Psychometric validation of symptom severity measures in irritable bowel syndrome with constipation.

BACKGROUND: Historically, measures of symptom severity of irritable bowel syndrome with constipation (IBS-C) in clinical trials have not met the evidence requirements described in the FDA guidance on patient-reported outcomes (PROs), which describes the evidentiary requirements and review criteria for patient-reported outcome measures intended to support product approval or labelling claims. AIM: Data from two phase 3 trials (N = 1608) of linaclotide for the treatment of IBS-C were analysed to evaluate the psychometric properties of patient-reported outcome measures assessing changes in the severity of abdominal and bowel symptoms. METHODS: A set of patient-reported outcome assessments addressing abdominal and bowel symptoms, the IBS-C Symptom Severity Measures, were administered daily using interactive voice response system technology. Intraclass correlation coefficients (ICCs), Pearson correlations, factor analyses, F-tests and effect sizes were computed to evaluate the reliability, construct validity, discriminating ability and responsiveness of the IBS-C Symptom Severity Measures in a clinical trial context. RESULTS: The IBS-C Symptom Severity Measures showed highly satisfactory test-retest reliability (ICCs ranging from 0.79 to 0.95) and construct validity. Factor analyses indicated one factor for abdominal symptoms and another for bowel symptoms. Known-groups F-tests comparing subgroups based on various responder definitions were statistically significant and in the expected direction, substantiating the discriminating ability of the IBS-C Symptom Severity Measures. Responsiveness statistics (ranging from 0.6 to 2.1) demonstrated these measures are also capable of detecting change. CONCLUSIONS: The psychometric analysis results strongly support the reliability, construct validity, discriminating ability and responsiveness of the IBS-C Symptom Severity Measures and substantiate the conclusion of linaclotide treatment benefit.

An evaluation of the FDA responder endpoint for IBS-C clinical trials: analysis of data from linaclotide Phase 3 clinical trials.

BACKGROUND: Our objective was to evaluate the performance of the Food and Drug Administration (FDA) Responder Endpoint for clinical trials in IBS-C, using data from two large Phase 3 clinical trials of linaclotide. The FDA interim endpoint requires that, for 50% of trial weeks, patients report ≥30% decrease in Abdominal Pain at its worst and (in the same week) an increase in Complete Spontaneous Bowel Movements (CSBMs) of ≥1 from baseline. METHODS: Anchor-based methodology was used to estimate thresholds of clinically meaningful change using symptom-specific patient rating of change questions (PRCQs) and symptom severity questions. The diagnostic accuracy of the FDA Responder Endpoint was assessed using sensitivity/specificity-based methods. KEY RESULTS: Using anchor-based methods, the estimates of the clinically meaningful improvement thresholds for Abdominal Pain ranged from 25.9% to 32.4% and thresholds for increase in weekly CSBM rate ranged from 1.4 to 1.6 CSBMs per week. Compared with the symptom-specific PRCQs for patient rating of relief, the FDA Responder Endpoint has a sensitivity of 60.7%, a specificity of 93.5%, and an accuracy of 82.0%. Changing the number of weeks required to be a responder or the percentage improvement in the Abdominal Pain criteria did not result in notable improvement in the accuracy of the FDA Responder Endpoint. CONCLUSIONS & INFERENCES: The FDA Responder Endpoint for IBS-C clinical trials represents clinically meaningful improvements in IBS-C symptoms for patients with excellent specificity and reasonable sensitivity.

Prevalence and impact of antidepressant-associated sexual dysfunction in three European countries: replication in a cross-sectional patient survey.

Sexual dysfunction is a common but often unrecognized side effect of many antidepressants. Building upon the results of a previous investigation, this study aimed to assess the prevalence and impact of antidepressant-associated sexual dysfunction (AASD) in three European countries. A cross-sectional survey of 704 adults in Germany, Spain, and The Netherlands was used in the study. All participants had recently started taking a selective serotonin reuptake inhibitor or serotonin- noradrenaline reuptake inhibitor. Information about other medications and conditions known to impair sexual functioning was gathered, and changes in sexual functioning and the impact of such changes were assessed. The SF-12 and Arizona Sexual Experience Scale (ASEX) were administered to measure health status and sexual functioning. AASD was defined using ASEX scores and information regarding changes in sexual functioning. ASEX scores generally exceeded the threshold defining sexual dysfunction: 67.2% in the German, 79.4% in the Spanish, and 73.3% in the Dutch samples. The prevalence of AASD was conservatively estimated to be between 37.1% (German sample) and 61.5% (Spanish sample). Overall, 46.4% of male and 52.1% of female participants were classified with AASD. Patients classified with AASD reported significantly worse quality of life (QoL), self-esteem, mood, and relationships with partners, compared with non-AASD patients. There were significant differences between patients with and without AASD in SF-12 Mental Component scores, with AASD patients displaying poorer mental well-being. Sexual dysfunction is a frequent occurrence during antidepressant treatment, and is associated with reduced QoL and self-esteem, and negative effects on mood and relationships.