Table 2.

Adjusted Analyses of Alcohol-Positive Drivers Involved in an Injury-Crash, Maryland, 2001–2013 (Model 1)

Alcohol-positive drivers by age group	Rates and RRsa	95% CI	p-value change of trend
All b
Pre-trendc	0.998***	0.997, 0.999	0.03*
Post-trendd	0.993***	0.988, 0.998
Immediate effect of alcohol tax	1.007	0.910, 1.110	—
15–20 years e
Pre-trend	0.993***	0.993, 0.994	0.007**
Post-trend	0.983***	0.976, 0.991
Immediate effect of alcohol tax	0.943	0.789, 1.128	—
21–34 years b
Pre-trend	1.000	0.999, 1.001	< 0.001***
Post-trend	0.990***	0.986, 0.994
Immediate effect of alcohol tax	1.015	0.934, 1.103	—
35–54 years f
Linear trendg	0.998***	0.997, 0.999	0.96
Immediate effect of alcohol tax	0.980	0.893, 1.087	—
≥ 55 years e
Pre-trend	0.996***	0.996, 0.997	< 0.001***
Post-trend	1.000	0.998, 1.002
Immediate effect of alcohol tax	1.102***	1.043, 1.164	—

Note: Boldface indicates statistical significance (^*p < 0.05, ^**p < 0.01, ^***p < 0.001).

^aStatistical analysis based on generalized estimating equation models with autoregressive covariance matrix with log population as offset.

^bModel adjusted for quarters 1–4, unemployment, and sales tax 2008.

^cPre-trend: from January 2001 to July 2011.

^dPost-trend: from August 2011 to December 2013.

^eModel adjusted for unemployment and quarters 1–4.

^fModel adjusted for quarters 1–4 unemployment, and sales tax 2008.

^gLinear trend assumes one continuous linear trend across study period as no significant difference between pre- and post-intervention trends was found. It can be interpreted as the monthly change in the outcome of interest during the overall study period.

RR, rate ratio.