AbstractBackgroundDihydropiridine calcium channel blockers (dCCB) (e.g. amlodipine) are widely used for treating hypertension. Pharmacogenetic variants impact treatment efficacy, yet evidence on clinical outcomes in routine primary care is limited. We aimed to estimate associations between reported pharmacogenetic variants and incident adverse events in a community-based cohort prescribed dCCB, including in high-risk subgroups.MethodsWe analysed up to 32,360 UK Biobank European-ancestry participants prescribed dCCB in primary care electronic health records (from UK General Practices, 1990 to 2017). We investigated 23 genetic variants in 16 genes reported in PharmGKB, including CYP3A5 and RYR3. Outcomes were incident diagnosis of coronary heart disease (CHD), heart failure (HF), chronic kidney disease (CKD), edema, and switching antihypertensive medication. Secondary analysis in patients with history of heart disease was also performed.ResultsParticipants were aged 40 to 79 years at first dihydropyridine prescription (treatment duration 1 month to 40 years, mean 5.9 years). Carriers of rs877087 T allele in the ryanodine receptor 3 (RYR3) had increased risk of HF (Hazard Ratio 1.13: 95% Confidence Intervals 1.02 to 1.25, p=0.02). We estimated that if rs877087 T allele carriers were prescribed an alternative treatment the incidence of HF in patients prescribed dCCB would reduce by 9.2% (95%CI 3.1 to 15.4). In patients with a history of heart disease when first prescribed dCCB (N=2,296), RYR3 rs877087 homozygotes had increased risk of new CHD or HF compared to CC variant (HR 1.25, 95%CI 1.09 to 1.44, p=0.002). Two variants increased likelihood of switching to an alternate antihypertensive medication (rs10898815 in gene NUMA1 HR 1.16: 95%CI 1.07 to 1,27, p=0.0009; rs776746 in CYP3A5 HR 1.59: 95%CI 1.09 to 2.32, p=0.02). rs776746 in CYP3A5 also increased CKD risk (HR 2.12, p=0.002). The remaining previously reported variants were not strongly or consistently associated with the studied clinical outcomes.ConclusionsIn this large primary care cohort, patients with common genetic variants in NUMA1, CYP3A5 and RYR3 had increased adverse clinical outcomes. Work is needed to establish whether outcomes of dCCB prescribing could be improved by prior knowledge of such pharmacogenetics variants supported by clinical evidence of association with adverse events.

AbstractBackgroundCalcium channel blockers (CCBs) are common antihypertensive medications. Pharmacogenetic variants affect CCB clinical outcomes, although effect sizes are modest in community samples. Variation in patient characteristics may also predict CCB outcomes, and variation attributable to relevant polygenic scores is less prone to confounding. We aimed to test associations between genetically predicted patient characteristics plus pharmacogenetic variants with CCB outcomes in a large community cohort.MethodsWe extended our analysis of 32,000 UK Biobank dihydropiridine CCBs treated participants (mean duration 5.9 years) testing 23 variants, whereNUMA1rs10898815 andRYR3rs877087 showed the most robust associations (for discontinuation and heart failure, respectively). We calculated polygenic scores for systolic and diastolic blood pressures (SBP and DBP), body fat mass, waist hip ratio, lean mass, serum calcium, eGFR, lipoprotein A, urinary sodium, and liver fibrosis. Outcomes were CCB discontinuation, heart failure, coronary heart disease and chronic kidney disease.ResultsFor heart failure, the highest risk 20% of polygenic scores for fat mass, lean mass and lipoprotein a were associated with increased risks (Hazard-Ratio (HR)Fat-mass 1.46, 95% CI 1.25-1.70, p=1*10-6; HRLean-mass 1.20, 95%CI 1.04-1.38, p=0.01; HRLipoproteinA 1.29, 95% CI 1.12 to 1.48, p= 4*10-4), versus the lowest risk 20% of each score respectively. Across the cohort,RYR3T-allele modestly increased heart failure risks (HR 1.13: 1.02-1.25) versus non-carriers, but in subsets with high fat mass, lean mass, and lipoprotein a scores, estimates were substantially larger, e.g. in females aged 65-70 the heart failure Relative Risk was 4.4 (95% CI 1.54-12.4) versus no T-alleles and low scores.For CCB discontinuation, high polygenic scores for fat mass and lean mass increased risks versus the lowest 20%, whereas high SBP and DBP scores decreased discontinuation risks. Hazard ratios for discontinuation with the pharmacogenetic NUMA1 rs10898815 A-allele (overall HR 1.07: 1.02-1.12) were higher (HR 1.17: 1.05-1.29) in those with high polygenic scores for fat mass and lean mass.ConclusionPolygenic scores affecting adiposity and lipoprotein a levels add to known pharmacogenetic variants in predicting key clinical outcomes in CCB treatment. Combining pharmacogenetic variants and relevant individual characteristic polygenic scores may help for personalizing prescribing.What is needed, what do we add?We previously showed that pharmacogenetic variants inRYR3andNUMA1were associated with key clinical outcomes in community CCB patients, although effect sizes were modest. Various patient characteristics reportedly affect CCB outcomes. We therefore tested effects of relevant patient characteristics using polygenic scores. They minimize the effect of unmeasured confounders as genotypes are invariant since conception and reflect lifetime exposure to the risk factor. We showed that combining associated scores with the pharmacogenetic variants improved outcome prediction.

AbstractBackgroundThe antiplatelet drug clopidogrel is commonly prescribed for stroke and myocardial infarction (MI) prevention. Clopidogrel prodrug is predominantly activated by liver enzyme CYP2C19. CYP2C19 Loss-of-function (LoF) genetic variants have been linked to excess morbidity mainly in patients hospitalized for acute ischemic events and related interventions. Little is known about the magnitude of impact of LoF variants in family practice, especially over long periods of exposure. We aimed to determine whether CYP2C19 LoF alleles increase risk of ischemic stroke and MI in primary care patients prescribed clopidogrel for up to 18 years.MethodsRetrospective cohort analysis of 7,483 European-ancestry adults from the UK Biobank study with genetic and linked primary care data, aged 36 to 79 years at first clopidogrel prescription. We examined CYP2C19 LoF variant (*2-*8) associations with incident hospital-diagnosed ischemic stroke and MI in patients prescribed clopidogrel for at least 2 months using time-to-event models, with secondary analysis of the. 17 gain of function variant.Results28.7% (n=2,144/7,483) of included subjects (mean age 63 years at first clopidogrel prescription) carried at least one CYP2C19 intermediate or low metabolizer LoF variant. 1.9% of LoF variant carriers had an incident ischemic stroke whilst prescribed clopidogrel (mean 2.6 years, range 2 months to 18 years), versus 1.3% without the variants (0.6% absolute excess: Hazard Ratio 1.53: 95% CI 1.04 to 2.26, p=0.031). Additionally, 26.4% of CYP2C19 LoF variant carriers had an incident MI versus 24.1% (HR 1.14: 1.04 to 1.26, p=.008). Adjustment for aspirin co-prescription produced similar estimates. In lifetables using observed incidence rates, 22.5% (95% CI 14.4% to 34.0%) of CYP2C19 LoF carriers on clopidogrel were projected to develop an ischemic stroke by age 79 (the oldest age in the study), compared with 15.4% (95% CI 11.4% to 20.5%) in non-carriers: the absolute excess stroke incidence with LoF variants was 7.1% by age 79.ConclusionIn family practice patients on clopidogrel, CYP2C19 LoF variants are associated with substantially higher incidence of ischemic events. Genotype-guided (or routine) prescription of antiplatelet medications unaffected by CYP2C19 variants may improve outcomes in patients for whom clopidogrel is currently indicated.

ABSTRACTObjectiveTo estimate the effect of the SLCO1B1*5 genotype (decreases statin transport) on cholesterol control and treatment duration in male and female primary care patients prescribed common statin medications.Methods and Analysis69,185 European-ancestry UK Biobank cohort participants prescribed simvastatin or atorvastatin (aged 40 to 79 years at first prescription; treatment duration 1 month to 29 years, mean 5.7 years). Principal outcomes were clinically high total cholesterol (>5mmol/L) at baseline, plus treatment discontinuation.Results48.4% of 591 females homozygous for SLCO1B1*5 decreased function genotype had raised cholesterol, vs. 41.7% of those with functioning SLCO1B1 (Odds Ratio 1.31: 95% Confidence Intervals 1.1 to 1.55, p=0.001). Fewer males had high cholesterol, and the genotype effect was attenuated. In primary care prescribing, females homozygous for SLCO1B1*5 were more likely to stop receiving these statins (29.5%) than women with normal SLCO1B1 (25.7%) (Hazard Ratio 1.19: 95%CI 1.03 to 1.37, p=0.01), amounting to five discontinuations per 100 statin-years in the SLCO1B1*5 group vs four in the normal SLCO1B1 function group. This remained significant after the first year of treatment (HR for discontinuing >1 year after first prescription 1.3: 95%CI 1.08 to 1.56; p=0.006). In men SLCO1B1*5 was only associated with treatment discontinuation in the first year.ConclusionsIn this large community sample of patients on commonly prescribed statins, the SLCO1B1*5 decreased function variant had much larger effects on cholesterol control and treatment duration in women than in men. Efforts to improve effectiveness of statin therapy in women may need to include SLCO1B1*5 genotype-guided statin selection.What is already known about this subjectGenetic variants affecting SLCO1B1 (statin transporter) gene function increase concentrations of unmetabolized statin molecules (mostly simvastatin and atorvastatin). Previous studies of statin-treated patients have reported reduced likelihood of achieving target cholesterol levels plus increased adverse effects and medication non-adherence mainly in the first year of treatment.However, little data have been available on key outcomes over longer follow-ups or on outcomes by sex, despite large differences in statin treatment patterns between men and women.What this study addsIn 69,185 UK Biobank participants reporting simvastatin or atorvastatin use at baseline assessment, substantially more women had clinically high total cholesterol (>5 mmol/L) compared to men (42% vs. 25%). Female carriers of the SLCO1B1*5 (decreased SLCO1B1 function) genetic variant were especially likely to have high cholesterol, despite being on statin treatment.In primary care records of atorvastatin and simvastatin prescribing (>10 years follow-up), female carriers of SLCO1B1*5 were more likely to stop statins. In men, SLCO1B1*5 was only associated with discontinuing statin treatment in the first year after starting treatment.

In this paper we review the methodological underpinnings of the general pharmacogenetic approach for uncovering genetically-driven treatment effect heterogeneity. This typically utilises only individuals who are treated and relies on fairly strong baseline assumptions to estimate what we term the ‘genetically moderated treatment effect’ (GMTE). When these assumptions are seriously violated, we show that a robust but less efficient estimate of the GMTE that incorporates information on the population of untreated individuals can instead be used. In cases of partial violation, we clarify when Mendelian randomization and a modified confounder adjustment method can also yield consistent estimates for the GMTE. A decision framework is then described to decide when a particular estimation strategy is most appropriate and how specific estimators can be combined to further improve efficiency. Triangulation of evidence from different data sources, each with their inherent biases and limitations, is becoming a well established principle for strengthening causal analysis. We call our framework ‘Triangulation WIthin a STudy’ (TWIST)’ in order to emphasise that an analysis in this spirit is also possible within a single data set, using causal estimates that are approximately uncorrelated, but reliant on different sets of assumptions. We illustrate these approaches by re-analysing primary-care-linked UK Biobank data relating to CYP2C19 genetic variants, Clopidogrel use and stroke risk, and data relating to APOE genetic variants, statin use and Coronary Artery Disease.