Predictive value of preceding fever or rigor for septic arthritis in acute monoarthritis: A retrospective...

Previous studies of septic arthritis (SA) have assessed the predictive value of fever without regard to its relationship with the onset of systemic and articular symptoms. The present study aimed to assess the diagnostic value to fever and rigor with respect to the onset of articular symptoms.

The present study retrospectively reviewed 234 adult patients with acute monoarthritis who underwent synovial fluid analysis at the emergency department of a tertiary hospital. SA was defined by modified Newman's criteria. Diagnostic accuracy was compared between the index history, defined as the occurrence of fever (axillary temperature ≥ 37.5 °C) or rigor ≥1 day before the onset of articular symptoms, and the occurrence of fever or rigor, assessed individually, irrespective of the onset of articular symptoms.

SA was diagnosed in 18 (7.7 %) of the 234 patients. Fever or rigor ≥1 day before articular-symptom onset had sensitivity 27.8 % (95 % [confidence interval] CI: 9.7 %-53.5 %), specificity 96.8 % (95 % CI: 93.4 %-98.7 %), positive likelihood ratio (PLR) 8.57 (95% CI: 3.02-24.30), and positive predictive value 41.7 % (95 % CI: 15.2 %-72.3 %) for SA. In contrast, the occurrence of a fever at any time up to presentation had a lower specificity and PLR of 61.6 % (95 % CI: 54.7 %-68.1 %) and 1.59 (95 % CI: 1.06-2.39), respectively. Rigor alone had 0 % sensitivity for SA.

The onset of a fever or rigor before that of the articular symptoms increased the probability of SA. Clinicians should consider the temporal relationship of the onset of systemic and articular symptoms.