Chronic PainMethadonePainAnalgesics, OpioidPain ClinicsOpioid-Related DisordersPain MeasurementChronic DiseaseCarisoprodolPain, IntractablePain ManagementCatastrophizationSubstance Abuse DetectionDrug IncompatibilityHydrocodoneOxycodoneFibromyalgiaAnalgesicsNarcoticsUrinalysisLow Back PainDrug MonitoringOpiate Substitution TreatmentQuestionnairesPain ThresholdBack PainHeroin DependenceFacial PainDisability EvaluationMusculoskeletal PainAdaptation, PsychologicalNeck PainNeuralgiaDepressionChest PainPain, ReferredBuprenorphinePain, PostoperativeMethadyl AcetatePain PerceptionHydromorphoneAcute PainPelvic PainHyperalgesiaNeonatal Abstinence SyndromeAbdominal PainHeroinMorphineStreet DrugsTemporomandibular Joint DisordersTreatment OutcomeSubstance-Related DisordersAnalgesiaShoulder PainNarcotic AntagonistsDrug OverdoseTime FactorsReproducibility of ResultsProspective StudiesNociceptorsNociceptive PainIntervertebral Disc DisplacementPyrrolidinesSeverity of Illness IndexComplex Regional Pain SyndromesActivities of Daily LivingAnxietyManipulation, SpinalQuality of LifeFollow-Up StudiesNaloxoneAnalysis of VariancePsychometricsCross-Sectional StudiesDouble-Blind MethodSubstance Withdrawal SyndromeDextropropoxyphenePrevalenceSubstance Abuse, IntravenousArthralgiaPhysical Therapy ModalitiesDose-Response Relationship, DrugPhysical StimulationPrimary Health CareAbsenteeismPredictive Value of TestsMyofascial Pain SyndromesInjections, SpinalRetrospective StudiesPatellofemoral Pain SyndromeDisabled PersonsOpiumRisk FactorsAnalgesics, Non-NarcoticCentral Nervous System SensitizationEmergency Service, HospitalCohort StudiesCocaine-Related DisordersCodeineReceptors, Opioid, mu