Psychometric validation of the SF-36<Superscript>®</Superscript> Health Survey in ulcerative colitis: results from a systematic literature review

Purpose

To conduct a systematic literature review of the reliability, construct validity, and responsiveness of the SF-36^® Health Survey (SF-36) in patients with ulcerative colitis (UC).

Methods

We performed a systematic search of electronic medical databases to identify published peer-reviewed studies which reported scores from the eight scales and/or two summary measures of the SF-36 collected from adult patients with UC. Study findings relevant to reliability, construct validity, and responsiveness were reviewed.

Results

Data were extracted and summarized from 43 articles meeting inclusion criteria. Convergent validity was supported by findings that 83% (197/236) of correlations between SF-36 scales and measures of disease symptoms, disease activity, and functioning exceeded the prespecified threshold (r ≥ |0.40|). Known-groups validity was supported by findings of clinically meaningful differences in SF-36 scores between subgroups of patients when classified by disease activity (i.e., active versus inactive), symptom status, and comorbidity status. Responsiveness was supported by findings of clinically meaningful changes in SF-36 scores following treatment in non-comparative trials, and by meaningfully larger improvements in SF-36 scores in treatment arms relative to controls in randomized controlled trials. The sole study of SF-36 reliability found evidence supporting internal consistency (Cronbach’s α ≥ 0.70) for all SF-36 scales and test–retest reliability (intraclass correlation coefficient ≥0.70) for six of eight scales.

Conclusions

Evidence from this systematic literature review indicates that the SF-36 is reliable, valid, and responsive when used with UC patients, supporting the inclusion of the SF-36 as an endpoint in clinical trials for this patient population.

     

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.

     

Use of Evidence-Based Interventions and Implementation Strategies to Increase Colorectal Cancer Screening in Federally Qualified Health Centers

While colorectal cancer (CRC) screening rates have been increasing in the general population, rates are considerably lower in Federally Qualified Health Centers (FQHCs), which serve a large proportion of uninsured and medically vulnerable patients. Efforts to screen eligible patients must be accelerated if we are to reach the national screening goal of 80% by 2018 and beyond. To inform this work, we conducted a survey of key informants at FQHCs in eight states to determine which evidence-based interventions (EBIs) to promote CRC screening are currently being used, and which implementation strategies are being employed to ensure that the interventions are executed as intended. One hundred and forty-eight FQHCs were invited to participate in the study, and 56 completed surveys were received for a response rate of 38%. Results demonstrated that provider reminder and recall systems were the most commonly used EBIs (44.6%) while the most commonly used implementation strategy was the identification of barriers (84.0%). The mean number of EBIs that were fully implemented at the centers was 2.4 (range 0–7) out of seven. Almost one-quarter of respondents indicated that their FQHCs were not using any EBIs to increase CRC screening. Full implementation of EBIs was correlated with higher CRC screening rates. These findings identify gaps as well as the preferences and needs of FQHCs in selecting and implementing EBIs for CRC screening.