Long-term treatment outcomes – what have we learnt from Hong Kong pharmacoepidemiological studies

Abstract

While placebo-controlled clinical trials are particularly useful in the evaluation of efficacy, they are less helpful in studying adverse events and other realworld outcomes. Studies with large databases are currently the most viable option to monitor rare adverse effects, long-term safety/tolerability and other real-world outcomes of ADHD medications. Whilst observational studies have a range of limitations such as the potential for selection biases, they have a key strength with regards to the potential for large sample sizes and in the richness of the available data. In recent years, several self-controlled methods have been developed such as self-controlled case series. These studies are designed to make comparisons within the same subject during times that they are on and off medication. They have advantages over traditional cohort and case control studies as they remove the effects of time invariant confounders (e.g., genetic influences) and significantly reduce the problem of confounding by indication. This talk will present studies using self-controlled case series method to analyse data from the Clinical Data Analysis and Reporting System (CDARS). CDARS is an electronic database system managed by the Hong Kong Hospital Authority for both audit and research purposes. Our published studies have demonstrated medication-related real world outcomes such as trauma-related emergency room visit [1], without increased risk of psychosis [2] or suicidal attempt [3]. Notwithstanding the methodological challenges, careful analysis of accurately ascertained and linked large-scale data in health care records provide an important avenue of research. Finally, we will also present a study using databases from 14 countries [4] to examine trend of ADHD medication prescribing. References: 1. Man KK, Chan EW, Coghill D et al. Methylphenidate and the risk of trauma. Pediatrics. 2015 Jan;135(1):40-8. doi: 10.1542/peds.2014-1738. Epub 2014 Dec 15. 2. Man KK, Coghill D, Chan EW et al. Methylphenidate and the risk of psychotic disorders and hallucinations in children and adolescents in a large health system. Transl Psychiatry. 2016 Nov 15;6(11):e956. doi: 10.1038/tp.2016.216. 3. Man KKC, Coghill D, Chan EW et al. Association of Risk of Suicide Attempts With Methylphenidate Treatment. JAMA Psychiatry. 2017 Oct 1;74(10):1048-1055. doi: 10.1001/jamapsychiatry.2017.2183. 4. Raman SR, Man KKC, Ip P, et al. Regional, and national trends in attention-deficit/hyperactivity disorder (ADHD) medication use: a multinational study in North America, Europe, Asia and Australia. Lancet Psychiatry In Press 2018.