AspirinPainChronic PainPain ManagementPain ThresholdPain, PostoperativeLow Back PainBack PainPlatelet Aggregation InhibitorsPain MeasurementAnti-Inflammatory Agents, Non-SteroidalAbdominal PainNeck PainPain, IntractablePelvic PainPain PerceptionFacial PainAcute PainPain, ReferredShoulder PainMusculoskeletal PainTiclopidineThromboxane B2