQ and the U-UDI were incorporated in a single arm study of an investigational once-a-day formulation of oxybutynin (Ditropan^® XL) for urge incontinence. The U-IIQ contains 7 scales scored separately: Travel, Activities, Physical activities, Feelings, Relationships, Sexual function and Nighttime bladder control. We also calculated a single index score. The U-UDI contains 9 items summarized in a single score that measures the extent to which incontinence symptoms bother patients and an urge symptoms summary score. Patients completed the questions at: start of baseline week, end of baseline week, week 4 and week 12 (final dose). Results: The questions were completed by the 257 patients enrolled in the study (91% female, mean age = 60 years). All item responses showed good variability. Internal-consistency reliability was very good (Cronbach's = 0.82–0.96). Test–retest reliability was good for all scales ([ICC] = 0.68–0.83). Discriminant validity was noted for all scales for patients with and without frequent incontinence (p 0.006 all scales). All scales demonstrated responsiveness to change over time (Guyatt's statistic = |–1.04| – |–1.71|). Conclusions: Psychometric testing indicated that the scales measured distinct and relevant domains of HRQOL for patients with urge incontinence, and that these two instruments are reliable, valid, and responsive to change in this condition.     

Validating the Migraine-Specific Quality of Life Questionnaire v2.1 (MSQ) in Italian inpatients with chronic migraine with a history of medication overuse

Purpose

The purpose of the study is to assess validity, reliability and factor structure of the Italian version of Migraine-Specific Quality of Life Questionnaire v2.1 (MSQ) in patients suffering from chronic migraine (CM) with a history of medication overuse (MO).

Methods

Patients were enroled at hospital admission for withdrawal from MO. Factor analysis was used to confirm the latent structure of the MSQ. Reliability was measured with Cronbach’s alpha coefficient, item-total correlation and inter-item correlation. Construct validity was assessed with Pearson’s coefficient and known-group analysis.

Results

The three-factor structure is basically confirmed. Cronbach’s alpha varied between 0.85 and 0.92; item-total correlations were on average higher than 0.70; average inter-item correlation ranged between 0.63 and 0.65. Correlations were all significant; known-group analysis shows that MSQ score was lower consistently with disease severity.

Conclusions

Our findings confirm the factor structure, reliability and validity of the MSQ and expand results of previous validation studies to the Italian language and to a group of patients with severe CM requiring withdrawal treatment for MO.     

Psychometric evaluation of the Schizophrenia Quality of Life Scale (SQLS) in English- and Chinese-speaking Asians in Singapore

Objective To assess the psychometric properties of the Schizophrenia Quality of Life Scale (SQLS) in Asians with schizophrenia in Singapore. Methods A consecutive sample of outpatients with schizophrenia completed the English or Chinese version of the SQLS and the Short-Form 36 Health Survey (SF-36) twice during two different clinic visits. The patients were also assessed for presence or absence of 22 psychiatric symptoms. Results About 202 patients (English-speaking: 140) participated in the study. Correlations between SQLS scales and other measures assessing similar constructs ranged from 0.46 to 0.69 (P < 0.001 for all). For SQLS psychosocial and symptoms/side effects scales, item-to-scale correlations were >0.4, Cronbach’s alpha and intra-class correlation coefficient values were close to or exceed 0.7, and Cohen’s effect size, standardized response mean, and Guyatt’s responsiveness index values approximated or exceeded 0.2 for both SQLS language versions; however, for the energy/motivation scale, item-to-scale correlations (range: 0.08–0.51), reliability (range: 0.46–0.66) and responsiveness (range: 0.04–0.08) statistics were not satisfactory for both SQLS versions. Conclusions The SQLS psychosocial and symptoms/side effects scales are valid, reliable and responsive in Singaporean patients with schizophrenia; the appropriateness of energy/motivation scale requires further investigation.     

Use of item response theory to develop a shortened version of the EORTC QLQ-C30 emotional functioning scale

Background: As part of a larger study whose objective is to develop an abbreviated version of the EORTC QLQ-C30 suitable for research in palliative care, analyses were conducted to determine the feasibility of generating a shorter version of the 4-item emotional functioning (EF) scale that could be scored in the original metric. Methods: We used data from 24 European cancer studies conducted in 10 different languages (n=8242). Item selection was based on analyses by item response theory (IRT). Based on the IRT results, a simple scoring algorithm was developed to predict the original 4-item EF sum scale score from a reduced number of items. Results: Both a 3-item and a 2-item version (item 21 ‘Did you feel tense?’ and item 24 ‘Did you feel depressed?’) predicted the total score with excellent agreement and very little bias. In group comparisons, the 2-item scale led to the same conclusions as those based on the original 4-item scale with little or no loss of measurement efficiency. Conclusion: Although these results are promising, confirmatory studies are needed based on independent samples. If such additional studies yield comparable results, incorporation of the 2-item EF scale in an abbreviated version of the QLQ-C30 for use in palliative care research settings would be justified. The analyses reported here demonstrate the usefulness of the IRT-based methodology for shortening questionnaire scales.     

Responsiveness of the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI)

Objectives: The NIH-Chronic Prostatitis Symptom Index (NIH-CPSI) was developed to assess symptoms and quality of life in men with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). We assessed the responsiveness of the NIH-CPSI to change over time and defined thresholds for changes perceptible to patients. Methods: We studied 174 men with CP/CPPS who participated in a placebo-controlled randomized clinical trial. Changes from baseline to six weeks in the NIH-CPSI total score and pain, urinary, and quality of life subscores were compared to a global response assessment (GRA). Effect sizes and Guyatt statistics were calculated to evaluate responsiveness; 95% confidence intervals were produced using bootstrapping. Results: All scores decreased over time with the largest decrease in subjects who reported on the GRA that they were markedly improved. The NIH-CPSI total, pain, and quality of life scores were highly responsive in the improved groups; the urinary score showed minimal responsiveness. There was no evidence of responsiveness among those subjects who worsened on the trial. ROC curves identified a 6-point decline in the NIH-CPSI total score as the optimal threshold to predict treatment response. Conclusions: The NIH-CPSI total score and pain and quality of life subscores are responsive to change over␣time.     

Comparative responsiveness and minimal change for the Oxford Elbow Score following surgery

Purpose  To assess the responsiveness and minimal change for the Oxford Elbow Score (OES) using anchor- and distribution-based approaches. Methods  A prospective observational study of 104 patients undergoing elbow surgery at a specialist orthopaedic hospital was carried out. Patients completed the OES and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires (both scored on a 0 to 100 scale) pre- and 6 months post-surgery. Transition items (used as anchors) assessed perceived changes following surgery. Indicators of responsiveness were the effect size; the anchor-based minimal clinically important difference (MCID) and best cut-point on the receiver operator characteristic (ROC) curve; and the distribution-based minimal detectable change (MDC). Results  The three elbow-specific OES scales (Function, Pain, Social-Psychological) produced generally larger effect sizes (0.79, 1.14 and 1.18, respectively) than the upper-limb-specific DASH scale (0.76). Clear associations were observed between transition items and all OES and DASH scores (all r > |0.35|). The MCIDs for the OES Function scale and the DASH were similar (≈10), but were larger for the OES Pain and Social-Psychological scales (≈18), reflecting their lower (i.e. poorer) baseline scores and larger effect sizes. The MCIDs were, however, only consistently larger than the MDCs for the OES Pain domain. The OES Function scale and the DASH performed similarly on ROC analysis, but with the OES Pain and Social-Psychological scales demonstrating superior efficiency. Conclusions  For elbow surgery, the 12-item three-scale OES is highly responsive to 6-month post-operative outcomes, with its performance being generally better than that of the 30-item one-scale DASH. Study estimates of minimal change for the OES may be useful for informing sample size calculations and interpreting outcomes in future clinical trials.     

Usefulness of the SF-8™ Health Survey for comparing the impact of migraine and other conditions

Background: Migraine headaches have been shown to have substantial personal and societal implications. Health-related quality of life (HRQOL) assessments of migraineurs have been used to monitor and evaluate patient- and population-based outcomes, and to evaluate effectiveness and responsiveness to treatment. In this paper, we test a new, even shorter generic health survey, the SF-8 Health Survey (SF-8), an alternate form that uses one question to measure each of the eight SF-36^® Health Survey (SF-36^®) domains, in a sub-sample of migraine sufferers. Methods: Data from 7557 participants surveyed via the Internet and mail were used to document the burden of migraine on HRQOL and to compare the relative burden of migraine with other chronic conditions using the SF-8. Results: Migraineurs' HRQOL is similar to those with congestive heart failure, hypertension and diabetes, and is better than those with depression. Migraine sufferers experience better physical health and worse mental health (MH) than those with osteoarthritis. Results support prior research indicating that the burden of migraine on functional health and well-being is considerable and comparable to other chronic conditions known to have substantial impact on HRQOL. Conclusions: The SF-8 may provide a more practical and efficient method to describe the burden of migraine in population studies.     

Measuring disease specific quality of life in localized prostate cancer: The Dutch experience

Objective: We aimed at developing and testing a Dutch health-related quality of life measure for localized prostate cancer patients. Methods: Scales on urinary and bowel function and bother from the UCLA Prostate Cancer Index (PCI) underwent formal linguistic and cultural translation. PCI sexual scales were replaced by an existing Dutch sexual activities module (SAc). After qualitative pilot testing 389 patients with localized prostate cancer (mean age 67 ± 7 years) completed the measure before and at 2 time points after primary treatment. Psychometric properties (feasibility, score distribution, reliability, construct validity and responsiveness to change) of the new instrument were analyzed. Results: Response rates ranged from 93% at baseline to 87% after treatment. Urinary and bowel function scales showed Cronbach's s >0.7. Urinary function and bother, and bowel function and bother were significantly correlated. Pre- vs. post-prostatectomy effect sizes were >0.9 only for urinary scales; while pre- vs. post-radiotherapy effect sizes were >0.75 only for bowel scales. Six months after baseline erectile dysfunction was reported by 64% of respondents, either as a problem in sexual activity or as a reason for not being sexually active. Conclusion: The Dutch PCI and SAc performed well in men treated for early stage prostate cancer.     

The impact of migraine prevention on daily activities: a longitudinal and responder analysis from three topiramate placebo-controlled clinical trials

Background  

Topiramate is approved for the prophylaxis (prevention) of migraine headache in adults. The most common adverse events in the three pivotal, randomized, double-blind, placebo-controlled trials were paresthesia, fatigue, cognitive impairment, anorexia, nausea, and taste alteration. In these trials, topiramate 100 mg/d significantly improved Migraine-Specific Questionnaire (MSQ) scores versus placebo (p < 0.001). The MSQ measures how much migraine limits/interrupts daily performance. Pooled analyses of pivotal trial data were conducted to further assess how topiramate 100 mg/d affects daily activities and patient functioning.     

Responsiveness of the Quality of Life in Epilepsy Inventory (QOLIE-89) in an Antiepileptic Drug Trial

This study examined relationships among responsiveness indices for health-related quality of life (HRQOL) measures administered to adults with epilepsy enrolled in an antiepileptic drug trial. The Quality of Life in Epilepsy (QOLIE)-89 was completed at baseline and at a 28-week follow-up. Six responsiveness indices (effect size (ES), standardized response mean (SRM), responsiveness statistic, paired t-test, area under receiver operating characteristic curve or ROC, F-statistic) were calculated for each of the 16 QOLIE-89 scales, using two different external criteria for clinically significant change: (1) attainment of freedom from seizures with altered awareness, and (2) a two-category improvement between baseline and follow-up in a self-rating of the subject's overall condition. Spearman correlations among the six responsiveness indices for the 16 QOLIE-89 scales tended to be moderate to large (Spearman's = 0.53–1.00; p's > 0.05 for 29 out of the 30 correlations). Rankings of the 16 scales across the two external criteria for change were similar for the responsiveness statistic (Spearman's = 0.62; p > 0.05), but dissimilar for the other responsiveness indices (all p > 0.05). Both ES and SRM were well predicted by the other indices, except for ROC, using regression modeling. In conclusion, results using different responsiveness indices are comparable for a given external criterion. However, only the responsiveness statistic yielded robust results across two different external criteria. Responsiveness of this HRQOL measure can be reported in terms of previously established benchmarks for ESs, which can be predicted from other indices.     

A patient-reported pressure ulcer health-related quality of life instrument for use in prevention trials (PU-QOL-P): psychometric evaluation

Introduction

Pressure ulcer-specific patient-reported outcome (PRO) instruments should be used to inform patient care and provide a strong evidence base for interventions aimed at preventing pressure ulcers. The aim was to carry out a comprehensive evaluation of the psychometric properties of a PRO instrument designed to assess symptoms and functional outcomes in patients at high-risk of developing pressure ulcers, the PU-QOL-P instrument.

Methods

We modified the original PU-QOL instrument to be suitable for patients at high risk of pressure ulcer development based on feedback from patients, specialist nurses and PRO methodologists. The modified PU-QOL-P instrument was administered to a sub-set of patients participating in the PRESSURE 2 trial. Patients completed PU-QOL-P and SF12 instruments at baseline, weeks 1 and 3, and 30?days post-treatment. We undertook psychometric evaluation of the modified PU-QOL-P to test scale targeting, scaling assumptions, reliability, validity and responsiveness.

Results

The analysis sample consisted of 617 patients that completed both instruments at baseline. We found that the PU-QOL-P instrument, consisting of nine PU-specific outcomes: three symptom and six function scales, meets established criteria for reliability, construct validity, and responsiveness. Internal consistency reliability was high with all scale Cronbach alpha >?0.795 (range 0.795–0.970). The factor analysis mostly supported the six-function scale structure. Scaling assumptions were satisfied; all item-total correlations above 0.30. Convergent validity was confirmed by significant correlations between hypothesized scales as expected. PU-QOL-P scales were responsive to change: mean scale scores from baseline to 30?days post-treatment were statistically significant for all scales apart the daily activities scale (effect sizes ranged from moderate to high). As expected, worse symptoms and functioning was observed in patients who had a category 1 or 2 PU compared to patients who did not have a PU.

Conclusions

The PU-QOL-P provides a standardised method for assessing pressure ulcer-specific symptoms and functional outcomes for quantifying the benefits of associated interventions from the patient’s perspective. It can be used in research with adults at risk of pressure ulcer development in all UK healthcare settings.

     

Validation of the Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ v. 2.1) for patients undergoing prophylactic migraine treatment

OBJECTIVE: Health-related quality of life (HRQoL) is an important outcome measure of migraine treatments. Although a number of migraine-specific HRQoL questionnaires exist, their measurement characteristics have only been examined for patients undergoing acute treatment of migraine. The goal of the current study was to evaluate measurement properties of the widely used Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ v. 2.1) within a group of patients undergoing prophylactic migraine treatment. METHODS: Various measurement properties of the MSQ were examined in a sample of 916 migraineurs undergoing prophylactic treatment who had scores at baseline and follow-up, as well as baseline SF-36. First, we used confirmatory factor analysis (CFA) and differential item functioning (DIF) to assure the accuracy and stability across groups of the MSQ scoring for all three subscales (Role Restrictive, Role Preventive, and Emotional Functioning). Next, item- and scale-level properties were examined, such as item-total correlations, internal consistency, and convergent and discriminant validity. RESULTS: Initial findings revealed that item 12 (measuring frustration on the Emotional Functioning subscale) performed poorly. Subsequent to its removal, the 13-item MSQ displayed excellent measurement properties, including stable latent structure at baseline and endpoint, no gender or age biases on items, appropriate item-level and scale-level reliabilities, and markedly higher convergent validity compared to discriminant validity. CONCLUSION: The 13-item MSQ appears to be an appropriate measure of migraine-specific HRQoL for patients undergoing migraine prophylaxis. Moreover, given the stability of the latent structure over time, the interpretation of scores is likely to remain quite consistent throughout a clinical trial.     

Development and validation of a new health-related quality of life instrument for patients with sinusitis

Background and Objective: There are few validated measures of sinusitis-specific health-related quality of life (HRQL). This study used patient focus and pretesting groups followed by a prospective cohort study to develop and validate a HRQL instrument for patients with sinusitis. Methods: Instrument development involved a systematic literature review, use of expert input, and patient focus and pretesting groups. Patients were recruited from the practices of primary care providers and otolaryngologists. The derived survey instrument then underwent prospective testing in patients with acute sinusitis, chronic sinusitis, allergic rhinitis, and asymptomatic controls. Reduced item scales of the original instrument were developed for symptom frequency and bothersomeness. The psychometric properties of the survey instrument were evaluated for reliability, construct validity, responsiveness, and interpretability. Results: In the prospective study, 47 patients with acute sinusitis and 50 patients with chronic sinusitis were compared to 18 patients with allergic rhinitis and 60 patients without nasal symptoms. Forty-three (91.5) patients with acute sinusitis completed the questionnaire at baseline and at 1-month follow-up. Internal consistency was high for the symptom impact scale for acute and chronic sinusitis patients. The symptom frequency and especially bothersomeness scales had lower internal consistency particularly for acute sinusitis patients. Reproducibility among surgical patients retested prior to their procedure was good for each scale. A high degree of disciminant validity was demonstrated when comparing sinusitis patients to other groups, and a high degree of convergent validity was seen when the new measures were compared to other HRQL measures at baseline. Among patients with acute sinusitis, the responsiveness and interpretability of the symptom frequency, bothersomeness and impact scales were excellent. Conclusions: This study developed and validated a new sinusitis-specific HRQL instrument. The instrument included symptom frequency, bothersomeness and impact scales. It was shown to be valid in patients with acute and chronic sinusitis, and highly responsive and interpretable in acute sinusitis patients managed in the primary care setting.