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. Author manuscript; available in PMC: 2020 Aug 1.
Published in final edited form as: J Rheumatol. 2019 Mar 1;46(8):943–951. doi: 10.3899/jrheum.180775

Table 3.

Association of explanatory factors with ARLA

Univariate
analysis		  Multivariable analysis
Primary or
secondary
explanatory
variable		 Analysis of
primary
explanatory
variables
(N=237)		 Primary
explanatory
variables plus
secondary
treatment factors
(N=237)
Clinical characteristic unadjusted OR
(95% CI)		  adjusted OR1 (95% CI)
Demographics
Age ≥10 years old  3.5 (1.8, 6.7)  2.5 (1.1, 5.6)  3.0 (1.2,7.3)
Male sex  0.8 (0.4, 1.6)  -  -
Clinical features at presentation
Acute migratory arthritis  1.8 (0.9, 3.7)  -  -
Prior, self-resolving episodes of
joint swelling		  0.5 (0.3, 1.1)  -  -
Continuous joint symptoms for at
least 6 weeks		  13.9 (4.0, 48.6)  9.4 (2.5, 34.7)  8.0 (2.0, 31.9)
Severe phenotype2  0.2 (0.1, 0.5)  0.4 (0.2, 0.9)  0.4 (0.2, 0.99)
≥9 bands on Western blot  1.2 (0.6, 2.5)  -  -
2 or more active joints  0.1 (0.03, 0.5)  -  -
Arthritis limited to knee(s)  5.6 (1.7, 18.9)  5.1 (1.4, 19.2)  4.9 (1.3, 19.4)
Premature IAGC injection  3.9 (0.5, 28.4)  -  -
Clinical features within first 6
weeks after treatment initiation
Clinical worsening on treatment3  5.0 (1.9, 13.1)  4.2 (1.4, 12.6)  4.5 (1.4, 14.2)
Features of spondyloarthritis4  1.9 (0.2, 21.5)  -  -
Presence of chronic joint changes5  0.5 (0.2, 1.3)  -  -
Exploratory treatment
characteristics
Dose of first antibiotic course too
low6 		 4.0 (1.2, 14.6)  -  7.3 (1.4, 37.3)
Documented treatment non-
adherence7 		 4.0 (0.8, 20.2)  -  2.4 (1.1, 5.3)

ARLA, antibiotic-refractory Lyme arthritis; CI, confidence interval; IAGC, intra-articular glucocorticoid; OR, odds ratio

1

Multivariable logistic models including all independent variables shown

2

Unexplained fever, severe pain, hospitalization for severe pain, or measured sedimentation rate ≥40 mm/hr

3

Massive effusion, rupture of joint capsule or popliteal cyst, or symptomatic joint recruitment after antibiotic initiation

4

(1) Presence of inflammatory back pain, enthesitis (tenderness at bony insertions of tendons and ligaments), tendonitis, or dactylitis, or (2) personal history of psoriasis, inflammatory bowel disease, or acute anterior uveitis

5

(1) Flexion contracture greater than 20° or presence of flexion contracture without massive effusion, (2) Muscle atrophy proximal to involved joint, (3) Hypertrophy of (knee) condyles, (4) Joint erosions on imaging

6

Antibiotic dose of first course too low per treatment guidelines(3, 4)

7

Treatment nonadherence defined as reported consumption of fewer than 80% of prescribed antibiotic doses