A call for a systems science approach to understanding drug use in urban environments
Authors: Danielle C Ompad
Journal: The Lancet Global Health (2019)

In The Lancet Global Health, Lindsey Hines and colleagues quantify the association between injecting drug use and development indicators.1Hines LA Trickey A Leung J et al.Associations between national development indicators and the age profile of people who inject drugs: results from a global systematic review and meta-analysis.Lancet Glob Health. 2020; 8: e76-e91Google Scholar The authors found that higher rates of urban population growth were associated with older age at onset of injecting drug use (1·40 years per annual percentage change, 95% CI 0·41–2·40) and lower gross domestic product was associated with a lower median age of people who inject drugs (PWID; 0·13 years per US$1000 GDP increase, 0·06–0·20; p<0·0001) and shorter duration of injecting drug use (0·11 years per $1000 GDP increase, 0·04–0·18; p=0·002). These findings have clear implications for Sustainable Development Goal (SDG) 3, which is aimed at ensuring healthy lives and promoting wellbeing for all at all ages. One of the SDG 3 targets is to strengthen the prevention and treatment of substance abuse. Furthermore, although SDG 11 does not have specific drug use-related targets, these findings also suggest that the urban environment is an important contextual variable for injecting drug use. Moreover, urbanisation is occurring most quickly in low-income and middle-income countries (LMICs); 65·9% of countries with urbanisation rates equal to or higher than the median among urbanising countries (ie, excluding countries that have negative urban growth) in 2015 were also LMICs, suggesting a possible interaction between gross domestic product and urbanisation. Many countries do not report indicators of drug use. Of the 181 countries for which data on age and injecting parameters were extracted by Hines and colleagues, only 108 (60%) had available data for at least one of the drug use indicators (number of PWID, percentage of young PWID, average age of PWID, average age of onset of injecting, or median duration of injecting drug use). To assess the impact of missing data in these analyses, I extracted the 2015 urbanisation data from the World Bank World Development Indicators; urbanisation estimates were missing for Swaziland and Taiwan and estimates from the UK were applied to England, Northern Ireland, Scotland, and Wales because these countries were not disaggregated in the World Bank World Development Indicators. Interestingly, countries without data on injecting drug use onset had significantly higher mean annual urban population growth in 2015 than did those with data (2·3% vs 1·4%, t-test p=0·001). Thus, it is possible that the association between urbanisation and injecting drug use onset was underestimated. Why is faster urbanisation associated with older age at initiation of injecting drug use? The urban health advantage perspective postulates that urbanisation and the development associated with this process can lead to improvements in the health of urban residents.2Vlahov D Galea S Freudenberg N The urban health “advantage”.J Urban Health. 2005; 82: 1-4Google Scholar However, the findings reported by Hines and colleagues suggest a potential urban health penalty3Freudenberg N Galea S Vlahov D Beyond urban penalty and urban sprawl: back to living conditions as the focus of urban health.J Community Health. 2005; 30: 1-11Google Scholar for drug use outcomes among older adults (aged >25 years). Published reviews have examined the pathways between urbanisation and substance use4Morgan N Mall S Pathways between urbanization and harmful substance use.Curr Opin Psychiatry. 2019; 32: 218-223Google Scholar and urban mental health.5Okkels N Kristiansen CB Munk-Jorgensen P Sartorius N Urban mental health: challenges and perspectives.Curr Opin Psychiatry. 2018; 31: 258-264Google Scholar Although most of the substance use studies considered focused on tobacco and alcohol use, some potential parallels can be identified. Urbanisation and modernisation have been implicated in increasing the prevalence of alcohol use disorders.6Yang J Kang C Li J Li P Zhao X A three-decade repeated cross-sectional survey on mental health of the Chinese Jino minority.Aust N Z J Psychiatry. 2017; 51: 1134-1141Google Scholar Financial, environmental, and cultural challenges associated with urban living might result in the need to cope with the resultant stress, depression, or anxiety, and drug use is one possible coping mechanism.4Morgan N Mall S Pathways between urbanization and harmful substance use.Curr Opin Psychiatry. 2019; 32: 218-223Google Scholar, 5Okkels N Kristiansen CB Munk-Jorgensen P Sartorius N Urban mental health: challenges and perspectives.Curr Opin Psychiatry. 2018; 31: 258-264Google Scholar Access to drug prevention, treatment, and harm reduction programmes is poor in many LMICs,7O'Keefe D Stoove M Doyle J Dietze P Hellard M Injecting drug use in low and middle-income countries: opportunities to improve care and prevent harm.J Viral Hepat. 2017; 24: 714-724Google Scholar as a result of a shortage of resources or punitive drug policies. The reasons for the association between urbanisation and injection drug use remain unclear and are likely to be multifactorial. Urbanisation and features of urban environments are known to be associated with drug use outcomes,8Galea S Ahern J Vlahov D Contextual determinants of drug use risk behavior: a theoretic framework.J Urban Health. 2003; 80: iii50-iii58Google Scholar but the mechanisms by which this association occurs have not been fully elucidated. The urban health conceptual framework postulated by Galea and colleagues9Galea S Freudenberg N Vlahov D Cities and population health.Soc Sci Med. 2005; 60: 1017-1033Google Scholar is a useful guide for understanding urban environments, and recent conceptualisations with regard to the urban environment describe the urban context as a series of interrelated, complex, and dynamic systems that can shape human health.10Ompad DC Tozan Y A systems science approach to urban health.in: Galea S Ettman CK Vlahov D Urban Health. Oxford University Press, New York2019: 179-187Google Scholar Three key features of the urban environment have been described (the physical environment, the social environment, and the resource infrastructure), which are influenced by the prevailing political and economic systems and major global and national trends.9Galea S Freudenberg N Vlahov D Cities and population health.Soc Sci Med. 2005; 60: 1017-1033Google Scholar A systems approach would be valuable for the assessment of these associations, to determine whether causal pathways exist that link urbanisation and urban environments to drug use, and to identify features or processes in urban environments that can be manipulated to prevent injection drug use or reduce the associated harms. I report grants from the National Institute on Drug Abuse of the National Institutes of Health. The views expressed in this Comment are those of the author and do not necessarily represent the official views of the National Institutes of Health. Associations between national development indicators and the age profile of people who inject drugs: results from a global systematic review and meta-analysisVariation in the age profile of PWID was associated with GDP and urbanisation. Regions with the highest prevalence of young PWID (aged ≤25 years) had low coverage of interventions to prevent the spread of blood-borne viruses. Data quality highlights the need for improvements in monitoring of PWID populations. Full-Text PDF Open Access