TABLE 3

Univariate Analysis Comparing Lyme and Septic Arthritis

VariableLyme (N = 55)Septic (N = 46)P
Knee, n (%)47 (85)10 (22)<.001
Recent fever, n (%)25 (45)38 (83)<.001
Temperature ≥ 38.0°C, n (%)13 (24)22 (48).01
Tick-bite history, n (%)9 (16)1 (2).02
Peripheral WBC count, median (IQR), 103 cells per μL10.6 (9–11.8)11 (7.8–14.8).67
Peripheral ANC, median (IQR), 103 cells per μL6.7 (5.6–8.4)7.5 (4.9–10.4).2
ESR, median (IQR), mm/h45 (28–57)63 (38–88)<.01
CRP, median (IQR) mg/dL2.7 (1.3–4.6)11.1 (4.9–15.8)<.001
Joint fluid
    WBC count, median (IQR), 103 cells per μL43.1 (23.9–62.4)54.6 (30.4–93.2).03
    Neutrophils, median (IQR), %86 (82–90)93 (86–95)<.001
    Lymphocytes, median (IQR), %2 (0–4)2 (0–4).58
    Monocytes, median (IQR), %9 (5–15)5 (2–11)<.01