Evaluating the impact of gastrointestinal episodes on the health-related quality of life of solid organ transplant recipients: sensitivity to change of the SIGIT-QoL questionnaire: Mypaciente-2 study

A significant proportion of transplant patients undergoing immunosuppressant therapy experience gastrointestinal (GI) symptoms. The SIGIT-QoL is a brief instrument developed to measure adverse gastrointestinal effects on patients' health-related quality of life (HRQoL). The goal of this study was to analyze the psychometric properties of the SIGIT-QoL that are required for its use in clinical research and practice, especially its value for detecting changes in the impact of gastrointestinal symptoms on HRQoL of solid organ transplant (SOT) recipients. To this end, an observational, multicenter, prospective study was conducted. SOT patients aged ≥18 years who had received the graft 3 to 24 months before and were experiencing gastrointestinal symptoms were evaluated at baseline, 1 to 2 weeks later, and 3 months after baseline. Sociodemographic and clinical data recorded included: age, sex, SOT type (lung, kidney, liver, or heart), acute allograft rejection, gastrointestinal etiology, Clinical Global Impressions (CGI) and Patient Global Impression (PGI) Severity of Illness (SI) and Global Improvement (GI) scores, and the SIGIT-QoL (scores range from 0 [maximum impact] to 68 [minimum disruption]). Intraclass correlation coefficients, differences between baseline and last visit (Wilcoxon test), effect size (Cohen's d), the minimal important differences (using CGI and PGI scores as anchors in General Linear Models), and the cutoff score (receiver-operating characteristic analysis) were calculated. In total, 277 SOT patients (61.4% male) were included. Mean ± SD age was 52.69 ± 11.65 years, time since transplantation was 12.31 ± 6.74 months, and 22.4% experienced an acute allograft rejection. At baseline, total SIGIT-QoL mean scores (51.21 ± 11.25) showed an impact on patients' HRQoL that was diminished 3 months later (57.40 ± 8.38; P < .001). SIGIT-QoL test-retest reliability was adequate (intraclass correlation coefficient, 0.740-0.895). A moderate effect size (d = -0.550) was found. Moreover, a minimal important difference of 4.2 points in total scores was found (F4,223 = 16.917 [P < .001] and F4,224 = 25.138 [P < .001]). Finally, a cutoff point (55.00 points) was estimated (area under the concentration-time curve, 0.846 [95% confidence interval, 0.798-0.894], P < .001; sensitivity, 0.793; specificity, 0.713; negative likelihood ratio, 0.290; positive likelihood ratio, 2.762). We concluded that the SIGIT-QoL is a feasible (average completion time, <6.5 minutes), reliable, and valid instrument for assessing the impact of gastrointestinal symptoms on the HRQoL of SOT patients.