Determinants of lipid clinic referral and attendance in a multi-ethnic adult population in south London: a cross-sectional study.

BACKGROUND

Primary dyslipidaemias, including familial hypercholesterolaemia, are underdiagnosed genetic disorders that substantially increase risk for premature coronary artery disease in adults. Early identification of primary dyslipidaemias via lipid clinic referral optimises patient management and enables cascade screening of relatives. Improving the identification of primary dyslipidaemias, and understanding disparities in ascertainment and management, is an NHS priority. We aimed to assess determinants of lipid clinic referral or attendance (LCR) in ethnically diverse adults.

METHODS

We did a retrospective cross-sectional study using the Lambeth DataNet containing anonymised data from 41 general practitioner (GP) practices in south London. We looked at referral data for adult patients aged 18 years and older from Jan 1, 1995, until May 14, 2018. LCR was the main outcome. We used sequential multilevel logistic regression models adjusted for practice effects to estimate the odds of LCR assessed across six ethnic groups (reference group White) and patient-level factors (demographic, socioeconomic, lifestyle, comorbidities, total cholesterol [TC] >7·5mmol/L, statin prescription, and practice factors). The study was approved by NHS South East London Clinical Commissioning Group (CCG) and NHS Lambeth CCG.

FINDINGS

780 (0·23%) of 332 357 adult patients were coded as referred (n=538) or seen (n=252) in a lipid clinic. 164 487 (46·49%) were women (appendix). The fully adjusted model for odds of LCR showed the following significant associations for age (odds ratio [OR] 0·96, 95% CI 0·96-0·97, p<0·001); Black, African, Caribbean, or Black-British ethnicity (0·67, 0·53-0·84, p=0·001); ex-smoker status (1·29, 1·05-1·57, p=0·014); TC higher than 7·5 mmol/L (12·18, 9·60-15·45, p<0·001); statin prescription (14·01, 10·85-18·10, p<0·001); diabetes (0·72, 0·58-0·91, p=0·005); high-frequency GP attendance at seven or more GP consultations in the past year (1·49, 1·21-1·84, p<0·001); high GP-density (0·5-0·99 full-time equivalent GPs per 1000 patients; 2·70, 1·23-5·92, p=0·013). Sensitivity analyses for LCR restricted to familial hypercholesterolaemia-coded patients (n=581) found associations with TC higher than 7·5 mmol/L (4·26, 1·89-9·62, p<0·001), statin prescription (16·96, 2·19-131·36, p=0·007), and high GP-density (5·73, 1·27-25·93, p=0·023), with no significant associations with ethnicity. The relative contribution of GP practices to LCR was 6·32% of the total variance. There were no significant interactions between ethnicity and deprivation, age, or obesity.

INTERPRETATION

While interpretation is limited by the accuracy and completeness of coded records, the study showed factors associated with a higher likelihood of LCR included individuals recorded as having TC higher than 7·5 mmol/L, statin prescription, ex-smoker status, high-frequency GP attendance, and registration at a GP practice with 0·5-0·99 GP density. Patients with increasing age; Black, African, Caribbean, or Black-British ethnicity patients; and patients with diabetes had lower odds of LCR. Finally, the difference in odds of LCR between Black and White patients highlights potential health inequalities.

FUNDING

NHS Race & Health Observatory.