Table 2.

Final multivariable mixed logistic regression model for canine leptospirosis PCR tests in the United States

Variable	Odds Ratio (95% CI)	p-value
Dog age (years)		< 0.001
0–4	Reference
5–7	0.71 (0.63, 0.80)	< 0.001
8–10	0.48 (0.43, 0.55)	< 0.001
> 10	0.35 (0.30, 0.40)	< 0.001
Dog sex		< 0.001
Female	Reference
Male	1.28 (1.17, 1.40)
Year test performed		< 0.001
2009	Reference
2010	0.63 (0.44, 0.90)	0.012
2011	0.65 (0.46, 0.93)	0.018
2012	1.02 (0.73, 1.41)	0.925
2013	2.08 (1.55, 2.80)	< 0.001
2014	1.93 (1.45, 2.57)	< 0.001
2015	1.45 (1.09, 1.93)	0.010
2016	1.22 (0.91, 1.62)	0.178
Region1		0.0398
Midwest	Reference
Southwest	1.05 (0.68, 1.64)	0.816
West	0.67 (0.47, 0.94)	0.022
Southeast	0.68 (0.51, 0.91)	0.009
Northeast	0.80 (0.59, 1.09)	0.165
State climate division Palmer Drought Severity Index1,2		< 0.001
≤ 0 (dry conditions)	Reference
> 0 (wet conditions)	1.24 (1.10, 1.38)
State climate division precipitation (centimeters)1,2		0.0104
0–2.5	Reference
2.6–7.6	1.30 (1.10, 1.54)	0.002
7.7–12.7	1.32 (1.10, 1.58)	0.003
> 12.7	1.35 (1.10, 1.65)	0.003
Season test performed		< 0.001
Fall	Reference
Winter	0.41 (0.32, 0.54)	< 0.001
Spring	0.18 (0.11, 0.29)	< 0.001
Summer	0.93 (0.73, 1.18)	0.537
State climate division temperature (°C)1,2		< 0.001
≤ 4	Reference
5–13	0.84 (0.65, 1.08)	0.182
14–21	0.61 (0.47, 0.79)	< 0.001
> 21	0.49 (0.35, 0.68)	< 0.001
Interaction between season test performed and state climate division temperature (°C)3		< 0.001

Final model includes data from 2009 through 2016.

¹Location based on veterinary facility that submitted sample for testing

²Climate data for month and year test was performed

³Stratum-specific odds ratios not reported