What's the best approach to this common scenario of a patient on long-term pain relief?

There's lots to consider- 

• Management of pain, the patient's experience of pain from a biological. psychological, social and even spiritual perspective, 
• Medication interactions and polypharmacy.
• Beaumont & Childress Ethical Principles of Autonomy, Beneficence, Non-maleficence & Justice

This is a doctor-initiated scenario so the GP uses 'signposting' to explain the concepts involved, the reasons he's asking the questions and the rationale behind recalling the patient to review his medication.