Principles & Practice of Pain Medicine > Part II. Pain: General Principles and Evaluation > Chapter 4. Definitions and Classification of Pain Jyotsna Nagda and Zahid H. Bajwa

Definitions and Classification of Pain: Introduction

"Relief of pain is one of the great objectives of medicine. Pain is the most common symptom reported to physicians; more than 80% of all patients who see physicians do so because of pain. It has been a predominant concern of humankind since the beginning of recorded history. Chronic pain affects hundreds of millions of people worldwide, altering their physical and emotional functioning, decreasing their quality of life, and impairing the ability to work. It affects general health, psychological health, and social and economic well-being. Patients in chronic pain use health services up to five times more frequently than the rest of the population. The cost of unrelieved chronic pain in the United States is more than $50 billion per year (more than $80 billion per year if lost wages from work are counted) and in the age of steady cost-cutting in a managed care environment, we can no longer afford it. More than 550 million workdays are lost every year because of chronic pain. Yet 40% of all cancer patients, 50% of nursing home patients, 55% of postoperative patients, and 70% of patients with acquired immunodeficiency syndrome (AIDS) have unrelieved or inadequately relieved pain...."