Sample Bias in Web-Based Patient-Generated Health Data of Dutch Patients with Gastrointestinal Stromal Tumor: Survey Study

Background: Increasingly, social media is being recognized as a potential resource for patient-generated health data, for example, for pharmacovigilance. Although the representativeness of the web-based patient population is often noted as a concern, studies in this field are limited. Objective: This study aimed to investigate the sample bias of...

On the assessment of adverse drug reactions from spontaneous reporting systems: The influence of under-reporting on odds ratios

A well-known problem in spontaneous reporting systems (SRSs) for adverse drug reactions (ADRs) is under-reporting, that is, the problem that not all occurrences of ADRs are reported to the SRS. We look at the question of how to draw statistical conclusions from analyses of SRS data using reporting odds ratios. We will show that certain under...