Validity of two new patient-reported outcome measures in systemic sclerosis: Patient-Reported Outcomes Measurement Information System 29-item Health Profile and Functional Assessment of Chronic Illness Therapy-Dyspnea short form

Systemic sclerosis (SSc)/scleroderma is a rare, chronic connective tissue disease that causes skin and internal organ fibrosis, production of autoantibodies and deregulation of vascular homeostasis. Given the systemic nature of the disease, SSc can greatly impact quality of life(1). Accepted SSc clinical trial outcomes include assessment of functional, laboratory and radiographic disease markers, and patient reported outcomes (PRO). A PRO instrument is a patient-completed questionnaire that assesses a symptom or functional limitation. A multitude of PRO instruments including the St. George’s Respiratory Questionnaire (SGRQ)(2), Short-Form-36 (SF-36)(3), Health Assessment Questionnaire-Disability Index (HAQ-DI)(3, 4), Medical Research Council (MRC) Dyspnea Score, and others have been developed, validated in SSc (as indicated) and used to assess treatment response in SSc clinical trials. However, the lack of a standardized and uniformly scored set of PRO instruments to measure various SSc manifestations complicates between-study comparisons and interpretation of PRO results. In order to address this impediment to SSc and other disease-focused research, the National Institutes of Health (NIH) established the Patient Reported Outcomes Measurement Information System/PROMIS (www.nihpromis.org). The PROMIS is a network of NIH-funded research sites and coordinating centers working collaboratively to develop a series of dynamic tools to reliably and validly measure PROs(5). In 2004, PROMIS investigators developed a plan to create a bank of PRO items and short forms that could be used by all investigators conducting patient-oriented research. Multidimensional scales including PROMIS-29 Health Profile (PROMIS-29), and symptom-specific instruments such as the Functional Assessment of Chronic Illness Therapy (FACIT)-Dyspnea short form were created in English and Spanish. PROMIS-29 and FACIT-Dyspnea were validated in the general US, and chronic obstructive pulmonary disease (COPD) populations respectively, and were standardized using a T-score metric with a mean set to 50 (standard deviation=10) to ensure simple scoring and interpretable results(6–8). The purpose of the study was to assess the construct validity for discriminative purposes of the PROMIS-29 and FACIT-Dyspnea for the measurement of general health and dyspnea in SSc. We hypothesized that these new instruments to assess global health and dyspnea would perform as well as legacy instruments (SGRQ, MRC Dyspnea Score, HAQ-DI, SF-36) that have been used in SSc clinical trials. The benefit of the new instruments is that they are available in multiple languages (English and Spanish), free, and simple to administer, score and interpret.