Participants aged 16–24 were classified as students (103 in 2000; 106 in 2007; 122 in 2014) or non-students (563 in 2000; 462 in 2007; 438 in 2014). The proportion of the sample identified as students increased from 16.2% in 2000, to 20.7% in 2007, and 24.2% in 2014.
At each point in time, the prevalence of CMD was similar in students and non-students and there was little evidence of increases in either group over time (Fig. 1, Supplementary Table 1).
After adjustment for age, sex, socioeconomic factors, and alcohol use, the odds of CMD in students compared to non-students were 0.96 in 2000 (95% CI 0.45, 2.07), 0.78 in 2007 (95% CI 0.38, 1.61), and 1.03 in 2014 (95% CI 0.56, 1.90) (Supplementary Table 2).
In 2000 and 2007 the relationship between student status and CMD was similar for men and women. However, in 2014 an interaction between student status and sex was evident (p = 0.001). In 2014, student status as a predictor of CMD had an adjusted odds ratio (aOR) of 0.40 in men (p = 0.107, 95% CI 0.13, 1.22), but 1.53 in women (p = 0.267 95% CI 0.72, 3.25). Figure 1b shows that the proportion of male students with CMD remained stable over time, while Fig. 1c indicates the rate of CMD in female students may have risen, from 17.7% (95% CI 9.9%, 29.8%) in 2007 to 35.5% (95% CI 26.8%, 45.2%) in 2014. No comparable increase was evident in female non-students, nor in male students or non-students.
An upward trend in lifetime NSSH was evident in both male and female students: from 6.1% (95% CI 2.7%, 13.2%) in 2000 to 10.9% (95% CI 7.8%, 15.0%) in 2014 (Supplementary Fig. 1a). Non-students experienced a similar rise from 5.2% (95% CI 3.5%, 7.7%) in 2000 to 14.6% (95% CI 12.3%, 17.2%) in 2014. Supplementary Fig. 1b shows that the prevalence of having made a suicide attempt consistently appeared lower in students (4.9% [95% CI 2.6%, 9.0%] in 2014) than in non-students (7.9% [95% CI 6.1%, 9.4%]), although confidence intervals were very wide and overlapped. There was little clear evidence of change over time or differences between men and women in suicide attempts.