medwireNews: Reasons for ethnic disparities in statin prescribing in UK residents with type 2 diabetes are not clear, but may result in preventable atherosclerotic cardiovascular disease (ASCVD) events, research suggests.
“By equalising statin initiation rates between people of South Asian or African/African Caribbean ethnicity and those of European ethnicity, up to an additional 12,600 ASCVD events in people with type 2 diabetes could be prevented,” say Sophie Eastwood (University College London, UK) and study co-authors.
They note this estimate is “likely to be conservative,” because it was based on reported ASCVD risk reductions in clinical trials with 4–5 years of follow-up, rather than on lifetime risk.
“Therefore, further research must urgently seek explanations for underprescribing of statins, particularly in African/African Caribbean people,” they write in PLOS Medicine.
The team used the UK’s Clinical Practice Research Datalink to identify 31,093 people who had type 2 diabetes and were not taking a statin but were eligible to do so, of whom 27,511 (88%) were of European ethnicity, 2386 (8%) of South Asian ethnicity, and 1142 (4%) people of African or African–Caribbean ethnicity.
During a median follow-up of 0.7 years, 68% of the European study participants started taking a statin, compared with 62% of the South Asian people and 53% of the African/Afro-Caribbean group, giving rates per 1000 person–years of 0.40, 0.36, and 0.24, respectively.
South Asian and African/Afro-Caribbean people had significant 12% and 33% reductions in the likelihood of receiving a statin, compared with those of European descent, independent of age and sex, and the time to statin initiation was longer for the ethnic minority groups.
The only baseline factor to notably influence the size of these relationships was the ratio of total to high-density lipoprotein cholesterol; adjusting for this attenuated the reductions to a still significant 7% and 23%, respectively.
By contrast, adjusting for deprivation, smoking, healthcare usage, BMI, comorbidities, polypharmacy, and antihypertensive use had no effect.
“Therefore, some of the underprescription may have resulted from primary care physicians making prescribing decisions based on cholesterol value alone, rather than considering overall ASCVD risk, especially in the pre-2014 era of treating to cholesterol targets in diabetes,” say Eastwood and team.
However, they stress that ethnic differences in statin prescription remained after accounting for lipid levels, and that “marked underprescription” existed even for African/Afro-Caribbean people with high ratios of total to high-density lipoprotein cholesterol.
The ethnic minority underprescription effect was less marked in London healthcare practices than in others, with South Asians as likely to receive statins as Europeans, although there remained a 13% reduced likelihood for African/Afro-Caribbean people.
The researchers noted that they could rarely distinguish between people not offered a statin and those who declined one, “so it is impossible to pinpoint exact reasons for underprescribing.”
They suggest that any practitioner-driven underprescribing could be partly because of “inadequate knowledge of ethnic differences in ASCVD risk (e.g., that whilst African/African Caribbean people have lower risk of coronary disease, their risk of stroke far surpasses that of Europeans, regardless of cholesterol levels.”
Indeed, the team notes that the ethnic disparities in statin prescription became less marked during the most recent years of the study (2014–2019), which could reflect improvements in healthcare provider knowledge.
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