Pharmacovigilance in hospice/palliative care: Net effect of pregabalin for neuropathic pain

Introduction: Real-world effectiveness of many medications has been poorly researched, including in hospice/palliative care. Directly extrapolating findings from other clinical settings may not yield robust clinical advice. Pharmacovigilance studies provide an opportunity to understand better the net impact of medications. The study aimed to examine immediate and short-term benefits and harms of pregabalin in routine practice for neuropathic pain in hospice/palliative care. Methods: A consecutive cohort of 155 patients from 62 centres in 5 countries was started on pregabalin and studied prospectively. Data were collected at three time points: baseline; day 7 (immediate, short-term harms); ad hoc reports of any harms ≤21 days; and day 21 (short-term benefits). Results: Median dose for 155 patients at day 21 was 150 mg/24 h. Benefits were reported by 61 patients (39%), of whom 11 (7%) experienced complete pain resolution. Harms were reported by 51 (35%) patients at or before 7 days, the most frequent of which were somnolence, fatigue, cognitive disturbance and dizziness. 10 patients (6%) ceased pregabalin due to harms, but 82 patients (53%) were being treated at 21 days. In regression modelling, people with worse baseline pain derived more benefit (OR=8.5 (95% CI 2.5 to 28.68). Conclusions: Pregabalin delivered benefit to many patients, with 4 of 10 experiencing pain reductions by 21 days. Harms, occurring in 1 in 3 patients, may be difficult to detect in clinical practice, as they mostly involve worsening of symptoms prevalent at baseline.