Spatial clustering of codeine use and its association with depression: a geospatial analysis of nationally representative South African data

Abstract

• We spatially identified geographical clusters of codeine use in South Africa, and investigated onset of depression overtime among depression-free individuals in communities with high concentration of codeine use. • The clusters of codeine use were found to be concentrated in the northern parts of South Africa. • Residing in a community with high concentration codeine use was associated with higher subsequent depression incidence. • Whilst opioid crisis has been believed to be epidemic in the global north particularly USA, it is also taking place in sub-Saharan Africa. There is an alarming trend in sub-Saharan Africa in the use of codeine-containing pharmaceuticals, but its risk of common comorbidities, such as mental health, remains unquantified at a national-level. We investigated the relationship between codeine use and onset of depression in South Africa at a population-level. We used nationally representative panel data from the South Africa National Income Dynamic Study to investigate the relationship between exposure to codeine use in the community (i.e. residing in a codeine hotspot) and onset of depression. Geographical hotspots of codeine use were identified using Kulldorff spatial scan statistic in SaTScan. We quantified depression onset at Wave 5 (year 2017) between individuals residing inside and outside a codeine hotspot who were depression-free at enrolment (Wave 4: 2015) using generalised estimating equation (GEE) regression models. We identified four statistically significant hotspots of codeine use, mostly located at the northern part of the country. Among 13,020 participants who were depression-free at enrolment, residing within a codeine use hotspot was significantly associated with higher subsequent onset of depression (aRR=1.21, 95% CI:1.08-1.44). Data on diagnosis of depressive disorder were not available. South Africa, a resource scarce nation with chronically limited mental health services, is not spared from the global opioid epidemic and its impact on depression. Targeted scale-up access to agonist therapy to effectively treat (opioid) addiction in communities at risk for high exposure to codeine use could reduce the risk of subsequent mental health challenges.