Table 2.

Relative Risk and 95% Confidence Intervals of Emergent Kidney Stone Presentations Cumulated over 10 days Following Daily Maximum Wet-Bulb Temperatures at the 99th Percentile Compared to 10 °C (Overall), Moderate Temperatures, and Extreme Temperatures.

Characteristics		Overall		Interaction p-value*	Moderate temperatures		Extreme temperatures
		RR	95% CI		RR	95% CI	RR	95% CI
Total		1.48	1.37, 1.60		1.35	1.27, 1.44	1.09	1.04,1.14
Sex	Male	1.73	1.56, 1.91	<0.001	1.54	1.42, 1.67	1.12	1.06, 1.19
	Female	1.15	1.01, 1.32		1.09	0.99, 1.21	1.05	0.98, 1.14
Age	≤ 65 years	1.5	1.38, 1.63	0.067	1.35	1.26, 1.44	1.11	1.06, 1.17
	> 65 years	1.35	1.07, 1.71		1.37	1.15, 1.64	0.99	0.87, 1.12
Race	White	1.48	1.35, 1.61	0.199	1.37	1.28, 1.46	1.08	1.03, 1.14
	African-American	1.36	1.09, 1.69		1.21	1.02, 1.44	1.12	0.99, 1.26
Payer category	Public	1.42	1.27, 1.58	0.714	1.33	1.22, 1.44	1.07	1, 1.14
	Private	1.39	1.18, 1.63		1.31	1.15, 1.48	1.06	0.97, 1.16
Climatic area	Warm	1.45	1.29, 1.63	0.695	1.39	1.28, 1.51	1.05	0.97, 1.12
	Cold	1.46	1.3, 1.64		1.29	1.17, 1.42	1.13	1.07, 1.2

Moderate temperatures were defined as the 90th percentile of daily maximum wet-bulb temperature with 10 °C as reference. Extreme temperatures were defined as the 99th percentile of daily maximum wet-bulb temperature with the 90th percentile as reference. The exposure-response relationship was modeled through a cross-basis term, with a natural cubic spline with 2 internal knots placed at the 50^th and 90^th percentile of the temperature indicator for the exposure-response function, and a natural cubic spline with intercept and 2 internal knots equally-spaced in the log scale in the lag dimension.

^*P-value of the test for interaction between levels of characteristics in the overall estimates.