Composite scores in comparative effectiveness research: counterbalancing parsimony and dimensionality in patient-reported outcomes

Clinical research challenges posed by difficult-to-treat depression

Approximately one-third of individuals in a major depressive episode will not achieve sustained remission despite multiple, well-delivered treatments. These patients experience prolonged suffering and disproportionately utilize mental and general health care resources. The recently proposed clinical heuristic of 'difficult-to-treat depression' (DTD) aims to broaden our understanding and focus attention on the identification, clinical management, treatment selection, and outcomes of such individuals. Clinical trial methodologies developed to detect short-term therapeutic effects in treatment-responsive populations may not be appropriate in DTD. This report reviews three essential challenges for clinical intervention research in DTD: (1) how to define and subtype this heterogeneous group of patients; (2) how, when, and by what methods to select, acquire, compile, and interpret clinically meaningful outcome metrics; and (3) how to choose among alternative clinical trial design options to promote causal inference and generalizability. The boundaries of DTD are uncertain, and an evidence-based taxonomy and reliable assessment tools are preconditions for clinical research and subtyping. Traditional outcome metrics in treatment-responsive depression may not apply to DTD, as they largely reflect the only short-term symptomatic change and do not incorporate durability of benefit, side effect burden, or sustained impact on quality of life or daily function. The trial methodology will also require modification as trials will likely be of longer duration to examine the sustained impact, raising complex issues regarding control group selection, blinding and its integrity, and concomitant treatments.

Health-related quality of life in glomerular disease

There is scant literature describing the effect of glomerular disease on health-related quality of life (HRQOL). The Cure Glomerulonephropathy study (CureGN) is an international longitudinal cohort study of children and adults with four primary glomerular diseases (minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and IgA nephropathy). HRQOL is systematically assessed using items from the Patient-Reported Outcomes Measurement Informative System (PROMIS). We assessed the relationship between HRQOL and demographic and clinical variables in 478 children and 1115 adults at the time of enrollment into CureGN. Domains measured by PROMIS items included global assessments of health, mobility, anxiety, fatigue, and sleep impairment, as well as a derived composite measure incorporating all measured domains. Multivariable models were created that explained 7 to 32% of variance in HRQOL. Patient-reported edema consistently had the strongest and most robust association with each measured domain of HRQOL in multivariable analysis (adjusted β [95% CI] for composite PROMIS score in children, -5.2 [-7.1 to -3.4]; for composite PROMIS score in adults, -6.1 [-7.4 to -4.9]). Female sex, weight (particularly obesity), and estimated glomerular filtration rate were also associated with some, but not all, domains of HRQOL. Primary diagnosis, disease duration, and exposure to immunosuppression were not associated with HRQOL after adjustment. Sensitivity analyses and interaction testing demonstrated no significant association between disease duration or immunosuppression and any measured domain of HRQOL. Thus, patient-reported edema has a consistent negative association with HRQOL in patients with primary glomerular diseases, with substantially greater impact than other demographic and clinical variables.

Refining a Web-based goal assessment interview: item reduction based on reliability and predictive validity

BACKGROUND

Goals are an important basis for patients' cognitive appraisal processes underlying quality-of-life (QOL) assessment because they are the foundation to one's frame of reference. We sought to identify the best of six goal delineation items and relevant themes for two new versions of the QOL Appraisal Profile: an interview tool using a subset of the best open-ended goal delineation items, and a shorter close-ended version for use in survey research.

METHODS

This is a secondary analysis of longitudinal data (n = 1126) of participants in the North American Research Committee on Multiple Sclerosis (MS) registry. The open-ended data were coded by at least two trained coders with moderately high inter-rater agreement. There were 31 themes reflecting goal content such as health, interpersonal, independence, mental health, and financial themes. Descriptive statistics identified most prevalent themes. Reliability analysis (alpha, item-total correlations) and hierarchical linear modeling identified the best goal items.

RESULTS

Based on these qualitative and quantitative analyses, Solve (item 2) is the best single item because it is clear anchor for about a third of the goal themes, and explains the most variance in outcomes and demographic characteristics, suggesting that it taps into and reveals diversity in the sample. The next best items are Accomplish and Maintain (items 1 and 4), which are useful in tapping into and revealing diversity among people reporting cognitive deficits (Accomplish), and demographic factors (both Accomplish and Maintain items).

CONCLUSIONS

The goal delineation items identified as best performers in this study will be used to develop a shorter open-ended version of the QOL Appraisal Profile, and an entirely close-ended version of the QOL Appraisal Profile for use in more standard survey research settings. These tools will enable coaching patients in medical decision making as well as investigations of appraisal and response shift in QOL research.