The impacts of migraine on functioning: Results from two qualitative studies of people living with migraine.

OBJECTIVE: To describe the impact of migraine on functioning based on comprehensive data collection, analysis, and reporting of patients' experiences. BACKGROUND: Qualitative research conducted to understand patients' perspectives on living with migraine has often focused on narrow topics or specific groups of patients or has been selectively reported. METHODS: Qualitative interviews with 71 participants were conducted during two concept elicitation studies as part of the Migraine Clinical Outcome Assessment System (MiCOAS) project, an FDA grant-funded program designed to develop a core set of patient-centered outcome measures for migraine clinical trials. Participants self-reported being diagnosed with migraine by a healthcare professional and participated in semi-structured qualitative interviews about their experiences with the symptoms and impacts of migraine. Interview transcripts were coded to identify and define concepts, which were then grouped into broad domains based on conceptual similarities. RESULTS: A total of 66 concepts were identified: 12 for physical functioning, 16 for cognitive functioning, 10 for social role functioning, 19 for emotional and psychological functioning, and 9 related to migraine management. Participants described a complex and varied relationship between migraine attack symptoms and impacts on functioning. Impacts from migraine were further influenced by numerous contextual factors, such as people's individual social environments and the level of day-to-day demand for functioning they face. CONCLUSION: Findings showed that migraine impacted individual functioning in multiple ways and the nature of these impacts was dependent on social-contextual factors. The results are being used in the development of core measures designed to improve our understanding of the burden of migraine and the efficacy of migraine therapies. The results also offer new insights and raise new questions about migraine experience that can be used to guide future research.

Priority acute and preventive migraine treatment benefits: Results of the Migraine Clinical Outcome Assessment System (MiCOAS) qualitative study of people living with migraine.

BACKGROUND: There is renewed emphasis on including patients in determining, defining, and prioritizing outcomes for migraine treatment. OBJECTIVES: To obtain insights directly from people living with migraine on their priorities for treatment. METHODS: A total of 40 qualitative interviews were conducted as part of the Migraine Clinical Outcome Assessment System project, a United States Food and Drug Administration grant-funded program to develop a core set of patient-centered outcome measures for migraine clinical trials. Interviews included a structured exercise in which participants rank-ordered pre-defined lists of potential benefits for acute and preventive migraine therapy. The 40 study participants who reported being diagnosed with migraine by a clinician ranked the benefits and explained their rationale. RESULTS: Study participants consistently ranked either pain relief or absence of pain as their top priority for acute treatment. Relief/absence of other migraine symptoms and improved functioning were also prioritized. For preventive treatment, participants prioritized reductions in migraine frequency, symptom severity, and attack duration. Few differences were found between participants with episodic migraine and those with chronic migraine. However, participants with chronic migraine ranked "increased predictability of attacks" much higher than those with episodic migraine. Participants' rankings were influenced by prior expectations and experiences of migraine treatments, which caused many participants to deprioritize desired benefits as unrealistic. Participants also identified several additional priorities, including limited side-effects and reliable treatment efficacy in both acute and preventive treatments. CONCLUSION: The results showed the participants prioritized treatment benefits aligned with existing core clinical outcomes used in migraine research, but also valued benefits that are not typically assessed, such as predictability. Participants also deprioritized important benefits when they believed treatment was unlikely to deliver those outcomes.

Patient-reported experiences with migraine-related cognitive symptoms: Results of the MiCOAS qualitative study.

OBJECTIVES: To capture patients' perspectives on migraine-related cognitive symptoms during pre-headache, headache, post-headache, and interictal periods. BACKGROUND: Migraine-related cognitive symptoms are reported by people with migraine both during and between attacks. Associated with disability, they are increasingly viewed as a priority target for treatment. The Migraine Clinical Outcome Assessment System (MiCOAS) project is focused on developing a patient-centered core set of outcome measures for the evaluation of migraine treatments. The project focuses on incorporating the experience of people living with migraine and the outcomes most meaningful to them. This includes an examination of the presence and functional impact of migraine-related cognitive symptoms and their perceived impact on quality of life and disability. METHODS: Forty individuals with self-reported medically diagnosed migraine were recruited via iterative purposeful sampling for semi-structured qualitative interviews conducted using audio-only web conferencing. Thematic content analysis was performed to identify key concepts around migraine-related cognitive symptoms. Recruitment continued until concept saturation was achieved. RESULTS: Participants described symptoms consistent with migraine-related deficits in language/speech, sustained attention, executive function, and memory that manifest during pre-headache (36/40 [90%] reported ≥1 cognitive feature), headache (35/40 [88%] reported ≥1 cognitive feature), post-headache (27/40 [68%] reported ≥1 cognitive feature), and interictal periods (13/40 [33%] reported ≥1 cognitive feature). Among participants reporting cognitive symptoms during pre-headache, 32/40 (81%) endorsed 2-5 cognitive symptoms. Findings were similar during the headache phase. Participants reported language/speech problems consistent with, for example, impairments in receptive language, expressive language, and articulation. Issues with sustained attention included fogginess, confusion/disorientation, and trouble with concentration/focus. Deficits in executive function included difficulty processing information and reduced capacity for planning and decision-making. Memory issues were reported across all phases of the migraine attack. CONCLUSIONS: This patient-level qualitative study suggests that cognitive symptoms are common for persons with migraine, particularly in the pre-headache and headache phases. These findings highlight the importance of assessing and ameliorating these cognitive problems.

Measuring headache day severity using multiple features in daily diary designs.

OBJECTIVE: Though migraine is thought of as a symptom complex, symptoms are typically assessed one at a time. For use in clinical research, we developed a composite measure of headache day severity by combining eight well-known symptoms captured in daily diaries. SUBJECTS AND METHODS: Data came from adults with a self-reported diagnosis of migraine (n = 4380) who provided daily diary information assessed using a novel digital platform. Nine observed features theoretically linked to headache day severity were analyzed using latent variable modeling to create a psychometrically robust headache day severity score. Logistic regression was used to assess the cross-sectional relationships of headache day severity scores against an array of clinically-relevant outcomes. RESULTS: Participants were largely females (90%), approaching middle age (mean age of 37.3) and living in the United States (49%) or United Kingdom (23%). Findings supported a single latent headache day severity construct based on eight observed headache features. Headache day severity scores were associated with an increased odds of physician visits (Odds ratio[95% CI]: 1.71[1.32-2.21]), emergency department visits (4.12[2.23-7.60]), missed school/work (2.90[2.56-3.29]), missed household work (3.37[3.06-3.72]), and missed other activities (3.29[2.97-3.64]) (p < .0001 for all). CONCLUSIONS: Modern measurement techniques support a single headache day severity construct that reflects migraine is a symptom complex. The headache day severity scores were associated with external validators and initial visualizations showed how headache day severity scores can be applied broadly in clinical practice and research.

What do people want to know about "Growing Up with Migraine"? Results of a preference survey of people with lived experience to guide future research.

In recent years, emphasis has been placed on conducting headache research that is patient-centered to more explicitly incorporate the input of people who live with headache diseases. The Growing Up with Migraine Study was developed with this intention using a two-step process: 1. develop and administer a survey to identify research areas that matter most to people with adolescent migraine and/or their caregivers and 2. use the survey results to guide future secondary data analyses. This brief report summarizes the survey results from 373 individuals impacted by adolescent migraine. Findings suggested that people with history of adolescent migraine and/or their caregivers are most interested in research about migraine comorbidities and effects on psychological/social/emotional health, along with health-related outcomes and family-related topics. Future quantitative studies are planned that will explore these patient-identified priorities through secondary data analysis of an existing dataset.

Evaluating the clinical utility of the patient-identified most bothersome symptom measure from PROMISE-2 for research in migraine prevention.

OBJECTIVE: To assess the utility of the novel patient-identified (PI) most bothersome symptom (MBS) measure from PROMISE-2, a phase 3 trial of eptinezumab for the preventive treatment of chronic migraine. BACKGROUND: Relief of bothersome migraine symptoms can influence satisfaction with treatment and therapeutic persistence. Understanding the impact of preventive treatment on a PI-MBS could improve clinical decision-making. METHODS: In PROMISE-2, patients with chronic migraine received eptinezumab 100, 300 mg, or placebo administered intravenously every 12 weeks for up to 2 doses (n = 1072). PI-MBS was an exploratory outcome requiring each patient to self-report their MBS in response to an open-ended question. At baseline and week 12, patients rated overall improvement in PI-MBS. The relationships among PI-MBS at week 12 and change in monthly migraine days (MMDs) from baseline to month 3 (weeks 9-12), Patient Global Impression of Change at week 12, and changes from baseline to week 12 in the 6-item Headache Impact Test total, EuroQol 5-dimensions 5-levels visual analog scale, and 36-item Short-Form Health Survey component scores were assessed. RESULTS: Treatment groups had similar baseline characteristics and reported a total of 23 unique PI-MBS, most commonly light sensitivity (200/1072, 18.7%), nausea/vomiting (162/1072, 15.1%), and pain with activity (147/1072, 13.7%). Improvements in PI-MBS at week 12 correlated with changes in MMDs (ρ = -0.49; p < 0.0001) and other patient-reported outcomes. Controlling for changes in MMDs, PI-MBS improvement predicted other patient-reported outcomes in expected directions. The magnitude of the standardized mean differences between placebo and active treatment for PI-MBS were 0.31 (p < 0.0001 vs. placebo) and 0.54 (p < 0.0001 vs. placebo) for eptinezumab 100 and 300 mg, respectively. CONCLUSIONS: Improvement in PI-MBS at week 12 was associated with improvement in other patient-reported outcome measures, and PI-MBS may be an important patient-centered measure of treatment benefits in patients with chronic migraine.

Impact of the COVID-19 pandemic on people living with migraine: Results of the MiCOAS qualitative study.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is an ongoing global health crisis that has had a range of impacts on people living with migraine. METHODS: Qualitative interviews performed as part of the Migraine Clinical Outcome Assessment System project, a multi-stage Food and Drug Administration-grant funded program to develop a patient-centered core set of outcome measures for use in migraine clinical trials, offered an opportunity to explore the experience of living with migraine during the pandemic as well as to examine whether migraine treatment priorities, symptoms, and associated disability changed due to the pandemic. Semi-structured interviews were conducted in the United States between the summer and fall of 2020 with 40 individuals with self-reported, medically diagnosed migraine who self-reported that they had not tested positive for or been diagnosed with COVID-19. RESULTS: Seventy percent (n = 28) of the sample reported ≥1 pandemic-related impact on their life with migraine. Fourteen participants reported both positive and negative impacts, twelve reported negative impacts only, and two reported positive impacts only. Among those reporting ≥1 pandemic-related impact, nine participants (32%) reported more frequent and five (17%) reported less frequent migraine attacks. Other negative impacts included interrupted medical care (n = 9; 32%), and greater stress (n = 13; 46%). The most frequent positive impact reported was greater access to health care (n = 8; 29%). Ictal and interictal symptoms were not noted to change due to the pandemic, but some respondents reported less disability due to increased flexibility of schedules and reduced expectations. Treatment priorities did not change due to the pandemic. CONCLUSION: The global COVID-19 pandemic has resulted in both negative and positive impacts for people living with migraine. Lessons to be considered when moving into a post-pandemic world include benefits of and satisfaction with telehealth and the benefits and importance of healthy lifestyle habits and flexibility such as improved sleep, reduced stress, and fewer social expectations.

Using validity theory and psychometrics to evaluate and support expanded uses of existing scales.

BACKGROUND: Scale development is a complex activity requiring significant investments of time and money to produce evidence of a scale's ability to produce reliable scores and valid inferences. With increasing use of clinical outcome assessments (COAs) in medical product development, evidentiary expectations of regulatory bodies to support inferences are a key consideration. The goal of this paper is to demonstrate how existing methods in measurement science can be used to identify and fill evidence gaps when considering re-purposing an existing scale for a new use case (e.g., new patient population, altering the recall period), rather than creating a new COA tool. METHODS: We briefly review select validity theory and psychometric concepts, linking them to the nomenclature in the COA/regulated space. Four examples (two in-text and two in online supplemental materials) of modifications are presented to demonstrate these ideas in practice for quality of life (QOL)-related measures. RESULTS: Each example highlights the initial process of evaluating the desired validity claims, identifying gaps in evidence to support these claims, and determining how such gaps could be filled, often without having to develop a new measure. CONCLUSIONS: If an existing scale, with minimal modification or additional evidence, can be shown to be fit for a new purpose, considerable effort can be saved and research waste avoided. In many cases, a new instrument is simply unnecessary. Far better to recycle an "old" scale for a new use-with sufficient evidence that it is fit for that purpose-than to "buy" a new one.

Systematic review of outcomes and endpoints in acute migraine clinical trials.

BACKGROUND/OBJECTIVE: To review the acute migraine clinical trial literature and provide a summary of the endpoints and outcomes used in such trials. METHOD: A systematic literature review, following a prespecified (but unregistered) protocol developed to adhere to recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, was conducted to understand endpoints and outcomes used in acute migraine clinical trials. Predefined terms were searched in PubMed to locate clinical trials assessing acute migraine treatments. Final database search was conducted on October 28, 2019. Identified publications were reviewed against established inclusion and exclusion criteria to determine eligibility. Data related to general trial design characteristics, sample characteristics, and outcomes and endpoints reported in each publication were extracted from eligible publications. Descriptive summaries of design features, sample characteristics, and the endpoints and outcomes employed across publications were constructed. Outcomes are presented within four broad categories: (a) pain-related outcomes (pain relief, pain freedom, etc.), (b) associated symptoms (nausea, photophobia, etc.), (c) disability/impairment/impact, (d) patient-reported outcome measures (PROMs, general health and migraine/headache-specific). Endpoint types were categorized within three broad categories: (a) change from baseline, (b) fixed timepoint, and (c) responder definitions (e.g., 50% reduction). This review focuses on a subset of recent (1998 or later) randomized and blinded publications evaluating drugs or medical devices. RESULTS: Of 1567 publications found through the initial search and reference section reviews, 705 met criteria and were included for data extraction. Inter-rater agreement kappas for the descriptive variables extracted had an average kappa estimate of 0.86. The more recent, randomized and blinded pharmaceutical and medical device article subset includes 451 publications (451/705, 63.9%). The outcomes and endpoints varied substantially across trials, ranging from pain relief or freedom, freedom from or relief of migraine-associated symptoms, use of acute or rescue medication, and various other PROMs, including measures of satisfaction and quality of life. Within the recent randomized and blinded article subset, most articles examined ≥1 pain-related outcome (430/451, 95.3%). Of the publications that examined pain, outcomes most often used were pain relief (310/430, 72.1%), pain freedom (279/430, 64.9%), and headache recurrence (202/43,051, 47.0%) or rescue medication use (278/430, 64.9%). Associated symptoms such as nausea, photophobia, and phonophobia were more frequently measured (299/451, 66.3%) compared to most bothersome associated symptom (16/451, 3.5%), as it is a new addition to regulatory guidance. Over one-third of eligible publications examined disability/impairment (186/451, 41.2%) or ≥1 PROM (159/451, 35.3%). The definition of the endpoints used (e.g., change from baseline, fixed timepoint comparisons, categorization of "responders" to treatment based on wide variety of "responder definitions") also differed substantially across publications. CONCLUSION: Acute migraine clinical trials exhibit a large amount of variability in outcomes and endpoints used, in addition to the variability in how outcomes and endpoints were used from trial-to-trial. There were some common elements across trials that align with guidance from the International Headache Society, the Food and Drug Administration and other regulatory agencies (e.g., assessing pain and associated symptoms, 2-hour post-treatment). Other aspects of acute migraine clinical trial design did not follow guidance. For example, multi-item PROMs intended to measure constructs (e.g., scales) are rarely used, the use of pain-related outcomes is inconsistent, some associated symptom assessments are idiosyncratic, and the timing of the assessment of primary endpoints is variable. The development of a core set of outcomes and endpoints for acute migraine clinical trials that are patient-centered and statistically robust could improve the conduct of individual trials, facilitate cross-trial comparisons, and better support informed treatment decisions by healthcare professionals and patients.

Systematic review of outcomes and endpoints in preventive migraine clinical trials.

BACKGROUND: Over the last six decades (earliest included publication from 1959), clinical trials of migraine preventive treatments have led to the regulatory approval of many medications and devices. Despite similar clinical goals, the outcomes and endpoints used in these trials are broad and not well standardized. OBJECTIVE: To describe results from a systematic literature review focused on outcomes and endpoints used in preventive migraine clinical trials. METHOD: A systematic literature review, following a pre-specified (unregistered) protocol developed to adhere to recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, was conducted to characterize the endpoints and outcomes used in preventive migraine clinical trials. Predetermined terms were searched in PubMed on October 28, 2019. Data related to trial design, subject characteristics, outcomes, and endpoints reported in each publication were extracted. Descriptive summaries of these features were tabulated for the recent subset of publications, published during or after 1988, that were randomized, blinded, and focused on pharmacological or device therapies for the preventive treatment of migraine. RESULTS: The initial literature search identified 1506 publications, of which 757 publications were eligible for data extraction. Of specific clinical interest were the recent subset of 268 articles (268/757, 35.4%) fulfilling the targeted criteria. Results showed that the outcomes used to define endpoints varied substantially across publications. For example, in the recent subset of publications, 68.7% (184/268) of the publications examined ≥1 migraine-specific outcome, 39.6% (106/268) examined ≥1 headache-specific outcome, 50.7% (136/268) examined ≥1 acute/rescue medication use outcome, 40.3% (108/268) examined ≥1 headache-related patient-reported outcome measure (PROM), and 22.0% (59/268) examined ≥1 non-headache-specific PROM. Furthermore, the definition of the endpoints used (e.g., change from baseline, fixed timepoint comparisons, categorization of "responders" to treatment based on wide variety of "responder definitions") also differed across publications. CONCLUSION: Publications from clinical trials of preventive migraine pharmacologic and device treatments differed in terms of study design, endpoint definitions, and how endpoints and outcomes were measured. Although there were common outcomes and endpoints used across publications, no clear "standardized" set of endpoints and outcomes emerged. The inconsistencies in endpoints and outcomes within this literature suggest that the development of a uniform set of outcomes and endpoints could improve the clinical meaningfulness of clinical trial results, facilitate cross-trial comparisons and better inform patient care. This standard set of outcomes and endpoints should be statistically robust and informed by the priorities of various stakeholders, most importantly, the needs and preferences of people living with migraine.

Reliability and validity of the 6-item Headache Impact Test in chronic migraine from the PROMISE-2 study.

PURPOSE: We examined the reliability and validity of the 6-item Headache Impact Test (HIT-6) specifically on patients with chronic migraine (CM) from the PROMISE-2 clinical trial. METHODS: The conceptual framework of HIT-6 was evaluated using baseline data from the PROMISE-2 study (NCT02974153; N = 1072). A unidimensional graded response model within the item response theory (IRT) framework was used to evaluate model fit and item characteristics. Using baseline and week 12 data, convergent and discriminant validity of the HIT-6 was evaluated by correlation coefficients. Sensitivity to change was assessed by evaluating correlations between HIT-6 scores and change scores for other established reference measures. All examined correlations were specified a priori with respect to direction and magnitude. Known-groups analyses were anchored using Patient Global Impression of Change and monthly headache days at week 12. RESULTS: A unidimensional model fit the data well, supporting that the 6 items measure a single construct. All item slopes and thresholds were within acceptable ranges. In both the validity and sensitivity to change analyses, all observed correlations conformed to directional expectations, and most conformed to magnitude expectations. Known-groups analyses demonstrated that the HIT-6 total score can distinguish between clinically meaningful CM subgroups. CONCLUSION: The HIT-6 was successfully calibrated using IRT with data from PROMISE-2. Results from these analyses were generally consistent with previous literature and provided supportive evidence that the HIT-6 is well suited for measuring the impact of headache and migraine in the CM population.

Determining Thresholds for Meaningful Change for the Headache Impact Test (HIT-6) Total and Item-Specific Scores in Chronic Migraine.

OBJECTIVE: The objective of the analyses described here was to develop thresholds defining clinically meaningful response on the total and item scores of the 6-item short-form Headache Impact Test (HIT-6) in a population of patients with chronic migraine (CM). BACKGROUND: The HIT-6 is a short, easily understood, and useful measure of the impact of headache on daily life. Though widely used, limited literature supports a threshold value for clinically meaningful response within individuals over time for the HIT-6 total score and for the item scores, especially in the CM population. METHODS: PROMISE-2 is a randomized, double-blind, multicenter study comparing intravenous eptinezumab 100 and 300 mg with placebo for the preventive treatment of CM. Responder definitions for HIT-6 total and items scores using data from PROMISE-2 study were calculated via distribution-based and anchor-based methods. Distribution-based methods included half of the baseline standard deviation and baseline standard error of measurement. The change from baseline to week 12 in HIT-6 scores was assessed using the following anchors: patient global impression of change, reduction in migraine frequency, and change in EuroQol 5 dimensions 5 levels visual analog scale. Values from the literature and PROMISE-2 analyses were plotted against the cumulative distribution function of change values (baseline to week 12) and used to triangulate to empirically support clinically meaningful change definitions for the HIT-6 total and item scores in patients with CM. RESULTS: From the literature, 5 articles provided 7 candidate values for a responder threshold for the HIT-6 total score. From distribution- and anchor-based methods, 5 candidate values were derived from PROMISE-2 data. Using the median of all candidate values, a HIT-6 total score responder definition estimate of -6 (ie, ≥6-point improvement in the total score) appears most appropriate for discriminating between individuals with CM who have experienced meaningful change over time and those who have not. For item-level analyses using anchor-based methods, the responder definition for items 1-3 ("severe pain," "limits daily activities," and "lie down") was a 1-category improvement in response (eg, from Sometimes to Rarely); for items 4-6 ("too tired," "felt fed up or irritated," and "limits concentration"), a 2-category improvement in response (eg, from Always to Sometimes) was clinically meaningful. CONCLUSIONS: Using a multifaceted, statistically-based approach, the recommended responder definition for the HIT-6 total score in the CM population is a ≥6-point decrease, consistent with previous literature. Anchor-based item-level responder thresholds were defined as a decrease of 1 or 2 categories, depending on the item. These CM-specific values will provide researchers and clinicians a means to interpret clinically meaningful change in the HIT-6 total and item scores and may facilitate the measurement of treatment benefits in specific functional domains of the HIT-6.

Content Validity of HIT-6 as a Measure of Headache Impact in People With Migraine: A Narrative Review.

BACKGROUND: The short-form Headache Impact Test (HIT-6) is a widely used patient-reported outcome measure that assesses the negative effects of headaches on normal activity. It was developed using the general headache population and prior to the establishment of the now well-accepted FDA patient-reported guidance. OBJECTIVE: The objective of this narrative review was to examine existing qualitative research in patients with migraine and headache, providing insight into the relevance and meaningfulness of HIT-6 items to the lives of migraine patients. METHODS: Articles were identified through database searches (National Library of Medicine and Google Scholar) and review of reference lists of candidate articles. RESULTS: A total of 3227 articles were identified through database and hand searching. Of these, 12 contained patient- or expert-generated qualitative information regarding headache patients' experience (8 specific to migraine [episodic and chronic] patients and 4 citing general headache patients). The combined publications described a total of 283 patient interviews. Overarching themes and specific information were identified that provide support of the relevance of content for each HIT-6 item to migraine patients' lives. Identified effects of headaches on patients with migraine included limitations in daily activities, needing to lie down during headaches, feeling tired, being irritated by headaches, difficulty concentrating, and the experience of pain. Further, previous research specific to the HIT-6 indicated that patients understood the instructions, items, and response scales as intended by the instrument authors. CONCLUSIONS: This narrative literature review demonstrates qualitative research support for the relevance of the items of the HIT-6 in migraine patients, supporting its ongoing use in clinical migraine research and practice.

Growth Curves for Headache Research: A Multilevel Modeling Perspective.

OBJECTIVE: To introduce growth curve modeling for longitudinal headache research. BACKGROUND: Longitudinal data play an important role in the study of headache-related outcomes by allowing researchers to test hypotheses about change over time. However, headache researchers are often unfamiliar with the flexibility and power that growth curves can offer in analyzing longitudinal data. The goals of this paper are to introduce growth curve models within the multilevel modeling framework for analyzing longitudinal headache-related data and to show how these models can be applied in practice. METHODS: Longitudinal data for the empirical example came from publicly available data from Wave I to Wave IV of the National Longitudinal Study of Adolescent to Adult Health. In total, 5608 individuals were included in the study and multilevel models were fit to examine, for individuals with and without adolescent migraine, longitudinal changes in depression from age 13 to 27 years old. RESULTS: Findings showed that individuals varied in their longitudinal depression trajectories. A cubic time trend best approximated the data with depression increasing through adolescence, decreasing during young adulthood, and then beginning to increase again in adulthood. Further, results also indicated that individuals with adolescent migraine had higher levels of depression throughout the age span compared those without adolescent migraine, but the shape of change did not differ across the groups. CONCLUSION: Growth curve models offer a flexible alternative to traditional statistical methods and can rigorously evaluate a wide array of headache-related hypotheses.

Measurement invariance, the lack thereof, and modeling change.

PURPOSE: Measurement invariance issues should be considered during test construction. In this paper, we provide a conceptual overview of measurement invariance and describe how the concept is implemented in several different statistical approaches. Typical applications look for invariance over things such as mode of administration (paper and pencil vs. computer based), language/translation, age, time, and gender, to cite just a few examples. To the extent that the relationships between items and constructs are stable/invariant, we can be more confident in score interpretations. METHODS: A series of simulated examples are reported which highlight different kinds of non-invariance, the impact it can have, and the effect of appropriately modeling a lack of invariance. One example focuses on the longitudinal context, where measurement invariance is critical to understanding trends over time. Software syntax is provided to help researchers apply these models with their own data. RESULTS: The simulation studies demonstrate the negative impact an erroneous assumption of invariance may have on scores and substantive conclusions drawn from naively analyzing those scores. CONCLUSIONS: Measurement invariance implies that the links between the items and the construct of interest are invariant over some domain, grouping, or classification. Examining a new or existing test for measurement invariance should be part of any test construction/implementation plan. In addition to reviewing implications of the simulation study results, we also provide a discussion of the limitations of current approaches and areas in need of additional research.

Scale development with small samples: a new application of longitudinal item response theory.

PURPOSE: Measurement development in hard-to-reach populations can pose methodological challenges. Item response theory (IRT) is a useful statistical tool, but often requires large samples. We describe the use of longitudinal IRT models as a pragmatic approach to instrument development when large samples are not feasible. METHODS: The statistical foundations and practical benefits of longitudinal IRT models are briefly described. Results from a simulation study are reported to demonstrate the model's ability to recover the generating measurement structure and parameters using a range of sample sizes, number of items, and number of time points. An example using early-phase clinical trial data in a rare condition demonstrates these methods in practice. RESULTS: Simulation study results demonstrate that the longitudinal IRT model's ability to recover the generating parameters rests largely on the interaction between sample size and the number of time points. Overall, the model performs well even in small samples provided a sufficient number of time points are available. The clinical trial data example demonstrates that by using conditional, longitudinal IRT models researchers can obtain stable estimates of psychometric characteristics from samples typically considered too small for rigorous psychometric modeling. CONCLUSION: Capitalizing on repeated measurements, it is possible to estimate psychometric characteristics for an assessment even when sample size is small. This allows researchers to optimize study designs and have increased confidence in subsequent comparisons using scores obtained from such models. While there are limitations and caveats to consider when using these models, longitudinal IRT modeling may be especially beneficial when developing measures for rare conditions and diseases in difficult-to-reach populations.

A review of empirical research related to the use of small quantitative samples in clinical outcome scale development.

INTRODUCTION: There has been a notable increase in the advocacy of using small-sample designs as an initial quantitative assessment of item and scale performance during the scale development process. This is particularly true in the development of clinical outcome assessments (COAs), where Rasch analysis has been advanced as an appropriate statistical tool for evaluating the developing COAs using a small sample. METHODS: We review the benefits such methods are purported to offer from both a practical and statistical standpoint and detail several problematic areas, including both practical and statistical theory concerns, with respect to the use of quantitative methods, including Rasch-consistent methods, with small samples. CONCLUSIONS: The feasibility of obtaining accurate information and the potential negative impacts of misusing large-sample statistical methods with small samples during COA development are discussed.

Development of the Contact Lens User Experience: CLUE Scales.

PURPOSE: The field of optometry has become increasingly interested in patient-reported outcomes, reflecting a common trend occurring across the spectrum of healthcare. This article reviews the development of the Contact Lens User Experience: CLUE system designed to assess patient evaluations of contact lenses. CLUE was built using modern psychometric methods such as factor analysis and item response theory. METHODS: The qualitative process through which relevant domains were identified is outlined as well as the process of creating initial item banks. Psychometric analyses were conducted on the initial item banks and refinements were made to the domains and items. Following this data-driven refinement phase, a second round of data was collected to further refine the items and obtain final item response theory item parameters estimates. RESULTS: Extensive qualitative work identified three key areas patients consider important when describing their experience with contact lenses. Based on item content and psychometric dimensionality assessments, the developing CLUE instruments were ultimately focused around four domains: comfort, vision, handling, and packaging. Item response theory parameters were estimated for the CLUE item banks (377 items), and the resulting scales were found to provide precise and reliable assignment of scores detailing users' subjective experiences with contact lenses. CONCLUSIONS: The CLUE family of instruments, as it currently exists, exhibits excellent psychometric properties.

Attitudes about hypnosis: factor analyzing the VSABTH-C with an American sample.

In the present study, the authors factor-analyzed responses from 1,141 American undergraduate students to the Valencia Scale of Attitudes and Beliefs Toward Hypnosis-Client Version. They obtained an 8-factor solution accounting for 66% of the total variance in responses. A confirmatory factor analysis indicated acceptable fit of their model and those reported earlier by Carvalho et al. (2007) and Capafons, Mendoza, et al. (2008) using Portuguese and international samples, respectively. Unlike previous factor analyses of the scale, the authors obtained an independent clusters solution. Distinctions between the authors' model and those reported previously are discussed.

Psychometric performance of the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) in a randomized, double-blind, placebo-controlled crossover study in subjects with mitochondrial disease.

BACKGROUND: The Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) is a 10-item patient-reported outcome (PRO) measure designed to assess the severity of mitochondrial disease symptoms. Analyses of data from a clinical trial with PMM patients were conducted to evaluate the psychometric properties of the PMMSA and to provide score interpretation guidelines for the measure. METHODS: The PMMSA was completed as a daily diary for approximately 14 weeks by individuals in a Phase 2 randomized, placebo-controlled crossover trial evaluating the safety, tolerability, and efficacy of subcutaneous injections of elamipretide in patents with mitochondrial disease. In addition to the PMMSA, performance-based assessments, clinician ratings, and other PRO measures were also completed. Descriptive statistics, psychometric analyses, and score interpretation guidelines were evaluated for the PMMSA. RESULTS: Participants (N = 30) had a mean age of 45.3 years, with the majority of the sample being female (n = 25, 83.3%) and non-Hispanic white (n = 29, 96.6%). The 10 PMMSA items assessing a diverse symptomology were not found to form a single underlying construct. However, four items assessing tiredness and muscle weakness were grouped into a "general fatigue" domain score. The PMMSA Fatigue 4 summary score (4FS) demonstrated stable test-retest scores, internal consistency, correlations with the scores produced by reference measures, and the ability to differentiate between different global health levels. Changes on the PMMSA 4FS were also related to change scores produced by the reference measures. PMMSA severity scores were higher for the symptom rated as "most bothersome" by each subject relative to the remaining nine PMMSA items (most bothersome symptom mean = 2.88 vs. 2.18 for other items). Distribution- and anchor-based evaluations suggested that reduction in weekly scores between 0.79 and 2.14 (scale range: 4-16) may represent a meaningful change on the PMMSA 4FS and reduction in weekly scores between 0.03 and 0.61 may represent a responder for each of the remaining six non-fatigue items, scored independently. CONCLUSIONS: Upon evaluation of its psychometric properties, the PMMSA, specifically the 4FS domain, demonstrated strong reliability and construct-related validity. The PMMSA can be used to evaluate treatment benefit in clinical trials with individuals with PMM. Trial registration ClinicalTrials.gov identifier, NCT02805790; registered June 20, 2016; https://clinicaltrials.gov/ct2/show/NCT02805790 .