Investigating the clinical outcomes of drug combinations (opioid + medication acting on the central nervous system) in patients suffering from persistent pain (pain lasting for at least three months) through patient-reported outcomes.

This study is part of the QSPainRelief project funded by the European Union's Horizon 2020 research and innovation program (grant agreement 848068; http://qspainrelief.eu).

The QSPainRelief project aims to setup, calibrate and validate a platform to predict the effects of treatment combinations according to patient characteristics such as age and sex (QSPainRelief platform) which integrates recently developed (1) physiologically based pharmacokinetic models to quantitate and adequately predict drug pharmacokinetics in human CNS, (2) target-binding kinetic models; (3) cellular signaling models and (4) a proprietary neural circuit model to quantitate the drug effects on the activity of relevant brain neuronal networks, that also adequately predicts clinical outcome.

To develop the QSPainrelief platform, a large dataset assessing perceived clinical outcome by real-world patients treated with a drug combination and stratified according to age and sex is required. To generate this dataset, we will conduct a questionnaire-based clinical study using an online platform (Redcap) and/or phone interviews to assess baseline patient characteristics and clinical outcome. Eligible patients are any patient treated with an opioid analgesic to whom an add-on treatment acting on the CNS is prescribed.

This study will focus on pain relief and its impact on daily life activities as therapeutic effects, and on drug-induced sedation, drug-induced cognitive dysfunction (memory and attention) and pain medication misuse as adverse effects. These adverse effects have been chosen because they can be readily assessed in patients after a short treatment period using validated patient-reported outcome measures (PROMs).

QSPainRelief-patientSTRAT is a monocentric prospective longitudinal questionnaire-based study conducted in patients suffering from persistent pain (pain lasting for at least three months), already treated with an opioid medication (treatment A) and to whom the treating physician is about to prescribe a CNS-acting add-on drug such as an antiepileptic, an antidepressant, a benzodiazepine or an alpha2-agonist (treatment B: the combination treatment).

Inclusion Criteria:

1. Aged over 18 years.
2. Current treatment with an opioid for the treatment of pain, along with possible other drugs (see Table 1 for the list of eligible opioid medications - patients will be invited to indicate their treatment by selecting its name using a dropdown list).
3. Decision by the treating physician to introduce an additional non-opioid CNS-acting treatment such as an antiepileptic, an anti-depressant or benzodiazepine (see Table 2 for the list of eligible medications - patients will be invited to indicate their treatment by selecting its name using a dropdown list).
4. Capacity to understand and provide informed consent.

Exclusion Criteria:

1. Insufficient French language skills.
2. Epilepsy treated by an anti-epileptic.
3. Alzheimer's disease.
4. Parkinson's disease
5. History of cancer diagnosed less than 5 years ago, treated by chemotherapy or radiotherapy.