Construct Validity of the Patient‐Reported Outcomes Measurement Information System Gastrointestinal Symptom Scales in Systemic Sclerosis

Abstract

Objective Gastrointestinal (GI) involvement is common in patients with systemic sclerosis (SSc). The Patient-Reported Outcomes Measurement Information System (PROMIS®) GI Symptom item bank captures upper and lower GI symptoms (reflux, disrupted swallowing, nausea/vomiting, belly pain, gas /bloating /flatulence, diarrhea, constipation, and fecal incontinence). The objective of this study was to evaluate the construct validity of the PROMIS-GI bank in SSc. Methods 167 patients with SSc were administered the PROMIS GI bank and the UCLA Scleroderma Clinical Trials Consortium Gastrointestinal Scale (GIT 2.0) instrument. GIT 2.0 is a multi-item instrument that measures SSc-associated GI symptoms. Product-moment correlations and a multitrait-multimethod analysis of the PROMIS GI scales with the GIT 2.0 symptom scales were used to evaluate convergent and discriminant validity. Results Patients with SSc GI involvement had PROMIS GI scale scores 0.2–0.7 SD worse than US population. Correlations among scales measuring the same domains for the PROMIS GI and GIT 2.0 measures were large, ranging from 0.61 to 0.87 (average r = 0.77). The average correlation between different symptom scales was 0.22, supporting discriminant validity. Conclusion This study provides support for the construct validity of the PROMIS GI scales in SSc. Future research is needed to assess the responsiveness to change of these scales in patients with SSc.

An Update of Outcome Measures in Systemic Sclerosis

“…Cronbach’s coefficient α was more than 0.70 for all scales, demonstrating good internal consistency reliability in SSc (36,37).…”

Review article: pathogenesis and clinical manifestations of gastrointestinal involvement in systemic sclerosis

“…Compared to GIT 2.0, the PROMIS GI bank has additional scales for disrupted swallowing and nausea/vomiting. A recent study comparing PROMIS to the legacy instrument GIT 2.0 in SSc revealed large correlation and demonstrated satisfactory reliability amongst the two scales . PROMIS instruments have an added advantage of reduction in respondent burden, easy comprehensibility and usability across diverse populations.…”

Prevalence and Burden of Illness of Rome IV Chronic Idiopathic Constipation, Opioid-Induced Constipation, and Opioid-Exacerbated Constipation in the United States

“…Third, our study population largely resembled the general US population for demographics and was not limited to patients being seen in health care settings indicating that our results are generalizable and less susceptible to the Berkson bias—a form of selection bias that may result in false correlations due to only including patients in health care settings. Fourth, our use of the validated Rome IV questionnaires (5) and GI PROMIS scales (9–11) allowed us to objectively quantify and compare constipation symptom severity among those with CIC, OIC, and OEC.…”