Background: Gastrointestinal (GI) complications are frequently reported postrenal transplant and are often associated with immunosuppressant regimens including mycophenolate mofetil (MMF). This study evaluated the ability of two GI-specific patient-reported outcome (PRO) instruments to differentiate between patients with and without GI complaints.
Methods: Discriminant validity of the Gastrointestinal Symptom Rating Scale (GSRS) and Gastrointestinal Quality of Life Index (GIQLI), as well as two generic instruments (Psychological General Well-Being Index (PGWB) and EQ-5D, was assessed in a multinational study of renal transplant recipients. Patients received therapy that included a calcineurin inhibitor and MMF. Both t-tests and ANOVAs were used to examine differences between patients with and without GI complaints, among levels of severity, and between patients reporting presence/absence of specific GI side effects.
Results: Of 96 patients recruited (56% male), 43% had none, 39% mild, 13% moderate, and 6% severe GI symptoms. All GSRS subscales and the GIQLI total and four of the five subscale scores significantly differentiated between patients with/without GI complications (P < .05). The PGWB total score and three subscales, the EQ-5D significantly differentiated between the two groups (P < .05). Only GI-specific instruments discriminated between some severity levels; for example, the GSRS abdominal pain subscale discriminated between patients at all levels of severity (P < .05). The GIQLI total score and symptoms subscale differentiated between patients with no symptoms and those with mild or moderate or severe symptoms (P < .05).
Conclusions: The GSRS and GIQLI differentiated between patients with/without GI side effects and by symptom severity better than did generic instruments, demonstrating excellent discriminant ability in this population.