Limitations
death, ADHD
Although within-individual analyses eliminate selection bias, they do not eliminate protopathic bias. In other words, pharmacological treatments are often discontinued when clinical state has improved and are started when clinical state deteriorates. Therefore, the results may underestimate the putative beneficial effect with treatments, and this may partly explain the poor results for antidepressants, benzodiazepines, and antipsychotics. To control for this bias, we conducted sensitivity analyses by omitting the first 30 days of use, and the results were in line with main analyses. One of the limitations of this study is that we had no information on possibly reduced amphetamine or methamphetamine consumption or total abstinence. In addition, there was no information on the possible effects of withdrawal symptoms or craving of amphetamine or methamphetamine. Thus, we evaluated the effectiveness of different medications by estimating the risk for unfavorable outcomes (hospitalizations or death), as these outcomes represent significant disadvantages and costs for both the individual and society. Another limitation of this study is that we did not know how many of the studied medications were indicated for some specific comorbidity. For example, we do not know whether lisdexamphetamine was used to treat ADHD or (off-label) MAUD. However, the positive findings with lisdexamphetamine were consistent in all studied outcomes, encouraging the conducting of randomized clinical trials in the future.