Breakthrough PainAdministration, BuccalFentanylAnalgesics, OpioidPainLabor PainPain MeasurementAnalgesicsPain ManagementChronic PainAnalgesia, EpiduralDouble-Blind MethodPain, PostoperativePain, IntractablePrescription Drug MisuseNeoplasmsChronic DiseaseTreatment OutcomeArthralgiaPlacebo EffectMedication ErrorsMedication AdherenceNeuralgiaPalliative CareQuestionnairesProspective StudiesAnti-Inflammatory Agents, Non-SteroidalPain ThresholdTime FactorsSeverity of Illness IndexRadionuclide GeneratorsRetrospective StudiesBack PainLow Back PainQuality of LifeFollow-Up StudiesPatient SatisfactionAbdominal PainNeck PainComorbidityMedication ReconciliationMedication SystemsMedication Systems, HospitalCohort StudiesPelvic PainPain PerceptionFacial Pain