How differing methods of ascribing ethnicity and socio-economic status affect risk estimates for hospitalisation with infectious disease

Effects of Ethnic Classification on Substantive Findings in Adolescent Mental Health Outcomes

Although most adolescents are healthy, epidemiological studies show that a significant number experience mental health challenges, and that Indigenous and ethnic minority youth tend to have poorer mental health outcomes. However, ethnic classification in adolescence is complex due to increasing multi-ethnic identification, and little is known about how different classification methods affect research conclusions. This study used a nationally representative adolescent sample from Aotearoa New Zealand (N = 8275; ages 12–18; 55% female; 32% multi-ethnic) to investigate the effects that five ethnic classification methods have on substantive findings in three mental health outcomes: overall psychosocial difficulties, deliberate self-harm, and suicide attempts. The results showed that, depending on the classification method used, reported outcomes within the same nominal ethnic group varied by an effect size (d) of up to 0.12, and the reported magnitude of difference between nominal ethnic groups varied by an effect size (d) of up to 0.25. These effects are substantial given that they are solely due to a change in method. The impact that ethnic classification method has on substantive findings highlights the importance of criticality and transparency in research involving ethnicity data.

Complex differences in infection rates between ethnic groups in Scotland: a retrospective, national census-linked cohort study of 1.65 million cases

BACKGROUND

Ethnicity can influence susceptibility to infection, as COVID-19 has shown. Few countries have systematically investigated ethnic variations in infection.

METHODS

We linked the Scotland 2001 Census, including ethnic group, to national databases of hospitalizations/deaths and serological diagnoses of bloodborne viruses for 2001-2013. We calculated age-adjusted rate ratios (RRs) in 12 ethnic groups for all infections combined, 15 infection categories, and human immunodeficiency virus (HIV), hepatitis B (HBV) and hepatitis C (HCV) viruses.

RESULTS

We analysed over 1.65 million infection-related hospitalisations/deaths. Compared with White Scottish, RRs for all infections combined were 0.8 or lower for Other White British, Other White and Chinese males and females, and 1.2-1.4 for Pakistani and African males and females. Adjustment for socioeconomic status or birthplace had little effect. RRs for specific infection categories followed similar patterns with striking exceptions. For HIV, RRs were 136 in African females and 14 in males; for HBV, 125 in Chinese females and 59 in males, 55 in African females and 24 in males; and for HCV, 2.3-3.1 in Pakistanis and Africans.

CONCLUSIONS

Ethnic differences were found in overall rates and many infection categories, suggesting multiple causative pathways. We recommend census linkage as a powerful method for studying the disproportionate impact of COVID-19.