TABLE 2.
Erythema migrans (EM) characteristics of 56 participantsa with clinically diagnosed early Lyme disease, by PCR/ESI-MS-defined subgroup
| EM characteristic | No. (%) of participants with the characteristic or value for characteristicb
|
P valuec
|
||||||
|---|---|---|---|---|---|---|---|---|
| All groups (n = 56) | Group 1 (PCRneg/neg) (n = 13) | Group 2 (PCRpos/neg) (n = 25) | Group 3 (PCRpos/pos) (n = 18) | Overall | Group 1 vs group 2 | Group 2 vs group 3 | Group 1 vs group 3 | |
| Disseminated EM | 15 (26.8) | 3 (23.1) | 5 (20.0) | 7 (38.9) | 0.37 | 1.00 | 0.17 | 0.45 |
| EM size (cm2) | 94.5 (49.0–165.5) [16.0–900.0] | 60.0 (36.0–100.0) [24.0–256.0] | 108.0 (60.0–225.0) [16.0–900.0] | 98.5 (44.0–162.0) [25.0–240.0] | 0.08 | 0.04 | 0.28 | 0.25 |
| EM shape | ||||||||
| Round | 31 (55.4) | 10 (76.9) | 13 (52.0) | 8 (44.4) | 0.18 | 0.14 | 0.62 | 0.07 |
| Oval/irregular | 25 (44.6) | 3 (23.1) | 12 (48.0) | 10 (55.6) | ||||
| EM color | ||||||||
| Red | 43 (76.8) | 12 (92.3) | 19 (76.0) | 12 (66.7) | 0.24 | 0.39 | 0.50 | 0.19 |
| Blue/red | 13 (23.2) | 1 (7.7) | 6 (24.0) | 6 (33.3) | ||||
| EM pattern | 0.01 | 0.009 | 0.58 | 0.005 | ||||
| Ring within a ring | 14 (25.0) | 3 (23.1) | 5 (20.0) | 6 (33.3) | ||||
| Central darkness | 20 (35.7) | 4 (30.8) | 9 (36.0) | 7 (38.9) | ||||
| Central lightness | 8 (14.3) | 6 (46.2) | 2 (8.0) | 0 (0.0) | ||||
| Uniform | 14 (25.0) | 0 (0.0) | 9 (36.0) | 5 (27.8) | ||||
| EM vesicles present | 7 (12.5) | 0 (0.0) | 6 (24.0) | 1 (5.6) | 0.08 | 0.08 | 0.21 | 1.00 |
| EM tick bite puncture present | 26 (46.4) | 11 (84.6) | 8 (32.0) | 7 (38.9) | 0.007 | 0.005 | 0.64 | 0.01 |
a
One participant in group 1 who was misclassified by the PCR/ESI-MS test was removed from this analysis. Groups are distinguished by and labeled with their PCRskin/blood result status.
b
Mean ± standard deviation for normally distributed variables, median (IQR) [range] for nonnormally distributed continuous variables, and n (%) for categorical variables are presented.
c
All P values are two sided.