Childhood osteomyelitis-incidence and differentiation from other acute onset musculoskeletal features in a population-based study.

BACKGROUND: Osteomyelitis can be difficult to diagnose and there has previously not been a prospective approach to identify all children in a defined geographic area. The aim of this study was to assess the annual incidence of osteomyelitis in children, describe the patient and disease characteristics in those with acute (< 14 days disease duration) and subacute osteomyelitis (> or = 14 days disease duration), and differentiate osteomyelitis patients from those with other acute onset musculoskeletal features. METHODS: In a population-based Norwegian study physicians were asked to refer all children with suspected osteomyelitis. Children with osteomyelitis received follow-up at six weeks, six months and thereafter as long as clinically needed. RESULTS: The total annual incidence rate of osteomyelitis was 13 per 100,000 (acute osteomyelitis 8 and subacute osteomyelitis 5 per 100,000). The incidence was higher in patients under the age of 3 than in older children (OR 2.9, 95%: CI 2.3-3.7). The incidence of non-vertebral osteomyelitis was higher than the incidence of vertebral osteomyelitis (10 vs. 3 per 100 000; p = .002). Vertebral osteomyelitis was more frequent in girls than in boys (OR 7.0, 95%: CI 3.3-14.7). ESR > or = 40 mm/hr had the highest positive predictive laboratory value to identify osteomyelitis patients at 26% and MRI had a positive predictive value of 85%. Long-bone infection was found in 16 (43%) patients. ESR, CRP, white blood cell count, neutrophils and platelet count were higher for patients with acute osteomyelitis than for patients with subacute osteomyelitis. Subacute findings on MRI and doctor's delay were more common in subacute osteomyelitis than in acute osteomyelitis patients. Blood culture was positive in 26% of the acute osteomyelitis patients and was negative in all the subacute osteomyelitis patients. CONCLUSION: The annual incidence of osteomyelitis in Norway remains high. ESR values and MRI scan may help to identify osteomyelitis patients and differentiate acute and subacute osteomyelitis.

Incidence and characteristics of arthritis in Norwegian children: a population-based study.

OBJECTIVE: The purpose of this work was to assess the annual incidence of arthritis in children and describe early disease and patient characteristics, microbiologic features, and immunogenetic factors in children with different subgroups of childhood arthritis. PATIENTS AND METHODS: A population-based multicenter study was performed in southeastern Norway between June 1, 2004, and May 31, 2005. The total population of children under 16 years of age was 255,303. Physicians were asked to refer their patients with suspected arthritis to the local department of pediatrics or rheumatology. The children were assessed on the basis of clinical, radiologic, and laboratory examinations at inclusion and followed up at 6 weeks, 6 months, and thereafter as long as clinically indicated. A chart review was performed to identify patients with arthritis who had not been included prospectively. RESULTS: The total annual incidence of arthritis was 71 per 100,000 children. Transient arthritis, juvenile idiopathic arthritis, postinfectious arthritis, and infectious arthritis were found in 43, 14, 9, and 5 of 100,000 children, respectively. The incidence was higher in children under the age of 8 years than in older children (107 vs 34 per 100,000). Arthritis occurred more frequently in boys than in girls before the age of 8 years but not thereafter. The median age of onset was lower in children with infectious arthritis than in those with other types of arthritis. Monarthritis was less frequent in patients with juvenile idiopathic arthritis than in the other subgroups (64% vs 83%-100%). Ten percent of the patients had poststreptococcal reactive arthritis, and only 1 had enteropathic arthritis. Autoantibodies and the presence of HLA-B27 were associated with juvenile idiopathic arthritis. CONCLUSIONS: The annual incidence of childhood arthritis was 71 per 100,000 children. We found several factors that may help in differentiating between subgroups of arthritis.