eight years. After eight years, the majority of youth still experienced pain and disability in physical, social, and psychological areas. At the last follow-up, all participants reported experiencing one or more fibromyalgia symptoms such pain, fatigue, and/or sleep problems, with 58% matching the complete ACR 2010 criteria for fibromyalgia. Based on the WPI and SS score cut-points, the remaining 42% exhibited subclinical symptoms. Pain and emotional symptom trajectories, on the other hand, displayed a variety of longitudinal patterns. The study concluded that while most patient's fibromyalgia symptoms endure, the severity of their pain tends to reduce over time. Baseline depressive symptoms in adolescents appear to predict worse pain at follow-up periods. Epidemiology Fibromyalgia is estimated to affect 2–4% of the population. Females are affected about twice as often as males based on criteria as of 2014. History Chronic widespread pain had already been described in the literature in the 19th century but the term fibromyalgia was not used until 1976 when Dr P.K. Hench used it to describe these symptoms. Many names, including "muscular rheumatism", "fibrositis", "psychogenic rheumatism", and "neurasthenia" were applied historically to symptoms resembling those of fibromyalgia. The term fibromyalgia was coined by researcher Mohammed Yunus as a synonym for fibrositis and was first used in a scientific publication in 1981. Fibromyalgia is from the Latin fibra (fiber) and the Greek words myo (muscle) and algos (pain). Historical perspectives on the development of the fibromyalgia concept note the "central importance" of a 1977 paper by Smythe and Moldofsky on fibrositis. The first clinical, controlled study of the characteristics of fibromyalgia syndrome was published in 1981, providing support for symptom associations. In 1984, an interconnection between fibromyalgia syndrome and other similar conditions was proposed, and in 1986, trials of the first proposed medications for fibromyalgia were published. A 1987 article in the Journal of the American Medical Association used the term "fibromyalgia syndrome" while saying it was a "controversial condition". The American College of Rheumatology (ACR) published its first classification criteria for fibromyalgia in 1990. Later revisions were made in 2010, 2016, and 2019. Society and culture Economics People with fibromyalgia generally have higher healthcare costs and utilization rates. A review of 36 studies found that fibromyalgia causes a significant economic burden on health care systems. Annual costs per patient were estimated to be up to $35,920 in the US and $8,504 in Europe. Controversies Fibromyalgia was defined relatively