Objectives-To determine the incidence and sources of bacterial arthritis in the Amsterdam health district and the maximum percentage of cases that theoretically would be preventable. Methods-Patients with bacterial arthritis diagnosed between 1 October 1990 and 1 October 1993 were prospectively reported to the study centre by all 12 hospitals serving the district. Data were gathered on previous health status, source of infection, and microorganisms involved. Results-188 episodes of bacterial arthritis were found in 186 patients. Most of the 38 children were previously healthy. Fifty per cent of the adults were 65 years or older. Of the adults 84% had an underlying disease, in 59% a joint disorder. Joint surgery constituted the largest part of direct infections (33%) and skin defects were the most important source of haematogenous infections (67%). Infection of joints containing prosthetic or osteosynthetic material by a known haematogenous source occurred 15 times (8%). Staphylococcus aureus was the causative organism in 44% of all positive cultures. Conclusion-The incidence of bacterial arthritis was 5.7 per 100 000 inhabitants per year. Preventive measures directed to patients with prosthetic joints or osteosynthetic material, and a known haematogenous source would have prevented at most 8% of all cases.

Objective. To quantify potential risk factors for septic arthritis, in order to identify a basis for prevention.Methods. The occurrence of potential risk factors for septic arthritis in patients with joint diseases attending a rheumatic disease clinic was prospectively monitored at 3-month intervals over a period of 3 years. Potential risk factors investigated were type of joint disease, comorbidity, medication, joint prosthesis, infections, and invasive procedures. The frequencies of risk factors in patients with and those without septic arthritis were compared using multiple logistic regression analysis.Results. There were 37 patients with and 4,870 without septic arthritis. Risk factors for developing septic arthritis were age 280 years (odds ratio [OR] Conclusion. These findings indicate that preventive measures against septic arthritis in patients with joint diseases should mainly be directed at those with joint prostheses and/or skin infection.

Objective. To assess the outcome and adverse prognostic factors of bacterial arthritis (BA). Methods. In a prospective community survey of BA, data were collected at the time of diagnosis and at a mean of 2 years later. A poor patient outcome was defined as death due to BA or severe overall functional deterioration. A poor joint outcome was defined as amputation, arthrodesis, prosthetic surgery, or severe functional deterioration. Possible prognostic factors were analyzed by univariate analysis. Results. BA was diagnosed in 154 patients, 121 adults and 33 children. One‐half of the adults had a preexisting joint disease and 29% of the infected joints contained synthetic material. The patient outcome was poor in 21% of all patients, and the joint outcome was poor in 33% of the surviving patients. Adverse prognostic factors were an older age, preexisting joint disease, and an infected joint containing synthetic material. These factors were interrelated. There was no association between a poor outcome and young age, comorbidity, immunosuppressive medication, functional class, multiple infected joints, type of microorganism, or treatment delay. Conclusion. BA had a poor outcome in almost one‐half of the patients. Patients who were older, had a preexisting joint disease, and/or had an infected joint containing synthetic material had the poorest prognosis.

Objective-To assess the cost eVectiveness of antibiotic prophylaxis for haematogenous bacterial arthritis in patients with joint disease. Methods-In a decision analysis, data from a prospective study on bacterial arthritis in 4907 patients with joint disease were combined with literature data to assess risks and benefits of antibiotic prophylaxis. EVectiveness and cost eVectiveness calculations were performed on antibiotic prophylaxis for various patient groups. Grouping was based on (a) type of event leading to transient bacteraemiathat is, infections (dermal, respiratory/ urinary tract) and invasive medical procedures-and (b) the patient's susceptibility to bacterial arthritis which was increased in the presence of rheumatoid arthritis, large joint prostheses, comorbidity, and old age. Results-Of the patients with joint disease, 59% had no characteristics that increased susceptibility to bacterial arthritis, and 31% had one. For dermal infections, the eVectiveness of antibiotic prophylaxis was maximally 35 quality adjusted life days (QALDs) and the cost eVectiveness maximally $52 000 per quality adjusted life year (QALY). For other infections, the eVectiveness of prophylaxis was lower and the cost eVectiveness higher. Prophylaxis for invasive medical procedures seemed to be acceptable only in patients with high susceptibility: 1 QALD at a cost of $1300/QALY; however, the results were influenced substantially when the level of eYcacy of the prophylaxis or cost of prophylactic antibiotics was changed. Conclusion-Prophylaxis seems to be indicated only for dermal infections, and for infections of the urinary and respiratory tract in patients with increased

The outcome of bacterial arthritis is generally poor: the mortality is 10 - 15% and there is loss of joint function in 25 - 50% of the survivors. The incidence of bacterial arthritis is low: 2 - 6 cases per 100,000 people per year. Risk factors are age, joint disease (especially rheumatoid arthritis [RA]), diabetes mellitus and the presence of a prosthetic joint. The predominant situations that can lead to bacterial arthritis are skin infections of the feet and rarely invasive medical or dental procedures. Due to the severity of the disease, antibiotic prophylaxis of haematogenous bacterial arthritis in patients with prosthetic joints is advocated. However, due to the rarity of the disease it is unclear whether the advantages of prophylaxis outweigh the disadvantages of the large-scale use of antibiotics, such as side effects, costs and bacterial resistance. In a decision-analysis of a large group of patients with joint diseases, antibiotic treatment of skin infections appeared to be cost-effective in the prevention of haematogenous bacterial arthritis, mainly in high-risk patients. On the other hand, prophylaxis around medical or dental procedures was not cost-effective, except possibly in a small group of patients with increased risk.