What are Rheumatic Diseases?

Rheumatic diseases are a diverse group of chronic diseases united by the presence of chronic inflammation, usually of unknown cause, affecting structures of the musculoskeletal system, blood vessels, and other tissues. Pediatric rheumatology, the study of rheumatic diseases in children and adolescents, had its origins in the first half of the 20th century, principally as a study of chronic inflammatory arthritis, the most common of the childhood rheumatic diseases.

Historical Aspects

Archeological evidence supports the existence of chronic arthritis in children as long ago as 900 AD. The first English-language reference to “rheumatism” in children is in the 1545 text by Thomas Phaire. In this work, the author refers to the “stifnes or starckenes of the limmes” resulting from exposure of a child to cold, a complaint that may not represent any specific rheumatic disease. Three hundred years later (1864) Cornil described a woman in whom polyarthritis had developed when she was 12 years old. Autopsy at 28 years of age documented ankylosis of some joints and synovial proliferation with marked destruction of cartilage in others. Several small case series were published in the last half of the 19th century, but the disease was thought to be very rare. The diversity of chronic arthritis was recognized in the latter part of the 19th century. In 1883, Barlow chaired a discussion on rheumatism in childhood at a meeting of the British Medical Association, Section of Diseases of Children. In the report of this meeting, the term rheumatism was used to describe poststreptococcal disease, including acute rheumatic fever. Barlow recognized the extent and complexity of these disorders in childhood: “For there are in children many affections of joints, and of structures around joints, which do not suppurate, and yet are not rheumatic; and there is much rheumatism in children which does not affect joints.” Disorders known today as toxic synovitis of the hip, acute pyogenic arthritis, syphilitic arthritis, hemophiliac arthropathy, Henoch–Schönlein purpura, poststreptococcal arthritis, and acute rheumatic fever, including carditis, arthritis, nodules, erythema marginatum, and chorea, are all identifiable in this paper.

In 1891, Diamant-Berger published the first detailed account of chronic arthritis in 38 children whom he had seen or whose cases had been documented in the literature. In 1896, George Frederic Still described 22 cases of acute and chronic arthritis in children, almost all of whom were observed at the Hospital for Sick Children, London. This treatise, written under the mentorship of Barlow, documented the clinical characteristics and the differing modes of onset of disease in these children. Still was the first English physician to confine his practice to diseases of children and the first professor of pediatrics at King’s College Hospital Medical School, London. After his classic study, however, he rarely returned to the field of pediatric rheumatology. In the same year, Koplick described the first American child with chronic arthritis.

Although these publications that described arthritis in childhood marked important milestones in the early development of pediatric rheumatology, other rheumatic diseases were identified in children in the 19th century. The clinical characteristics of leukocytoclastic vasculitis were described by Schönlein and Henoch in the early to mid-1800s. Juvenile dermatomyositis was first identified by Unverricht and others in 1887, although it was not until the mid-1960s that significant experience with this disease in childhood was reported. Systemic lupus erythematosus (SLE) has been recognized in children since at least 1904. The original description of scleroderma was in a 17-year-old girl, but the disease was rarely diagnosed in children until the early 1960s. Ankylosing spondylitis was perhaps first identified in a child —it was certainly known to occur in childhood in the 1950s —but specific studies of the disorder in children did not emerge until the late 1960s.

As awareness of the broader spectrum of rheumatic diseases in children and adolescents emerged, it slowly became apparent that there was a body of knowledge and expertise—pediatric rheumatology—that was related to, but quite separate from, adult rheumatology, pediatrics, and orthopedics. Professor Eric Bywaters and Dr. Barbara Ansell at the Canadian Red Cross Memorial Hospital in Taplow, England, were among the earliest (1940s and 1950s) clinician-investigators to be identified with the new discipline. Dr. Elizabeth Stoeber at Garmisch-Partenkirchen, Germany, also pioneered the field in the mid-twentieth century. The second generation of pediatric rheumatologists emerged in the 1950s and 1960s in the United States, Canada, and many countries in Europe, and in 1976, the first North American pediatric rheumatology meeting, Park City I, and the European League Against Rheumatism/World Health Organization (EULAR/WHO) Workshop on the Care of Rheumatic Children in Oslo in 1977 laid the groundwork for the development of the discipline. Reminiscences of some of the pioneers of pediatric rheumatology are recommended to the interested reader. A summary of the history of arthritis in children has been published by Hayem.

Pediatric rheumatology continues to grow and evolve. More recent additions to the family of rheumatic diseases in children include Kawasaki disease, which was described in detail in 1967, although its clinical characteristics in infants dying of “polyarteritis nodosa” were described by Munro-Faure in 1959. Other rheumatic diseases, such as neonatal lupus, and an ever-growing array of autoinflammatory disorders have more recently been identified. The discovery of Borrelia burgdorferi as the etiologic agent responsible for Lyme arthritis is but one example of the role that infection plays in rheumatic diseases. Noninflammatory musculoskeletal pain syndromes are more recent additions to the expanding list of disorders that cause musculoskeletal pain and dysfunction in children and adolescents. Many of the diseases or their complications are confined to the childhood and adolescent population but have lasting effects on health, quality of life, and socioeconomic well-being throughout life.

Pediatric Rheumatology Today

Today the specialty of pediatric rheumatology is concerned with the diverse group of disorders described in this book, most of which are systemic disorders that require great expertise for prompt diagnosis and optimal management. There are few definitive diagnostic tests, sparse pathognomonic clinical signs, and therapy too often lacks specificity. This specialty requires a diagnostic and therapeutic approach to the “whole” child and family unit, and careful observation over long periods. Sometimes only the passage of time makes a diagnosis possible.

The spectrum of disease in children seen in specialized pediatric rheumatology clinics varies considerably, reflecting referral biases as well as geographically differing frequencies of specific diseases ( Table 1-1 ). In addition to the diagnoses listed in Table 1-1 , there are children with related disorders such as chronic anterior uveitis, Raynaud phenomenon, and autoinflammatory diseases that may be unaccounted for in these registries.

The Burden of Disease

Fundamental to estimating the burden of pediatric rheumatic diseases in a society is the question: “How many children and adolescents have each of the identifiable rheumatic diseases?” It has been difficult to accurately establish the extent of childhood rheumatic disease. In many of the most densely populated areas of the world, incidence and prevalence data for such diseases do not exist. In the developed world, inconsistencies of definition and classification, the rarity of occurrence for many of these disorders, and the brevity of follow-up have hindered the accumulation of a substantial body of epidemiological data.

It is apparent that some diseases are much more prevalent in children of certain ethnicities (e.g., SLE is more common in children of Asian origin than in those of European origin; Kawasaki disease is much more common in children of Japanese ancestry than in others). Using prevalence data derived from one ethnic group cannot, therefore, be used to accurately determine the prevalence in another ethnic group. Community-based studies provide insight into disease prevalence that is more representative than those originating from tertiary care centers. One such study by Manners and Diepeveen in Western Australia reported the prevalence of chronic arthritis in 12-year-old school children at 4 per 1,000, and documented that many cases of chronic arthritis in children were undiagnosed and untreated. In Finland, Kunnamo and colleagues surveyed all children under 16 years of age who had swelling or limitation of joint motion, walked with a limp, or had hip pain, as determined by a primary care physician, pediatrician, or orthopedic surgeon. All of these patients were subsequently examined by a single group of pediatric rheumatologists. Overall, the incidence of arthritis was estimated at 109 per 100,000 children per year. Transient synovitis of the hip accounted for 48%, other acute transient arthritis for 24% (Henoch–Schönlein purpura, serum sickness), chronic arthritis for 17%, septic arthritis for 6%, and reactive arthritis for 5%. Connective tissue diseases such as SLE were not identified in this survey.

The effect of childhood rheumatic diseases on life expectancy, their contribution to morbidity and costs of medical care, and the effect on quality of life are all important outcome parameters for which little information exists, even in North America and Europe; there is no information whatsoever on the global scene. There can be little doubt, however, that many children with, for example, arthritis beginning at 2 or 3 years of age will carry a lifelong burden in one or more of these areas. Indications of increased cardiovascular morbidity and malignancy have been studied. The expense and inconvenience for other members of the family are also significant.

A number of studies have estimated the cost of caring for a child with juvenile idiopathic arthritis. Although newer therapies, such as biological response modifiers, are expensive, the added cost of the therapy is at least partially offset by the reduced morbidity and improved quality of life.