Evidence-based Diagnostics: Adult Septic Arthritis

Abstract

Background Acutely swollen or painful joints are common complaints in the emergency department (ED). Septic arthritis in adults is a challenging diagnosis, but prompt differentiation of a bacterial etiology is crucial to minimize morbidity and mortality. Objectives The objective was to perform a systematic review describing the diagnostic characteristics of history, physical examination, and bedside laboratory tests for nongonococcal septic arthritis. A secondary objective was to quantify test and treatment thresholds using derived estimates of sensitivity and specificity, as well as best-evidence diagnostic and treatment risks and anticipated benefits from appropriate therapy. Methods Two electronic search engines (PUBMED and EMBASE) were used in conjunction with a selected bibliography and scientific abstract hand search. Inclusion criteria included adult trials of patients presenting with monoarticular complaints if they reported sufficient detail to reconstruct partial or complete 2 × 2 contingency tables for experimental diagnostic test characteristics using an acceptable criterion standard. Evidence was rated by two investigators using the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS). When more than one similarly designed trial existed for a diagnostic test, meta-analysis was conducted using a random effects model. Interval likelihood ratios (LRs) were computed when possible. To illustrate one method to quantify theoretical points in the probability of disease whereby clinicians might cease testing altogether and either withhold treatment (test threshold) or initiate definitive therapy in lieu of further diagnostics (treatment threshold), an interactive spreadsheet was designed and sample calculations were provided based on research estimates of diagnostic accuracy, diagnostic risk, and therapeutic risk/benefits. Results The prevalence of nongonococcal septic arthritis in ED patients with a single acutely painful joint is approximately 27% (95% confidence interval [CI] = 17% to 38%). With the exception of joint surgery (positive likelihood ratio [+LR] = 6.9) or skin infection overlying a prosthetic joint (+LR = 15.0), history, physical examination, and serum tests do not significantly alter posttest probability. Serum inflammatory markers such as white blood cell (WBC) counts, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) are not useful acutely. The interval LR for synovial white blood cell (sWBC) counts of 0 × 109–25 × 109/ L was 0.33; for 25 × 109–50 × 109/L, 1.06; for 50 × 109–100 × 109/L, 3.59; and exceeding 100 × 109/L, infinity. Synovial lactate may be useful to rule in or rule out the diagnosis of septic arthritis with a +LR ranging from 2.4 to infinity, and negative likelihood ratio (−LR) ranging from 0 to 0.46. Rapid polymerase chain reaction (PCR) of synovial fluid may identify the causative organism within 3 hours. Based on 56% sensitivity and 90% specificity for sWBC counts of >50 × 109/L in conjunction with best-evidence estimates for diagnosis-r...

Gram and acridine orange staining for diagnosis of septic arthritis in different patient populations

“…Papanicolas et al identified a CRP >100 mg/l as predictive of septic arthritis with a sensitivity of 86 %, but a low specificity of 48 % [20]. Other reports challenged the predictive value of serum inflammatory markers for the diagnosis of septic arthritis [7]. While our study detected a significant association of a CRP value above 150 mg/l as "predictive" in multivariate analysis, the corresponding ROC curve was moderate at best.…”

“…In the literature, the overall sensitivity ranges between 30 and 60 % [1,3,7], whereas for prosthetic joint infections, Morgan et al identified a 27 % sensitivity of intraoperative Gram staining [17], while the value of inflammatory markers for predicting culture-positive arthritis was less convincing. Several studies mentioned a positive association between occurrence of septic arthritis and elevated serum CRP levels [17].…”

“…(2) The design of our study reflected a real-life situation and hence did not address potential innovative microbiological techniques in the rapid diagnostics of septic arthritis, such as the use of polymerase chain reactions [7,26], synovial fluid glucose [1,3,7], proteins [1,3], lactic acid [7,9], serum erythrocyte sedimentation rate (ESR) [1,7,14,16], lactate dehydrogenase [1], various interleukins [7] or procalcitonin levels [10,13,27], which may potentially help to discriminate septic from non-septic arthritis.…”

“…The sensitivity of Gram staining is known to be suboptimal for the diagnosis of native joint septic arthritis [1,[5][6][7][8]. Previous reports usually evaluated small sized groups including less than 80 patients [4][5][6][8][9][10][11][12][13] and mainly focused on episodes of native joint septic arthritis [4][5][6][8][9][10][11][12][13][14].…”

Diagnosing Septic Arthritis in the Synovial White Cell Count “Gray Zone”

“…Since their inception, these risk factors have been used as a tool to guide management with hip aspiration and synovial fluid analysis in cases when multiple risk factors are present. After an aspiration has been performed, it has generally been accepted that a synovial white cell count greater than 100,000 cells/mm 3 likely [3] represents a septic hip requiring surgical management. Values between 25,000 and 75,000 cells/mm 3 represent a Bgray zone^where professional opinion and management differs among treating physicians.…”