Anti-Inflammatory Agents, Non-Steroidal/adverse effects; Anti-Ulcer Agents/therapeutic use; Cyclooxygenase 2 Inhibitors/adverse effects; Naproxen/adverse effects; Omeprazole/analogs & derivatives; Peptic Ulcer/prevention & control; Pyrazoles/adverse effects; Sulfonamides/adverse effects; 2-Pyridinylmethylsulfinylbenzimidazoles; Adult; Aged; Anti-Inflammatory Agents, Non-Steroidal/administration & dosage; Anti-Inflammatory Agents, Non-Steroidal/therapeutic use; Anti-Ulcer Agents/administration & dosage; Celecoxib; Cyclooxygenase 2 Inhibitors/therapeutic use; Drug Therapy, Combination; Dyspepsia/chemically induced; Female; Follow-Up Studies; Helicobacter Infections/drug therapy; Helicobacter pylori; Humans; Incidence; Lansoprazole; Male; Middle Aged; Naproxen/administration & dosage; Naproxen/therapeutic use; Omeprazole/administration & dosage; Omeprazole/therapeutic use; Peptic Ulcer/chemically induced; Peptic Ulcer/epidemiology; Peptic Ulcer Hemorrhage/chemically induced; Prospective Studies; Proton Pump Inhibitors; Pyrazoles/therapeutic use; Recurrence; Risk Factors; Sulfonamides/therapeutic use; Treatment Outcome