Fig. 4From: Positive drug test trends in fatally-injured drivers in the United States from 2007 to 2017Trend in yearly prevalence in alcohol test result among drug-positive drivers who died within 1 h of crashing. Cochran–Armitage tests were used to assess the statistical significance of changes in the percentage of alcohol involvement in drug tested positive fatally-injured drivers over time (Alcohol+: Z = 7.5, p < 0.001; Alcohol-: Z = -6.6, p < 0.001; Alcohol test unknown: Z = -3.9, p < 0.001)Back to article page